Ceratopsians

@article{colbert1948evolution,
    author = "Colbert, Edwin H.",
    title = "EVOLUTION OF THE HORNED DINOSAURS",
    year = "1948",
    journal = "Evolution",
    url = "https://doi.org/10.1111/j.1558-5646.1948.tb02737.x",
    doi = "10.1111/j.1558-5646.1948.tb02737.x",
    number = "2",
    openalex = "W2313943141",
    pages = "145-163",
    volume = "2",
    references = "doi101111j174966321940tb57047x, doi101111j216409471940tb00068x, doi1023071375443, doi102475ajss425149387, doi105281zenodo18028696, doi105479si0096380155226097, doi105962bhltitle102117, doi105962bhltitle5716, openalexw2591879035, openalexw568618627"
}

@misc{colbert1948evolution1,
    author = "Colbert, E. H",
    title = "Evolution of the horned dinosaurs",
    year = "1948",
    howpublished = "Evolution, v. 2, p. 145-163",
    note = "talkorigins\_source = {true}; raw\_reference = {Colbert, E. H., 1948, Evolution of the horned dinosaurs: Evolution, v. 2, p. 145-163.}"
}

@article{openalexw150710194,
    author = "Colbert, Edwin H.",
    title = "Evolutionary growth rates in the dinosaurs.",
    year = "1949",
    journal = "PubMed",
    openalex = "W150710194"
}

Journal Article FUNCTIONAL MORPHOLOGY AND EVOLUTION OF THE CERATOPSIAN DINOSAURS Get access John H. Ostrom John H. Ostrom Peabody Museum of Natural History Department of Geology Yale University Search for other works by this author on: Oxford Academic Google Scholar Evolution, Volume 20, Issue 3, 1 September 1966, Pages 290–308, https://doi.org/10.1111/j.1558-5646.1966.tb03367.x Published: 01 September 1966 Article history Accepted: 30 March 1966 Published: 01 September 1966

@article{doi101111j155856461966tb03367x,
    author = "Ostrom, John H.",
    title = "FUNCTIONAL MORPHOLOGY AND EVOLUTION OF THE CERATOPSIAN DINOSAURS",
    year = "1966",
    journal = "Evolution",
    abstract = "Journal Article FUNCTIONAL MORPHOLOGY AND EVOLUTION OF THE CERATOPSIAN DINOSAURS Get access John H. Ostrom John H. Ostrom Peabody Museum of Natural History Department of Geology Yale University Search for other works by this author on: Oxford Academic Google Scholar Evolution, Volume 20, Issue 3, 1 September 1966, Pages 290–308, https://doi.org/10.1111/j.1558-5646.1966.tb03367.x Published: 01 September 1966 Article history Accepted: 30 March 1966 Published: 01 September 1966",
    url = "https://doi.org/10.1111/j.1558-5646.1966.tb03367.x",
    doi = "10.1111/j.1558-5646.1966.tb03367.x",
    openalex = "W2314234887",
    references = "colbert1948evolution, doi102475ajs2477492, doi102475ajss425149387, doi104095105052, doi104095105056, doi104095105057, doi105281zenodo15892419, doi105962bhltitle5716, openalexw150710194"
}

Hornlike organs evolved independently in a number of mammalian families. Though these organs assumed great diversity they did evolve into several general functional types. A short review of the structure and development of hornlike organs is given. Some views on horn function and evolution are critically discussed. The evolution of hornlike organs is visualised as follows: In primitive large mammals the head blow became effective as a fighting form due to increased mass and inertia of the heads. Some forms grasped this potential. Combats were carried out from the broadside while opponents delivered head blows on each others body. Skull protuberances now became adaptive. Concurrently, defensive mechanisms evolve, decreasing the effectiveness of these protuberances. Foremost among them is a thick, heavy hide or specialised dermal shield. These adaptive syndromes gave no impetus towards larger and more complex horns. This impetus arose with the appearance of a new method of defense - catching the opponent's blows with the horned head. This leads to the evolution of heavy skulls and horns capable of catching and holding the opponent's head. The target area of attack remained the body. Frontal engagements resulted from the opponents' attempts to control each others horned head. It is shown that bovids and suids followed similar evolutionary roads in their mode of combat. The tusks of the suidae fulfill the same function and were subject to similar selection as the horns of short horned bovids. Thus Sus and Oreaisinos, and Bos and Phacochoerus are entirely similar in their mode of combat, hornlike organs and defense mechanisms. The primitive frontal engagement gave rise to two different modes of combat, ramming and wrestling. The wrestlers evolved complex horns, whose function is to bind opponents together, thus allowing them to develop full strength wrestling and pushing matches. The rammers evolved a heavy skull and heavy horns. A trend towards cephalisation of display organs can be detected in ruminants and suids. Display organs are interpreted as attention guiding adaptations. It is shown that the distribution of display organs correlates with the display. A broadside body display is found in ruminants with a diffuse distribution of display organs. If display organs are cephalised, the broadside display disappears. This is found in the North American wild sheep. Display centers about one heavy, very large horns of males. Next it is verified that the rams horns are display organs. It is shown, the horn display is the prerogative of the dominant; sheep can differentiate horn size classes; large horned males enjoy reproductive advantage; horn size carries a priori dominance status. Hence horns evolved to function as weapons inflicting damage; as defense organs shielding their owner; as binding organs allowing opponents a secure lock in battle; as display organs having an a priori intimidating effect on certain conspecifics. Some species of ruminants possess hornlike organs which change progressively in size with the age of their owner. It is postulated that, as in North American wild sheep, horn size parallels dominance order. Conspecifics learn to associate horn size and agonistic potential of opponents. Hence horn size signals to conspecifics predictable social relationships. In large cervids from temperate and cold climates this system must save stored energy during the rut, which males need for the severe winter. Graded horn sizes allow wild sheep to live in an open society in which strange individuals may meet and fit into the dominance hierarchy with a minimum of combat. Graded horn sizes hence serve as rank indicators. It is next made plausible that territories in ruminants function in conjunction with displaying males as rank indicators. Outside the territories males mix freely. Hence graded horn sizes and territoriality may enable open societies, by acting as communication mechanisms and creating a predictable, social environment. A hypothesis is presented explaining the selective forces for the evolution of display. It predicts that, antagonistic selection forces shape display and display-organs, that a potential exists for rapid spread in a population of differences in behaviour and morphology, that intimidation mechanisms evolved for all sensory pathways, that external appearance af animals changes more repidly than their primary adaptations.

@article{doi101163156853966x00155,
    author = "Geist, Valerius",
    title = "The Evolution of Horn-Like Organs",
    year = "1966",
    journal = "Behaviour",
    abstract = "Hornlike organs evolved independently in a number of mammalian families. Though these organs assumed great diversity they did evolve into several general functional types. A short review of the structure and development of hornlike organs is given. Some views on horn function and evolution are critically discussed. The evolution of hornlike organs is visualised as follows: In primitive large mammals the head blow became effective as a fighting form due to increased mass and inertia of the heads. Some forms grasped this potential. Combats were carried out from the broadside while opponents delivered head blows on each others body. Skull protuberances now became adaptive. Concurrently, defensive mechanisms evolve, decreasing the effectiveness of these protuberances. Foremost among them is a thick, heavy hide or specialised dermal shield. These adaptive syndromes gave no impetus towards larger and more complex horns. This impetus arose with the appearance of a new method of defense - catching the opponent's blows with the horned head. This leads to the evolution of heavy skulls and horns capable of catching and holding the opponent's head. The target area of attack remained the body. Frontal engagements resulted from the opponents' attempts to control each others horned head. It is shown that bovids and suids followed similar evolutionary roads in their mode of combat. The tusks of the suidae fulfill the same function and were subject to similar selection as the horns of short horned bovids. Thus Sus and Oreaisinos, and Bos and Phacochoerus are entirely similar in their mode of combat, hornlike organs and defense mechanisms. The primitive frontal engagement gave rise to two different modes of combat, ramming and wrestling. The wrestlers evolved complex horns, whose function is to bind opponents together, thus allowing them to develop full strength wrestling and pushing matches. The rammers evolved a heavy skull and heavy horns. A trend towards cephalisation of display organs can be detected in ruminants and suids. Display organs are interpreted as attention guiding adaptations. It is shown that the distribution of display organs correlates with the display. A broadside body display is found in ruminants with a diffuse distribution of display organs. If display organs are cephalised, the broadside display disappears. This is found in the North American wild sheep. Display centers about one heavy, very large horns of males. Next it is verified that the rams horns are display organs. It is shown, the horn display is the prerogative of the dominant; sheep can differentiate horn size classes; large horned males enjoy reproductive advantage; horn size carries a priori dominance status. Hence horns evolved to function as weapons inflicting damage; as defense organs shielding their owner; as binding organs allowing opponents a secure lock in battle; as display organs having an a priori intimidating effect on certain conspecifics. Some species of ruminants possess hornlike organs which change progressively in size with the age of their owner. It is postulated that, as in North American wild sheep, horn size parallels dominance order. Conspecifics learn to associate horn size and agonistic potential of opponents. Hence horn size signals to conspecifics predictable social relationships. In large cervids from temperate and cold climates this system must save stored energy during the rut, which males need for the severe winter. Graded horn sizes allow wild sheep to live in an open society in which strange individuals may meet and fit into the dominance hierarchy with a minimum of combat. Graded horn sizes hence serve as rank indicators. It is next made plausible that territories in ruminants function in conjunction with displaying males as rank indicators. Outside the territories males mix freely. Hence graded horn sizes and territoriality may enable open societies, by acting as communication mechanisms and creating a predictable, social environment. A hypothesis is presented explaining the selective forces for the evolution of display. It predicts that, antagonistic selection forces shape display and display-organs, that a potential exists for rapid spread in a population of differences in behaviour and morphology, that intimidation mechanisms evolved for all sensory pathways, that external appearance af animals changes more repidly than their primary adaptations.",
    url = "https://doi.org/10.1163/156853966x00155",
    doi = "10.1163/156853966x00155",
    openalex = "W2044070101",
    references = "openalexw659460302"
}

@article{coombs1980juvenile,
    author = "Coombs, Walter P.",
    title = "Juvenile ceratopsians from Mongolia—the smallest known dinosaur specimens",
    year = "1980",
    journal = "Nature",
    url = "https://doi.org/10.1038/283380a0",
    doi = "10.1038/283380a0",
    number = "5745",
    pages = "380-381",
    volume = "283"
}

@misc{edwords1982the2,
    author = "Edwords, F",
    title = "The dilemma of the horned dinosaurs",
    year = "1982",
    howpublished = "Creation/Evolution, v. 3, p. 1-11",
    note = "talkorigins\_source = {true}; raw\_reference = {Edwords, F., 1982, The dilemma of the horned dinosaurs: Creation/Evolution, v. 3, p. 1-11.}"
}

@article{doi101038358059a0,
    author = "Horner, John R. and Varricchio, David J. and Goodwin, Mark B.",
    title = "Marine transgressions and the evolution of Cretaceous dinosaurs",
    year = "1992",
    journal = "Nature",
    url = "https://doi.org/10.1038/358059a0",
    doi = "10.1038/358059a0",
    openalex = "W2002331232",
    references = "doi101017s0094837300011374, doi101111j216409471954tb01172x, doi101139e89118, doi1023073037993"
}

ABSTRACT Two new ceratopsid dinosaurs, Einiosaurus procurvicornis and Achelousaurus horneri, are described from the Two Medicine Formation (Upper Cretaceous) of Montana. E. procurvicornis is known from three skulls and numerous cranial and postcranial elements from two bonebed assemblages. A. horneri is based on three skulls, one with associated postcranial elements. A phylogenetic review of the subfamily Centrosaurinae reveals two clades, one containing Centrosaurus and Styracosaurus and the other Pachyrhinosaurus plus the two new taxa from Montana. Diagnostic traits for resolving within-group relationships are found only in the skull roof in association with what appear to be secondary sexual characters, probably the result of sexual selection. In addition to illuminating the pattern of ceratopsian evolution, these taxa suggest an increased rate of evolution that may correlate with the late Campanian transgression of the Bearpaw Sea.

@article{doi10108002724634199510011259,
    author = "Sampson, Scott D.",
    title = "Two new horned dinosaurs from the upper Cretaceous Two Medicine Formation of Montana; with a phylogenetic analysis of the Centrosaurinae (Ornithischia: Ceratopsidae)",
    year = "1995",
    journal = "Journal of Vertebrate Paleontology",
    abstract = "ABSTRACT Two new ceratopsid dinosaurs, Einiosaurus procurvicornis and Achelousaurus horneri, are described from the Two Medicine Formation (Upper Cretaceous) of Montana. E. procurvicornis is known from three skulls and numerous cranial and postcranial elements from two bonebed assemblages. A. horneri is based on three skulls, one with associated postcranial elements. A phylogenetic review of the subfamily Centrosaurinae reveals two clades, one containing Centrosaurus and Styracosaurus and the other Pachyrhinosaurus plus the two new taxa from Montana. Diagnostic traits for resolving within-group relationships are found only in the skull roof in association with what appear to be secondary sexual characters, probably the result of sexual selection. In addition to illuminating the pattern of ceratopsian evolution, these taxa suggest an increased rate of evolution that may correlate with the late Campanian transgression of the Bearpaw Sea.",
    url = "https://doi.org/10.1080/02724634.1995.10011259",
    doi = "10.1080/02724634.1995.10011259",
    openalex = "W1977193143",
    references = "doi105479si0096380155226097"
}

@article{padian1996ceratopsians,
    author = "Padian, K.",
    title = "Ceratopsians: The Horned Dinosaurs.",
    year = "1996",
    journal = "Science",
    url = "https://doi.org/10.1126/science.274.5286.367a",
    doi = "10.1126/science.274.5286.367a",
    number = "5286",
    openalex = "W2002279642",
    pages = "367a-367a",
    volume = "274"
}

@article{crossref1997the,
    title = "The horned dinosaurs: a natural history",
    year = "1997",
    journal = "Choice Reviews Online",
    url = "https://doi.org/10.5860/choice.34-3871",
    doi = "10.5860/choice.34-3871",
    number = "07",
    openalex = "W4206114810",
    pages = "34-3871-34-3871",
    volume = "34"
}

▪ Abstract Phylogenetic studies and new fossil evidence have yielded fundamental insights into the pattern and timing of dinosaur evolution and the emergence of functionally modern birds. The dinosaurian radiation began in the Middle Triassic, significantly predating the global dominance of dinosaurs by the end of the period. The phylogenetic history of ornithischian and saurischian dinosaurs reveals evolutionary trends such as increasing body size. Adaptations to herbivory in dinosaurs were not tightly correlated with marked floral replacements. Dinosaurian biogeography during the era of continental breakup principally involved dispersal and regional extinction.

@article{doi101146annurevearth251435,
    author = "Sereno, Paul C.",
    title = "THE ORIGIN AND EVOLUTION OF DINOSAURS",
    year = "1997",
    journal = "Annual Review of Earth and Planetary Sciences",
    abstract = "▪ Abstract Phylogenetic studies and new fossil evidence have yielded fundamental insights into the pattern and timing of dinosaur evolution and the emergence of functionally modern birds. The dinosaurian radiation began in the Middle Triassic, significantly predating the global dominance of dinosaurs by the end of the period. The phylogenetic history of ornithischian and saurischian dinosaurs reveals evolutionary trends such as increasing body size. Adaptations to herbivory in dinosaurs were not tightly correlated with marked floral replacements. Dinosaurian biogeography during the era of continental breakup principally involved dispersal and regional extinction.",
    url = "https://doi.org/10.1146/annurev.earth.25.1.435",
    doi = "10.1146/annurev.earth.25.1.435",
    openalex = "W2081551955",
    references = "coria1995a, crossref1976allosaurus, doi101007bf02986571, doi1010160031018272900491, doi1010160195667191900155, doi101017cbo9780511608377010, doi101017cbo9780511608551, doi101017cbo9781139167826, doi101017s0022336000026706, doi101017s0094837300004310, doi101038248168a0, doi101038274661a0, doi101038292051a0, doi101038378774a0, doi10108002724634199010011815, doi10108002724634199110011386, doi10108002724634199110011426, doi10108002724634199210011473, doi10108002724634199410011523, doi10108002724634199410011524, doi101111j109583121965tb00944x, doi101111j109583121976tb00244x, doi101111j109600311988tb00514x, doi101111j155856461996tb04496x, doi101111j174966321940tb57047x, doi101111j216409471940tb00068x, doi101126science24348951145, doi101126science2725264986, doi101139e93176, doi101139e93179, doi101139e93187, doi101146annureven10010165000525, doi101353book34649, doi1023071441916, doi105281zenodo16171435, doi105479si03629236110i, doi105860choice331556, doi105962bhltitle5716, doi105962p226819, galton1977onstaurikosaums, gregor1988the, openalexw1574544995, openalexw2310875238, openalexw2788234611, parrish1987late, rowe1989a"
}

A data-matrix of 205 osteological characters for 26 sauropod taxa is subjected to cladistic analysis. Two most parsimonious trees are produced, differing only in the relationships between Euhelopu, Onieisaurus and Mamenchisaurus. The monophyly of the Euhelopodidae (including Shunosaurus) is supported by seven synapomorphies. The Cetiosauridae (Patagosaurus, Cetiosaurus and Hafilocanthosaurusj is paraphyletic with respect to the Neosauropoda. The latter clade divides into two major radiations-the 'Brachiosauria' (Camarasaurus, brachiosaurids and titanosauroids), and the Diplodocoidea (nemegtosaurids, dicraeosaurids, diplodocids and Rebbachisaurus). Further evidence for the inclusion of Opisthocoeluaudia in the Titanosauroidea is presented. Phuwiangosaurus, a problematic sauropod from Thailand, may represent one of the most plesiomorphic titanosauroids. 'Peg'-like teeth have evolved at least twice within the Sauropoda. The postspinal lamina, on the neural spines of middle and caudal dorsal vertebrae, represents a neomorph rather than a fusion of pre-existing structures. Forked chevrons may have evolved convergently in the Euhelopodidae and the diplodocid-dicraeosaurid clade, or they may have been acquired early in sauropod evolution and subsequently lost in the 'Brachiosauria'. The strengths and weaknesses of the data-matrix and tree topologies are explored using bootstrapping, decay analysis and randomization tests. Several nodes are only poorly supported, but this seems to reflect the large proportion of missing data in the matrix (-46'/0), rather than an abnormally high level of homoplasy. The results of the randomization tests indicate that the 'data-matrix probably contains a strong phylogenetic 'signal'. The relationships of some forms, such as Haplocanthosaurus, are influenced by the inclusion or exclusion of certain taxa with unusual combinations of character states. Such a result suggests that there are dangers inherent in the view that 'higher' level sauropod phylogeny can be accurately reconstructed using only a small number of well-known taxa.

@article{doi101006zjls19970138,
    author = "Upchurch, Paul",
    title = "The phylogenetic relationships of sauropod dinosaurs",
    year = "1998",
    journal = "Zoological Journal of the Linnean Society",
    abstract = "A data-matrix of 205 osteological characters for 26 sauropod taxa is subjected to cladistic analysis. Two most parsimonious trees are produced, differing only in the relationships between Euhelopu, Onieisaurus and Mamenchisaurus. The monophyly of the Euhelopodidae (including Shunosaurus) is supported by seven synapomorphies. The Cetiosauridae (Patagosaurus, Cetiosaurus and Hafilocanthosaurusj is paraphyletic with respect to the Neosauropoda. The latter clade divides into two major radiations-the 'Brachiosauria' (Camarasaurus, brachiosaurids and titanosauroids), and the Diplodocoidea (nemegtosaurids, dicraeosaurids, diplodocids and Rebbachisaurus). Further evidence for the inclusion of Opisthocoeluaudia in the Titanosauroidea is presented. Phuwiangosaurus, a problematic sauropod from Thailand, may represent one of the most plesiomorphic titanosauroids. 'Peg'-like teeth have evolved at least twice within the Sauropoda. The postspinal lamina, on the neural spines of middle and caudal dorsal vertebrae, represents a neomorph rather than a fusion of pre-existing structures. Forked chevrons may have evolved convergently in the Euhelopodidae and the diplodocid-dicraeosaurid clade, or they may have been acquired early in sauropod evolution and subsequently lost in the 'Brachiosauria'. The strengths and weaknesses of the data-matrix and tree topologies are explored using bootstrapping, decay analysis and randomization tests. Several nodes are only poorly supported, but this seems to reflect the large proportion of missing data in the matrix (-46'/0), rather than an abnormally high level of homoplasy. The results of the randomization tests indicate that the 'data-matrix probably contains a strong phylogenetic 'signal'. The relationships of some forms, such as Haplocanthosaurus, are influenced by the inclusion or exclusion of certain taxa with unusual combinations of character states. Such a result suggests that there are dangers inherent in the view that 'higher' level sauropod phylogeny can be accurately reconstructed using only a small number of well-known taxa.",
    url = "https://doi.org/10.1006/zjls.1997.0138",
    doi = "10.1006/zjls.1997.0138",
    openalex = "W4248246119",
    references = "doi105962bhltitle102117"
}

ABSTRACT Although sauropods played a major role in terrestrial ecosystems during much of the Mesozoic Era, little effort has been directed toward diagnosing Sauropoda and establishing higher-level interrelationships among sauropods. As a consequence, the origin and evolution of major skeletal adaptations in sauropods has remained largely speculative. The cladistic analysis presented here focuses on higher-level relationships among sauropods. Based on 109 characters (32 cranial, 24 axial, 53 appendicular) for 10 sauropod taxa, the most parsimonious arrangement places four genera (Vulcanodon, Shunosaurus, Barapasaurus, and Omeisaurus) as a sequence of sister-taxa to a group of advanced sauropods, defined here as Neosauropoda. Neosauropoda, in turn, is composed of the sister-clades Diplodocoidea and Macronaria; the latter is a new taxon that includes Haplocanthosaurus, Camarasaurus, and Titanosauriformes. Titanosauriformes includes Brachiosauridae and Somphospondyli, a new taxon uniting Euhelopus and Titanosauria. Among macronarians, the position of Haplocanthosaurus is the least stable as a result of the absence of cranial remains. The basic structure of the phylogeny is resilient to various tests and establishes the evolutionary sequence of many functionally significant sauropod adaptations, such as the digitigrade posture of the manus in neosauropods. Other characteristic sauropod adaptations, such as narrow tooth crowns, increases in length and number of cervical vertebrae, and bifid neural spines, are shown to have evolved more than once. As these results underscore, the higher-level phylogeny of sauropods must be based on a broad sampling of character data. The fossil record of sauropods, although relatively limited during the early phase of the radiation (Late Triassic through Early Jurassic), nonetheless indicates that all major clades were established prior to the Late Jurassic, when substantial faunal interchange among major continental regions was still possible. The functional, temporal, and biogeographic implications of the higher-level phylogeny of sauropods are explored.

@article{doi10108002724634199810011115,
    author = "Wilson, Jeffrey A. and Sereno, Paul C.",
    title = "Early Evolution and Higher-Level Phylogeny of Sauropod Dinosaurs",
    year = "1998",
    journal = "Journal of Vertebrate Paleontology",
    abstract = "ABSTRACT Although sauropods played a major role in terrestrial ecosystems during much of the Mesozoic Era, little effort has been directed toward diagnosing Sauropoda and establishing higher-level interrelationships among sauropods. As a consequence, the origin and evolution of major skeletal adaptations in sauropods has remained largely speculative. The cladistic analysis presented here focuses on higher-level relationships among sauropods. Based on 109 characters (32 cranial, 24 axial, 53 appendicular) for 10 sauropod taxa, the most parsimonious arrangement places four genera (Vulcanodon, Shunosaurus, Barapasaurus, and Omeisaurus) as a sequence of sister-taxa to a group of advanced sauropods, defined here as Neosauropoda. Neosauropoda, in turn, is composed of the sister-clades Diplodocoidea and Macronaria; the latter is a new taxon that includes Haplocanthosaurus, Camarasaurus, and Titanosauriformes. Titanosauriformes includes Brachiosauridae and Somphospondyli, a new taxon uniting Euhelopus and Titanosauria. Among macronarians, the position of Haplocanthosaurus is the least stable as a result of the absence of cranial remains. The basic structure of the phylogeny is resilient to various tests and establishes the evolutionary sequence of many functionally significant sauropod adaptations, such as the digitigrade posture of the manus in neosauropods. Other characteristic sauropod adaptations, such as narrow tooth crowns, increases in length and number of cervical vertebrae, and bifid neural spines, are shown to have evolved more than once. As these results underscore, the higher-level phylogeny of sauropods must be based on a broad sampling of character data. The fossil record of sauropods, although relatively limited during the early phase of the radiation (Late Triassic through Early Jurassic), nonetheless indicates that all major clades were established prior to the Late Jurassic, when substantial faunal interchange among major continental regions was still possible. The functional, temporal, and biogeographic implications of the higher-level phylogeny of sauropods are explored.",
    url = "https://doi.org/10.1080/02724634.1998.10011115",
    doi = "10.1080/02724634.1998.10011115",
    openalex = "W1981694118",
    references = "crossref1976allosaurus, doi1010079789400904095, doi101038063003a0, doi101038114085a0, doi10108002724634199110011386, doi10108002724634199410011523, doi10108002724634199410011524, doi10108002724634199710011027, doi101093oxfordjournalsafrafa100309, doi101098rstb19950125, doi101111j109583121965tb00944x, doi101111j109636421985tb00871x, doi101111j150239311985tb00690x, doi101126science2562999, doi101126science2665183267, doi101127njgpa210199841, doi1023071292217, doi1023073514751, doi1023073514816, doi102307jctv143mdjg, doi102475ajss31695411, doi102475ajss319111253, doi102475ajss321125417, doi102475ajss32313381, doi105281zenodo16171435, doi105860choice331556, openalexw1025856234, openalexw2173200745, openalexw2472827083, openalexw616953834, openalexw653009579"
}

Thematic Table of Contents. Contributors. A Guide to Using the Encyclopedia. Michael Crichton, Foreword. Preface. Dedication. F.E. Novas, Abelisauridae. L.L. Jacobs, African Dinosaurs. G. Erickson, Age Determination. A. Chinsamy, Albany K. Padian and J.R. Hutchinson, Allosauroidea. P. Dodson, American Dinosaurs. L. Dingus, American Museum of Natural History. K. Carpenter, Ankylosauria. J.M. Parrish, Archosauria. J.R. Hutchinson and K. Padain, Arctometatarsalia. R.E. Molnar, Australasian Dinosaurs. L.M. Chiappe, Aves. The Editors, Avetheropoda. K. Padian, Avialae. H. Osmolska, Barun Goyot Formation. J.L. Sanz, Bastus Nesting Site. The Editors, Bavarian State Collection for Paleontology and Historical Geology. P. Currie, Bayan Mandahu. H. Osmolska, Bayn Dzak. J.R. Horner, Behavior. A. Chinsamy, Bernard Price Institute for Paleontological Research. J. Le Loeuff, Biogeography. R.M. Alexander, Biomechanics. R. Chapman, Biometrics. C. Trueman, Biomineralization. S.G. Lucas, Biostratigraphy. K. Padian, Bipedality. K. Padian, Bird Origins. B. Breithaupt, Bone Cabin Quarry. P. Currie, Braincase Anatomy. K. Padain and J.R. Hutchinson, Bullatosauria. M. Lockley, Cabo Espichel. J.S. Moratalla and J.L. Sanz, Cameros Basin Megatracksite. C. Coy, Canadian Dinosaurs. K. Carpenter, Canon City. M. Lockley, Carenque. J.S. McIntosh, Carnegie Museum of Natural History. J.R. Hutchinson and K. Padian, Carnosauria. J. Kirkland, Cedar Mountain Formation. M. Norell, Central Asiatic Expeditions. The Editors, Cerapoda. P. Dodson, Ceratopsia. T. Rowe, R. Tykoski, and J.R. Hutchinson, Ceratosauria. H. Bocherens, Chemical Composition of Dinosaur Fossils. D. Zhiming, Chinese Dinosaurs. J.M. Parrish, Chinle Formation. J.B. Smith, Cleveland-Lloyd Dinosaur Quarry. D. Maxwell, Cloverly Formation. J.R. Hutchinson and K. Padian, Coelurosauria. M.J. Ryan and A.P. Russell, Color. B. Breithaupt, Como Bluff. R.E. Chapman and D.B. Weishampel, Computers and Related Technology. J. Wright, Connecticut River Valley. D.B. Weishampel, Constructional Morphology. K. Chin, Coprolites. L.M. Witmer, Craniofacial Air Sinus Systems. E-B. Koppelhus, Cretaceous Period. J.M. Clark, Crocodylia. W.A.S. Sarjeant, Crystal Palace Dinosaurs. B. Britt and K.L. Stadtman, Dalton Wells Quarry. A. Sahni, Deccan Basalt. The Editors, Deinonychosauria. K. Carpenter, Denver Museum of Natural History. C. Coy, Devil's Coulee Dinosaur Egg Historic Site. M.J. Ryan and M.K. Vickaryous, Diet. K. Padian, Dinosauria: Definition. D. Chure, Dinosaur National Monument. A.B. Arcucci, Dinosauromorpha. C. Coy, Dinosaur Provincial Park. M. Lockley, Dinosaur Ridge. Don Lesson, Dinosaur Society. M. Lockley, Dinosaur Valley. M. Lockley, Dinoturbation. P. Dodson, Distribution and Diversity. T. Jerzykiewicz, Djadokhta Formation. P.A. Murry and R.A. Long, Dockum Group. P. Currie, Dromaeosaridae. B. Britt and B.I. Curtice, Dry Mesa Quarry. M.J. Ryan, Dryosauridae. D.A. Eberth, Edmonton Group. J.R. Horner, Egg Mountain. K.E. Mikhailov, Eggs, Eggshells, and Nests. P. Currie, Elmisauridae. The Editors, Enantiornithes. P. Currie, Erenhot Dinosaur The Editors, Euornithopoda. E. Buffetaut, European Dinosaurs. J.D. Archibald, Evolution. J.D. Archibald, Extinction, Cretaceous. M.J. Benton, Extinction, Triassic. P. Guangzhao, Fabrosauridae. M. Lockley, Fatima. P. Currie, Feathered Dinosaurs. M. Lockley, Footprints and Trackways. Per Christiansen, Forelimbs and Hands. J.I. Kirkland, Fruita Paleontological Area. M.J. Ryan, Fruitland Formation. X-C. Wu, Functional Morphology. L. Claessens, Gastralia. D.D. Gillette, Gastroliths. The Editors, Genasauria. J.M. Parrish, Genetics. C.C. Swisher, Geologic Time. C. Coy, Ghost Ranch. K. Padian, Glen Canyon Group. D.A. Winkler, Glen Rose, Texas. P. Currie, Graduate Studies. D.J. Varricchio, Growth and Embryology. K. Padian, Growth Lines. C.A. Forster, Hadrosauridae. K.R. Johnson, Hell Creek Flora. D.F. Lofgren, Hell Creek Formation. F.E. Novas, Herrerasauridae. J.A. Long and K.J. McNamara, Heterochrony. J.B. Smith, Heterodontosauridae. Per Christiansen, Hind Limbs and Feet. R.E.H. Reid, Histology of Bones and Teeth. W.A.S. Sarjeant, History of Dinosaur Discoveries: Early Discoveries. B. Breithaupt, History of Dinosaur Discoveries: First Golden Period. E. Buffetaut, History of Dinosaur Discoveries: Quiet Times. L. Psihoyos, History of Dinosaur Discoveries: Research Today. B. Breithaupt, Howe Quarry. H-D. Sues, Hypsilophodontidae. C.A. Forster, Iguanodontidae. A. Sahni, Indian Dinosaurs. The Editors, Institute de Paleontologie, Museum National d'Histoire Naturelle, Paris, France. D. Zhiming, Institute of Vertebrate Paleontology and Paleoanthropology, Beijing, China. D.A. Russell, Intelligence. R.R. Rogers, Ischigualasto Formation. Y. Azuma and Y. Tamida, Japanese Dinosaurs. D.A. Eberth, Judith River Wedge. D. Lessem and M. Schweitzer, Jurassic Park. P. Dodson, Jurassic Period. H. Haubold, Keuper Formation. M. Lockley, Khodja-Pil-Ata. M.J. Ryan, Kirtland Formation. A. Sahni, Lameta Formation. B. Breithaupt, Lance Formation. S.G. Lucas, Land-Mammal Ages. B.P. Perez-Moreno and J.L. Sanz, Las Hoyas. V.L. Santucci, Legislation Protecting Dinosaur Fossils. D.B. Weishampel, Life History. M. Lockley, Lommiswil. E. Frey and J. Martin, Long Necks of Sauropods. D. Zhiming, Lufeng. K. Padian, Maniraptora. K. Padian, Maniraptoriformes. The Editors, Marginocephalia. K. Padian, Megalosaurus. M. Lockley, Megatracksites. K. Padian, Mesozoic Era. H-D. Sues, Mesozoic Faunas. J. Basinger, Mesozoic Floras. R. Hernandez-Rivera, Mexican Dinosaurs. J.A. Schiebout, Microvertebrate Sites. M.J. Ryan, Middle Asian Dinosaurs. G.S. Paul, Migration. R. Barsbold, Mongolian Dinosaurs. K. Carpenter, Morrison Formation. J.M. Parrish, Musculature. J. Le Loeuff, Musee des Dinosaures, Esperaza, Aude, France. The Editors, Museum of Comparative Zoology, Harvard University. D.K. Smith, Museum of Earth Science, Brigham Young University. M. Schweitzer, Museum of the Rockies. D. Chure, Museums and Displays. A. Chinsamy, National Museum, Bloemfontein, South Africa. P. Davis, Natual History Museum, London. H. Osmolska, Nemegt Formation. P. Dodson, Neoceratopsia. The Editors, Neotetanurae. H-D. Sues, Newark Supergroup. K. Padian, Origin of Dinosaurs. L.B. Tatarinov, Orlov Museum of Paleontology. M.K. Vickaryous and M.J. Ryan, Ornamentation. K. Padian, Ornithischia. K. Padian, Ornithodira. H. Osmolska, Ornithomimosauria. The Editors, Ornithopoda. K. Padian, Ornithosuchia. R. Barsbold, Oviraptorosauria. J.B. Smith, Oxford Clay. H-D. Sues, Pachycephalosauria. H. Haubold, Paleoclimatology. P. Dodson, Paleoecology. J.F. Lerbekmo, Paleomagnetic Correlation. E.A. Buchholtz, Paleoneurology. P.J. Currie, Paleontogical Museum, Ulaan Baatar. P. Davis, Paleontology. D.H. Tanke and B.M. Rothschild, Paleopathology. K. Padian, Pectoral Girdle. D. Rasskin-Gutman, Pelvis, Comparative Anatomy. C. Trueman, Permineralization. J.M. Parrish, Petrified Forest. K. Padian, Phylogenetic System. K. Padian, Phylogeny of Dinosaurs. K. Padian, Physiology. B. Tiffney, Plants and Dinosaurs. E. Hoch, Plate Tectonics. T.H. Rich, R.A. Gangloff, and W.R. Hammer, Polar Dinosaurs. H. Osmolska, Polish-Mongolian Paleontological Expeditions. D.F. Glut, Popular Culture, Literature. P. Makovicky, Postcranial Axial Skeleton. B. Britt, Postcranial Pneumaticity. R.E. Molnar, Problems with the Fossil Record. P. Upchurch, Prosauropoda. P. Davis, Pseudofossils. K. Padian, Pseudosuchia. P. Sereno, Psittacosauridae. K. Padian, Pterosauria. K. Padian, Pterosauromopha. M. Lockney, Purgatoire. K. Padian, Quadrupedality. D.A. Eberth, Radiometric Dating. P. Currie, Raptors. S.J. Czerkas, Reconstruction and Restoration. G.S. Paul, Reproductive Behavior and Rates. M.J. Benton, Reptiles. J. Wright, Rocky Hill Dinosaur Park. H-D. Sues, Royal Ontario B.G. Naylor, Royal Tyrrell Museum of Palaeontology. M. Lockley, Samcheonpo. K. Padian, Saurischia. J.S. McIntosh, Sauropoda. P. Upchurch, Sauropodomorpha. P. Currie, Sino-Canadian Dinosaur Project. P. Currie, Sino-Soviet Expeditions. N.J. Mateer, Sino-Swedish Expeditions. E.H. Colbert, Size. R.M. Alexander, Size and Scaling. K. Padian, Skeletal Structures. S.A. Czerkas, Skin. The Editors, Skull, Comparative Anatomy. M.K. Brett-Surman, Smithsonian Institution. H. Haubold, Solnhofen Formation. A. Chinsamy, South African F.E. Novas, South American Dinosaurs. E. Buffetaut, Southeast Asian Dinosaurs. C. Coy, Soviet-Mongolian Paleontological Expeditions. J.D. Archibald, Speciation. J.D. Archibald, Species. A. Milner, Spinosauridae and Baryonychidae. The Editors, State Museum for Natural History, Stuttgart, Germany. K. Padian, Staurikosauridae. P. Galton, Stegosauria. X-C. Wu and A.P. Russell, Systematics. A.R. Fiorillo, Taphonomy. P.M. Sander, Teeth and Jaws. G. Maier, Tendaguru. J.R. Hutchinson and K. Padian, Tetanurae. K. Padian, Thecodontia. D.A. Russell, Therizinosauria. P.J. Currie, Theropoda. K. Carpenter, Thyreophora. A.R. Jacobsen, Tooth Marks. G.M. Erickson, Tooth Replacement Patterns. W.L. Abler, Tooth Serrations in Carnivorous Dinosaurs. A.R. Fiorillo and D.B. Weishampel, Tooth Wear. K. Padian, Trace Fossils. J.M. Parrish, Triassic Period. D.J. Varricchio, Troodontidae. J.O. Farlow, Trophic Groups. D.B. Weishampel, Trossingen. R.R. Rogers, Two Medicine Formation. K. Carpenter, Tyrannosauridae. M. Norell, Ukhaa Tolgod. The Editors, University of California Museum of Paleontology. S.D. Sampson and M.J. Ryan, Variation. M.J. Benton, Vertebrata. P. Davis, Vertebrate Paleontology. G.M. Erickson, Von Ebner Incremental Growth Lines. D. Norman, Wealden Group. J.R. Horner, Willow Creek Anticline. M.A. Turner, Yale Peabody D. Zhiming, Zigong Museum. Resources. Index.

@article{doi105860choice353642,
    title = "Encyclopedia of dinosaurs",
    year = "1998",
    journal = "Choice Reviews Online",
    abstract = "Thematic Table of Contents. Contributors. A Guide to Using the Encyclopedia. Michael Crichton, Foreword. Preface. Dedication. F.E. Novas, Abelisauridae. L.L. Jacobs, African Dinosaurs. G. Erickson, Age Determination. A. Chinsamy, Albany K. Padian and J.R. Hutchinson, Allosauroidea. P. Dodson, American Dinosaurs. L. Dingus, American Museum of Natural History. K. Carpenter, Ankylosauria. J.M. Parrish, Archosauria. J.R. Hutchinson and K. Padain, Arctometatarsalia. R.E. Molnar, Australasian Dinosaurs. L.M. Chiappe, Aves. The Editors, Avetheropoda. K. Padian, Avialae. H. Osmolska, Barun Goyot Formation. J.L. Sanz, Bastus Nesting Site. The Editors, Bavarian State Collection for Paleontology and Historical Geology. P. Currie, Bayan Mandahu. H. Osmolska, Bayn Dzak. J.R. Horner, Behavior. A. Chinsamy, Bernard Price Institute for Paleontological Research. J. Le Loeuff, Biogeography. R.M. Alexander, Biomechanics. R. Chapman, Biometrics. C. Trueman, Biomineralization. S.G. Lucas, Biostratigraphy. K. Padian, Bipedality. K. Padian, Bird Origins. B. Breithaupt, Bone Cabin Quarry. P. Currie, Braincase Anatomy. K. Padain and J.R. Hutchinson, Bullatosauria. M. Lockley, Cabo Espichel. J.S. Moratalla and J.L. Sanz, Cameros Basin Megatracksite. C. Coy, Canadian Dinosaurs. K. Carpenter, Canon City. M. Lockley, Carenque. J.S. McIntosh, Carnegie Museum of Natural History. J.R. Hutchinson and K. Padian, Carnosauria. J. Kirkland, Cedar Mountain Formation. M. Norell, Central Asiatic Expeditions. The Editors, Cerapoda. P. Dodson, Ceratopsia. T. Rowe, R. Tykoski, and J.R. Hutchinson, Ceratosauria. H. Bocherens, Chemical Composition of Dinosaur Fossils. D. Zhiming, Chinese Dinosaurs. J.M. Parrish, Chinle Formation. J.B. Smith, Cleveland-Lloyd Dinosaur Quarry. D. Maxwell, Cloverly Formation. J.R. Hutchinson and K. Padian, Coelurosauria. M.J. Ryan and A.P. Russell, Color. B. Breithaupt, Como Bluff. R.E. Chapman and D.B. Weishampel, Computers and Related Technology. J. Wright, Connecticut River Valley. D.B. Weishampel, Constructional Morphology. K. Chin, Coprolites. L.M. Witmer, Craniofacial Air Sinus Systems. E-B. Koppelhus, Cretaceous Period. J.M. Clark, Crocodylia. W.A.S. Sarjeant, Crystal Palace Dinosaurs. B. Britt and K.L. Stadtman, Dalton Wells Quarry. A. Sahni, Deccan Basalt. The Editors, Deinonychosauria. K. Carpenter, Denver Museum of Natural History. C. Coy, Devil's Coulee Dinosaur Egg Historic Site. M.J. Ryan and M.K. Vickaryous, Diet. K. Padian, Dinosauria: Definition. D. Chure, Dinosaur National Monument. A.B. Arcucci, Dinosauromorpha. C. Coy, Dinosaur Provincial Park. M. Lockley, Dinosaur Ridge. Don Lesson, Dinosaur Society. M. Lockley, Dinosaur Valley. M. Lockley, Dinoturbation. P. Dodson, Distribution and Diversity. T. Jerzykiewicz, Djadokhta Formation. P.A. Murry and R.A. Long, Dockum Group. P. Currie, Dromaeosaridae. B. Britt and B.I. Curtice, Dry Mesa Quarry. M.J. Ryan, Dryosauridae. D.A. Eberth, Edmonton Group. J.R. Horner, Egg Mountain. K.E. Mikhailov, Eggs, Eggshells, and Nests. P. Currie, Elmisauridae. The Editors, Enantiornithes. P. Currie, Erenhot Dinosaur The Editors, Euornithopoda. E. Buffetaut, European Dinosaurs. J.D. Archibald, Evolution. J.D. Archibald, Extinction, Cretaceous. M.J. Benton, Extinction, Triassic. P. Guangzhao, Fabrosauridae. M. Lockley, Fatima. P. Currie, Feathered Dinosaurs. M. Lockley, Footprints and Trackways. Per Christiansen, Forelimbs and Hands. J.I. Kirkland, Fruita Paleontological Area. M.J. Ryan, Fruitland Formation. X-C. Wu, Functional Morphology. L. Claessens, Gastralia. D.D. Gillette, Gastroliths. The Editors, Genasauria. J.M. Parrish, Genetics. C.C. Swisher, Geologic Time. C. Coy, Ghost Ranch. K. Padian, Glen Canyon Group. D.A. Winkler, Glen Rose, Texas. P. Currie, Graduate Studies. D.J. Varricchio, Growth and Embryology. K. Padian, Growth Lines. C.A. Forster, Hadrosauridae. K.R. Johnson, Hell Creek Flora. D.F. Lofgren, Hell Creek Formation. F.E. Novas, Herrerasauridae. J.A. Long and K.J. McNamara, Heterochrony. J.B. Smith, Heterodontosauridae. Per Christiansen, Hind Limbs and Feet. R.E.H. Reid, Histology of Bones and Teeth. W.A.S. Sarjeant, History of Dinosaur Discoveries: Early Discoveries. B. Breithaupt, History of Dinosaur Discoveries: First Golden Period. E. Buffetaut, History of Dinosaur Discoveries: Quiet Times. L. Psihoyos, History of Dinosaur Discoveries: Research Today. B. Breithaupt, Howe Quarry. H-D. Sues, Hypsilophodontidae. C.A. Forster, Iguanodontidae. A. Sahni, Indian Dinosaurs. The Editors, Institute de Paleontologie, Museum National d'Histoire Naturelle, Paris, France. D. Zhiming, Institute of Vertebrate Paleontology and Paleoanthropology, Beijing, China. D.A. Russell, Intelligence. R.R. Rogers, Ischigualasto Formation. Y. Azuma and Y. Tamida, Japanese Dinosaurs. D.A. Eberth, Judith River Wedge. D. Lessem and M. Schweitzer, Jurassic Park. P. Dodson, Jurassic Period. H. Haubold, Keuper Formation. M. Lockley, Khodja-Pil-Ata. M.J. Ryan, Kirtland Formation. A. Sahni, Lameta Formation. B. Breithaupt, Lance Formation. S.G. Lucas, Land-Mammal Ages. B.P. Perez-Moreno and J.L. Sanz, Las Hoyas. V.L. Santucci, Legislation Protecting Dinosaur Fossils. D.B. Weishampel, Life History. M. Lockley, Lommiswil. E. Frey and J. Martin, Long Necks of Sauropods. D. Zhiming, Lufeng. K. Padian, Maniraptora. K. Padian, Maniraptoriformes. The Editors, Marginocephalia. K. Padian, Megalosaurus. M. Lockley, Megatracksites. K. Padian, Mesozoic Era. H-D. Sues, Mesozoic Faunas. J. Basinger, Mesozoic Floras. R. Hernandez-Rivera, Mexican Dinosaurs. J.A. Schiebout, Microvertebrate Sites. M.J. Ryan, Middle Asian Dinosaurs. G.S. Paul, Migration. R. Barsbold, Mongolian Dinosaurs. K. Carpenter, Morrison Formation. J.M. Parrish, Musculature. J. Le Loeuff, Musee des Dinosaures, Esperaza, Aude, France. The Editors, Museum of Comparative Zoology, Harvard University. D.K. Smith, Museum of Earth Science, Brigham Young University. M. Schweitzer, Museum of the Rockies. D. Chure, Museums and Displays. A. Chinsamy, National Museum, Bloemfontein, South Africa. P. Davis, Natual History Museum, London. H. Osmolska, Nemegt Formation. P. Dodson, Neoceratopsia. The Editors, Neotetanurae. H-D. Sues, Newark Supergroup. K. Padian, Origin of Dinosaurs. L.B. Tatarinov, Orlov Museum of Paleontology. M.K. Vickaryous and M.J. Ryan, Ornamentation. K. Padian, Ornithischia. K. Padian, Ornithodira. H. Osmolska, Ornithomimosauria. The Editors, Ornithopoda. K. Padian, Ornithosuchia. R. Barsbold, Oviraptorosauria. J.B. Smith, Oxford Clay. H-D. Sues, Pachycephalosauria. H. Haubold, Paleoclimatology. P. Dodson, Paleoecology. J.F. Lerbekmo, Paleomagnetic Correlation. E.A. Buchholtz, Paleoneurology. P.J. Currie, Paleontogical Museum, Ulaan Baatar. P. Davis, Paleontology. D.H. Tanke and B.M. Rothschild, Paleopathology. K. Padian, Pectoral Girdle. D. Rasskin-Gutman, Pelvis, Comparative Anatomy. C. Trueman, Permineralization. J.M. Parrish, Petrified Forest. K. Padian, Phylogenetic System. K. Padian, Phylogeny of Dinosaurs. K. Padian, Physiology. B. Tiffney, Plants and Dinosaurs. E. Hoch, Plate Tectonics. T.H. Rich, R.A. Gangloff, and W.R. Hammer, Polar Dinosaurs. H. Osmolska, Polish-Mongolian Paleontological Expeditions. D.F. Glut, Popular Culture, Literature. P. Makovicky, Postcranial Axial Skeleton. B. Britt, Postcranial Pneumaticity. R.E. Molnar, Problems with the Fossil Record. P. Upchurch, Prosauropoda. P. Davis, Pseudofossils. K. Padian, Pseudosuchia. P. Sereno, Psittacosauridae. K. Padian, Pterosauria. K. Padian, Pterosauromopha. M. Lockney, Purgatoire. K. Padian, Quadrupedality. D.A. Eberth, Radiometric Dating. P. Currie, Raptors. S.J. Czerkas, Reconstruction and Restoration. G.S. Paul, Reproductive Behavior and Rates. M.J. Benton, Reptiles. J. Wright, Rocky Hill Dinosaur Park. H-D. Sues, Royal Ontario B.G. Naylor, Royal Tyrrell Museum of Palaeontology. M. Lockley, Samcheonpo. K. Padian, Saurischia. J.S. McIntosh, Sauropoda. P. Upchurch, Sauropodomorpha. P. Currie, Sino-Canadian Dinosaur Project. P. Currie, Sino-Soviet Expeditions. N.J. Mateer, Sino-Swedish Expeditions. E.H. Colbert, Size. R.M. Alexander, Size and Scaling. K. Padian, Skeletal Structures. S.A. Czerkas, Skin. The Editors, Skull, Comparative Anatomy. M.K. Brett-Surman, Smithsonian Institution. H. Haubold, Solnhofen Formation. A. Chinsamy, South African F.E. Novas, South American Dinosaurs. E. Buffetaut, Southeast Asian Dinosaurs. C. Coy, Soviet-Mongolian Paleontological Expeditions. J.D. Archibald, Speciation. J.D. Archibald, Species. A. Milner, Spinosauridae and Baryonychidae. The Editors, State Museum for Natural History, Stuttgart, Germany. K. Padian, Staurikosauridae. P. Galton, Stegosauria. X-C. Wu and A.P. Russell, Systematics. A.R. Fiorillo, Taphonomy. P.M. Sander, Teeth and Jaws. G. Maier, Tendaguru. J.R. Hutchinson and K. Padian, Tetanurae. K. Padian, Thecodontia. D.A. Russell, Therizinosauria. P.J. Currie, Theropoda. K. Carpenter, Thyreophora. A.R. Jacobsen, Tooth Marks. G.M. Erickson, Tooth Replacement Patterns. W.L. Abler, Tooth Serrations in Carnivorous Dinosaurs. A.R. Fiorillo and D.B. Weishampel, Tooth Wear. K. Padian, Trace Fossils. J.M. Parrish, Triassic Period. D.J. Varricchio, Troodontidae. J.O. Farlow, Trophic Groups. D.B. Weishampel, Trossingen. R.R. Rogers, Two Medicine Formation. K. Carpenter, Tyrannosauridae. M. Norell, Ukhaa Tolgod. The Editors, University of California Museum of Paleontology. S.D. Sampson and M.J. Ryan, Variation. M.J. Benton, Vertebrata. P. Davis, Vertebrate Paleontology. G.M. Erickson, Von Ebner Incremental Growth Lines. D. Norman, Wealden Group. J.R. Horner, Willow Creek Anticline. M.A. Turner, Yale Peabody D. Zhiming, Zigong Museum. Resources. Index.",
    url = "https://doi.org/10.5860/choice.35-3642",
    doi = "10.5860/choice.35-3642",
    openalex = "W647458292"
}

The ascendancy of dinosaurs on land near the close of the Triassic now appears to have been as accidental and opportunistic as their demise and replacement by therian mammals at the end of the Cretaceous. The dinosaurian radiation, launched by 1-meter-long bipeds, was slower in tempo and more restricted in adaptive scope than that of therian mammals. A notable exception was the evolution of birds from small-bodied predatory dinosaurs, which involved a dramatic decrease in body size. Recurring phylogenetic trends among dinosaurs include, to the contrary, increase in body size. There is no evidence for co-evolution between predators and prey or between herbivores and flowering plants. As the major land masses drifted apart, dinosaurian biogeography was molded more by regional extinction and intercontinental dispersal than by the breakup sequence of Pangaea.

@article{doi101126science28454232137,
    author = "Sereno, Paul C.",
    title = "The Evolution of Dinosaurs",
    year = "1999",
    journal = "Science",
    abstract = "The ascendancy of dinosaurs on land near the close of the Triassic now appears to have been as accidental and opportunistic as their demise and replacement by therian mammals at the end of the Cretaceous. The dinosaurian radiation, launched by 1-meter-long bipeds, was slower in tempo and more restricted in adaptive scope than that of therian mammals. A notable exception was the evolution of birds from small-bodied predatory dinosaurs, which involved a dramatic decrease in body size. Recurring phylogenetic trends among dinosaurs include, to the contrary, increase in body size. There is no evidence for co-evolution between predators and prey or between herbivores and flowering plants. As the major land masses drifted apart, dinosaurian biogeography was molded more by regional extinction and intercontinental dispersal than by the breakup sequence of Pangaea.",
    url = "https://doi.org/10.1126/science.284.5423.2137",
    doi = "10.1126/science.284.5423.2137",
    openalex = "W1974320804",
    references = "brouwers1987dinosaurs, coria1995a, doi101007978364268836217, doi10100797836426953391, doi1010160031018272900491, doi1010160031018282900852, doi1010160198025483901334, doi101017s0022336000026706, doi101017s0094837300004310, doi101017s0094837300026543, doi10103820167, doi101038248168a0, doi101038277560a0, doi10103831927, doi10103832642, doi10103834356, doi101038378774a0, doi101038385247a0, doi101038387390a0, doi10108002724634199010011815, doi10108002724634199110011386, doi10108002724634199210011473, doi10108002724634199310011490, doi10108002724634199410011523, doi10108002724634199510011250, doi10108002724634199810011101, doi10108002724634199810011115, doi101093oso97801985491780010001, doi101098rstb19950125, doi101111j109636421998tb00569x, doi101111j1469185x1997tb00024x, doi101111j155856461973tb05912x, doi101111j155856461996tb04496x, doi101111j174966321940tb57047x, doi101111j216409471940tb00068x, doi101126science2645160828, doi101126science2725264986, doi101126science27953581915, doi101126science28053661048, doi101126science28253921298, doi101126science2845414616, doi101127njgpa210199841, doi101139e93187, doi101146annurevea03050175000415, doi101146annurevearth251435, doi1015159780691224244, doi1023071292217, doi1023073514751, doi1023073515466, openalexw1528487914, rowe1989a, sereno1997the"
}

Angiosperms first appeared in northern Gondwana during the Early Cretaceous, approximately 135 million years ago. Several authors have hypothesised that the origin of angiosperms, and the tempo and pattern of their subsequent radiation, was mediated by changes in the browsing behaviour of large herbivorous dinosaurs (sauropods and ornithischians). Moreover, the taxonomic and ecological radiation of angiosperms has been associated with the evolution of complex jaw mechanisms among ornithischian dinosaurs. Here, we review critically the evidence for dinosaur-angiosperm interactions during the Cretaceous Period, providing explicit spatiotemporal comparisons between evolutionary and palaeoecological events in both the dinosaur and angiosperm fossil records and an assessment of the direct and indirect evidence for dinosaur diets. We conclude that there are no strong spatiotemporal correlations in support of the hypothesis that dinosaurs were causative agents in the origin of angiosperms; however, dinosaur-angiosperm interactions in the Late Cretaceous may have resulted in some coevolutionary interactions, although direct evidence of such interactions is scanty at present. It is likely that other animal groups (insects, arboreal mammals) had a greater impact on angiosperm diversity during the Cretaceous than herbivorous dinosaurs. Elevated levels of atmospheric CO2 might have played a critical role in the initial stages of the angiosperm radiation.

@article{doi101017s1464793101005735,
    author = "Barrett, Paul M. and Willis, Katherine J.",
    title = "Did dinosaurs invent flowers? Dinosaur—angiosperm coevolution revisited",
    year = "2001",
    journal = "Biological reviews/Biological reviews of the Cambridge Philosophical Society",
    abstract = "Angiosperms first appeared in northern Gondwana during the Early Cretaceous, approximately 135 million years ago. Several authors have hypothesised that the origin of angiosperms, and the tempo and pattern of their subsequent radiation, was mediated by changes in the browsing behaviour of large herbivorous dinosaurs (sauropods and ornithischians). Moreover, the taxonomic and ecological radiation of angiosperms has been associated with the evolution of complex jaw mechanisms among ornithischian dinosaurs. Here, we review critically the evidence for dinosaur-angiosperm interactions during the Cretaceous Period, providing explicit spatiotemporal comparisons between evolutionary and palaeoecological events in both the dinosaur and angiosperm fossil records and an assessment of the direct and indirect evidence for dinosaur diets. We conclude that there are no strong spatiotemporal correlations in support of the hypothesis that dinosaurs were causative agents in the origin of angiosperms; however, dinosaur-angiosperm interactions in the Late Cretaceous may have resulted in some coevolutionary interactions, although direct evidence of such interactions is scanty at present. It is likely that other animal groups (insects, arboreal mammals) had a greater impact on angiosperm diversity during the Cretaceous than herbivorous dinosaurs. Elevated levels of atmospheric CO2 might have played a critical role in the initial stages of the angiosperm radiation.",
    url = "https://doi.org/10.1017/s1464793101005735",
    doi = "10.1017/s1464793101005735",
    openalex = "W2139189634",
    references = "doi10100797836426953391, doi1010160031018275900279, doi1010160031018291900605, doi101017cbo9780511565441, doi101017s0094837300007557, doi101017s009483730001410x, doi101038277560a0, doi101038374027a0, doi10103846528, doi10103846536, doi10108002724634198510011859, doi101086284406, doi101111j150239311985tb00690x, doi101111j155856461966tb03367x, doi101126science2815376555, doi1011300091761319910190547lpoeef23co2, doi101146annureves26110195002305, doi101163156853974x00345, doi1011632294193290000239, doi1023072258301, doi1023072412923, doi1023073243920, lehman1987late, openalexw2603335639"
}

ABSTRACT Histological evidence of the bones of pterosaurs and dinosaurs indicates that the typically large forms of these groups grew at rates more comparable to those of birds and mammals than to those of other living reptiles. However, Scutellosaurus, a small, bipedal, basal thyreophoran ornithischian dinosaur of the Early Jurassic, shows histological features in its skeletal tissues that suggest relatively lower growth rates than in those of larger dinosaurs. In these respects Scutellosaurus, like other small dinosaurs such as Orodromeus and some basal birds, is more like young, rapidly growing crocodiles than larger, more derived ornithischians (hadrosaurs) and all saurischians (sauropods and theropods). Similar patterns can be seen in small, mostly basal pterosaurs such as Eudimorphodon and Rhamphorhynchus. However, superficial similarities to crocodile bone growth belie some important differences, which are most usefully interpreted in phylogenetic and ontogenetic contexts. Large size evolved secondarily in several dinosaurian and pterosaurian lineages. We hypothesize that this larger size was made possible by rapid growth strategies that are reflected by characteristic highly vascularized fibro-lamellar bone tissues that comprise most of the cortex. Dinosaurs and pterosaurs, like other tetrapodes, generally grew more quickly in early stages and more slowly as growth neared completion. As in other vertebrate groups, taxa of small adult size may have grown at lower rates or for shorter durations than larger taxa did. Phylogenetic patterns suggest that by themselves, the low vascularity and inferred low growth rates seen in small dinosaurs and pterosaurs are not good indicators of thermometabolic regime, because they are correlated so strongly with size. They may reflect mechanical exigencies of small size rather than especially lower growth rates, tied to the process of deposition of particular kinds of bone tissues. The evolution of life history strategies in dinosaurs and pterosaurs, as they relate to rates of growth and adult body sizes, will be better understood as more complete histological studies place these data into phylogenetic and ontogenetic contexts.

@article{doi1016710272463420040240555gisdap20co2,
    author = "Padian, Kevin and Horner, John R. and de Ricqlès, Armand",
    title = "Growth in small dinosaurs and pterosaurs: the evolution of archosaurian growth strategies",
    year = "2004",
    journal = "Journal of Vertebrate Paleontology",
    abstract = "ABSTRACT Histological evidence of the bones of pterosaurs and dinosaurs indicates that the typically large forms of these groups grew at rates more comparable to those of birds and mammals than to those of other living reptiles. However, Scutellosaurus, a small, bipedal, basal thyreophoran ornithischian dinosaur of the Early Jurassic, shows histological features in its skeletal tissues that suggest relatively lower growth rates than in those of larger dinosaurs. In these respects Scutellosaurus, like other small dinosaurs such as Orodromeus and some basal birds, is more like young, rapidly growing crocodiles than larger, more derived ornithischians (hadrosaurs) and all saurischians (sauropods and theropods). Similar patterns can be seen in small, mostly basal pterosaurs such as Eudimorphodon and Rhamphorhynchus. However, superficial similarities to crocodile bone growth belie some important differences, which are most usefully interpreted in phylogenetic and ontogenetic contexts. Large size evolved secondarily in several dinosaurian and pterosaurian lineages. We hypothesize that this larger size was made possible by rapid growth strategies that are reflected by characteristic highly vascularized fibro-lamellar bone tissues that comprise most of the cortex. Dinosaurs and pterosaurs, like other tetrapodes, generally grew more quickly in early stages and more slowly as growth neared completion. As in other vertebrate groups, taxa of small adult size may have grown at lower rates or for shorter durations than larger taxa did. Phylogenetic patterns suggest that by themselves, the low vascularity and inferred low growth rates seen in small dinosaurs and pterosaurs are not good indicators of thermometabolic regime, because they are correlated so strongly with size. They may reflect mechanical exigencies of small size rather than especially lower growth rates, tied to the process of deposition of particular kinds of bone tissues. The evolution of life history strategies in dinosaurs and pterosaurs, as they relate to rates of growth and adult body sizes, will be better understood as more complete histological studies place these data into phylogenetic and ontogenetic contexts.",
    url = "https://doi.org/10.1671/0272-4634(2004)024[0555:gisdap]2.0.co;2",
    doi = "10.1671/0272-4634(2004)024[0555:gisdap]2.0.co;2",
    openalex = "W2176430550",
    references = "crossref1998encyclopedia, doi101007bf02118752, doi101016s0764446900001815, doi101016s1631069102014294, doi101017s0094837300021308, doi101038282296a0, doi10108002724634199310011490, doi101093clinids222240, doi101093oso97801951060840010001, doi101111j109636422000tb02201x, doi1015159781400853724, doi1016660094837320000260466lhotts20co2, doi1016660094837320010270039coosea20co2, doi1016660094837320030290105dbttoo20co2, doi1016710272463420000200115lbhoth20co2, doi1023071444685, doi1023073514751, openalexw225597919, openalexw2607033038, openalexw563887495, vitt1982the"
}

Both ornaments and weapons of sexual selection frequently exhibit prolific interspecific diversity of form. Yet, most studies of this diversity have focused on ornaments involved with female mate choice, rather than on the weapons of male competition. With few exceptions, the mechanisms of divergence in weapon morphology remain largely unexplored. Here, we characterize the evolutionary radiation of one type of weapon: beetle horns. We use partial sequences from four nuclear and three mitochondrial genes to develop a phylogenetic hypothesis for a worldwide sample of 48 species from the dung beetle genus Onthophagus (Coleoptera: Scarabaeidae). We then use these data to test for multiple evolutionary origins of horns and to characterize the evolutionary radiation of horns. Although our limited sampling of one of the world's most species-rich genera almost certainly underestimates the number of evolutionary events, our phylogeny reveals prolific evolutionary lability of these exaggerated sexually selected weapons (more than 25 separate gains and losses of five different horn types). We discuss these results in the context of the natural history of these beetles and explore ways that sexual selection and ecology may have interacted to generate this extraordinary diversity of weapon morphology.

@article{doi101111j001438202005tb01044x,
    author = "Emlen, Douglas J. and Marangelo, Jennifer and Ball, Bernard and Cunningham, Cliff",
    title = "DIVERSITY IN THE WEAPONS OF SEXUAL SELECTION: HORN EVOLUTION IN THE BEETLE GENUS ONTHOPHAGUS (COLEOPTERA: SCARABAEIDAE)",
    year = "2005",
    journal = "Evolution",
    abstract = "Both ornaments and weapons of sexual selection frequently exhibit prolific interspecific diversity of form. Yet, most studies of this diversity have focused on ornaments involved with female mate choice, rather than on the weapons of male competition. With few exceptions, the mechanisms of divergence in weapon morphology remain largely unexplored. Here, we characterize the evolutionary radiation of one type of weapon: beetle horns. We use partial sequences from four nuclear and three mitochondrial genes to develop a phylogenetic hypothesis for a worldwide sample of 48 species from the dung beetle genus Onthophagus (Coleoptera: Scarabaeidae). We then use these data to test for multiple evolutionary origins of horns and to characterize the evolutionary radiation of horns. Although our limited sampling of one of the world's most species-rich genera almost certainly underestimates the number of evolutionary events, our phylogeny reveals prolific evolutionary lability of these exaggerated sexually selected weapons (more than 25 separate gains and losses of five different horn types). We discuss these results in the context of the natural history of these beetles and explore ways that sexual selection and ecology may have interacted to generate this extraordinary diversity of weapon morphology.",
    url = "https://doi.org/10.1111/j.0014-3820.2005.tb01044.x",
    doi = "10.1111/j.0014-3820.2005.tb01044.x",
    openalex = "W2175906304",
    references = "doi105962bhltitle5716"
}

A new basal neoceratopsian taxon from the eastern Gobi Desert is described. Yamaceratops dorngobiensis, tax. nov., is probably of late Early Cretaceous age, and occupies a phylogenetic position intermediate between Liaoceratops and Archaeoceratops. It is the most basal taxon to display a number of traditional neoceratopsian synapomorphies concentrated in the cheek region and mandible. These include presence of an epijugal, lateral displacement of the coronoid process, a lateral ridge on the surangular for insertion of the jaw adductors, and a lateral wall to the mandibular glenoid. Yamaceratops shares two synapomorphies (tubercles on the ventral edge of the angular and shape of the jugal) with Liaoceratops, indicating that the transient presence of derived characters may be prevalent in the early evolutionary history of Ceratopsia. Yamaceratops shares aspects of frill morphology with Liaoceratops and Leptoceratops that suggest a function unrelated to display for this anatomical structure in basal neoceratopsians, and hints at a more complex evolutionary history for ceratopsian frills. Considerations of patristic distances and mosaic evolution among basal neoceratopsian taxa indicate that a greater diversity of these animals remains undiscovered.

@article{doi10120600030082200635301ydanpc20co2,
    author = "Makovicky, Peter J. and Norell, Mark A.",
    title = "Yamaceratops Dorngobiensis, a New Primitive Ceratopsian (Dinosauria: Ornithischia) from the Cretaceous of Mongolia",
    year = "2006",
    journal = "American Museum Novitates",
    abstract = "A new basal neoceratopsian taxon from the eastern Gobi Desert is described. Yamaceratops dorngobiensis, tax. nov., is probably of late Early Cretaceous age, and occupies a phylogenetic position intermediate between Liaoceratops and Archaeoceratops. It is the most basal taxon to display a number of traditional neoceratopsian synapomorphies concentrated in the cheek region and mandible. These include presence of an epijugal, lateral displacement of the coronoid process, a lateral ridge on the surangular for insertion of the jaw adductors, and a lateral wall to the mandibular glenoid. Yamaceratops shares two synapomorphies (tubercles on the ventral edge of the angular and shape of the jugal) with Liaoceratops, indicating that the transient presence of derived characters may be prevalent in the early evolutionary history of Ceratopsia. Yamaceratops shares aspects of frill morphology with Liaoceratops and Leptoceratops that suggest a function unrelated to display for this anatomical structure in basal neoceratopsians, and hints at a more complex evolutionary history for ceratopsian frills. Considerations of patristic distances and mosaic evolution among basal neoceratopsian taxa indicate that a greater diversity of these animals remains undiscovered.",
    url = "https://doi.org/10.1206/0003-0082(2006)3530[1:ydanpc]2.0.co;2",
    doi = "10.1206/0003-0082(2006)3530[1:ydanpc]2.0.co;2",
    openalex = "W1991875889",
    references = "currie1993palaeontology, doi1010160195667191900155, doi10108002724634199610011283, doi101086273307, doi101111j109600311994tb00179x, doi101111j155856461966tb03367x, doi101111j155856461988tb02497x, doi101126science28454232137, doi10136002tb9031, doi105962bhltitle52196, doi105962p313819, openalexw1535663436"
}

Synopsis Ornithischia is a familiar and diverse clade of dinosaurs whose global phylogeny has remained largely unaltered since early cladistic analyses in the mid 1980s. Current understanding of ornithischian evolution is hampered by a paucity of explicitly numerical phylogenetic analyses that consider the entire clade. As a result, it is difficult to assess the robustness of current phylogenetic hypotheses for Ornithischia and the effect that the addition of new taxa or characters is likely to have on the overall topology of the clade. The new phylogenetic analysis presented here incorporates a range of new basal taxa and characters in an attempt to rigorously test global ornithischian phylogeny. Parsimony analysis is carried out with 46 taxa and 221 characters. Although the strict component consensus tree shows poor resolution in a number of areas, application of reduced consensus methods provides a well‐resolved picture of ornithischian interrelationships. Surprisingly, Heterodontosauridae is placed as the most basal group of all well‐known ornithischians, phylogenetically distant from a stem‐defined Ornithopoda, creating a topology that is more congruent with the known ornithischian stratigraphical record. There is no evidence for a monophyletic ‘Fabrosauridae’, and Lesothosaurus (the best‐known ‘fabrosaur') occupies an unusual position as the most basal member of Thyreophora. Other relationships within Thyreophora remain largely stable. The primitive thyreophoran Scelidosaurus is the sister taxon of Eurypoda (stegosaurs and ankylosaurs), rather than a basal ankylosaur as implied by some previous studies. The taxonomic content of Ornithopoda differs significantly from previous analyses and basal relationships within the clade are weakly supported, requiring further investigation. ‘Hypsilopho‐dontidae’ is paraphyletic, with some taxa (Agilisaurus, Hexinlusaurus, Othnielia) placed outside of Ornithopoda as non‐cerapodans. Ceratopsia and Pachycephalosauria are monophyletic and are united as Marginocephalia; however, the stability of these clades is reduced by a number of poorly preserved basal taxa. This analysis reaffirms much of the currently accepted ornithischian topology. Nevertheless, instability in the position and content of several clades (notably Heterodontosauridae and Ornithopoda) indicates that considerable future work on ornithischian phylogeny is required and causes problems for several current phylogenetic definitions.

@article{doi101017s1477201907002271,
    author = "Butler, Richard J. and Upchurch, Paul and Norman, David",
    title = "The phylogeny of the ornithischian dinosaurs",
    year = "2007",
    journal = "Journal of Systematic Palaeontology",
    abstract = "Synopsis Ornithischia is a familiar and diverse clade of dinosaurs whose global phylogeny has remained largely unaltered since early cladistic analyses in the mid 1980s. Current understanding of ornithischian evolution is hampered by a paucity of explicitly numerical phylogenetic analyses that consider the entire clade. As a result, it is difficult to assess the robustness of current phylogenetic hypotheses for Ornithischia and the effect that the addition of new taxa or characters is likely to have on the overall topology of the clade. The new phylogenetic analysis presented here incorporates a range of new basal taxa and characters in an attempt to rigorously test global ornithischian phylogeny. Parsimony analysis is carried out with 46 taxa and 221 characters. Although the strict component consensus tree shows poor resolution in a number of areas, application of reduced consensus methods provides a well‐resolved picture of ornithischian interrelationships. Surprisingly, Heterodontosauridae is placed as the most basal group of all well‐known ornithischians, phylogenetically distant from a stem‐defined Ornithopoda, creating a topology that is more congruent with the known ornithischian stratigraphical record. There is no evidence for a monophyletic ‘Fabrosauridae’, and Lesothosaurus (the best‐known ‘fabrosaur') occupies an unusual position as the most basal member of Thyreophora. Other relationships within Thyreophora remain largely stable. The primitive thyreophoran Scelidosaurus is the sister taxon of Eurypoda (stegosaurs and ankylosaurs), rather than a basal ankylosaur as implied by some previous studies. The taxonomic content of Ornithopoda differs significantly from previous analyses and basal relationships within the clade are weakly supported, requiring further investigation. ‘Hypsilopho‐dontidae’ is paraphyletic, with some taxa (Agilisaurus, Hexinlusaurus, Othnielia) placed outside of Ornithopoda as non‐cerapodans. Ceratopsia and Pachycephalosauria are monophyletic and are united as Marginocephalia; however, the stability of these clades is reduced by a number of poorly preserved basal taxa. This analysis reaffirms much of the currently accepted ornithischian topology. Nevertheless, instability in the position and content of several clades (notably Heterodontosauridae and Ornithopoda) indicates that considerable future work on ornithischian phylogeny is required and causes problems for several current phylogenetic definitions.",
    url = "https://doi.org/10.1017/s1477201907002271",
    doi = "10.1017/s1477201907002271",
    openalex = "W2107074601",
    references = "doi101007bf00377897, doi101007bf02988144, doi101017s1477201906001970, doi101038248168a0, doi10108002724634198310011956, doi10108002724634198510011859, doi10108002724634199010011815, doi10108002724634199110011386, doi10108002724634199110011426, doi10108002724634199410011523, doi10108002724634199410011524, doi10108002724634199410011538, doi10108008912960600719988, doi101086273307, doi101093oxfordjournalsafrafa100309, doi101098rspb20043047, doi101098rspl18870117, doi101098rstb19650003, doi101111j109636421998tb02533x, doi101111j155856461988tb02497x, doi101111j174966321940tb57047x, doi101111j216409471940tb00068x, doi101126science2562999, doi101127njgpa210199841, doi10120600030082200635301ydanpc20co2, doi1015259780520941434, doi1015468gbdyof, doi101671a1097, doi1023071292217, doi1023072408870, doi102475ajss319111253, doi105281zenodo16171435, doi105281zenodo16673433, doi105479si00963801361666197, doi105860choice325663, doi105860choice393984, openalexw1535663436, openalexw1574544995, openalexw225597919, openalexw2310875238, openalexw2603335639, openalexw2894525608, openalexw3215057009, openalexw616953834, owen2015monograph, padian1989presence"
}

A fossil discovery in the mid-Cretaceous Blackleaf Formation of southwest Montana, USA, has yielded the first trace and body fossil evidence of burrowing behaviour in a dinosaur. Skeletal remains of an adult and two juveniles of Oryctodromeus cubicularis gen. et sp. nov. a new species of hypsilophodont-grade dinosaur, were found in the expanded distal chamber of a sediment-filled burrow. Correspondence between burrow and adult dimensions supports Oryctodromeus as the burrow maker. Additionally, Oryctodromeus exhibits features of the snout, shoulder girdle and pelvis consistent with digging habits while retaining cursorial hindlimb proportions. Association of adult and young within a terminal chamber provides definitive evidence of extensive parental care in the Dinosauria. As with modern vertebrate cursors that dig, burrowing in Oryctodromeus may have been an important adaptation for the rearing of young. Burrowing also represents a mechanism by which small dinosaurs may have exploited the extreme environments of polar latitudes, deserts and high mountain areas. The ability among dinosaurs to find or make shelter may contradict some scenarios of the Cretaceous-Paleogene impact event. Burrowing habits expand the known range of nonavian dinosaur behaviours and suggest that the cursorial ancestry of dinosaurs did not fully preclude the evolution of different functional regimes, such as fossoriality.

@article{doi101098rspb20060443,
    author = "Varricchio, David J. and Martin, Anthony J. and Katsura, Yoshihiro",
    title = "First trace and body fossil evidence of a burrowing, denning dinosaur",
    year = "2007",
    journal = "Proceedings of the Royal Society B Biological Sciences",
    abstract = "A fossil discovery in the mid-Cretaceous Blackleaf Formation of southwest Montana, USA, has yielded the first trace and body fossil evidence of burrowing behaviour in a dinosaur. Skeletal remains of an adult and two juveniles of Oryctodromeus cubicularis gen. et sp. nov. a new species of hypsilophodont-grade dinosaur, were found in the expanded distal chamber of a sediment-filled burrow. Correspondence between burrow and adult dimensions supports Oryctodromeus as the burrow maker. Additionally, Oryctodromeus exhibits features of the snout, shoulder girdle and pelvis consistent with digging habits while retaining cursorial hindlimb proportions. Association of adult and young within a terminal chamber provides definitive evidence of extensive parental care in the Dinosauria. As with modern vertebrate cursors that dig, burrowing in Oryctodromeus may have been an important adaptation for the rearing of young. Burrowing also represents a mechanism by which small dinosaurs may have exploited the extreme environments of polar latitudes, deserts and high mountain areas. The ability among dinosaurs to find or make shelter may contradict some scenarios of the Cretaceous-Paleogene impact event. Burrowing habits expand the known range of nonavian dinosaur behaviours and suggest that the cursorial ancestry of dinosaurs did not fully preclude the evolution of different functional regimes, such as fossoriality.",
    url = "https://doi.org/10.1098/rspb.2006.0443",
    doi = "10.1098/rspb.2006.0443",
    openalex = "W2159630773",
    references = "doi101038282296a0, doi101038385247a0, doi101126science28454232137, doi1011300016760619931050129cop23co2, doi101130spe216p1, doi101353book59141, doi1016710272463420040240555gisdap20co2, doi102307622963, openalexw1968568170, openalexw1996683265, openalexw225597919, openalexw2603335639"
}

@article{lee2007bone,
    author = "Lee, AH",
    title = "Bone Microstructure Reflects Evolution of Large Size in Horned Dinosaurs",
    year = "2007",
    journal = "Microscopy and Microanalysis",
    url = "https://doi.org/10.1017/s1431927607078658",
    doi = "10.1017/s1431927607078658",
    number = "S02",
    openalex = "W2065749185",
    volume = "13"
}

Jaw muscles are key components of the head and critical to testing hypotheses of soft-tissue homology, skull function, and evolution. Dinosaurs evolved an extraordinary diversity of cranial forms adapted to a variety of feeding behaviors. However, disparate evolutionary transformations in head shape and function among dinosaurs and their living relatives, birds and crocodylians, impair straightforward reconstructions of muscles, and other important cephalic soft tissues. This study presents the osteological correlates and inferred soft tissue anatomy of the jaw muscles and relevant neurovasculature in the temporal region of the dinosaur head. Hypotheses of jaw muscle homology were tested across a broad range archosaur and sauropsid taxa to more accurately infer muscle attachments in the adductor chambers of non-avian dinosaurs. Many dinosaurs likely possessed m. levator pterygoideus, a trait shared with lepidosaurs but not extant archosaurs. Several major clades of dinosaurs (e.g., Ornithopoda, Ceratopsidae, Sauropoda) eliminated the epipterygoid, thus impacting interpretations of m. pseudotemporalis profundus. M. pseudotemporalis superficialis most likely attached to the caudoventral surface of the laterosphenoid, a trait shared with extant archosaurs. Although mm. adductor mandibulae externus profundus and medialis likely attached to the caudal half of the dorsotemporal fossa and coronoid process, clear osteological correlates separating the individual bellies are rare. Most dinosaur clades possess osteological correlates indicative of a pterygoideus ventralis muscle that attaches to the lateral surface of the mandible, although the muscle may have extended as far as the jugal in some taxa (e.g., hadrosaurs, tyrannosaurs). The cranial and mandibular attachments of mm adductor mandibulae externus superficialis and adductor mandibulae posterior were consistent across all taxa studied. These new data greatly increase the interpretive resolution of head anatomy in dinosaurs and provide the anatomical foundation necessary for future analyses of skull function and evolution in an important vertebrate clade.

@article{doi101002ar20982,
    author = "Holliday, Casey M.",
    title = "New Insights Into Dinosaur Jaw Muscle Anatomy",
    year = "2009",
    journal = "The Anatomical Record",
    abstract = "Jaw muscles are key components of the head and critical to testing hypotheses of soft-tissue homology, skull function, and evolution. Dinosaurs evolved an extraordinary diversity of cranial forms adapted to a variety of feeding behaviors. However, disparate evolutionary transformations in head shape and function among dinosaurs and their living relatives, birds and crocodylians, impair straightforward reconstructions of muscles, and other important cephalic soft tissues. This study presents the osteological correlates and inferred soft tissue anatomy of the jaw muscles and relevant neurovasculature in the temporal region of the dinosaur head. Hypotheses of jaw muscle homology were tested across a broad range archosaur and sauropsid taxa to more accurately infer muscle attachments in the adductor chambers of non-avian dinosaurs. Many dinosaurs likely possessed m. levator pterygoideus, a trait shared with lepidosaurs but not extant archosaurs. Several major clades of dinosaurs (e.g., Ornithopoda, Ceratopsidae, Sauropoda) eliminated the epipterygoid, thus impacting interpretations of m. pseudotemporalis profundus. M. pseudotemporalis superficialis most likely attached to the caudoventral surface of the laterosphenoid, a trait shared with extant archosaurs. Although mm. adductor mandibulae externus profundus and medialis likely attached to the caudal half of the dorsotemporal fossa and coronoid process, clear osteological correlates separating the individual bellies are rare. Most dinosaur clades possess osteological correlates indicative of a pterygoideus ventralis muscle that attaches to the lateral surface of the mandible, although the muscle may have extended as far as the jugal in some taxa (e.g., hadrosaurs, tyrannosaurs). The cranial and mandibular attachments of mm adductor mandibulae externus superficialis and adductor mandibulae posterior were consistent across all taxa studied. These new data greatly increase the interpretive resolution of head anatomy in dinosaurs and provide the anatomical foundation necessary for future analyses of skull function and evolution in an important vertebrate clade.",
    url = "https://doi.org/10.1002/ar.20982",
    doi = "10.1002/ar.20982",
    openalex = "W2082845355",
    references = "crossref1997the, doi101002ar20794, doi101002jmor10018, doi101002jmor10470, doi101017s1477201907002271, doi101038nature01342, doi101038nature02898, doi10108002724634199710011027, doi101098rspb20042986, doi101111j109636422001tb01314x, doi101111j155856461966tb03367x, doi101126science28454232137, doi1023072413454, doi10230730135049, doi102475ajss425149387, doi105281zenodo16171435, doi105860choice326223, openalexw3184837389"
}

Dinosaur behaviour has little legacy in the fossil record and the rarity of fossil soft tissues makes it difficult to evaluate.Indirect evidence from bonebeds, trackways, nesting traces and in-group comparisons with extant Archosauria suggests that the only substantive arguments to be made for dinosaur sociality concern cranial ornamentation and herding behaviour.There is currently no reliable method to determine gender from skeletal remains.Dinosaur reproductive anatomy was a unique combination of crocodilian and avian characters and extant models indicate that dinosaurs copulated using a reptilian 'leg over back' posture.Reliable evidence for post-hatching care in dinosaurs is lacking and extant archosaurs yield little insight.A hypothesis is proposed that for the majority of dinosaurs there was no post-hatching care provided which would have allowed adults energy acquisition that would otherwise have been required for defence and provisioning to be redirected towards growth and increased fecundity, both traits for which there is fossil evidence.Arguments suggesting that the more advanced aspects of extant avian care boasting an explicit coelurosaurian theropod origin are rejected as these behaviours appear unique to the Neornithes.Three ancestral care hypotheses are tested and none conform in a satisfactory manner with body fossil and ichnological evidence.

@article{doi10108008912960903450505,
    author = "Isles, Timothy E.",
    title = "The socio-sexual behaviour of extant archosaurs: implications for understanding dinosaur behaviour",
    year = "2009",
    journal = "Historical Biology",
    abstract = "Dinosaur behaviour has little legacy in the fossil record and the rarity of fossil soft tissues makes it difficult to evaluate.Indirect evidence from bonebeds, trackways, nesting traces and in-group comparisons with extant Archosauria suggests that the only substantive arguments to be made for dinosaur sociality concern cranial ornamentation and herding behaviour.There is currently no reliable method to determine gender from skeletal remains.Dinosaur reproductive anatomy was a unique combination of crocodilian and avian characters and extant models indicate that dinosaurs copulated using a reptilian 'leg over back' posture.Reliable evidence for post-hatching care in dinosaurs is lacking and extant archosaurs yield little insight.A hypothesis is proposed that for the majority of dinosaurs there was no post-hatching care provided which would have allowed adults energy acquisition that would otherwise have been required for defence and provisioning to be redirected towards growth and increased fecundity, both traits for which there is fossil evidence.Arguments suggesting that the more advanced aspects of extant avian care boasting an explicit coelurosaurian theropod origin are rejected as these behaviours appear unique to the Neornithes.Three ancestral care hypotheses are tested and none conform in a satisfactory manner with body fossil and ichnological evidence.",
    url = "https://doi.org/10.1080/08912960903450505",
    doi = "10.1080/08912960903450505",
    openalex = "W2088920978",
    references = "crossref1997the, doi1010160022519371901895, doi1010160022519375901113, doi101038262207a0, doi101126science327542, doi101139z84267, doi1015159780691206981, doi1015159780691207209, doi1015159780691207278, doi101537ase188722495, doi1023072874, doi102307jctvs32ssj, doi105962bhltitle27468, seymour1976dinosaurs"
}

Palaeobiodiversity analysis underpins macroevolutionary investigations, allowing identification of mass extinctions and adaptive radiations. However, recent large-scale studies on marine invertebrates indicate that geological factors play a central role in moulding the shape of diversity curves and imply that many features of such curves represent sampling artefacts, rather than genuine evolutionary events. In order to test whether similar biases affect diversity estimates for terrestrial taxa, we compiled genus-richness estimates for three Mesozoic dinosaur clades (Ornithischia, Sauropodomorpha and Theropoda). Linear models of expected genus richness were constructed for each clade, using the number of dinosaur-bearing formations available through time as a proxy for the amount of fossiliferous rock outcrop. Modelled diversity estimates were then compared with observed patterns. Strong statistically robust correlations demonstrate that almost all aspects of ornithischian and theropod diversity curves can be explained by geological megabiases, whereas the sauropodomorph record diverges from modelled predictions and may be a stronger contender for identifying evolutionary signals. In contrast to other recent studies, we identify a marked decline in dinosaur genus richness during the closing stages of the Cretaceous Period, indicating that the clade decreased in diversity for several million years prior to the final extinction of non-avian dinosaurs at the Cretaceous-Palaeocene boundary.

@article{doi101098rspb20090352,
    author = "Barrett, Paul M. and McGowan, Alistair J. and Page, Victoria",
    title = "Dinosaur diversity and the rock record",
    year = "2009",
    journal = "Proceedings of the Royal Society B Biological Sciences",
    abstract = "Palaeobiodiversity analysis underpins macroevolutionary investigations, allowing identification of mass extinctions and adaptive radiations. However, recent large-scale studies on marine invertebrates indicate that geological factors play a central role in moulding the shape of diversity curves and imply that many features of such curves represent sampling artefacts, rather than genuine evolutionary events. In order to test whether similar biases affect diversity estimates for terrestrial taxa, we compiled genus-richness estimates for three Mesozoic dinosaur clades (Ornithischia, Sauropodomorpha and Theropoda). Linear models of expected genus richness were constructed for each clade, using the number of dinosaur-bearing formations available through time as a proxy for the amount of fossiliferous rock outcrop. Modelled diversity estimates were then compared with observed patterns. Strong statistically robust correlations demonstrate that almost all aspects of ornithischian and theropod diversity curves can be explained by geological megabiases, whereas the sauropodomorph record diverges from modelled predictions and may be a stronger contender for identifying evolutionary signals. In contrast to other recent studies, we identify a marked decline in dinosaur genus richness during the closing stages of the Cretaceous Period, indicating that the clade decreased in diversity for several million years prior to the final extinction of non-avian dinosaurs at the Cretaceous-Palaeocene boundary.",
    url = "https://doi.org/10.1098/rspb.2009.0352",
    doi = "10.1098/rspb.2009.0352",
    openalex = "W2148963181",
    references = "doi101017s1477201907002271, doi101073pnas0606028103, doi10108008912960600719988, doi105860choice435907, smith2007marine"
}

Interpreting key ecological parameters, such as diet, of extinct organisms without the benefit of direct observation or explicit fossil evidence poses a formidable challenge for paleobiological studies. To date, dietary categorizations of extinct taxa are largely generated by means of modern analogs; however, for many species the method is subject to considerable ambiguity. Here we present a refined approach for assessing trophic habits in fossil taxa and apply the method to coelurosaurian dinosaurs--a clade for which diet is particularly controversial. Our findings detect 21 morphological features that exhibit statistically significant correlations with extrinsic fossil evidence of coelurosaurian herbivory, such as stomach contents and a gastric mill. These traits represent quantitative, extrinsically founded proxies for identifying herbivorous ecomorphology in fossils and are robust despite uncertainty in phylogenetic relationships among major coelurosaurian subclades. The distribution of these features suggests that herbivory was widespread among coelurosaurians, with six major subclades displaying morphological evidence of the diet, and that contrary to previous thought, hypercarnivory was relatively rare and potentially secondarily derived. Given the potential for repeated, independent evolution of herbivory in Coelurosauria, we also test for repetitive patterns in the appearance of herbivorous traits within sublineages using rank concordance analysis. We find evidence for a common succession of increasing specialization to herbivory in the subclades Ornithomimosauria and Oviraptorosauria, perhaps underlain by intrinsic functional and/or developmental constraints, as well as evidence indicating that the early evolution of a beak in coelurosaurians correlates with an herbivorous diet.

@article{doi101073pnas1011924108,
    author = "Zanno, Lindsay E. and Makovicky, Peter J.",
    title = "Herbivorous ecomorphology and specialization patterns in theropod dinosaur evolution",
    year = "2010",
    journal = "Proceedings of the National Academy of Sciences",
    abstract = "Interpreting key ecological parameters, such as diet, of extinct organisms without the benefit of direct observation or explicit fossil evidence poses a formidable challenge for paleobiological studies. To date, dietary categorizations of extinct taxa are largely generated by means of modern analogs; however, for many species the method is subject to considerable ambiguity. Here we present a refined approach for assessing trophic habits in fossil taxa and apply the method to coelurosaurian dinosaurs--a clade for which diet is particularly controversial. Our findings detect 21 morphological features that exhibit statistically significant correlations with extrinsic fossil evidence of coelurosaurian herbivory, such as stomach contents and a gastric mill. These traits represent quantitative, extrinsically founded proxies for identifying herbivorous ecomorphology in fossils and are robust despite uncertainty in phylogenetic relationships among major coelurosaurian subclades. The distribution of these features suggests that herbivory was widespread among coelurosaurians, with six major subclades displaying morphological evidence of the diet, and that contrary to previous thought, hypercarnivory was relatively rare and potentially secondarily derived. Given the potential for repeated, independent evolution of herbivory in Coelurosauria, we also test for repetitive patterns in the appearance of herbivorous traits within sublineages using rank concordance analysis. We find evidence for a common succession of increasing specialization to herbivory in the subclades Ornithomimosauria and Oviraptorosauria, perhaps underlain by intrinsic functional and/or developmental constraints, as well as evidence indicating that the early evolution of a beak in coelurosaurians correlates with an herbivorous diet.",
    url = "https://doi.org/10.1073/pnas.1011924108",
    doi = "10.1073/pnas.1011924108",
    openalex = "W2133829099",
    references = "doi10103831635, doi101038nature00930, doi101038nature08322, doi10108008912960600719988, doi101098rspb19940006, doi101111j1469185x201000137x, doi101126science1161833, doi101126science13334591105, doi101139e03011, doi101139e72031, doi101159000156416, doi1023072285423, doi105281zenodo1040385, doi105860choice326223, doi105860choice392183, openalexw2097385721, openalexw2611511275"
}

The herbivorous sauropod dinosaurs of the Jurassic and Cretaceous periods were the largest terrestrial animals ever, surpassing the largest herbivorous mammals by an order of magnitude in body mass. Several evolutionary lineages among Sauropoda produced giants with body masses in excess of 50 metric tonnes by conservative estimates. With body mass increase driven by the selective advantages of large body size, animal lineages will increase in body size until they reach the limit determined by the interplay of bauplan, biology, and resource availability. There is no evidence, however, that resource availability and global physicochemical parameters were different enough in the Mesozoic to have led to sauropod gigantism.

@article{doi101111j1469185x201000137x,
    author = "Sander, P. Martin and Christian, Andreas and Clauß, Marcus and Fechner, Regina and Gee, Carole T. and Griebeler, Eva-Maria and Gunga, Hanns‐Christian and Hummel, Jürgen and Mallison, Heinrich and Perry, Steven F. and Preuschoft, Holger and Rauhut, Oliver W. M. and Remes, Kristian and Tütken, Thomas and Wings, Oliver and Witzel, U.",
    title = "Biology of the sauropod dinosaurs: the evolution of gigantism",
    year = "2010",
    journal = "Biological reviews/Biological reviews of the Cambridge Philosophical Society",
    abstract = "The herbivorous sauropod dinosaurs of the Jurassic and Cretaceous periods were the largest terrestrial animals ever, surpassing the largest herbivorous mammals by an order of magnitude in body mass. Several evolutionary lineages among Sauropoda produced giants with body masses in excess of 50 metric tonnes by conservative estimates. With body mass increase driven by the selective advantages of large body size, animal lineages will increase in body size until they reach the limit determined by the interplay of bauplan, biology, and resource availability. There is no evidence, however, that resource availability and global physicochemical parameters were different enough in the Mesozoic to have led to sauropod gigantism.",
    url = "https://doi.org/10.1111/j.1469-185x.2010.00137.x",
    doi = "10.1111/j.1469-185x.2010.00137.x",
    openalex = "W2090710319",
    references = "amiot2006oxygen, christiansen2004mass, crossref1998encyclopedia, doi101002jez513, doi1010079789400904095, doi101016jpalaeo200901002, doi101016jtree200508012, doi101017cbo9780511565441, doi101017cbo9780511608551, doi101017cbo9781139167826, doi101017s0094837300009866, doi101017s0094837300021321, doi101017s1464793101005735, doi101021j150446a008, doi101038262207a0, doi101038344858a0, doi10103835086558, doi101046j10963642200200029x, doi101073pnas0708903105, doi101073pnas251548698, doi10108002724634199410011538, doi10108002724634199510011575, doi10108002724634199810011115, doi10108002724634199910011178, doi101098rsbl20070254, doi101098rspb20080715, doi101098rstb19950125, doi101111j109636421985tb00871x, doi101111j109636421998tb00569x, doi101111j146979981985tb04915x, doi101126science1118806, doi101139e93176, doi101146annurevecolsys36102003152631, doi101146annureves26110195002305, doi101242jeb029009, doi101371journalpone0001230, doi101371journalpone0006924, doi1015159781400881376, doi101525california97805202420980030015, doi101525california97805202420980030031, doi101525california97805202462320010001, doi1016660094837320000260466lhotts20co2, doi1016660094837320030290105dbttoo20co2, doi1016660094837320080340247ositlb20co2, doi1016710272463420000200115lbhoth20co2, doi1022179revmacn7344, doi1023072407154, doi1023073889325, doi102475ajss319111253, doi10560219780801881206, doi105860choice271523, doi105860choice304997, doi105860choice326223, doi105860choice353642, doi105860choice490282, martinsander2006bone, openalexw1025856234, openalexw114509570, openalexw1504554173, openalexw1534857865, openalexw1558456135, openalexw1585246501, openalexw1607828269, openalexw2318111898, openalexw2618301958, openalexw2983381470, openalexw3015256845, openalexw575222456, seymour1976dinosaurs"
}

BACKGROUND: During much of the Late Cretaceous, a shallow, epeiric sea divided North America into eastern and western landmasses. The western landmass, known as Laramidia, although diminutive in size, witnessed a major evolutionary radiation of dinosaurs. Other than hadrosaurs (duck-billed dinosaurs), the most common dinosaurs were ceratopsids (large-bodied horned dinosaurs), currently known only from Laramidia and Asia. Remarkably, previous studies have postulated the occurrence of latitudinally arrayed dinosaur "provinces," or "biomes," on Laramidia. Yet this hypothesis has been challenged on multiple fronts and has remained poorly tested. METHODOLOGY/PRINCIPAL FINDINGS: Here we describe two new, co-occurring ceratopsids from the Upper Cretaceous Kaiparowits Formation of Utah that provide the strongest support to date for the dinosaur provincialism hypothesis. Both pertain to the clade of ceratopsids known as Chasmosaurinae, dramatically increasing representation of this group from the southern portion of the Western Interior Basin of North America. Utahceratops gettyi gen. et sp. nov.-characterized by short, rounded, laterally projecting supraorbital horncores and an elongate frill with a deep median embayment-is recovered as the sister taxon to Pentaceratops sternbergii from the late Campanian of New Mexico. Kosmoceratops richardsoni gen. et sp. nov.-characterized by elongate, laterally projecting supraorbital horncores and a short, broad frill adorned with ten well developed hooks-has the most ornate skull of any known dinosaur and is closely allied to Chasmosaurus irvinensis from the late Campanian of Alberta. CONCLUSIONS/SIGNIFICANCE: Considered in unison, the phylogenetic, stratigraphic, and biogeographic evidence documents distinct, co-occurring chasmosaurine taxa north and south on the diminutive landmass of Laramidia. The famous Triceratops and all other, more nested chasmosaurines are postulated as descendants of forms previously restricted to the southern portion of Laramidia. Results further suggest the presence of latitudinally arrayed evolutionary centers of endemism within chasmosaurine ceratopsids during the late Campanian, the first documented occurrence of intracontinental endemism within dinosaurs.

@article{doi101371journalpone0012292,
    author = "Sampson, Scott D. and Loewen, Mark A. and Farke, Andrew A. and Roberts, Eric M. and Forster, Catherine A. and Smith, Joshua A. and Titus, Alan L.",
    title = "New Horned Dinosaurs from Utah Provide Evidence for Intracontinental Dinosaur Endemism",
    year = "2010",
    journal = "PLoS ONE",
    abstract = {BACKGROUND: During much of the Late Cretaceous, a shallow, epeiric sea divided North America into eastern and western landmasses. The western landmass, known as Laramidia, although diminutive in size, witnessed a major evolutionary radiation of dinosaurs. Other than hadrosaurs (duck-billed dinosaurs), the most common dinosaurs were ceratopsids (large-bodied horned dinosaurs), currently known only from Laramidia and Asia. Remarkably, previous studies have postulated the occurrence of latitudinally arrayed dinosaur "provinces," or "biomes," on Laramidia. Yet this hypothesis has been challenged on multiple fronts and has remained poorly tested. METHODOLOGY/PRINCIPAL FINDINGS: Here we describe two new, co-occurring ceratopsids from the Upper Cretaceous Kaiparowits Formation of Utah that provide the strongest support to date for the dinosaur provincialism hypothesis. Both pertain to the clade of ceratopsids known as Chasmosaurinae, dramatically increasing representation of this group from the southern portion of the Western Interior Basin of North America. Utahceratops gettyi gen. et sp. nov.-characterized by short, rounded, laterally projecting supraorbital horncores and an elongate frill with a deep median embayment-is recovered as the sister taxon to Pentaceratops sternbergii from the late Campanian of New Mexico. Kosmoceratops richardsoni gen. et sp. nov.-characterized by elongate, laterally projecting supraorbital horncores and a short, broad frill adorned with ten well developed hooks-has the most ornate skull of any known dinosaur and is closely allied to Chasmosaurus irvinensis from the late Campanian of Alberta. CONCLUSIONS/SIGNIFICANCE: Considered in unison, the phylogenetic, stratigraphic, and biogeographic evidence documents distinct, co-occurring chasmosaurine taxa north and south on the diminutive landmass of Laramidia. The famous Triceratops and all other, more nested chasmosaurines are postulated as descendants of forms previously restricted to the southern portion of Laramidia. Results further suggest the presence of latitudinally arrayed evolutionary centers of endemism within chasmosaurine ceratopsids during the late Campanian, the first documented occurrence of intracontinental endemism within dinosaurs.},
    url = "https://doi.org/10.1371/journal.pone.0012292",
    doi = "10.1371/journal.pone.0012292",
    openalex = "W2027103072",
    references = "crossref1998encyclopedia, doi101007978140206754912413, doi101016jcretres200501002, doi101016jsedgeo200610001, doi101038358059a0, doi101086285558, doi101098rspl18870117, doi101111j10960031200800217x, doi101126science13234331023, doi101126science24348951145, doi101139e93016, doi105860choice353642, doi105860choice435902, lehman1987late, openalexw2611511275, openalexw3206657856, openalexw3215057009"
}

Theropod dinosaurs, an iconic clade of fossil species including Tyrannosaurus and Velociraptor, developed a great diversity of body size, skull form and feeding habits over their 160+ million year evolutionary history. Here, we utilize geometric morphometrics to study broad patterns in theropod skull shape variation and compare the distribution of taxa in cranial morphospace (form) to both phylogeny and quantitative metrics of biting behaviour (function). We find that theropod skulls primarily differ in relative anteroposterior length and snout depth and to a lesser extent in orbit size and depth of the cheek region, and oviraptorosaurs deviate most strongly from the "typical" and ancestral theropod morphologies. Noncarnivorous taxa generally fall out in distinct regions of morphospace and exhibit greater overall disparity than carnivorous taxa, whereas large-bodied carnivores independently converge on the same region of morphospace. The distribution of taxa in morphospace is strongly correlated with phylogeny but only weakly correlated with functional biting behaviour. These results imply that phylogeny, not biting function, was the major determinant of theropod skull shape.

@article{doi101111j14209101201102427x,
    author = "Brusatte, Stephen L. and Sakamoto, Manabu and Montanari, Shaena and SMITH, W. E. H. HARCOURT",
    title = "The evolution of cranial form and function in theropod dinosaurs: insights from geometric morphometrics",
    year = "2011",
    journal = "Journal of Evolutionary Biology",
    abstract = {Theropod dinosaurs, an iconic clade of fossil species including Tyrannosaurus and Velociraptor, developed a great diversity of body size, skull form and feeding habits over their 160+ million year evolutionary history. Here, we utilize geometric morphometrics to study broad patterns in theropod skull shape variation and compare the distribution of taxa in cranial morphospace (form) to both phylogeny and quantitative metrics of biting behaviour (function). We find that theropod skulls primarily differ in relative anteroposterior length and snout depth and to a lesser extent in orbit size and depth of the cheek region, and oviraptorosaurs deviate most strongly from the "typical" and ancestral theropod morphologies. Noncarnivorous taxa generally fall out in distinct regions of morphospace and exhibit greater overall disparity than carnivorous taxa, whereas large-bodied carnivores independently converge on the same region of morphospace. The distribution of taxa in morphospace is strongly correlated with phylogeny but only weakly correlated with functional biting behaviour. These results imply that phylogeny, not biting function, was the major determinant of theropod skull shape.},
    url = "https://doi.org/10.1111/j.1420-9101.2011.02427.x",
    doi = "10.1111/j.1420-9101.2011.02427.x",
    openalex = "W1903329682",
    references = "doi101002ar20982, doi101016c20100662092, doi101017cbo9780511573064, doi101073pnas1006970107, doi10108002724634199710011027, doi101086284325, doi101093sysbiosyp106, doi101111j001438202003tb00285x, doi101111j155856461998tb02006x, doi101111j17550998201002924x, doi101146annurevearth35031306140104, doi1016710272463420020220766tehits20co2, doi1023072534038, doi105281zenodo1038220"
}

Cranial ornamentation is widespread throughout the extinct non-avialian Ornithodira, being present throughout Pterosauria, Ornithischia and Saurischia. Ornaments take many forms, and can be composed of at least a dozen different skull bones, indicating multiple origins. Many of these crests serve no clear survival function and it has been suggested that their primary use was for species recognition or sexual display. The distribution within Ornithodira and the form and position of these crests suggest sexual selection as a key factor, although the role of the latter has often been rejected on the grounds of an apparent lack of sexual dimorphism in many species. Surprisingly, the phenomenon of mutual sexual selection – where both males and females are ornamented and both select mates – has been ignored in research on fossil ornithodirans, despite a rich history of research and frequent expression in modern birds. Here, we review the available evidence for the functions of ornithodiran cranial crests and conclude that mutual sexual selection presents a valid hypothesis for their presence and distribution. The integration of mutual sexual selection into future studies is critical to our understanding of ornithodiran ecology, evolution and particularly questions regarding sexual dimorphism.

@article{doi101111j15023931201100300x,
    author = "Hone, David W. E. and Naish, Darren and Cuthill, Innes C.",
    title = "Does mutual sexual selection explain the evolution of head crests in pterosaurs and dinosaurs?",
    year = "2011",
    journal = "Lethaia",
    abstract = "Cranial ornamentation is widespread throughout the extinct non-avialian Ornithodira, being present throughout Pterosauria, Ornithischia and Saurischia. Ornaments take many forms, and can be composed of at least a dozen different skull bones, indicating multiple origins. Many of these crests serve no clear survival function and it has been suggested that their primary use was for species recognition or sexual display. The distribution within Ornithodira and the form and position of these crests suggest sexual selection as a key factor, although the role of the latter has often been rejected on the grounds of an apparent lack of sexual dimorphism in many species. Surprisingly, the phenomenon of mutual sexual selection – where both males and females are ornamented and both select mates – has been ignored in research on fossil ornithodirans, despite a rich history of research and frequent expression in modern birds. Here, we review the available evidence for the functions of ornithodiran cranial crests and conclude that mutual sexual selection presents a valid hypothesis for their presence and distribution. The integration of mutual sexual selection into future studies is critical to our understanding of ornithodiran ecology, evolution and particularly questions regarding sexual dimorphism.",
    url = "https://doi.org/10.1111/j.1502-3931.2011.00300.x",
    doi = "10.1111/j.1502-3931.2011.00300.x",
    openalex = "W1945322031",
    references = "colbert1948evolution, doi101006bijl19960043, doi1010160031018272900491, doi101016s0169534799018005, doi10103712293000, doi10108008912960903450505, doi101093acprofoso97801985286090010001, doi101098rspb20060443, doi101111j15023931200900187x, doi101139e05044, doi101139e09050, doi10120600030082200635301ydanpc20co2, doi101371journalpone0007626, doi101537ase188722495, doi1016660094837320040300253chopom20co2, doi1023071292217, doi10432497813151292667, doi105962bhltitle121292, doi105962bhltitle2092, openalexw1550095290, openalexw2259418280, stevens2006binocular"
}

List of Contributors Preface List of Institutional Abbreviations Introduction 1. Sauropod Biology and the Evolution of Gigantism: What Do We Know? / Marcus Clauss Part 1. Nutrition 2. Sauropod Feeding and Digestive Physiology / Jurgen Hummel and Marcus Clauss 3. Dietary Options for the Sauropod Dinosaurs from an Integrated Botanical and Paleobotanical Perspective / Carole T. Gee 4. The Diet of Sauropod Dinosaurs: Implications of Carbon Isotope Analysis on Teeth, Bones, and Plants / Thomas Tutken Part 2. Physiology 5. Structure and Function of the Sauropod Respiratory System / Steven F. Perry, Thomas Breuer, and Nadine Pajor 6. Reconstructing Body Volume and Surface Area of Dinosaurs Using Laser Scanning and Photogrammetry / Stefan Stoinski, Tim Suthau, and Hanns-Christian Gunga 7. Body Mass Estimation, Thermoregulation, and Cardiovascular Physiology of Large Sauropods / Bergita Ganse, Alexander Stahn, Stefan Stoinski, Tim Suthau, and Hanns-Christian Gunga Part 3. Construction 8. How to Get Big in the Mesozoic: The Evolution of the Sauropodomorph Body Plan / Oliver W. M. Rauhut, Regina Fechner, Kristian Remes, and Katrin Reis 9. Characterization of Sauropod Bone Structure / Maitena Dumont, Anke Pyzalla, Aleksander Kostka, and Andras Borbely 10. Finite Element Analyses and Virtual Syntheses of Biological Structures and Their Application to Sauropod Skulls / Ulrich Witzel, Julia Mannhardt, Rainer Goessling, Pascal de Micheli, and Holger Preuschoft 11. Walking with the Shoulder of Giants: Biomechanical Conditions in the Tetrapod Shoulder Girdle as a Basis for Sauropod Shoulder Reconstruction / Bianca Hohn 12. Why So Huge? Biomechanical Reasons for the Acquisition of Large Size in Sauropod and Theropod Dinosaurs / Holger Preuschoft, Bianca Hohn, Stefan Stoinski, and Ulrich Witzel 13. Plateosaurus in 3D: How CAD Models and Kinetic-Dynamic Modeling Bring an Extinct Animal to Life / Heinrich Mallison 14. Rearing Giants: Kinetic-Dynamic Modeling of Sauropod Bipedal and Tripodal Poses / Heinrich Mallison 15. Neck Posture in Sauropods / Andreas Christian and Gordon Dzemski Part 4. Growth 16. The Life Cycle of Sauropod Dinosaurs / Eva-Maria Griebeler and Jan Werner 17. Sauropod Bone Histology and Its Implications for Sauropod Biology / P. Martin Sander, Nicole Klein, Koen Stein, and Oliver Wings Part 5. Epilogue 18. Skeletal Reconstruction of Brachiosaurus brancai in the Museum fur Naturkunde, Berlin: Summarizing 70 Years of Sauropod Research / Kristian Remes, David M. Unwin, Nicole Klein, Wolf-Dieter Heinrich, and Oliver Hampe Appendix: Compilation of Published Body Mass Data for a Variety of Basal Sauropodomorphs and Sauropods Index

@article{doi105860choice490282,
    title = "Biology of the sauropod dinosaurs: understanding the life of giants",
    year = "2011",
    journal = "Choice Reviews Online",
    abstract = "List of Contributors Preface List of Institutional Abbreviations Introduction 1. Sauropod Biology and the Evolution of Gigantism: What Do We Know? / Marcus Clauss Part 1. Nutrition 2. Sauropod Feeding and Digestive Physiology / Jurgen Hummel and Marcus Clauss 3. Dietary Options for the Sauropod Dinosaurs from an Integrated Botanical and Paleobotanical Perspective / Carole T. Gee 4. The Diet of Sauropod Dinosaurs: Implications of Carbon Isotope Analysis on Teeth, Bones, and Plants / Thomas Tutken Part 2. Physiology 5. Structure and Function of the Sauropod Respiratory System / Steven F. Perry, Thomas Breuer, and Nadine Pajor 6. Reconstructing Body Volume and Surface Area of Dinosaurs Using Laser Scanning and Photogrammetry / Stefan Stoinski, Tim Suthau, and Hanns-Christian Gunga 7. Body Mass Estimation, Thermoregulation, and Cardiovascular Physiology of Large Sauropods / Bergita Ganse, Alexander Stahn, Stefan Stoinski, Tim Suthau, and Hanns-Christian Gunga Part 3. Construction 8. How to Get Big in the Mesozoic: The Evolution of the Sauropodomorph Body Plan / Oliver W. M. Rauhut, Regina Fechner, Kristian Remes, and Katrin Reis 9. Characterization of Sauropod Bone Structure / Maitena Dumont, Anke Pyzalla, Aleksander Kostka, and Andras Borbely 10. Finite Element Analyses and Virtual Syntheses of Biological Structures and Their Application to Sauropod Skulls / Ulrich Witzel, Julia Mannhardt, Rainer Goessling, Pascal de Micheli, and Holger Preuschoft 11. Walking with the Shoulder of Giants: Biomechanical Conditions in the Tetrapod Shoulder Girdle as a Basis for Sauropod Shoulder Reconstruction / Bianca Hohn 12. Why So Huge? Biomechanical Reasons for the Acquisition of Large Size in Sauropod and Theropod Dinosaurs / Holger Preuschoft, Bianca Hohn, Stefan Stoinski, and Ulrich Witzel 13. Plateosaurus in 3D: How CAD Models and Kinetic-Dynamic Modeling Bring an Extinct Animal to Life / Heinrich Mallison 14. Rearing Giants: Kinetic-Dynamic Modeling of Sauropod Bipedal and Tripodal Poses / Heinrich Mallison 15. Neck Posture in Sauropods / Andreas Christian and Gordon Dzemski Part 4. Growth 16. The Life Cycle of Sauropod Dinosaurs / Eva-Maria Griebeler and Jan Werner 17. Sauropod Bone Histology and Its Implications for Sauropod Biology / P. Martin Sander, Nicole Klein, Koen Stein, and Oliver Wings Part 5. Epilogue 18. Skeletal Reconstruction of Brachiosaurus brancai in the Museum fur Naturkunde, Berlin: Summarizing 70 Years of Sauropod Research / Kristian Remes, David M. Unwin, Nicole Klein, Wolf-Dieter Heinrich, and Oliver Hampe Appendix: Compilation of Published Body Mass Data for a Variety of Basal Sauropodomorphs and Sauropods Index",
    url = "https://doi.org/10.5860/choice.49-0282",
    doi = "10.5860/choice.49-0282",
    openalex = "W293512402",
    references = "amiot2006oxygen, christiansen2004mass, doi101002mmng200900004, doi1010160012825273900287, doi1010160031018275900279, doi1010160375650595000240, doi101016b9780126764604500081, doi101016jpalaeo200401006, doi101016jpalaeo200901002, doi101017cbo9780511608551, doi101017cbo9781139167826, doi101017s009483730000676x, doi101017s0094837300009866, doi101038229172a0, doi101038262207a0, doi10103835086558, doi101038nature00930, doi101038nature04633, doi101046j10963642200200029x, doi101073pnas251548698, doi101073pnas932514623, doi10108002724634199910011178, doi101111j1469185x201000137x, doi101111j146979981985tb04915x, doi101126science1138709, doi101242jeb02443, doi101525california97805202462320010001, doi1016660094837320000260734aaateo20co2, doi1016660094837320030290105dbttoo20co2, doi1016660094837320030290243vpasat20co2, doi1016660094837320080340247ositlb20co2, doi101666080251, doi1016710272463420020220766tehits20co2, doi1023071310735, doi1023073515313, doi104039ent912935, doi105860choice271523, doi105860choice324505, doi105962bhltitle118957, martinsander2006bone, openalexw1534857865, openalexw1558456135, openalexw1590241584, openalexw2473973115, openalexw2729191089, openalexw603337959, seymour1976dinosaurs"
}

PREFACE: James O. Farlow and M. K. Brett-Surman PART ONE: THE DISCOVERY OF DINOSAURS The Earliest Discoveries: William A. S. Sarjeant European Dinosaur Hunters: Hans-Dieter Sues North American Dinosaur Hunters: Edwin H. Colbert Asian Dinosaur Hunters: John R. Lavas Dinosaur Hunters of the Southern Continents: Thomas R. Holtz, Jr. PART TWO: THE STUDY OF DINOSAURS Hunting for Dinosaur Bones: David D. Gillette The Osteology of the Dinosaurs: Thomas R. Holtz, Jr. and M. K.Brett-Surman The Taxonomy and Systematics of the Dinosaurs: Thomas R. Holtz, Jr. and M. K. Brett-Surman Dinosaurs and Geologic Time: James O. Farlow The Scientific Study of Dinosaurs: Ralph E. Chapman Molecular Paleontology: Rationale and Techniques for the Study of Ancient Biomolecules: Mary Higby Schweitzer Dinosaurs as Museum Exhibits: Kenneth Carpenter Restoring Dinosaurs as Living Animals: Douglas Henderson PART THREE: THE GROUPS OF DINOSAURS Introduction: James O. Farlow and M. K. Brett-Surman Politics and Paleontology: Richard Owen and the Invention of Dinosaurs: Hugh Torrens Evolution of the Archosaurs: J. Michael Parrish Origin and Early Evolution of Dinosaurs: Michael J. Benton Theropods: Philip J. Currie Segnosaurs (Therezinosaurs): Teresa Maryanska Prosauropods: Jacques VanHeerden Sauropods: John S. McIntosh, M. K. Brett-Surman, and James O. Farlow Stegosaurs: Peter M. Galton Ankylosaurs: Kenneth Carpenter Marginocephalians: Catherine A. Forster and Paul C. Sereno Ornithopods: M. K. Brett-Surman PART FOUR: BIOLOGY OF THE DINOSAURS Land Plants as Food and Habitat in the Age of Dinosaurs: Bruce H. Tiffney What Did Dinosaurs Eat? Coprolites and Other Direct Evidence of Dinosaur Diets: Karen Chin Dinosaur Combat and Courtship: Scott Sampson Dinosaur Eggs: Karl F. Hirsch and Darla K. Zelenitsky How Dinosaurs Grew: R. E. H. Reid Engineering a Dinosaur: R. McN. Alexander Dinosaurian Paleopathology: Bruce M. Rothschild Dinosaurian Physiology: the Case for Intermediate Dinosaurs: R. E. H. Reid Oxygen Isotopes in Dinosaur Bone: Reese E. Barrick, Michael K. Stoskopf, and William J. Showers A Blueprint for Giants: Do Living Reptiles, Birds or Mammals Provide the Best Model for the Physiology of Large Dinosaurs? Frank V. Paladino, James R. Spotila, and Peter Dodson New Insights into the Metabolic Physiology of Dinosaurs: John Ruben, Andrew Leitch, Willem Hillenius, Nicholas Geist, and Terry Jones The Scientific Study of Dinosaur Footprints: James O. Farlow and Ralph E. Chapman The Paleoecological and Paleoenvironmental Utility of Dinosaur Tracks: Martin G. Lockley PART FIVE: DINOSAUR EVOLUTION IN THE CHANGING WORLD OF THE MESOZOIC ERA Biogeography for Dinosaurs: Ralph E. Molnar Major Groups of Non-Dinosaurian Vertebrates of the Mesozoic Era: Michael Morales Continental Tetrapods of the Early Mesozoic: Faunas and Faunal Changes: Hans-Dieter Sues Dinosaurian Faunas of the Later Mesozoic: Dale A. Russell and Jose F. Bonaparte The Extinction of the Dinosaurs: A Dialogue Between a Catastrophist and a Gradualist: Dale A. Russell and Peter Dodson PART SIX: DINOSAURS AND THE MEDIA Dinosaurs and the Media: Donald F. Glut and M. K. Brett-Surman APPENDIX: A CHRONOLOGICAL HISTORY OF DINOSAUR PALEONTOLOGY: M. K. Brett-Surman GLOSSARY CONTRIBUTORS INDEX

@book{openalexw1585246501,
    author = "Farlow, James O. and Brett-Surman, Michael K.",
    title = "The Complete Dinosaur",
    year = "2012",
    booktitle = "Opus: Research \& Creativity (Indiana University – Purdue University Fort Wayne)",
    abstract = "PREFACE: James O. Farlow and M. K. Brett-Surman PART ONE: THE DISCOVERY OF DINOSAURS The Earliest Discoveries: William A. S. Sarjeant European Dinosaur Hunters: Hans-Dieter Sues North American Dinosaur Hunters: Edwin H. Colbert Asian Dinosaur Hunters: John R. Lavas Dinosaur Hunters of the Southern Continents: Thomas R. Holtz, Jr. PART TWO: THE STUDY OF DINOSAURS Hunting for Dinosaur Bones: David D. Gillette The Osteology of the Dinosaurs: Thomas R. Holtz, Jr. and M. K.Brett-Surman The Taxonomy and Systematics of the Dinosaurs: Thomas R. Holtz, Jr. and M. K. Brett-Surman Dinosaurs and Geologic Time: James O. Farlow The Scientific Study of Dinosaurs: Ralph E. Chapman Molecular Paleontology: Rationale and Techniques for the Study of Ancient Biomolecules: Mary Higby Schweitzer Dinosaurs as Museum Exhibits: Kenneth Carpenter Restoring Dinosaurs as Living Animals: Douglas Henderson PART THREE: THE GROUPS OF DINOSAURS Introduction: James O. Farlow and M. K. Brett-Surman Politics and Paleontology: Richard Owen and the Invention of Dinosaurs: Hugh Torrens Evolution of the Archosaurs: J. Michael Parrish Origin and Early Evolution of Dinosaurs: Michael J. Benton Theropods: Philip J. Currie Segnosaurs (Therezinosaurs): Teresa Maryanska Prosauropods: Jacques VanHeerden Sauropods: John S. McIntosh, M. K. Brett-Surman, and James O. Farlow Stegosaurs: Peter M. Galton Ankylosaurs: Kenneth Carpenter Marginocephalians: Catherine A. Forster and Paul C. Sereno Ornithopods: M. K. Brett-Surman PART FOUR: BIOLOGY OF THE DINOSAURS Land Plants as Food and Habitat in the Age of Dinosaurs: Bruce H. Tiffney What Did Dinosaurs Eat? Coprolites and Other Direct Evidence of Dinosaur Diets: Karen Chin Dinosaur Combat and Courtship: Scott Sampson Dinosaur Eggs: Karl F. Hirsch and Darla K. Zelenitsky How Dinosaurs Grew: R. E. H. Reid Engineering a Dinosaur: R. McN. Alexander Dinosaurian Paleopathology: Bruce M. Rothschild Dinosaurian Physiology: the Case for Intermediate Dinosaurs: R. E. H. Reid Oxygen Isotopes in Dinosaur Bone: Reese E. Barrick, Michael K. Stoskopf, and William J. Showers A Blueprint for Giants: Do Living Reptiles, Birds or Mammals Provide the Best Model for the Physiology of Large Dinosaurs? Frank V. Paladino, James R. Spotila, and Peter Dodson New Insights into the Metabolic Physiology of Dinosaurs: John Ruben, Andrew Leitch, Willem Hillenius, Nicholas Geist, and Terry Jones The Scientific Study of Dinosaur Footprints: James O. Farlow and Ralph E. Chapman The Paleoecological and Paleoenvironmental Utility of Dinosaur Tracks: Martin G. Lockley PART FIVE: DINOSAUR EVOLUTION IN THE CHANGING WORLD OF THE MESOZOIC ERA Biogeography for Dinosaurs: Ralph E. Molnar Major Groups of Non-Dinosaurian Vertebrates of the Mesozoic Era: Michael Morales Continental Tetrapods of the Early Mesozoic: Faunas and Faunal Changes: Hans-Dieter Sues Dinosaurian Faunas of the Later Mesozoic: Dale A. Russell and Jose F. Bonaparte The Extinction of the Dinosaurs: A Dialogue Between a Catastrophist and a Gradualist: Dale A. Russell and Peter Dodson PART SIX: DINOSAURS AND THE MEDIA Dinosaurs and the Media: Donald F. Glut and M. K. Brett-Surman APPENDIX: A CHRONOLOGICAL HISTORY OF DINOSAUR PALEONTOLOGY: M. K. Brett-Surman GLOSSARY CONTRIBUTORS INDEX",
    openalex = "W1585246501",
    references = "chatterjee2013a, chinsamy1998polar, deklerk2000a, doi101002ar20982, doi101002ara10097, doi101002jmor10406, doi101007s0011400804883, doi1010160031018291900605, doi1010160034666781900695, doi101016jannpal200803002, doi101016jepsl200801015, doi101016jpalaeo201002025, doi101017cbo9780511608551, doi101017s0022336000018862, doi101017s0094837300007557, doi101017s0094837300016900, doi101017s0094837300021321, doi101038262207a0, doi101038307360a0, doi10103832884, doi101038359117a0, doi101038362709a0, doi101038368196a0, doi101038nature03635, doi101038nature10906, doi101046j14401738200300386x, doi10108002724634199810011086, doi10108002724634199910011125, doi10108008912960903503345, doi10108010420940802471027, doi101086284406, doi101086422766, doi101098rspb20060443, doi101111j10963642200600245x, doi101111j10963642200900631x, doi101111j1469185x200900107x, doi101111j150239311985tb00690x, doi101111j15023931200900187x, doi101126science1157704, doi101126science1180219, doi101126science172397867, doi101126science24248841403, doi101126science27352791204, doi101127njgpm19831983141, doi1011300091761319930210503pioatv23co2, doi101130g23452a1, doi101130spe40p1, doi101144001676492006032, doi101144gslsp20042280106, doi101146annurevearth040610133502, doi101146annurevearth28119, doi101146annurevgenet37110801143214, doi10120600030082200635301ydanpc20co2, doi1012066391, doi101353book59141, doi101371journalpone0012292, doi1016660094837320000260450fpindi20co2, doi1016660094837320050310291teafot20co2, doi1016690883135120030180286rpoumt20co2, doi1016710272463420020220593cvancf20co2, doi1016710272463420020220766tehits20co2, doi101671a11168, doi102110palo2007p07070r, doi1023071445147, doi1023073514548, doi102475ajss425149387, doi104202app20080049, doi105281zenodo13315375, doi105281zenodo16692311, doi105281zenodo3739898, doi105962p339375, fiorillo2004the, jacobsen1998feeding, lehman1987late, nelson1980counts, openalexw1550095290, openalexw1558456135, openalexw2163397885, openalexw2242116350, openalexw2506868775, pontzer2009biomechanics, russell2002synopsis, seymour1976dinosaurs, sloan1986gradual, stevens2006binocular, witmer1991biomechanics, woodward1910on"
}

@article{doi101007s0011401310630,
    author = "Wick, Steven L. and Lehman, Thomas M.",
    title = "A new ceratopsian dinosaur from the Javelina Formation (Maastrichtian) of West Texas and implications for chasmosaurine phylogeny",
    year = "2013",
    journal = "Die Naturwissenschaften",
    url = "https://doi.org/10.1007/s00114-013-1063-0",
    doi = "10.1007/s00114-013-1063-0",
    openalex = "W2052843387",
    references = "openalexw568618627"
}

A recent study proposed that incubation behaviour (i.e. type of parental care) in theropod dinosaurs can be inferred from an allometric analysis of clutch volume in extant birds. However, the study in question failed to account for factors known to affect egg and clutch size in living bird species. A new scaling analysis of avian clutch mass demonstrates that type of parental care cannot be distinguished by conventional allometry because of the confounding effects of phylogeny and hatchling maturity. Precociality of young but not paternal care in the theropod ancestors of birds is consistent with the available data.

@article{doi101098rsbl20130036,
    author = "Birchard, Geoffrey F. and Ruta, Marcello and Deeming, D. Charles",
    title = "Evolution of parental incubation behaviour in dinosaurs cannot be inferred from clutch mass in birds",
    year = "2013",
    journal = "Biology Letters",
    abstract = "A recent study proposed that incubation behaviour (i.e. type of parental care) in theropod dinosaurs can be inferred from an allometric analysis of clutch volume in extant birds. However, the study in question failed to account for factors known to affect egg and clutch size in living bird species. A new scaling analysis of avian clutch mass demonstrates that type of parental care cannot be distinguished by conventional allometry because of the confounding effects of phylogeny and hatchling maturity. Precociality of young but not paternal care in the theropod ancestors of birds is consistent with the available data.",
    url = "https://doi.org/10.1098/rsbl.2013.0036",
    doi = "10.1098/rsbl.2013.0036",
    openalex = "W2132117810",
    references = "doi10108008912960903450505, doi103184175815508x402482"
}

Ornithischian dinosaurs were primitively bipedal with forelimbs modified for grasping, but quadrupedalism evolved in the clade on at least three occasions independently. Outside of Ornithischia, quadrupedality from bipedal ancestors has only evolved on two other occasions, making this one of the rarest locomotory transitions in tetrapod evolutionary history. The osteological and myological changes associated with these transitions have only recently been documented, and the biomechanical consequences of these changes remain to be examined. Here, we review previous approaches to understanding locomotion in extinct animals, which can be broadly split into form-function approaches using analogy based on extant animals, limb-bone scaling, and computational approaches. We then carry out the first systematic attempt to quantify changes in locomotor muscle function in bipedal and quadrupedal ornithischian dinosaurs. Using three-dimensional computational modelling of the major pelvic locomotor muscle moment arms, we examine similarities and differences among individual taxa, between quadrupedal and bipedal taxa, and among taxa representing the three major ornithischian lineages (Thyreophora, Ornithopoda, Marginocephalia). Our results suggest that the ceratopsid Chasmosaurus and the ornithopod Hypsilophodon have relatively low moment arms for most muscles and most functions, perhaps suggesting poor locomotor performance in these taxa. Quadrupeds have higher abductor moment arms than bipeds, which we suggest is due to the overall wider bodies of the quadrupeds modelled. A peak in extensor moment arms at more extended hip angles and lower medial rotator moment arms in quadrupeds than in bipeds may be due to a more columnar hindlimb and loss of medial rotation as a form of lateral limb support in quadrupeds. We are not able to identify trends in moment arm evolution across Ornithischia as a whole, suggesting that the bipedal ancestry of ornithischians did not constrain the development of quadrupedal locomotion via a limited number of functional pathways. Functional anatomy appears to have had a greater effect on moment arms than phylogeny, and the differences identified between individual taxa and individual clades may relate to differences in locomotor performance required for living in different environments or for clade-specific behaviours.

@article{doi101111brv12071,
    author = "Maidment, Susannah C. R. and Bates, Karl T. and Falkingham, Peter and VanBuren, Collin S. and Arbour, Victoria M. and Barrett, Paul M.",
    title = "Locomotion in ornithischian dinosaurs: an assessment using three‐dimensional computational modelling",
    year = "2013",
    journal = "Biological reviews/Biological reviews of the Cambridge Philosophical Society",
    abstract = "Ornithischian dinosaurs were primitively bipedal with forelimbs modified for grasping, but quadrupedalism evolved in the clade on at least three occasions independently. Outside of Ornithischia, quadrupedality from bipedal ancestors has only evolved on two other occasions, making this one of the rarest locomotory transitions in tetrapod evolutionary history. The osteological and myological changes associated with these transitions have only recently been documented, and the biomechanical consequences of these changes remain to be examined. Here, we review previous approaches to understanding locomotion in extinct animals, which can be broadly split into form-function approaches using analogy based on extant animals, limb-bone scaling, and computational approaches. We then carry out the first systematic attempt to quantify changes in locomotor muscle function in bipedal and quadrupedal ornithischian dinosaurs. Using three-dimensional computational modelling of the major pelvic locomotor muscle moment arms, we examine similarities and differences among individual taxa, between quadrupedal and bipedal taxa, and among taxa representing the three major ornithischian lineages (Thyreophora, Ornithopoda, Marginocephalia). Our results suggest that the ceratopsid Chasmosaurus and the ornithopod Hypsilophodon have relatively low moment arms for most muscles and most functions, perhaps suggesting poor locomotor performance in these taxa. Quadrupeds have higher abductor moment arms than bipeds, which we suggest is due to the overall wider bodies of the quadrupeds modelled. A peak in extensor moment arms at more extended hip angles and lower medial rotator moment arms in quadrupeds than in bipeds may be due to a more columnar hindlimb and loss of medial rotation as a form of lateral limb support in quadrupeds. We are not able to identify trends in moment arm evolution across Ornithischia as a whole, suggesting that the bipedal ancestry of ornithischians did not constrain the development of quadrupedal locomotion via a limited number of functional pathways. Functional anatomy appears to have had a greater effect on moment arms than phylogeny, and the differences identified between individual taxa and individual clades may relate to differences in locomotor performance required for living in different environments or for clade-specific behaviours.",
    url = "https://doi.org/10.1111/brv.12071",
    doi = "10.1111/brv.12071",
    openalex = "W2133932331",
    references = "coombs1980swimming, doi101007s1126300701073, doi101080027246342011606857, doi101098rsbl20120263, doi101109tpami2009161, doi101126science17940791201, doi101130g23452a1, doi10114511419111141964, doi101152ajpregu19772335r243, doi101371journalpone0004591, doi101371journalpone0067182, doi1016660094837320000260450fpindi20co2, doi101666100041, doi104159harvard9780674184404, doi105860choice326223, doi105860choice392183, openalexw2183707334, openalexw2473973115, openalexw638862129"
}

Skeletal pneumaticity is found in the presacral vertebrae of most sauropod dinosaurs, but pneumaticity is much less common in the vertebrae of the tail. We describe previously unrecognized pneumatic fossae in the mid-caudal vertebrae of specimens of Giraffatitan and Apatosaurus. In both taxa, the most distal pneumatic vertebrae are separated from other pneumatic vertebrae by sequences of three to seven apneumatic vertebrae. Caudal pneumaticity is not prominent in most individuals of either of these taxa, and its unpredictable development means that it may be more widespread than previously recognised within Sauropoda and elsewhere in Saurischia. The erratic patterns of caudal pneumatization in Giraffatitan and Apatosaurus, including the pneumatic hiatuses, show that pneumatic diverticula were more broadly distributed in the bodies of the living animals than are their traces in the skeleton. Together with recently published evidence of cryptic diverticula--those that leave few or no skeletal traces--in basal sauropodomorphs and in pterosaurs, this is further evidence that pneumatic diverticula were widespread in ornithodirans, both across phylogeny and throughout anatomy.

@article{doi101371journalpone0078213,
    author = "Wedel, Mathew J. and Taylor, Michael P.",
    title = "Caudal Pneumaticity and Pneumatic Hiatuses in the Sauropod Dinosaurs Giraffatitan and Apatosaurus",
    year = "2013",
    journal = "PLoS ONE",
    abstract = "Skeletal pneumaticity is found in the presacral vertebrae of most sauropod dinosaurs, but pneumaticity is much less common in the vertebrae of the tail. We describe previously unrecognized pneumatic fossae in the mid-caudal vertebrae of specimens of Giraffatitan and Apatosaurus. In both taxa, the most distal pneumatic vertebrae are separated from other pneumatic vertebrae by sequences of three to seven apneumatic vertebrae. Caudal pneumaticity is not prominent in most individuals of either of these taxa, and its unpredictable development means that it may be more widespread than previously recognised within Sauropoda and elsewhere in Saurischia. The erratic patterns of caudal pneumatization in Giraffatitan and Apatosaurus, including the pneumatic hiatuses, show that pneumatic diverticula were more broadly distributed in the bodies of the living animals than are their traces in the skeleton. Together with recently published evidence of cryptic diverticula--those that leave few or no skeletal traces--in basal sauropodomorphs and in pterosaurs, this is further evidence that pneumatic diverticula were widespread in ornithodirans, both across phylogeny and throughout anatomy.",
    url = "https://doi.org/10.1371/journal.pone.0078213",
    doi = "10.1371/journal.pone.0078213",
    openalex = "W2157389432",
    references = "doi105962bhltitle102117, doi107717peerj36"
}

Discerning modes and rates of biological evolution and speciation are some of the primary objectives of evolutionary biology. Much palaeobiological work has focused on developing robust methods for testing and fitting evolutionary models to samples of fossils across a stratigraphic or temporal axis, with most analyses centering on marine invertebrates. Recent extensive sampling of dinosaur deposits now allows for testing of evolutionary modes in this clade, a first for large-bodied terrestrial vertebrates. Within dinosaur palaeobiology, the relative roles of anagenesis and cladogenesis in diversification, particularly for horned dinosaurs, are hotly debated. Due to their large sample sizes, well-documented stratigraphic positions, highly diagnostic ornamentation, and monodominant bonebeds (representing populations), centrosaurine dinosaurs from the Belly River Group of Alberta make an ideal model system for testing the predictions of these two divergent evolutionary modes. \n\tDespite this unparalleled fossil record, it (as well as most fossil records) is limited by missing data, small sample size, taphonomic biases, and stratigraphic error. In this thesis, I present case studies that attempt to quantify and better understand these limitations, and inform best practices for overcoming them. The first four chapters, utilizing data sets for crocodilians (extant archosaurs) and a model geological system (upper Belly River Group), allow for a better-constrained quantitative evolutionary analysis of the Belly River Group centrosaurines in chapter five. Correlations and time-series analyses of morphology and stratigraphic position of Centrosaurus apertus and Styracosaurus albertensis are used to test for directional trends and evolutionary model fitting. Evolutionary results are robust to multiple simulations of stratigraphic uncertainty, and overlap between the taxa depends on a single locality. Results find no support for anagenesis, and rather are consistent with taxonomic turnover due to punctuated evolutionary events or, more likely, ecological replacement due to habitat tracking.

@phdthesis{openalexw2561546966,
    author = "Brown, Caleb M.",
    title = "Advances in Quantitative Methods in Dinosaur Palaeobiology: A Case Study in Horned Dinosaur Evolution",
    year = "2013",
    booktitle = "TSpace (University of Toronto)",
    abstract = "Discerning modes and rates of biological evolution and speciation are some of the primary objectives of evolutionary biology. Much palaeobiological work has focused on developing robust methods for testing and fitting evolutionary models to samples of fossils across a stratigraphic or temporal axis, with most analyses centering on marine invertebrates. Recent extensive sampling of dinosaur deposits now allows for testing of evolutionary modes in this clade, a first for large-bodied terrestrial vertebrates. Within dinosaur palaeobiology, the relative roles of anagenesis and cladogenesis in diversification, particularly for horned dinosaurs, are hotly debated. Due to their large sample sizes, well-documented stratigraphic positions, highly diagnostic ornamentation, and monodominant bonebeds (representing populations), centrosaurine dinosaurs from the Belly River Group of Alberta make an ideal model system for testing the predictions of these two divergent evolutionary modes. \n\tDespite this unparalleled fossil record, it (as well as most fossil records) is limited by missing data, small sample size, taphonomic biases, and stratigraphic error. In this thesis, I present case studies that attempt to quantify and better understand these limitations, and inform best practices for overcoming them. The first four chapters, utilizing data sets for crocodilians (extant archosaurs) and a model geological system (upper Belly River Group), allow for a better-constrained quantitative evolutionary analysis of the Belly River Group centrosaurines in chapter five. Correlations and time-series analyses of morphology and stratigraphic position of Centrosaurus apertus and Styracosaurus albertensis are used to test for directional trends and evolutionary model fitting. Evolutionary results are robust to multiple simulations of stratigraphic uncertainty, and overlap between the taxa depends on a single locality. Results find no support for anagenesis, and rather are consistent with taxonomic turnover due to punctuated evolutionary events or, more likely, ecological replacement due to habitat tracking.",
    url = "https://openalex.org/W2561546966",
    openalex = "W2561546966"
}

Herbivorous dinosaurs were abundant, species-rich components of Late Triassic–Cretaceous terrestrial ecosystems. Obligate high-fiber herbivory evolved independently on several occasions within Dinosauria, through the intermediary step of omnivory. Anatomical character complexes associated with this diet exhibit high levels of convergence and morphological disparity, and may have evolved by correlated progression. Dinosaur faunas changed markedly during the Mesozoic, from early faunas dominated by taxa with simple, uniform feeding mechanics to Cretaceous biomes including diverse sophisticated sympatric herbivores; the environmental and biological drivers causing these changes remain unclear. Isotopic, taphonomic, and anatomical evidence implies that niche partitioning reduced competition between sympatric herbivores, via morphological differentiation, dietary preferences, and habitat selection. Large body size in dinosaur herbivores is associated with low plant productivity, and gave these animals prominent roles as ecosystem engineers. Although dinosaur herbivores lived through several major events in floral evolution, there is currently no evidence for plant-dinosaur coevolutionary interactions.

@article{doi101146annurevearth042711105515,
    author = "Barrett, Paul M.",
    title = "Paleobiology of Herbivorous Dinosaurs",
    year = "2014",
    journal = "Annual Review of Earth and Planetary Sciences",
    abstract = "Herbivorous dinosaurs were abundant, species-rich components of Late Triassic–Cretaceous terrestrial ecosystems. Obligate high-fiber herbivory evolved independently on several occasions within Dinosauria, through the intermediary step of omnivory. Anatomical character complexes associated with this diet exhibit high levels of convergence and morphological disparity, and may have evolved by correlated progression. Dinosaur faunas changed markedly during the Mesozoic, from early faunas dominated by taxa with simple, uniform feeding mechanics to Cretaceous biomes including diverse sophisticated sympatric herbivores; the environmental and biological drivers causing these changes remain unclear. Isotopic, taphonomic, and anatomical evidence implies that niche partitioning reduced competition between sympatric herbivores, via morphological differentiation, dietary preferences, and habitat selection. Large body size in dinosaur herbivores is associated with low plant productivity, and gave these animals prominent roles as ecosystem engineers. Although dinosaur herbivores lived through several major events in floral evolution, there is currently no evidence for plant-dinosaur coevolutionary interactions.",
    url = "https://doi.org/10.1146/annurev-earth-042711-105515",
    doi = "10.1146/annurev-earth-042711-105515",
    openalex = "W2127568739",
    references = "doi10100797836426953391, doi101007s0001501000206, doi101016jpalaeo201206024, doi101016jpalaeo201206027, doi101038ncomms1815, doi101111j14209101201102427x, doi101111j150239311985tb00690x, doi101146annureves26110195002305, doi101186147267851314, doi101371journalpone0012553, doi101371journalpone0067182, doi105860choice490282, openalexw2971401580"
}

Large-scale adaptive radiations might explain the runaway success of a minority of extant vertebrate clades. This hypothesis predicts, among other things, rapid rates of morphological evolution during the early history of major groups, as lineages invade disparate ecological niches. However, few studies of adaptive radiation have included deep time data, so the links between extant diversity and major extinct radiations are unclear. The intensively studied Mesozoic dinosaur record provides a model system for such investigation, representing an ecologically diverse group that dominated terrestrial ecosystems for 170 million years. Furthermore, with 10,000 species, extant dinosaurs (birds) are the most speciose living tetrapod clade. We assembled composite trees of 614-622 Mesozoic dinosaurs/birds, and a comprehensive body mass dataset using the scaling relationship of limb bone robustness. Maximum-likelihood modelling and the node height test reveal rapid evolutionary rates and a predominance of rapid shifts among size classes in early (Triassic) dinosaurs. This indicates an early burst niche-filling pattern and contrasts with previous studies that favoured gradualistic rates. Subsequently, rates declined in most lineages, which rarely exploited new ecological niches. However, feathered maniraptoran dinosaurs (including Mesozoic birds) sustained rapid evolution from at least the Middle Jurassic, suggesting that these taxa evaded the effects of niche saturation. This indicates that a long evolutionary history of continuing ecological innovation paved the way for a second great radiation of dinosaurs, in birds. We therefore demonstrate links between the predominantly extinct deep time adaptive radiation of non-avian dinosaurs and the phenomenal diversification of birds, via continuing rapid rates of evolution along the phylogenetic stem lineage. This raises the possibility that the uneven distribution of biodiversity results not just from large-scale extrapolation of the process of adaptive radiation in a few extant clades, but also from the maintenance of evolvability on vast time scales across the history of life, in key lineages.

@article{doi101371journalpbio1001853,
    author = "Benson, Roger and Campione, Nicolás E. and Carrano, Matthew T. and Mannion, Philip D. and Sullivan, Corwin and Upchurch, Paul and Evans, David C.",
    title = "Rates of Dinosaur Body Mass Evolution Indicate 170 Million Years of Sustained Ecological Innovation on the Avian Stem Lineage",
    year = "2014",
    journal = "PLoS Biology",
    abstract = "Large-scale adaptive radiations might explain the runaway success of a minority of extant vertebrate clades. This hypothesis predicts, among other things, rapid rates of morphological evolution during the early history of major groups, as lineages invade disparate ecological niches. However, few studies of adaptive radiation have included deep time data, so the links between extant diversity and major extinct radiations are unclear. The intensively studied Mesozoic dinosaur record provides a model system for such investigation, representing an ecologically diverse group that dominated terrestrial ecosystems for 170 million years. Furthermore, with 10,000 species, extant dinosaurs (birds) are the most speciose living tetrapod clade. We assembled composite trees of 614-622 Mesozoic dinosaurs/birds, and a comprehensive body mass dataset using the scaling relationship of limb bone robustness. Maximum-likelihood modelling and the node height test reveal rapid evolutionary rates and a predominance of rapid shifts among size classes in early (Triassic) dinosaurs. This indicates an early burst niche-filling pattern and contrasts with previous studies that favoured gradualistic rates. Subsequently, rates declined in most lineages, which rarely exploited new ecological niches. However, feathered maniraptoran dinosaurs (including Mesozoic birds) sustained rapid evolution from at least the Middle Jurassic, suggesting that these taxa evaded the effects of niche saturation. This indicates that a long evolutionary history of continuing ecological innovation paved the way for a second great radiation of dinosaurs, in birds. We therefore demonstrate links between the predominantly extinct deep time adaptive radiation of non-avian dinosaurs and the phenomenal diversification of birds, via continuing rapid rates of evolution along the phylogenetic stem lineage. This raises the possibility that the uneven distribution of biodiversity results not just from large-scale extrapolation of the process of adaptive radiation in a few extant clades, but also from the maintenance of evolvability on vast time scales across the history of life, in key lineages.",
    url = "https://doi.org/10.1371/journal.pbio.1001853",
    doi = "10.1371/journal.pbio.1001853",
    openalex = "W2155522161",
    references = "doi101007b97636, doi101017s009483730001263x, doi101017s009483730001280x, doi10103835086500, doi10103844766, doi101038nature11631, doi10108010635150490445706, doi101086284325, doi101093bioinformaticsbtm538, doi101093oso97801985052350010001, doi101093oso97801985404720010001, doi101098rspb20122526, doi101111j001438202003tb00285x, doi101111j1469185x201000137x, doi101111j15585646201201723x, doi101126science1144066, doi101126science1161833, doi101146annurevecolsys39110707173447, doi101159000452856, doi101186174170071060, doi101198tech2003s146, doi101371journalpbio1001853, doi101371journalpone0007390, doi101371journalpone0044318, doi10166612041, martinsander2006bone, openalexw2145250129"
}

Jaw mechanics in ornithischian dinosaurs have been widely studied for well over a century. Most of these studies, however, use only one or few taxa within a given ornithischian clade as a model for feeding mechanics across the entire clade. In this study, mandibular mechanical advantages among 52 ornithischian genera spanning all subclades are calculated using 2D lever arm methods. These lever arm calculations estimate the effect of jaw shape and difference in adductor muscle line of action on relative bite forces along the jaw. Results show major instances of overlap between taxa in tooth positions at which there was highest mechanical advantage. A relatively low bite force is seen across the tooth row among thyreophorans (e.g., stegosaurs and ankylosaurs), with variation among taxa. A convergent transition occurs from a more evenly distributed bite force along the jaw in basal ornithopods and basal marginocephalians to a strong distal bite force in hadrosaurids and ceratopsids, respectively. Accordingly, adductor muscle vector angles show repeated trends from a mid-range caudodorsal orientation in basal ornithischians to a decrease in vector angles indicating more caudally oriented jaw movements in derived taxa (e.g., derived thyreophorans, basal ornithopods, lambeosaurines, pachycephalosaurs, and derived ceratopsids). Analyses of hypothetical jaw morphologies were also performed, indicating that both the coronoid process and lowered jaw joint increase moment arm length therefore increasing mechanical advantage of the jaw apparatus. Adaptive trends in craniomandibular anatomy show that ornithischians evolved more complex feeding apparatuses within different clades as well as morphological convergences between clades.

@article{doi101002ar23306,
    author = "Nabavizadeh, Ali",
    title = "Evolutionary Trends in the Jaw Adductor Mechanics of Ornithischian Dinosaurs",
    year = "2015",
    journal = "The Anatomical Record",
    abstract = "Jaw mechanics in ornithischian dinosaurs have been widely studied for well over a century. Most of these studies, however, use only one or few taxa within a given ornithischian clade as a model for feeding mechanics across the entire clade. In this study, mandibular mechanical advantages among 52 ornithischian genera spanning all subclades are calculated using 2D lever arm methods. These lever arm calculations estimate the effect of jaw shape and difference in adductor muscle line of action on relative bite forces along the jaw. Results show major instances of overlap between taxa in tooth positions at which there was highest mechanical advantage. A relatively low bite force is seen across the tooth row among thyreophorans (e.g., stegosaurs and ankylosaurs), with variation among taxa. A convergent transition occurs from a more evenly distributed bite force along the jaw in basal ornithopods and basal marginocephalians to a strong distal bite force in hadrosaurids and ceratopsids, respectively. Accordingly, adductor muscle vector angles show repeated trends from a mid-range caudodorsal orientation in basal ornithischians to a decrease in vector angles indicating more caudally oriented jaw movements in derived taxa (e.g., derived thyreophorans, basal ornithopods, lambeosaurines, pachycephalosaurs, and derived ceratopsids). Analyses of hypothetical jaw morphologies were also performed, indicating that both the coronoid process and lowered jaw joint increase moment arm length therefore increasing mechanical advantage of the jaw apparatus. Adaptive trends in craniomandibular anatomy show that ornithischians evolved more complex feeding apparatuses within different clades as well as morphological convergences between clades.",
    url = "https://doi.org/10.1002/ar.23306",
    doi = "10.1002/ar.23306",
    openalex = "W2206041925",
    references = "crossref1997the, doi101002jez1039, doi101002jmor10524, doi101017s1477201907002271, doi101046j13652435200200696x, doi10108002724634199110011386, doi101111j146979981978tb03282x, doi101111j155856461966tb03367x, doi101186147267851314, doi1012063521, doi101671a1097, doi102475ajss425149387, doi105962bhltitle5716, doi105962p313819, openalexw2138825607"
}

Herbivorous reptiles rarely evolve occluding dentitions that allow for the mastication (chewing) of plant matter. Conversely, most herbivorous mammals have occluding teeth with complex tissue architectures that self-wear to complex morphologies for orally processing plants. Dinosaurs stand out among reptiles in that several lineages acquired the capacity to masticate. In particular, the horned ceratopsian dinosaurs, among the most successful Late Cretaceous dinosaurian lineages, evolved slicing dentitions for the exploitation of tough, bulky plant matter. We show how Triceratops, a 9-m-long ceratopsian, and its relatives evolved teeth that wore during feeding to create fullers (recessed central regions on cutting blades) on the chewing surfaces. This unique morphology served to reduce friction during feeding. It was achieved through the evolution of a complex suite of osseous dental tissues rivaling the complexity of mammalian dentitions. Tribological (wear) properties of the tissues are preserved in ~66-million-year-old teeth, allowing the creation of a sophisticated three-dimensional biomechanical wear model that reveals how the complexes synergistically wore to create these implements. These findings, along with similar discoveries in hadrosaurids (duck-billed dinosaurs), suggest that tissue-mediated changes in dental morphology may have played a major role in the remarkable ecological diversification of these clades and perhaps other dinosaurian clades capable of mastication.

@article{doi101126sciadv1500055,
    author = "Erickson, Gregory M. and Sidebottom, Mark A. and Kay, David Ian and Turner, Kevin T. and Ip, Nathan and Norell, Mark A. and Sawyer, W. Gregory and Krick, Brandon A.",
    title = "Wear biomechanics in the slicing dentition of the giant horned dinosaur Triceratops",
    year = "2015",
    journal = "Science Advances",
    abstract = "Herbivorous reptiles rarely evolve occluding dentitions that allow for the mastication (chewing) of plant matter. Conversely, most herbivorous mammals have occluding teeth with complex tissue architectures that self-wear to complex morphologies for orally processing plants. Dinosaurs stand out among reptiles in that several lineages acquired the capacity to masticate. In particular, the horned ceratopsian dinosaurs, among the most successful Late Cretaceous dinosaurian lineages, evolved slicing dentitions for the exploitation of tough, bulky plant matter. We show how Triceratops, a 9-m-long ceratopsian, and its relatives evolved teeth that wore during feeding to create fullers (recessed central regions on cutting blades) on the chewing surfaces. This unique morphology served to reduce friction during feeding. It was achieved through the evolution of a complex suite of osseous dental tissues rivaling the complexity of mammalian dentitions. Tribological (wear) properties of the tissues are preserved in \textasciitilde 66-million-year-old teeth, allowing the creation of a sophisticated three-dimensional biomechanical wear model that reveals how the complexes synergistically wore to create these implements. These findings, along with similar discoveries in hadrosaurids (duck-billed dinosaurs), suggest that tissue-mediated changes in dental morphology may have played a major role in the remarkable ecological diversification of these clades and perhaps other dinosaurian clades capable of mastication.",
    url = "https://doi.org/10.1126/sciadv.1500055",
    doi = "10.1126/sciadv.1500055",
    openalex = "W2229357419",
    references = "doi101111j146979981973tb04654x, doi101111j155856461966tb03367x"
}

Conclusive evidence for sexual dimorphism in non-avian dinosaurs has been elusive. Here it is shown that dimorphism in the shape of the dermal plates of Stegosaurus mjosi (Upper Jurassic, western USA) does not result from non-sex-related individual, interspecific, or ontogenetic variation and is most likely a sexually dimorphic feature. One morph possessed wide, oval plates 45% larger in surface area than the tall, narrow plates of the other morph. Intermediate morphologies are lacking as principal component analysis supports marked size- and shape-based dimorphism. In contrast, many non-sex-related individual variations are expected to show intermediate morphologies. Taphonomy of a new quarry in Montana (JRDI 5ES Quarry) shows that at least five individuals were buried in a single horizon and were not brought together by water or scavenger transportation. This new site demonstrates co-existence, and possibly suggests sociality, between two morphs that only show dimorphism in their plates. Without evidence for niche partitioning, it is unlikely that the two morphs represent different species. Histology of the new specimens in combination with studies on previous specimens indicates that both morphs occur in fully-grown individuals. Therefore, the dimorphism is not a result of ontogenetic change. Furthermore, the two morphs of plates do not simply come from different positions on the back of a single individual. Plates from all positions on the body can be classified as one of the two morphs, and previously discovered, isolated specimens possess only one morph of plates. Based on the seemingly display-oriented morphology of plates, female mate choice was likely the driving evolutionary mechanism rather than male-male competition. Dinosaur ornamentation possibly served similar functions to the ornamentation of modern species. Comparisons to ornamentation involved in sexual selection of extant species, such as the horns of bovids, may be appropriate in predicting the function of some dinosaur ornamentation.

@article{doi101371journalpone0123503,
    author = "Saitta, Evan T.",
    title = "Evidence for Sexual Dimorphism in the Plated Dinosaur Stegosaurus mjosi (Ornithischia, Stegosauria) from the Morrison Formation (Upper Jurassic) of Western USA",
    year = "2015",
    journal = "PLoS ONE",
    abstract = "Conclusive evidence for sexual dimorphism in non-avian dinosaurs has been elusive. Here it is shown that dimorphism in the shape of the dermal plates of Stegosaurus mjosi (Upper Jurassic, western USA) does not result from non-sex-related individual, interspecific, or ontogenetic variation and is most likely a sexually dimorphic feature. One morph possessed wide, oval plates 45\% larger in surface area than the tall, narrow plates of the other morph. Intermediate morphologies are lacking as principal component analysis supports marked size- and shape-based dimorphism. In contrast, many non-sex-related individual variations are expected to show intermediate morphologies. Taphonomy of a new quarry in Montana (JRDI 5ES Quarry) shows that at least five individuals were buried in a single horizon and were not brought together by water or scavenger transportation. This new site demonstrates co-existence, and possibly suggests sociality, between two morphs that only show dimorphism in their plates. Without evidence for niche partitioning, it is unlikely that the two morphs represent different species. Histology of the new specimens in combination with studies on previous specimens indicates that both morphs occur in fully-grown individuals. Therefore, the dimorphism is not a result of ontogenetic change. Furthermore, the two morphs of plates do not simply come from different positions on the back of a single individual. Plates from all positions on the body can be classified as one of the two morphs, and previously discovered, isolated specimens possess only one morph of plates. Based on the seemingly display-oriented morphology of plates, female mate choice was likely the driving evolutionary mechanism rather than male-male competition. Dinosaur ornamentation possibly served similar functions to the ornamentation of modern species. Comparisons to ornamentation involved in sexual selection of extant species, such as the horns of bovids, may be appropriate in predicting the function of some dinosaur ornamentation.",
    url = "https://doi.org/10.1371/journal.pone.0123503",
    doi = "10.1371/journal.pone.0123503",
    openalex = "W2161724906",
    references = "doi101007s0001501000206"
}

@incollection{crossref20169,
    title = "9. CERATOPSIANS AND PACHYCEPHALOSAURS",
    year = "2016",
    booktitle = "Dinosaurs",
    url = "https://doi.org/10.7312/luca17310-011",
    doi = "10.7312/luca17310-011",
    pages = "149-168"
}

Identification of the ontogenetic status of an extinct organism is complex, and yet this underpins major areas of research, from taxonomy and systematics to ecology and evolution. In the case of the non-avialan dinosaurs, at least some were reproductively mature before they were skeletally mature, and a lack of consensus on how to define an 'adult' animal causes problems for even basic scientific investigations. Here we review the current methods available to determine the age of non-avialan dinosaurs, discuss the definitions of different ontogenetic stages, and summarize the implications of these disparate definitions for dinosaur palaeontology. Most critically, a growing body of evidence suggests that many dinosaurs that would be considered 'adults' in a modern-day field study are considered 'juveniles' or 'subadults' in palaeontological contexts.

@article{doi101098rsbl20150947,
    author = "Hone, David W. E. and Farke, Andrew A. and Wedel, Matt",
    title = "Ontogeny and the fossil record: what, if anything, is an adult dinosaur?",
    year = "2016",
    journal = "Biology Letters",
    abstract = "Identification of the ontogenetic status of an extinct organism is complex, and yet this underpins major areas of research, from taxonomy and systematics to ecology and evolution. In the case of the non-avialan dinosaurs, at least some were reproductively mature before they were skeletally mature, and a lack of consensus on how to define an 'adult' animal causes problems for even basic scientific investigations. Here we review the current methods available to determine the age of non-avialan dinosaurs, discuss the definitions of different ontogenetic stages, and summarize the implications of these disparate definitions for dinosaur palaeontology. Most critically, a growing body of evidence suggests that many dinosaurs that would be considered 'adults' in a modern-day field study are considered 'juveniles' or 'subadults' in palaeontological contexts.",
    url = "https://doi.org/10.1098/rsbl.2015.0947",
    doi = "10.1098/rsbl.2015.0947",
    openalex = "W2279103404",
    references = "carr1999craniofacial, doi101007s0001501000242, doi101017pab201519, doi10103835086558, doi101038nature04633, doi101073pnas0708903105, doi101073pnas1313334111, doi10108002724634199610011283, doi10108002724634199910011161, doi101080027246342010483632, doi101093sysbio24137, doi101098rsbl20070254, doi101111j109636421997tb00340x, doi101111j15023931201100300x, doi101146annurevearth060313054858, doi101371journalpone0021376, doi1016660094837320010270039coosea20co2, doi1016660094837320040300253chopom20co2, doi1016660094837320080340247ositlb20co2, doi1016690883135120010160482ttoaco20co2, doi1016710272463420000200115lbhoth20co2, doi10167102724634200727350asoitp20co2, doi1016710390290119, doi1023071564148, erickson2014on, martinsander2006bone"
}

@misc{dodson2017the,
    author = "Dodson, Peter",
    title = "The Horned Dinosaurs",
    year = "2017",
    url = "https://doi.org/10.1515/9781400887446",
    doi = "10.1515/9781400887446",
    openalex = "W4239052057"
}

Abstract The demonstration of sexual dimorphism in the fossil record can provide vital information about the role that sexual selection has played in the evolution of life. However, statistically robust inferences of sexual dimorphism in fossil organisms are exceedingly difficult to establish, owing to issues of sample size, experimental control, and methodology. This is particularly so in the case of dinosaurs, for which sexual dimorphism has been posited in many species, yet quantifiable data are often lacking. This study presents the first statistical investigation of sexual dimorphism across Dinosauria. It revisits prior analyses that purport to find quantitative evidence for sexual dimorphism in nine dinosaur species. After the available morphological data were subjected to a suite of statistical tests (normality and unimodality tests and mixture modeling), no evidence for sexual dimorphism was found in any of the examined taxa, contrary to conventional wisdom. This is not to say that dinosaurs were not sexually dimorphic (phylogenetic inference suggests they may well have been), only that the available evidence precludes its detection. A priori knowledge of the sexes would greatly facilitate the assessment of sexual dimorphism in the fossil record, and it is suggested that unambiguous indicators of sex (e.g., presence of eggs, embryos, medullary bone) be used to this end.

@article{doi101017pab201651,
    author = "Mallon, Jordan C.",
    title = "Recognizing sexual dimorphism in the fossil record: lessons from nonavian dinosaurs",
    year = "2017",
    journal = "Paleobiology",
    abstract = "Abstract The demonstration of sexual dimorphism in the fossil record can provide vital information about the role that sexual selection has played in the evolution of life. However, statistically robust inferences of sexual dimorphism in fossil organisms are exceedingly difficult to establish, owing to issues of sample size, experimental control, and methodology. This is particularly so in the case of dinosaurs, for which sexual dimorphism has been posited in many species, yet quantifiable data are often lacking. This study presents the first statistical investigation of sexual dimorphism across Dinosauria. It revisits prior analyses that purport to find quantitative evidence for sexual dimorphism in nine dinosaur species. After the available morphological data were subjected to a suite of statistical tests (normality and unimodality tests and mixture modeling), no evidence for sexual dimorphism was found in any of the examined taxa, contrary to conventional wisdom. This is not to say that dinosaurs were not sexually dimorphic (phylogenetic inference suggests they may well have been), only that the available evidence precludes its detection. A priori knowledge of the sexes would greatly facilitate the assessment of sexual dimorphism in the fossil record, and it is suggested that unambiguous indicators of sex (e.g., presence of eggs, embryos, medullary bone) be used to this end.",
    url = "https://doi.org/10.1017/pab.2016.51",
    doi = "10.1017/pab.2016.51",
    openalex = "W2598969013",
    references = "doi101002ar20991, doi101017pab201519, doi10108002724634198510011859, doi10108008912960903450505, doi101098rsbl20150947, doi101111j15023931201100300x, doi101371journalpone0029958, openalexw3215035079"
}

The early evolution of archosauromorphs (bird- and crocodile-line archosaurs and stem-archosaurs) represents an important case of adaptive radiation that occurred in the aftermath of the Permo-Triassic mass extinction. Here we enrich the early archosauromorph record with the description of a moderately large (3-4 m in total length), herbivorous new allokotosaurian, Shringasaurus indicus, from the early Middle Triassic of India. The most striking feature of Shringasaurus indicus is the presence of a pair of large supraorbital horns that resemble those of some ceratopsid dinosaurs. The presence of horns in the new species is dimorphic and, as occurs in horned extant bovid mammals, these structures were probably sexually selected and used as weapons in intraspecific combats. The relatively large size and unusual anatomy of Shringasaurus indicus broadens the morphological diversity of Early-Middle Triassic tetrapods and complements the understanding of the evolutionary mechanisms involved in the early archosauromorph diversification.

@article{doi101038s41598017086588,
    author = "Sengupta, Saradee and Ezcurra, Martín D. and Bandyopadhyay, Saswati",
    title = "A new horned and long-necked herbivorous stem-archosaur from the Middle Triassic of India",
    year = "2017",
    journal = "Scientific Reports",
    abstract = "The early evolution of archosauromorphs (bird- and crocodile-line archosaurs and stem-archosaurs) represents an important case of adaptive radiation that occurred in the aftermath of the Permo-Triassic mass extinction. Here we enrich the early archosauromorph record with the description of a moderately large (3-4 m in total length), herbivorous new allokotosaurian, Shringasaurus indicus, from the early Middle Triassic of India. The most striking feature of Shringasaurus indicus is the presence of a pair of large supraorbital horns that resemble those of some ceratopsid dinosaurs. The presence of horns in the new species is dimorphic and, as occurs in horned extant bovid mammals, these structures were probably sexually selected and used as weapons in intraspecific combats. The relatively large size and unusual anatomy of Shringasaurus indicus broadens the morphological diversity of Early-Middle Triassic tetrapods and complements the understanding of the evolutionary mechanisms involved in the early archosauromorph diversification.",
    url = "https://doi.org/10.1038/s41598-017-08658-8",
    doi = "10.1038/s41598-017-08658-8",
    openalex = "W2745137671",
    references = "doi101111j15023931201100300x"
}

Tooth attachment and implantation are two classical descriptors of dental anatomy. Tooth attachment distinguishes between teeth that are either fused to the jaw by bone, or suspended within a socket by a periodontal ligament. Tooth implantation describes the geometry of this attachment and has been broadly divided into acrodonty, pleurodonty, and thecodonty. Among extant amniotes, only mammals and crocodilians are considered truly thecodont, because they possess a complex attachment system that includes a periodontal ligament and true tooth sockets. These two amniote groups diverged from a common ancestor over 300 million years ago and are thought to have evolved thecodonty independently. This view has recently come under a great deal of scrutiny with the discovery of complex tooth attachment systems, including the presence of a ligamentous tooth attachment in numerous non-mammalian, non-crocodilian amniotes. This has spurred debate and inconsistencies over the conventional usage of tooth attachment and implantation categories and their evolutionary significance. We provide a comparative histological approach for describing tooth attachment and implantation in an exemplary, traditionally thecodont taxonomic group: the non-avian dinosaurs. The comparisons between theropod, hadrosaurid, and ceratopsid teeth show that all dinosaurs have ligamentous tooth attachments composed of identical dental tissues to those in mammals and crocodilians, but they show a diverse array of tooth attachment geometries, replacement modes, and bone architectures supporting the dentition. The methodology we follow allows researchers to tease apart phylogenetically and functionally significant features of tooth attachment and implantation that could be used in future studies.Citation for this article: LeBlanc, A. R. H., K. S. Brink, T. M. Cullen, and R. R. Reisz. 2017. Evolutionary implications of tooth attachment versus tooth implantation: a case study using dinosaur, crocodilian, and mammal teeth. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2017.1354006.

@article{doi1010800272463420171354006,
    author = "LeBlanc, Aaron R. H. and Brink, Kirstin S. and Cullen, Thomas M. and Reisz, Robert R.",
    title = "Evolutionary implications of tooth attachment versus tooth implantation: A case study using dinosaur, crocodilian, and mammal teeth",
    year = "2017",
    journal = "Journal of Vertebrate Paleontology",
    abstract = "Tooth attachment and implantation are two classical descriptors of dental anatomy. Tooth attachment distinguishes between teeth that are either fused to the jaw by bone, or suspended within a socket by a periodontal ligament. Tooth implantation describes the geometry of this attachment and has been broadly divided into acrodonty, pleurodonty, and thecodonty. Among extant amniotes, only mammals and crocodilians are considered truly thecodont, because they possess a complex attachment system that includes a periodontal ligament and true tooth sockets. These two amniote groups diverged from a common ancestor over 300 million years ago and are thought to have evolved thecodonty independently. This view has recently come under a great deal of scrutiny with the discovery of complex tooth attachment systems, including the presence of a ligamentous tooth attachment in numerous non-mammalian, non-crocodilian amniotes. This has spurred debate and inconsistencies over the conventional usage of tooth attachment and implantation categories and their evolutionary significance. We provide a comparative histological approach for describing tooth attachment and implantation in an exemplary, traditionally thecodont taxonomic group: the non-avian dinosaurs. The comparisons between theropod, hadrosaurid, and ceratopsid teeth show that all dinosaurs have ligamentous tooth attachments composed of identical dental tissues to those in mammals and crocodilians, but they show a diverse array of tooth attachment geometries, replacement modes, and bone architectures supporting the dentition. The methodology we follow allows researchers to tease apart phylogenetically and functionally significant features of tooth attachment and implantation that could be used in future studies.Citation for this article: LeBlanc, A. R. H., K. S. Brink, T. M. Cullen, and R. R. Reisz. 2017. Evolutionary implications of tooth attachment versus tooth implantation: a case study using dinosaur, crocodilian, and mammal teeth. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2017.1354006.",
    url = "https://doi.org/10.1080/02724634.2017.1354006",
    doi = "10.1080/02724634.2017.1354006",
    openalex = "W2757224171",
    references = "doi101002jmor10372, doi101002jmor20545, doi101111j155856461966tb03367x, doi101111joa12539, doi101371journalpone0088905, doi101371journalpone0098605"
}

from the upper Judith River Formation fills a gap in the ankylosaurine stratigraphic and geographical record in North America, and further highlights that Campanian ankylosaurines were undergoing rapid evolution and stratigraphic succession of taxa as observed for Laramidian ceratopsids, hadrosaurids, pachycephalosaurids and tyrannosaurids.

@article{doi101098rsos161086,
    author = "Arbour, Victoria M. and Evans, David C.",
    title = "A new ankylosaurine dinosaur from the Judith River Formation of Montana, USA, based on an exceptional skeleton with soft tissue preservation",
    year = "2017",
    journal = "Royal Society Open Science",
    abstract = "from the upper Judith River Formation fills a gap in the ankylosaurine stratigraphic and geographical record in North America, and further highlights that Campanian ankylosaurines were undergoing rapid evolution and stratigraphic succession of taxa as observed for Laramidian ceratopsids, hadrosaurids, pachycephalosaurids and tyrannosaurids.",
    url = "https://doi.org/10.1098/rsos.161086",
    doi = "10.1098/rsos.161086",
    openalex = "W2613812864",
    references = "crossref1998encyclopedia, doi101007s125490110068y, doi101016jpalaeo200902007, doi101038378774a0, doi101086684289, doi101098rspl18870117, doi101111cla12160, doi101111j10960031200800217x, doi101111j10963642200900617x, doi101139e93016, doi101186s1289801601068, doi101371journalpone0108804, doi102110palo2014084, doi105860choice353642, doi105860choice393984, doi105860choice435902, openalexw3215057009"
}

, largely known from the parietosquamosal frill. These specimens indicate the morphology of the supracranial sinus in early, long-horned members of the Ceratopsidae, and add to our understanding of the evolution of the cranial display structures in this iconic dinosaur clade.

@article{doi107717peerj4265,
    author = "Brown, Caleb M.",
    title = "Long-horned Ceratopsidae from the Foremost Formation (Campanian) of southern Alberta",
    year = "2018",
    journal = "PeerJ",
    abstract = ", largely known from the parietosquamosal frill. These specimens indicate the morphology of the supracranial sinus in early, long-horned members of the Ceratopsidae, and add to our understanding of the evolution of the cranial display structures in this iconic dinosaur clade.",
    url = "https://doi.org/10.7717/peerj.4265",
    doi = "10.7717/peerj.4265",
    openalex = "W2784080137",
    references = "doi101016jpalaeo201206024, doi101038358059a0, doi101098rspl18870117, doi101127njgpa210199841, doi101371journalpone0010660, doi101371journalpone0012292, doi101525california97805202420980030026, doi102475ajss339233418, doi105860choice353642, doi105860choice482098, openalexw2561546966"
}

The attachments of jaw muscles are typically implicated in the evolution and shape of the dorsotemporal fenestra on the skull roof of amniotes. However, the dorsotemporal fenestrae of many archosaurian reptiles possess smooth excavations rostral and dorsal to the dorsotemporal fossa which closely neighbors the dorsotemporal fenestra and jaw muscle attachments. Previous research has typically identified this region, here termed the frontoparietal fossa, to also have attachment surfaces for jaw-closing muscles. However, numerous observations of extant and extinct archosaurs described here suggest that other tissues are instead responsible for the size and shape of the frontoparietal fossa. This study reviewed the anatomical evidence that support soft-tissue hypotheses of the frontoparietal fossa and its phylogenetic distribution among sauropsids. Soft-tissue hypotheses (i.e., muscle, pneumatic sinus, vascular tissues) were analyzed using anatomical, imaging and in vivo thermography techniques within a phylogenetic framework using extant and extinct taxa to determine the inferential power underlying the reconstruction of the soft tissues in the skull roofs of dinosaurs, pseudosuchians, and other reptiles. Relevant anatomical features argue for rejection of the default hypothesis-that the fossa was muscular-due to a complete lack of osteological correlates reflective of muscle attachment. The most-supported inference of soft tissues is that the frontoparietal fossa contained a large vascular structure and adipose tissue. Despite the large sizes and diverse morphologies of these fossae found among dinosaur taxa, these data suggest that non-avian dinosaurs had the anatomical foundation to support physiologically significant vascular devices and/or vascular integumentary structures on their skull roofs. Anat Rec, 303:1060-1074, 2020. © 2019 Wiley Periodicals, Inc.

@article{doi101002ar24218,
    author = "Holliday, Casey M. and Porter, William Ruger and Vliet, Kent A. and Witmer, Lawrence M.",
    title = "The Frontoparietal Fossa and Dorsotemporal Fenestra of Archosaurs and Their Significance for Interpretations of Vascular and Muscular Anatomy in Dinosaurs",
    year = "2019",
    journal = "The Anatomical Record",
    abstract = "The attachments of jaw muscles are typically implicated in the evolution and shape of the dorsotemporal fenestra on the skull roof of amniotes. However, the dorsotemporal fenestrae of many archosaurian reptiles possess smooth excavations rostral and dorsal to the dorsotemporal fossa which closely neighbors the dorsotemporal fenestra and jaw muscle attachments. Previous research has typically identified this region, here termed the frontoparietal fossa, to also have attachment surfaces for jaw-closing muscles. However, numerous observations of extant and extinct archosaurs described here suggest that other tissues are instead responsible for the size and shape of the frontoparietal fossa. This study reviewed the anatomical evidence that support soft-tissue hypotheses of the frontoparietal fossa and its phylogenetic distribution among sauropsids. Soft-tissue hypotheses (i.e., muscle, pneumatic sinus, vascular tissues) were analyzed using anatomical, imaging and in vivo thermography techniques within a phylogenetic framework using extant and extinct taxa to determine the inferential power underlying the reconstruction of the soft tissues in the skull roofs of dinosaurs, pseudosuchians, and other reptiles. Relevant anatomical features argue for rejection of the default hypothesis-that the fossa was muscular-due to a complete lack of osteological correlates reflective of muscle attachment. The most-supported inference of soft tissues is that the frontoparietal fossa contained a large vascular structure and adipose tissue. Despite the large sizes and diverse morphologies of these fossae found among dinosaur taxa, these data suggest that non-avian dinosaurs had the anatomical foundation to support physiologically significant vascular devices and/or vascular integumentary structures on their skull roofs. Anat Rec, 303:1060-1074, 2020. © 2019 Wiley Periodicals, Inc.",
    url = "https://doi.org/10.1002/ar.24218",
    doi = "10.1002/ar.24218",
    openalex = "W2955120318",
    references = "crossref1997the, doi101046j14697580199819340481x, doi10108002724634199710011027, doi101111joa12449, doi101111joa12539, doi101126science1175553, doi101139e93179, doi1023071292217, doi1023072413454, doi10230730135049, doi105860choice326223, openalexw3184837389"
}

Herbivorous dinosaurs exhibited diverse cranial feeding mechanisms. Although osteological, microwear, and biomechanical research has revealed some of this diversity, the evolutionary reorientation of cranial musculature throughout nonavian herbivorous Dinosauria and its influence on feeding mechanisms requires more study. Here, cranial muscle reconstructions in herbivorous dinosaurs are reviewed and informative anatomical characters are compared across 142 dinosaur genera (84 ornithischians, 36 sauropodomorphs, and 22 herbivorous nonavian theropods), both through examination of specimens and literature. Traits include those relating to the temporal region, adductor chamber, palate, and mandibular attachments, such as the coronoid elevation and retroarticular process. Findings reveal many combinations of anatomical traits influencing a diversity of feeding mechanisms. Some primarily more orthal feeders, including herbivorous theropods, nonsauropod sauropodomorphs, basal ornithischians, and derived stegosaurs (which also show varying degrees of coinciding slight palinal motion and long-axis hemimandibular rotation), possess traits indicative of more prominent temporal musculature and moderately sized palatal musculature. However, orthal feeding sauropods and pachycephalosaurs possess traits indicative of greatly reduced, low-angled temporal musculature, and enhanced palatal musculature producing a primarily vertical, orthal feeding vector. Among ankylosaurs, hadrosaurids, and neoceratopsians, a rostrolabial temporal muscle expansion is present (with a tall coronoid elevation in hadrosaurids and ceratopsids) for greater temporal muscle support and mechanical advantage for complex palinal feeding motions. This also aids in long-axis hemimandibular rotation against the predentary in hadrosaurs and ankylosaurs. This diversity in cranial muscle architecture provides an informative spectrum of numerous adaptations acquired given the evolution of various anatomical constraints in the skull. Anat Rec, 303:1104-1145, 2020. © 2019 American Association for Anatomy.

@article{doi101002ar24283,
    author = "Nabavizadeh, Ali",
    title = "Cranial Musculature in Herbivorous Dinosaurs: A Survey of Reconstructed Anatomical Diversity and Feeding Mechanisms",
    year = "2019",
    journal = "The Anatomical Record",
    abstract = "Herbivorous dinosaurs exhibited diverse cranial feeding mechanisms. Although osteological, microwear, and biomechanical research has revealed some of this diversity, the evolutionary reorientation of cranial musculature throughout nonavian herbivorous Dinosauria and its influence on feeding mechanisms requires more study. Here, cranial muscle reconstructions in herbivorous dinosaurs are reviewed and informative anatomical characters are compared across 142 dinosaur genera (84 ornithischians, 36 sauropodomorphs, and 22 herbivorous nonavian theropods), both through examination of specimens and literature. Traits include those relating to the temporal region, adductor chamber, palate, and mandibular attachments, such as the coronoid elevation and retroarticular process. Findings reveal many combinations of anatomical traits influencing a diversity of feeding mechanisms. Some primarily more orthal feeders, including herbivorous theropods, nonsauropod sauropodomorphs, basal ornithischians, and derived stegosaurs (which also show varying degrees of coinciding slight palinal motion and long-axis hemimandibular rotation), possess traits indicative of more prominent temporal musculature and moderately sized palatal musculature. However, orthal feeding sauropods and pachycephalosaurs possess traits indicative of greatly reduced, low-angled temporal musculature, and enhanced palatal musculature producing a primarily vertical, orthal feeding vector. Among ankylosaurs, hadrosaurids, and neoceratopsians, a rostrolabial temporal muscle expansion is present (with a tall coronoid elevation in hadrosaurids and ceratopsids) for greater temporal muscle support and mechanical advantage for complex palinal feeding motions. This also aids in long-axis hemimandibular rotation against the predentary in hadrosaurs and ankylosaurs. This diversity in cranial muscle architecture provides an informative spectrum of numerous adaptations acquired given the evolution of various anatomical constraints in the skull. Anat Rec, 303:1104-1145, 2020. © 2019 American Association for Anatomy.",
    url = "https://doi.org/10.1002/ar.24283",
    doi = "10.1002/ar.24283",
    openalex = "W2987391580",
    references = "crossref1997the, doi101002ar23306, doi101002ar23592, doi101002ar23988, doi101002jmor10524, doi101017s1477201907002271, doi10103835059070, doi101073pnas1011924108, doi101073pnas1310711110, doi10108002724634199710011027, doi101098rstb19920117, doi101111j1469185x201000137x, doi101111j155856461966tb03367x, doi101130spe40p1, doi101371journalpone0001230, doi101371journalpone0098605, doi102475ajss425149387, openalexw606525048"
}

@article{doi101016jcub201910050,
    author = "Button, David J. and Zanno, Lindsay E.",
    title = "Repeated Evolution of Divergent Modes of Herbivory in Non-avian Dinosaurs",
    year = "2019",
    journal = "Current Biology",
    url = "https://doi.org/10.1016/j.cub.2019.10.050",
    doi = "10.1016/j.cub.2019.10.050",
    openalex = "W2993362957",
    references = "doi101002ar23306, doi101002ar23988, doi10100797836426953391, doi101007s0011401411439, doi101007s0042701605392, doi101016jcub201609040, doi101016jcub201610043, doi101016jpalaeo201803006, doi101038nature24679, doi101038ncomms3827, doi101038srep19165, doi101038srep44942, doi101073pnas1310711110, doi101073pnas1319091111, doi10108002724631003763516, doi101080147720192010488045, doi1010801477201920151059985, doi101086414425, doi101093bioinformatics176520, doi101093bioinformaticsbtg180, doi101093bioinformaticsbtm069, doi101098rsos161086, doi101098rspb20110410, doi101098rspb20122526, doi101098rspb20171219, doi101111j2041210x201100169x, doi101371journalpone0078573, doi101371journalpone0079420, doi101371journalpone0092022, doi101371journalpone0098605, doi101371journalpone0112055, doi1017161paleo180818764, doi102307jctvjsf433, doi105281zenodo13315375, doi105860choice396411, doi107717peerj1032, doi107717peerj1523, openalexw2282537990"
}

Bagaceratops rozhdestvenskyi is a ceratopsian dinosaur from the Late Cretaceous Baruungoyot Formation of the Gobi Desert, closely related to Protoceratops spp. Several Bag. rozhdestvenskyi skulls demonstrate a wide range of variation in their morphology and size. Here I argue that the observed variability is most likely of intraspecific nature. Specimens classified in a few allegedly distinct species from the same or near-contemporary sediments, namely Gobiceratops minutus, Lamaceratops tereschenkoi and Platyceratops tatarinovi from Baruungoyot Formation, and Magnirostris dodsoni from Bayan Mandahu, are younger subjective synonyms of Bag. rozhdestvenskyi. They plausibly represent an ontogenetic series within the latter. Breviceratops kozlowskiiis a distinct taxon. The evolutionary relationships within Protoceratopsidae are complicated by the mosaic distribution of plesiomorphic and derived features in distinct species. I suggest that taxa distribution and observed changes in morphology are an evidence for the ancestral position of Protoceratops andrewsi among protoceratopsids. It implies possible temporary separation between the geological formations of the Gobi Desert yielding distinct protoceratopsid species. The novel evolutionary scenario suggests number of convergences that occurred in Protoceratopsidae and Ceratopsoidea (reduction of the premaxillary dentition, fusion of nasals, development of the accessory antorbital fenestra). Present study reveals the significance of the intraspecific and ontogenetic variation in the study of the neoceratopsian taxonomy.

@article{doi1010800891296320191593404,
    author = "Czepiński, Łukasz",
    title = "Ontogeny and variation of a protoceratopsid dinosaur Bagaceratops rozhdestvenskyi from the Late Cretaceous of the Gobi Desert",
    year = "2019",
    journal = "Historical Biology",
    abstract = "Bagaceratops rozhdestvenskyi is a ceratopsian dinosaur from the Late Cretaceous Baruungoyot Formation of the Gobi Desert, closely related to Protoceratops spp. Several Bag. rozhdestvenskyi skulls demonstrate a wide range of variation in their morphology and size. Here I argue that the observed variability is most likely of intraspecific nature. Specimens classified in a few allegedly distinct species from the same or near-contemporary sediments, namely Gobiceratops minutus, Lamaceratops tereschenkoi and Platyceratops tatarinovi from Baruungoyot Formation, and Magnirostris dodsoni from Bayan Mandahu, are younger subjective synonyms of Bag. rozhdestvenskyi. They plausibly represent an ontogenetic series within the latter. Breviceratops kozlowskiiis a distinct taxon. The evolutionary relationships within Protoceratopsidae are complicated by the mosaic distribution of plesiomorphic and derived features in distinct species. I suggest that taxa distribution and observed changes in morphology are an evidence for the ancestral position of Protoceratops andrewsi among protoceratopsids. It implies possible temporary separation between the geological formations of the Gobi Desert yielding distinct protoceratopsid species. The novel evolutionary scenario suggests number of convergences that occurred in Protoceratopsidae and Ceratopsoidea (reduction of the premaxillary dentition, fusion of nasals, development of the accessory antorbital fenestra). Present study reveals the significance of the intraspecific and ontogenetic variation in the study of the neoceratopsian taxonomy.",
    url = "https://doi.org/10.1080/08912963.2019.1593404",
    doi = "10.1080/08912963.2019.1593404",
    openalex = "W2934239943",
    references = "doi101002ar23592, doi101002ar23988, doi101016jpalaeo201003028, doi10120600030082200635301ydanpc20co2, doi101371journalpone0112055, doi10167102724634200828134ooceit20co2"
}

Abstract Despite reports of sexual dimorphism in extinct taxa, such claims in non-avian dinosaurs have been rare over the last decade and have often been criticized. Since dimorphism is widespread in sexually reproducing organisms today, under-reporting in the literature might suggest either methodological shortcomings or that this diverse group exhibited highly unusual reproductive biology. Univariate significance testing, especially for bimodality, is ineffective and prone to false negatives. Species recognition and mutual sexual selection hypotheses, therefore, may not be required to explain supposed absence of sexual dimorphism across the grade (a type II error). Instead, multiple lines of evidence support sexual selection and variation of structures consistent with secondary sexual characteristics, strongly suggesting sexual dimorphism in non-avian dinosaurs. We propose a framework for studying sexual dimorphism in fossils, focusing on likely secondary sexual traits and testing against all alternate hypotheses for variation in them using multiple lines of evidence. We use effect size statistics appropriate for low sample sizes, rather than significance testing, to analyse potential divergence of growth curves in traits and constrain estimates for dimorphism magnitude. In many cases, estimates of sexual variation can be reasonably accurate, and further developments in methods to improve sex assignments and account for intrasexual variation (e.g. mixture modelling) will improve accuracy. It is better to compare estimates for the magnitude of and support for dimorphism between datasets than to dichotomously reject or fail to reject monomorphism in a single species, enabling the study of sexual selection across phylogenies and time. We defend our approach with simulated and empirical data, including dinosaur data, showing that even simple approaches can yield fairly accurate estimates of sexual variation in many cases, allowing for comparison of species with high and low support for sexual variation.

@article{doi101093biolinneanblaa105,
    author = "Saitta, Evan T. and Stockdale, Maximilian T. and Longrich, Nicholas R. and Bonhomme, Vincent and Benton, Michael J. and Cuthill, Innes C. and Makovicky, Peter J.",
    title = "An effect size statistical framework for investigating sexual dimorphism in non-avian dinosaurs and other extinct taxa",
    year = "2020",
    journal = "Biological Journal of the Linnean Society",
    abstract = "Abstract Despite reports of sexual dimorphism in extinct taxa, such claims in non-avian dinosaurs have been rare over the last decade and have often been criticized. Since dimorphism is widespread in sexually reproducing organisms today, under-reporting in the literature might suggest either methodological shortcomings or that this diverse group exhibited highly unusual reproductive biology. Univariate significance testing, especially for bimodality, is ineffective and prone to false negatives. Species recognition and mutual sexual selection hypotheses, therefore, may not be required to explain supposed absence of sexual dimorphism across the grade (a type II error). Instead, multiple lines of evidence support sexual selection and variation of structures consistent with secondary sexual characteristics, strongly suggesting sexual dimorphism in non-avian dinosaurs. We propose a framework for studying sexual dimorphism in fossils, focusing on likely secondary sexual traits and testing against all alternate hypotheses for variation in them using multiple lines of evidence. We use effect size statistics appropriate for low sample sizes, rather than significance testing, to analyse potential divergence of growth curves in traits and constrain estimates for dimorphism magnitude. In many cases, estimates of sexual variation can be reasonably accurate, and further developments in methods to improve sex assignments and account for intrasexual variation (e.g. mixture modelling) will improve accuracy. It is better to compare estimates for the magnitude of and support for dimorphism between datasets than to dichotomously reject or fail to reject monomorphism in a single species, enabling the study of sexual selection across phylogenies and time. We defend our approach with simulated and empirical data, including dinosaur data, showing that even simple approaches can yield fairly accurate estimates of sexual variation in many cases, allowing for comparison of species with high and low support for sexual variation.",
    url = "https://doi.org/10.1093/biolinnean/blaa105",
    doi = "10.1093/biolinnean/blaa105",
    openalex = "W3082435594",
    references = "doi101007s1065401601493, doi101016jcub201706071, doi101038246015a0, doi101038s4146701702088w, doi101038srep18952, doi101073pnas1313334111, doi1010800003130520161154108, doi10108008912960903450505, doi101111brv12436, doi101111j1469185x1970tb01176x, doi101111j1469185x200700027x, doi101126science13134091292, doi1015159780691207278, doi101537ase188722495, doi1016710390290119, doi1023072874"
}

). This is particularly interesting because it fills most of the ghost lineages that emerge from the Triassic. Following the present hypothesis, the lineage that encompasses the Jurassic ornithischians evolved from 'silesaurids' during the Middle to early Late Triassic, while typical 'silesaurids' shared the land ecosystems with their relatives until the Late Triassic, when the group completely vanished. Therefore, Ornithischia changes from an obscure to a well-documented clade in the Triassic and is represented by records from Gondwana and Laurasia. Furthermore, according to the present hypothesis, Ornithischia was the first group of dinosaurs to adopt an omnivorous/herbivorous diet. However, this behaviour was achieved as a secondary step instead of an ancestral condition for ornithischians, as the earliest member of the clade is a faunivorous taxon. This pattern was subsequently followed by sauropodomorph dinosaurs. Indeed, the present scenario favours the independent acquisition of an herbivorous diet for ornithischians and sauropodomorphs during the Triassic, whereas the previous hypotheses suggested the independent acquisition for sauropodomorphs, ornithischians, and 'silesaurids'.

@article{doi101098rsbl20200417,
    author = "Müller, Rodrigo Temp and Garcia, Maurício Silva",
    title = "A paraphyletic ‘Silesauridae' as an alternative hypothesis for the initial radiation of ornithischian dinosaurs",
    year = "2020",
    journal = "Biology Letters",
    abstract = "). This is particularly interesting because it fills most of the ghost lineages that emerge from the Triassic. Following the present hypothesis, the lineage that encompasses the Jurassic ornithischians evolved from 'silesaurids' during the Middle to early Late Triassic, while typical 'silesaurids' shared the land ecosystems with their relatives until the Late Triassic, when the group completely vanished. Therefore, Ornithischia changes from an obscure to a well-documented clade in the Triassic and is represented by records from Gondwana and Laurasia. Furthermore, according to the present hypothesis, Ornithischia was the first group of dinosaurs to adopt an omnivorous/herbivorous diet. However, this behaviour was achieved as a secondary step instead of an ancestral condition for ornithischians, as the earliest member of the clade is a faunivorous taxon. This pattern was subsequently followed by sauropodomorph dinosaurs. Indeed, the present scenario favours the independent acquisition of an herbivorous diet for ornithischians and sauropodomorphs during the Triassic, whereas the previous hypotheses suggested the independent acquisition for sauropodomorphs, ornithischians, and 'silesaurids'.",
    url = "https://doi.org/10.1098/rsbl.2020.0417",
    doi = "10.1098/rsbl.2020.0417",
    openalex = "W3080319382",
    references = "doi101002ar23306, doi101093zoolinneanzly009, doi107717peerj7963"
}

represents a transitional taxon within an anagenetic lineage of eucentrosauran centrosaurines.

@article{doi101098rsos200284,
    author = "Wilson, John P. and Ryan, Michael J. and Evans, David C.",
    title = "A new, transitional centrosaurine ceratopsid from the Upper Cretaceous Two Medicine Formation of Montana and the evolution of the ‘ Styracosaurus -line' dinosaurs",
    year = "2020",
    journal = "Royal Society Open Science",
    abstract = "represents a transitional taxon within an anagenetic lineage of eucentrosauran centrosaurines.",
    url = "https://doi.org/10.1098/rsos.200284",
    doi = "10.1098/rsos.200284",
    openalex = "W3022628852",
    references = "doi101016jcretres2019104308"
}

The evolutionary radiation of birds has produced incredible morphological variation, including a huge range of skull form and function. Investigating how this variation arose with respect to non-avian dinosaurs is key to understanding how birds achieved their remarkable success after the Cretaceous-Paleogene extinction event. Using a high-dimensional geometric morphometric approach, we quantified the shape of the skull in unprecedented detail across 354 extant and 37 extinct avian and non-avian dinosaurs. Comparative analyses reveal fundamental differences in how skull shape evolved in birds and non-avian dinosaurs. We find that the overall skull shape evolved faster in non-avian dinosaurs than in birds across all regions of the cranium. In birds, the anterior rostrum is the most rapidly evolving skull region, whereas more posterior regions-such as the parietal, squamosal, and quadrate-exhibited high rates in non-avian dinosaurs. These fast-evolving elements in dinosaurs are strongly associated with feeding biomechanics, forming the jaw joint and supporting the jaw adductor muscles. Rapid pulses of skull evolution coincide with changes to food acquisition strategies and diets, as well as the proliferation of bony skull ornaments. In contrast to the appendicular skeleton, which has been shown to evolve more rapidly in birds, avian cranial morphology is characterised by a striking deceleration in morphological evolution relative to non-avian dinosaurs. These results may be due to the reorganisation of skull structure in birds-including loss of a separate postorbital bone in adults and the emergence of new trade-offs with development and neurosensory demands. Taken together, the remarkable cranial shape diversity in birds was not a product of accelerated evolution from their non-avian relatives, despite their frequent portrayal as an icon of adaptive radiations.

@article{doi101371journalpbio3000801,
    author = "Felice, Ryan N. and Watanabe, Akinobu and Cuff, Andrew R. and Hanson, Michael and Bhullar, Bhart‐Anjan S. and Rayfield, Emily J. and Witmer, Lawrence M. and Norell, Mark A. and Goswami, Anjali",
    title = "Decelerated dinosaur skull evolution with the origin of birds",
    year = "2020",
    journal = "PLoS Biology",
    abstract = "The evolutionary radiation of birds has produced incredible morphological variation, including a huge range of skull form and function. Investigating how this variation arose with respect to non-avian dinosaurs is key to understanding how birds achieved their remarkable success after the Cretaceous-Paleogene extinction event. Using a high-dimensional geometric morphometric approach, we quantified the shape of the skull in unprecedented detail across 354 extant and 37 extinct avian and non-avian dinosaurs. Comparative analyses reveal fundamental differences in how skull shape evolved in birds and non-avian dinosaurs. We find that the overall skull shape evolved faster in non-avian dinosaurs than in birds across all regions of the cranium. In birds, the anterior rostrum is the most rapidly evolving skull region, whereas more posterior regions-such as the parietal, squamosal, and quadrate-exhibited high rates in non-avian dinosaurs. These fast-evolving elements in dinosaurs are strongly associated with feeding biomechanics, forming the jaw joint and supporting the jaw adductor muscles. Rapid pulses of skull evolution coincide with changes to food acquisition strategies and diets, as well as the proliferation of bony skull ornaments. In contrast to the appendicular skeleton, which has been shown to evolve more rapidly in birds, avian cranial morphology is characterised by a striking deceleration in morphological evolution relative to non-avian dinosaurs. These results may be due to the reorganisation of skull structure in birds-including loss of a separate postorbital bone in adults and the emergence of new trade-offs with development and neurosensory demands. Taken together, the remarkable cranial shape diversity in birds was not a product of accelerated evolution from their non-avian relatives, despite their frequent portrayal as an icon of adaptive radiations.",
    url = "https://doi.org/10.1371/journal.pbio.3000801",
    doi = "10.1371/journal.pbio.3000801",
    openalex = "W3079777033",
    references = "doi101002ar24283"
}

Three new chasmosaurines from the Kirtland Formation (~75.0-73.4 Ma), New Mexico, form morphological and stratigraphic intermediates between Pentaceratops (~74.7-75 Ma, Fruitland Formation, New Mexico) and Anchiceratops (~72-71 Ma, Horseshoe Canyon Formation, Alberta). The new specimens exhibit gradual enclosure of the parietal embayment that characterizes Pentaceratops, providing support for the phylogenetic hypothesis that Pentaceratops and Anchiceratops are closely related. This stepwise change of morphologic characters observed in chasmosaurine taxa that do not overlap stratigraphically is supportive of evolution by anagenesis. Recently published hypotheses that place Pentaceratops and Anchiceratops into separate clades are not supported. This phylogenetic relationship demonstrates unrestricted movement of large-bodied taxa between hitherto purported northern and southern provinces in the late Campanian, weakening support for the hypothesis of extreme faunal provincialism in the Late Cretaceous Western Interior.

@article{doi107717peerj9251,
    author = "Fowler, Denver W. and Fowler, Elizabeth A. Freedman",
    title = "Transitional evolutionary forms in chasmosaurine ceratopsid dinosaurs: evidence from the Campanian of New Mexico",
    year = "2020",
    journal = "PeerJ",
    abstract = "Three new chasmosaurines from the Kirtland Formation (\textasciitilde 75.0-73.4 Ma), New Mexico, form morphological and stratigraphic intermediates between Pentaceratops (\textasciitilde 74.7-75 Ma, Fruitland Formation, New Mexico) and Anchiceratops (\textasciitilde 72-71 Ma, Horseshoe Canyon Formation, Alberta). The new specimens exhibit gradual enclosure of the parietal embayment that characterizes Pentaceratops, providing support for the phylogenetic hypothesis that Pentaceratops and Anchiceratops are closely related. This stepwise change of morphologic characters observed in chasmosaurine taxa that do not overlap stratigraphically is supportive of evolution by anagenesis. Recently published hypotheses that place Pentaceratops and Anchiceratops into separate clades are not supported. This phylogenetic relationship demonstrates unrestricted movement of large-bodied taxa between hitherto purported northern and southern provinces in the late Campanian, weakening support for the hypothesis of extreme faunal provincialism in the Late Cretaceous Western Interior.",
    url = "https://doi.org/10.7717/peerj.9251",
    doi = "10.7717/peerj.9251",
    openalex = "W3033842760",
    references = "doi101016jcretres2019104308, doi101098rsbl20140875, openalexw2772929664"
}

The Dinosaur Park Formation (DPF) of Alberta, Canada, has produced one of the most diverse dinosaur faunas, with the record favouring large-bodied taxa, in terms of number and completeness of skeletons. Although small theropods are well documented in the assemblage, taxonomic assessments are frequently based on isolated, fragmentary skeletal elements. Here we reassess DPF theropod biodiversity using morphological comparisons, high-resolution biostratigraphy, and morphometric analyses, with a focus on specimens/taxa originally described from isolated material. In addition to clarifying taxic diversity, we test whether DPF theropods preserve faunal zonation/turnover patterns similar to those previously documented for megaherbivores. Frontal bones referred to a therizinosaur (cf. Erlikosaurus), representing among the only skeletal record of the group from the Campanian–Maastrichtian (83–66 Ma) fossil record of North America, plot most closely to troodontids in morphospace, distinct from non-DPF therizinosaurs, a placement supported by a suite of troodontid anatomical frontal characters. Postcranial material referred to cf. Erlikosaurus in North America is also reviewed and found most similar in morphology to caenagnathids, rather than therizinosaurs. Among troodontids, we document considerable morphospace and biostratigraphic overlap between Stenonychosaurus and the recently described Latenivenatrix, as well as a variable distribution of putatively autapomorphic characters, calling the validity of the latter taxon into question. Biostratigraphically, there are no broad-scale patterns of faunal zonation similar to those previously documented in ornithischians from the DPF, with many theropods ranging throughout much of the formation and overlapping extensively, possibly reflecting a lack of sensitivity to environmental changes, or other cryptic ecological or evolutionary factors.

@article{doi101139cjes20200145,
    author = "Cullen, Thomas M. and Zanno, Lindsay E. and Larson, Derek W. and Todd, Erinn and Currie, Philip J. and Evans, David C.",
    title = "Anatomical, morphometric, and stratigraphic analyses of theropod biodiversity in the Upper Cretaceous (Campanian) Dinosaur Park Formation 1",
    year = "2021",
    journal = "Canadian Journal of Earth Sciences",
    abstract = "The Dinosaur Park Formation (DPF) of Alberta, Canada, has produced one of the most diverse dinosaur faunas, with the record favouring large-bodied taxa, in terms of number and completeness of skeletons. Although small theropods are well documented in the assemblage, taxonomic assessments are frequently based on isolated, fragmentary skeletal elements. Here we reassess DPF theropod biodiversity using morphological comparisons, high-resolution biostratigraphy, and morphometric analyses, with a focus on specimens/taxa originally described from isolated material. In addition to clarifying taxic diversity, we test whether DPF theropods preserve faunal zonation/turnover patterns similar to those previously documented for megaherbivores. Frontal bones referred to a therizinosaur (cf. Erlikosaurus), representing among the only skeletal record of the group from the Campanian–Maastrichtian (83–66 Ma) fossil record of North America, plot most closely to troodontids in morphospace, distinct from non-DPF therizinosaurs, a placement supported by a suite of troodontid anatomical frontal characters. Postcranial material referred to cf. Erlikosaurus in North America is also reviewed and found most similar in morphology to caenagnathids, rather than therizinosaurs. Among troodontids, we document considerable morphospace and biostratigraphic overlap between Stenonychosaurus and the recently described Latenivenatrix, as well as a variable distribution of putatively autapomorphic characters, calling the validity of the latter taxon into question. Biostratigraphically, there are no broad-scale patterns of faunal zonation similar to those previously documented in ornithischians from the DPF, with many theropods ranging throughout much of the formation and overlapping extensively, possibly reflecting a lack of sensitivity to environmental changes, or other cryptic ecological or evolutionary factors.",
    url = "https://doi.org/10.1139/cjes-2020-0145",
    doi = "10.1139/cjes-2020-0145",
    openalex = "W3183001791",
    references = "béland1979ectothermy, crossref1998encyclopedia, doi101002ar24241, doi1010079780387981413, doi10100797833192427749, doi101016jcub201803042, doi101016jpalaeo201206027, doi1011112041210x12035, doi101111j2041210x201100153x, doi101130g473991, doi101139cjes20170034, doi101139e09050, doi101139e72031, doi101139e93016, doi101186s1289801601068, doi1018435vamp29362, doi1023072669711, doi105860choice353642, doi105860choice435902, openalexw2561546966"
}

Ornithischian dinosaurs were ecologically prominent herbivores of the Mesozoic Era that achieved a global distribution by the onset of the Cretaceous. The ornithischian body plan is aberrant relative to other ornithodiran clades, and crucial details of their early evolution remain obscure. We present a new, fully articulated skeleton of the early branching ornithischian Heterodontosaurus tucki. Phase-contrast enhanced synchrotron data of this new specimen reveal a suite of novel postcranial features unknown in any other ornithischian, with implications for the early evolution of the group. These features include a large, anteriorly projecting sternum; bizarre, paddle-shaped sternal ribs; and a full gastral basket - the first recovered in Ornithischia. These unusual anatomical traits provide key information on the evolution of the ornithischian body plan and suggest functional shifts in the ventilatory apparatus occurred close to the base of the clade. We complement these anatomical data with a quantitative analysis of ornithischian pelvic architecture, which allows us to make a specific, stepwise hypothesis for their ventilatory evolution.

@article{doi107554elife66036,
    author = "Radermacher, Viktor J. and Fernández, Vincent and Schachner, Emma R. and Butler, Richard J. and Bordy, Emese M. and Hudgins, Michael and de Klerk, W. J. and Chapelle, Kimberley E. J. and Choiniere, Jonah N.",
    title = "A new Heterodontosaurus specimen elucidates the unique ventilatory macroevolution of ornithischian dinosaurs",
    year = "2021",
    journal = "eLife",
    abstract = "Ornithischian dinosaurs were ecologically prominent herbivores of the Mesozoic Era that achieved a global distribution by the onset of the Cretaceous. The ornithischian body plan is aberrant relative to other ornithodiran clades, and crucial details of their early evolution remain obscure. We present a new, fully articulated skeleton of the early branching ornithischian Heterodontosaurus tucki. Phase-contrast enhanced synchrotron data of this new specimen reveal a suite of novel postcranial features unknown in any other ornithischian, with implications for the early evolution of the group. These features include a large, anteriorly projecting sternum; bizarre, paddle-shaped sternal ribs; and a full gastral basket - the first recovered in Ornithischia. These unusual anatomical traits provide key information on the evolution of the ornithischian body plan and suggest functional shifts in the ventilatory apparatus occurred close to the base of the clade. We complement these anatomical data with a quantitative analysis of ornithischian pelvic architecture, which allows us to make a specific, stepwise hypothesis for their ventilatory evolution.",
    url = "https://doi.org/10.7554/elife.66036",
    doi = "10.7554/elife.66036",
    openalex = "W3179652327",
    references = "doi101002ar23988, doi1010800272463420181509866"
}

Ornithischians form a large clade of globally distributed Mesozoic dinosaurs, and represent one of their three major radiations. Throughout their evolutionary history, exceeding 134 million years, ornithischians evolved considerable morphological disparity, expressed especially through the cranial and osteodermal features of their most distinguishable representatives. The nearly two-century-long research history on ornithischians has resulted in the recognition of numerous diverse lineages, many of which have been named. Following the formative publications establishing the theoretical foundation of phylogenetic nomenclature throughout the 1980s and 1990s, many of the proposed names of ornithischian clades were provided with phylogenetic definitions. Some of these definitions have proven useful and have not been changed, beyond the way they were formulated, since their introduction. Some names, however, have multiple definitions, making their application ambiguous. Recent implementation of the International Code of Phylogenetic Nomenclature (ICPN, or PhyloCode) offers the opportunity to explore the utility of previously proposed definitions of established taxon names. Since the Articles of the ICPN are not to be applied retroactively, all phylogenetic definitions published prior to its implementation remain informal (and ineffective) in the light of the Code. Here, we revise the nomenclature of ornithischian dinosaur clades; we revisit 76 preexisting ornithischian clade names, review their recent and historical use, and formally establish their phylogenetic definitions. Additionally, we introduce five new clade names: two for robustly supported clades of later-diverging hadrosaurids and ceratopsians, one uniting heterodontosaurids and genasaurs, and two for clades of nodosaurids. Our study marks a key step towards a formal phylogenetic nomenclature of ornithischian dinosaurs.

@article{doi107717peerj12362,
    author = "Madzia, Daniel and Arbour, Victoria M. and Boyd, Clint and Farke, Andrew A. and Cruzado‐Caballero, Penélope and Evans, David C.",
    title = "The phylogenetic nomenclature of ornithischian dinosaurs",
    year = "2021",
    journal = "PeerJ",
    abstract = "Ornithischians form a large clade of globally distributed Mesozoic dinosaurs, and represent one of their three major radiations. Throughout their evolutionary history, exceeding 134 million years, ornithischians evolved considerable morphological disparity, expressed especially through the cranial and osteodermal features of their most distinguishable representatives. The nearly two-century-long research history on ornithischians has resulted in the recognition of numerous diverse lineages, many of which have been named. Following the formative publications establishing the theoretical foundation of phylogenetic nomenclature throughout the 1980s and 1990s, many of the proposed names of ornithischian clades were provided with phylogenetic definitions. Some of these definitions have proven useful and have not been changed, beyond the way they were formulated, since their introduction. Some names, however, have multiple definitions, making their application ambiguous. Recent implementation of the International Code of Phylogenetic Nomenclature (ICPN, or PhyloCode) offers the opportunity to explore the utility of previously proposed definitions of established taxon names. Since the Articles of the ICPN are not to be applied retroactively, all phylogenetic definitions published prior to its implementation remain informal (and ineffective) in the light of the Code. Here, we revise the nomenclature of ornithischian dinosaur clades; we revisit 76 preexisting ornithischian clade names, review their recent and historical use, and formally establish their phylogenetic definitions. Additionally, we introduce five new clade names: two for robustly supported clades of later-diverging hadrosaurids and ceratopsians, one uniting heterodontosaurids and genasaurs, and two for clades of nodosaurids. Our study marks a key step towards a formal phylogenetic nomenclature of ornithischian dinosaurs.",
    url = "https://doi.org/10.7717/peerj.12362",
    doi = "10.7717/peerj.12362",
    openalex = "W4200166441",
    references = "crossref1998dinosaurs, doi101007s1254202100555w, doi101016jcretres2019104308, doi101016jcub201706071, doi101016jpalaeo201602033, doi101038s4158602030114, doi101038s41598020678541, doi101080027246342012694385, doi101080027246342013746229, doi1010800272463420181509866, doi1010800891296320201793979, doi1010801477201920151059985, doi1010801477201920171371258, doi101093sysbiosyab045, doi101098rsos161086, doi101098rspl18870117, doi101111pala12329, doi101111zoj12193, doi101126science28454232137, doi101139e11017, doi101146annureves23110192002313, doi101371journalpone0080405, doi101371journalpone0141304, doi101371journalpone0175253, doi101371journalpone0188426, doi1023071005355, doi1023071441916, doi1023072992353, doi102475ajss319111253, doi104202app006982019, doi104202app20110033, doi104202app20110051, doi105860choice353642, doi105860choice393984, doi105962bhltitle50608, doi107717peerj1523, doi107717peerj4066, doi107717peerj7963, openalexw568618627, tsogtbaatar2019a"
}

Modern birds are typified by the presence of feathers, complex evolutionary innovations that were already widespread in the group of theropod dinosaurs (Maniraptoriformes) that include crown Aves. Squamous or scaly reptilian-like skin is, however, considered the plesiomorphic condition for theropods and dinosaurs more broadly. Here, we review the morphology and distribution of non-feathered integumentary structures in non-avialan theropods, covering squamous skin and naked skin as well as dermal ossifications. The integumentary record of non-averostran theropods is limited to tracks, which ubiquitously show a covering of tiny reticulate scales on the plantar surface of the pes. This is consistent also with younger averostran body fossils, which confirm an arthral arrangement of the digital pads. Among averostrans, squamous skin is confirmed in Ceratosauria (Carnotaurus), Allosauroidea (Allosaurus, Concavenator, Lourinhanosaurus), Compsognathidae (Juravenator), and Tyrannosauroidea (Santanaraptor, Albertosaurus, Daspletosaurus, Gorgosaurus, Tarbosaurus, Tyrannosaurus), whereas dermal ossifications consisting of sagittate and mosaic osteoderms are restricted to Ceratosaurus. Naked, non-scale bearing skin is found in the contentious tetanuran Sciurumimus, ornithomimosaurians (Ornithomimus) and possibly tyrannosauroids (Santanaraptor), and also on the patagia of scansoriopterygids (Ambopteryx, Yi). Scales are surprisingly conservative among non-avialan theropods compared to some dinosaurian groups (e.g. hadrosaurids); however, the limited preservation of tegument on most specimens hinders further interrogation. Scale patterns vary among and/or within body regions in Carnotaurus, Concavenator and Juravenator, and include polarised, snake-like ventral scales on the tail of the latter two genera. Unusual but more uniformly distributed patterning also occurs in Tyrannosaurus, whereas feature scales are present only in Albertosaurus and Carnotaurus. Few theropods currently show compelling evidence for the co-occurrence of scales and feathers (e.g. Juravenator, Sinornithosaurus), although reticulate scales were probably retained on the mani and pedes of many theropods with a heavy plumage. Feathers and filamentous structures appear to have replaced widespread scaly integuments in maniraptorans. Theropod skin, and that of dinosaurs more broadly, remains a virtually untapped area of study and the appropriation of commonly used techniques in other palaeontological fields to the study of skin holds great promise for future insights into the biology, taphonomy and relationships of these extinct animals.

@article{doi101111brv12829,
    author = "Hendrickx, Christophe and Bell, Phil R. and Pittman, Michael and Milner, Andrew R. and Cuesta, Elena and O’Connor, Jingmai K. and Loewen, Mark A. and Currie, Philip J. and Mateus, Octávio and Kaye, Thomas G. and Delcourt, Rafael",
    title = "Morphology and distribution of scales, dermal ossifications, and other non‐feather integumentary structures in non‐avialan theropod dinosaurs",
    year = "2022",
    journal = "Biological reviews/Biological reviews of the Cambridge Philosophical Society",
    abstract = "Modern birds are typified by the presence of feathers, complex evolutionary innovations that were already widespread in the group of theropod dinosaurs (Maniraptoriformes) that include crown Aves. Squamous or scaly reptilian-like skin is, however, considered the plesiomorphic condition for theropods and dinosaurs more broadly. Here, we review the morphology and distribution of non-feathered integumentary structures in non-avialan theropods, covering squamous skin and naked skin as well as dermal ossifications. The integumentary record of non-averostran theropods is limited to tracks, which ubiquitously show a covering of tiny reticulate scales on the plantar surface of the pes. This is consistent also with younger averostran body fossils, which confirm an arthral arrangement of the digital pads. Among averostrans, squamous skin is confirmed in Ceratosauria (Carnotaurus), Allosauroidea (Allosaurus, Concavenator, Lourinhanosaurus), Compsognathidae (Juravenator), and Tyrannosauroidea (Santanaraptor, Albertosaurus, Daspletosaurus, Gorgosaurus, Tarbosaurus, Tyrannosaurus), whereas dermal ossifications consisting of sagittate and mosaic osteoderms are restricted to Ceratosaurus. Naked, non-scale bearing skin is found in the contentious tetanuran Sciurumimus, ornithomimosaurians (Ornithomimus) and possibly tyrannosauroids (Santanaraptor), and also on the patagia of scansoriopterygids (Ambopteryx, Yi). Scales are surprisingly conservative among non-avialan theropods compared to some dinosaurian groups (e.g. hadrosaurids); however, the limited preservation of tegument on most specimens hinders further interrogation. Scale patterns vary among and/or within body regions in Carnotaurus, Concavenator and Juravenator, and include polarised, snake-like ventral scales on the tail of the latter two genera. Unusual but more uniformly distributed patterning also occurs in Tyrannosaurus, whereas feature scales are present only in Albertosaurus and Carnotaurus. Few theropods currently show compelling evidence for the co-occurrence of scales and feathers (e.g. Juravenator, Sinornithosaurus), although reticulate scales were probably retained on the mani and pedes of many theropods with a heavy plumage. Feathers and filamentous structures appear to have replaced widespread scaly integuments in maniraptorans. Theropod skin, and that of dinosaurs more broadly, remains a virtually untapped area of study and the appropriation of commonly used techniques in other palaeontological fields to the study of skin holds great promise for future insights into the biology, taphonomy and relationships of these extinct animals.",
    url = "https://doi.org/10.1111/brv.12829",
    doi = "10.1111/brv.12829",
    openalex = "W4206485050",
    references = "crossref1998encyclopedia, doi101002jmor10382, doi101016jcub201706071, doi101016jcub202006105, doi101016jgca201006017, doi101016s001678780180047x, doi101017jpa202014, doi10103831635, doi10103834356, doi10103835047056, doi101038ncomms14972, doi101038s41598018371862, doi101038srep44942, doi1010800272463420211897604, doi101080147720192013781067, doi101093biolinneanblaa105, doi101093zoolinneanzly009, doi101111brv12829, doi101111cla12160, doi101126science28454232137, doi1011270077774920100125, doi101146annurevearth060313054858, doi1012063521, doi101371journalpone0044012, doi101371journalpone0125819, doi1017161paleo180818764, doi1017161pc180818764, doi10230725058147, doi105962bhltitle5716, doi107717peerj4066, doi107717peerj7247, doi107717peerj7963, doi107717peerj9192, erickson2014on, openalexw1915591379, openalexw2619609965"
}

Amazing how even after half of a century some things do not change. Together again at the University of Pennsylvania, Peter Dodson and editorial co-author JL are energetically talking about six things at once, catching up as old friends are wont to do. Walking along the beautiful, tree-lined, quiet of Locust walk, topics bounce from new dinosaur finds, to what the children (and grandchildren!) are up to, to which of our body parts are the latest to stop working well (hey, we have known each other for some 50 years!). As has been the case since our days together at Yale, JL is lagging behind as Peter's energy, now as back in New Haven, has him moving ever faster than his old anatomy table mate. “C'mon, Jeff,” the august Penn Prof admonishes, “we finally get an audience with Professor Leidy, and let's not be late!” Yes, indeed. We have finally arranged a formal audience to see Professor Joseph Leidy, or, more specifically, his brain. For those of you who are not acquainted with Professor Leidy (shame, shame!), he was America's first dinosaur paleontologist of note, having reported and named (in 1858 and 1865; Leidy, 1858, 1865) the first American dinosaur, the “duck-billed” Hadrosaurus, unearthed in New Jersey (and you thought the state's only remains of note were those of Mob boss Jimmy Hoffa!). Subsequently, Leidy reconstructed Hadrosaurus at the Philadelphia Academy of Natural Sciences in 1868, the first museum display of any dinosaur. He estimated it to be 25 ft long and, based on its small forelimbs and long hind limbs, gave it a “kangaroo-like” stance with a semi-upright posture. Indeed, this vertical position became the image of dinosaurs imprinted in our collective visualization that remains to this day (see Dodson, 2009 for discussion). Leidy's day job was as the Professor of Anatomy at the University of Pennsylvania School of Medicine (the first in the United States), and he was a polymath of such renown that his biographer boldly titled his story, Joseph Leidy: The Last Man Who Knew Everything (Warren, 1999). Indeed, when the parent organization of The Anatomical Record, the American Association for Anatomy was formed in 1888 (originally named the Association of American Anatomists, today seen as an exclusionary banner, but done then to highlight specifically the emergence of American—over European—science), Professor Leidy was unanimously chosen its first President, in absentia no less. He was seen by many as the embodiment of an American scientist, the greatest of his day. There are giants and then there are GIANT giants, and our Professor Leidy falls into the latter category (Figure 1). And this brings us back to another titan of his science, and the reason for this Special Issue, JL's fast moving colleague, Peter Dodson. Like his Penn ancestor, Peter (our ties are too close for continued formalities here) is a giant among dinosaurs, not an easy feat if you think about it. His contributions to understanding the world of dinosaurs—from his paleontological findings, scholarly writings, museum exhibit creations, and birthing of superb progeny—have made him stand out in the world of dinosaur science. Indeed, Peter has given much to our own journal, being a frequent contributor (e.g., Dodson, 2003, 2009, 2020; Hedrick et al., 2020, 2022; Schachner et al., 2009, 2011; Tumanova et al., 2023), and Guest Editing two of the most popular Special Issues in our history, “Unearthing the Anatomy of Dinosaurs: New Insights into their Functional Morphology and Paleobiology” (Dodson, 2009; Laitman, 2009; Laitman & Albertine, 2009) and “The Hidden World of Dinosaurs” (Hedrick & Dodson, 2020; Laitman & Albertine, 2020; Figure 2). The 2009 Special Issue, our first on dinosaurs, was so much in demand that our Publisher, Wiley, had to print additional copies for individual sale (Dodson Dinos make money, at least for Wiley!) Beyond the quality of his science, Peter has been given a gift that he has shared with those of us fortunate to be his student, mentee, or colleague: his boundless goodness and caring. This “Dodsoness” quality has spanned his career and has touched many. Indeed, editorial co-author JL has written previously on how Peter's kindness helped him as an insecure and shy (no comments out there, please!). Yale graduate student to survive his overwhelming fears at the onset of his own path (see Laitman, 2017). More to our point here is how his own dinosaur-philic graduate students and mentees have grown and prospered in significant part due to his loving guidance. This current special, Special Issue, “Dinosaurs: New Ideas from Old Bones” (Fiorillo et al., 2023) has been meticulously Guest-edited by three who have learned their craft upon poppa Dodson's knee as his graduate students: Anthony Fiorillo, Executive Director of the New Mexico Museum of Natural History and Science; Catherine Forster, Professor of Geology and of Biology at George Washington University; and David Weishampel, Professor of Functional Anatomy and Evolution at Johns Hopkins University. These three have themselves had extraordinary careers in the multifaceted world of dinosaur paleontology and biology, and have been referred to as “the Big Three” of PD's students (by Catherine; oy!, I can hear the growls from other PD progeny!). As we write this, Tony is likely thoroughly enjoying the warmth of New Mexico, having spent a good part of his career studying arctic dinosaurs (equally cold is that, sadly, he never achieved his childhood dream of playing center field for the New York Yankees; hey, Tony, they have not won a World Series since 2009 so you still might have a chance!); Catherine, Tony's graduate student office mate at Penn (she helped him in his dissertation field-work and he repaid her kindness by being her occasional dog-sitter), followed directly Poppa Dodson's love by embracing horned dinosaurs for much of her prolific career; and Dave, Peter's first graduate student gaining his PhD in 1981, and thus placing him as the “first” among all PD progeny (all others always compare themselves to one's first student—and usually wince when their name is mentioned!) has had a marvelous path, within which he authored what many consider the definitive work on dinosaurs, the Dinosauria (Weishampel et al., 2007), and was even a consultant for his friend Steven Spielberg's Jurassic Park series (wonder if he got free tickets to the movies?). While this extraordinarily successful trio have known each other since the Cretaceous, this is the first time they have come together on a major project. HS and JL get a big smile out of the fact that our journal has served as a vehicle for this historic marriage (Figure 3). As one will see from the issue, many of the best and brightest in the field responded eagerly to contribute to a volume honoring Peter. Indeed, while this Special Issue focuses on new findings in dinosaur biology, a recent mammoth, sister Special Issue on crocodiles, “The Age of Crocodilians and Their Kin: Anatomy, Physiology, and Evolution,” Guest Edited by Casey Holliday (an academic “grandson” of Peter) of the University of Missouri School of Medicine and Emma R. Schachner (another PhD student of Peter) then of Louisiana State University Health Sciences Center (Holliday & Schachner, 2022; Laitman & Smith, 2022), was also done largely as an homage to Peter. Just the mention of something that will say a “thanks” to Peter has colleagues and former students and grand-students coming out of the rock pile to contribute. Attesting to Peter's broad influence, the contributions do not focus solely upon his own particular interests/scholarship charting the rise and distribution of ceratopsian dinosaurs (he is their undisputed horned king!). Rather, to name just some, they span a glorious gamut: from detailed descriptions of unusual Therapods from New Jersey (really? hadrosaurs, Jimmy Hoffa…who knew Jersey was actually interesting; sorry, JL is a native New Yorker and has little control when commenting on New Jersey; Gallagher, 2023); reports on a new iguanodontian dinosaur from South Africa (Forster et al., 2023); new insights on evolutionary relationships from analyses of the hyolaryngeal apparatus in extant archosaurs (i.e., birds and crocodilians; Yoshida et al., 2023); new reconstructions of the pectoral girdle and forelimb musculature of Megaraptora (Rolando et al., 2023); insights from osteohistology of Dromornis stironi with implications for understanding the histology of Australian mihirung birds (Chinsamy et al., 2023); insightful observations on fracture and disease in a large-bodied ornithomimosaur with insights into identifying unusual endosteal bone in the fossil record (Chinzorig et al., 2023); a comprehensive assessment of the history and future of the study of morphometrics in the study on non-avian dinosaurs (Hedrick, 2023); detailed modeling to assess and predict the abundance of large carnivorous dinosaurs of the Upper Jurassic Morrison Formation and the Upper Cretaceous Dinosaur Park formation (by Peter and JL's Yale classmate, the ever-creative James Farlow; JL is still in awe at all the super-bright dino dudes that surrounded him at Yale “back in the day”; Farlow et al., 2023); to a number of papers—naturally—on Peter's great love, the ceratopsians, including those by lead Guest Editor Fiorillo (Fiorillo & Tykoski, 2023) and Peter's successor teaching anatomy at Penn, Ali Nabavizadeh (Nabavizadeh, 2023). Even the cover of this Special Issue has been a creative homage to Peter, lovingly created by Anatomical Record Associate Editor (and artist extraordinaire) Adam Hartstone-Rose (Hartstone-Rose et al., 2023). What an incredible smorgasbord of new ideas from the minds of some of today's best dinosaur workers. “Hurry up, Jeff,” Peter exhorts, “our appointment is for 10:00 sharp and the curator is expecting us.” Along with JL's accommodating wife Leila (who was pressed into service as our photographer; if it was not for her adoring Peter—who does not?—not a chance she would spend hours taking photos of poor JL!), we bundled into our Uber and headed to the glorious Mütter Museum and Professor Leidy. The first time Peter and JL tried to visit Professor Leidy was back in 2009 when he was then in residence at the Wistar Institute on Penn's campus (they were turned away as they did not have an appropriate appointment and told “the Professor did not receive just anyone”). Since then, Leidy's domicile has changed (fortunately) to the extraordinary Mütter Museum, named after surgeon Thomas Dent Mütter who in 1856 donated his extensive collections of anatomical and pathological specimens to the College of Physicians of Philadelphia, wherein they have both grown and been lovingly cared for (btw, this is a really cool place, and if you had to choose between some cracked Liberty Bell and the Mütter, go Mütter!; see Worden, 2002). For Peter and JL, visiting Professor Leidy was almost a religious experience, as the Professor was their direct ancestor in so many ways: For PD, as Professor of Anatomy at Penn Veterinary School, and the comparative anatomist and vertebrate paleontologist at Penn, the line is direct; for JL, also, as an anatomy professor and fossil aficionado, but also as a past President of the American Association for Anatomy, the society of which Leidy was the first President, the bond is also powerful. Both PD and JL were well aware that they were coming into the presence of both their past and present (Figure 4). Professor Leidy was brought to PD and JL in his permanent home, a thick and heavy glass jar. What remained of the Professor was his brain. While this may seem odd, it was not uncommon in the 19th century to preserve the brains of great people (when JL told his daughter of this custom, Miss Snarky responded “do not worry, dad, you are safe”). The Professor's brain had turned a rather eerie shade of green, probably due to the preservatives used. Green or not, encased or not, this extraordinary anatomical remain was the repository of arguably more scientific knowledge than was held by any other mortal in the latter half of the 19th century. Within lay the secrets of anatomy and the founding of dinosaur paleontology in the United States. Peter and JL were in the presence of greatness, a most special and rare moment. As the group left the Mütter that day—and headed to our next stop, Peter's second home, his beloved Philadelphia Academy of Natural Sciences—JL could not stop pondering the gravity of the encounter. There were two of the rarest gems in the history of American Paleontology, Professors Joseph Leidy and Peter Dodson, together. As JL's kids would say, “two heavy dudes.” As Peter, JL, and JL's wife Leila (our sometimes complaining photographer) came into the main hall of the Academy staring us in the face were exhibit after exhibit that Peter had lovingly created. His name and images were everywhere. One, in particular, caught JL's attention as it so accurately summarized the moment and the person of appreciation: there was a picture of Peter with his reconstruction of Avaceratops with a bold banner that read “A Rare Find” (Figure 5). It clearly identified both the fossil and the scientist. HS and JL are very proud, on behalf of The Anatomical Record, to share both the wonderful science and scientists that have come together to offer new ideas from old bones, and to give a heartfelt thanks to our “Rare Find” of a colleague, Peter Dodson. We hope that you will explore the articles within and enjoy and learn from them as much as we have. And give a smile and thanks when you think of our most dear colleague, Peter Dodson. Jeffrey T. Laitman: Conceptualization; writing – original draft; writing – review and editing; visualization. Heather F. Smith: Conceptualization; writing – original draft; writing – review and editing; visualization.

@article{doi101002ar25233,
    author = "Laitman, Jeffrey T. and Smith, Heather F.",
    title = "Dinosaurs of all ilks bow and pay tribute to Peter Dodson, their intrepid chronicler, in an Anatomical Record Special Issue in his honor",
    year = "2023",
    journal = "The Anatomical Record",
    abstract = "Amazing how even after half of a century some things do not change. Together again at the University of Pennsylvania, Peter Dodson and editorial co-author JL are energetically talking about six things at once, catching up as old friends are wont to do. Walking along the beautiful, tree-lined, quiet of Locust walk, topics bounce from new dinosaur finds, to what the children (and grandchildren!) are up to, to which of our body parts are the latest to stop working well (hey, we have known each other for some 50 years!). As has been the case since our days together at Yale, JL is lagging behind as Peter's energy, now as back in New Haven, has him moving ever faster than his old anatomy table mate. “C'mon, Jeff,” the august Penn Prof admonishes, “we finally get an audience with Professor Leidy, and let's not be late!” Yes, indeed. We have finally arranged a formal audience to see Professor Joseph Leidy, or, more specifically, his brain. For those of you who are not acquainted with Professor Leidy (shame, shame!), he was America's first dinosaur paleontologist of note, having reported and named (in 1858 and 1865; Leidy, 1858, 1865) the first American dinosaur, the “duck-billed” Hadrosaurus, unearthed in New Jersey (and you thought the state's only remains of note were those of Mob boss Jimmy Hoffa!). Subsequently, Leidy reconstructed Hadrosaurus at the Philadelphia Academy of Natural Sciences in 1868, the first museum display of any dinosaur. He estimated it to be 25 ft long and, based on its small forelimbs and long hind limbs, gave it a “kangaroo-like” stance with a semi-upright posture. Indeed, this vertical position became the image of dinosaurs imprinted in our collective visualization that remains to this day (see Dodson, 2009 for discussion). Leidy's day job was as the Professor of Anatomy at the University of Pennsylvania School of Medicine (the first in the United States), and he was a polymath of such renown that his biographer boldly titled his story, Joseph Leidy: The Last Man Who Knew Everything (Warren, 1999). Indeed, when the parent organization of The Anatomical Record, the American Association for Anatomy was formed in 1888 (originally named the Association of American Anatomists, today seen as an exclusionary banner, but done then to highlight specifically the emergence of American—over European—science), Professor Leidy was unanimously chosen its first President, in absentia no less. He was seen by many as the embodiment of an American scientist, the greatest of his day. There are giants and then there are GIANT giants, and our Professor Leidy falls into the latter category (Figure 1). And this brings us back to another titan of his science, and the reason for this Special Issue, JL's fast moving colleague, Peter Dodson. Like his Penn ancestor, Peter (our ties are too close for continued formalities here) is a giant among dinosaurs, not an easy feat if you think about it. His contributions to understanding the world of dinosaurs—from his paleontological findings, scholarly writings, museum exhibit creations, and birthing of superb progeny—have made him stand out in the world of dinosaur science. Indeed, Peter has given much to our own journal, being a frequent contributor (e.g., Dodson, 2003, 2009, 2020; Hedrick et al., 2020, 2022; Schachner et al., 2009, 2011; Tumanova et al., 2023), and Guest Editing two of the most popular Special Issues in our history, “Unearthing the Anatomy of Dinosaurs: New Insights into their Functional Morphology and Paleobiology” (Dodson, 2009; Laitman, 2009; Laitman \& Albertine, 2009) and “The Hidden World of Dinosaurs” (Hedrick \& Dodson, 2020; Laitman \& Albertine, 2020; Figure 2). The 2009 Special Issue, our first on dinosaurs, was so much in demand that our Publisher, Wiley, had to print additional copies for individual sale (Dodson Dinos make money, at least for Wiley!) Beyond the quality of his science, Peter has been given a gift that he has shared with those of us fortunate to be his student, mentee, or colleague: his boundless goodness and caring. This “Dodsoness” quality has spanned his career and has touched many. Indeed, editorial co-author JL has written previously on how Peter's kindness helped him as an insecure and shy (no comments out there, please!). Yale graduate student to survive his overwhelming fears at the onset of his own path (see Laitman, 2017). More to our point here is how his own dinosaur-philic graduate students and mentees have grown and prospered in significant part due to his loving guidance. This current special, Special Issue, “Dinosaurs: New Ideas from Old Bones” (Fiorillo et al., 2023) has been meticulously Guest-edited by three who have learned their craft upon poppa Dodson's knee as his graduate students: Anthony Fiorillo, Executive Director of the New Mexico Museum of Natural History and Science; Catherine Forster, Professor of Geology and of Biology at George Washington University; and David Weishampel, Professor of Functional Anatomy and Evolution at Johns Hopkins University. These three have themselves had extraordinary careers in the multifaceted world of dinosaur paleontology and biology, and have been referred to as “the Big Three” of PD's students (by Catherine; oy!, I can hear the growls from other PD progeny!). As we write this, Tony is likely thoroughly enjoying the warmth of New Mexico, having spent a good part of his career studying arctic dinosaurs (equally cold is that, sadly, he never achieved his childhood dream of playing center field for the New York Yankees; hey, Tony, they have not won a World Series since 2009 so you still might have a chance!); Catherine, Tony's graduate student office mate at Penn (she helped him in his dissertation field-work and he repaid her kindness by being her occasional dog-sitter), followed directly Poppa Dodson's love by embracing horned dinosaurs for much of her prolific career; and Dave, Peter's first graduate student gaining his PhD in 1981, and thus placing him as the “first” among all PD progeny (all others always compare themselves to one's first student—and usually wince when their name is mentioned!) has had a marvelous path, within which he authored what many consider the definitive work on dinosaurs, the Dinosauria (Weishampel et al., 2007), and was even a consultant for his friend Steven Spielberg's Jurassic Park series (wonder if he got free tickets to the movies?). While this extraordinarily successful trio have known each other since the Cretaceous, this is the first time they have come together on a major project. HS and JL get a big smile out of the fact that our journal has served as a vehicle for this historic marriage (Figure 3). As one will see from the issue, many of the best and brightest in the field responded eagerly to contribute to a volume honoring Peter. Indeed, while this Special Issue focuses on new findings in dinosaur biology, a recent mammoth, sister Special Issue on crocodiles, “The Age of Crocodilians and Their Kin: Anatomy, Physiology, and Evolution,” Guest Edited by Casey Holliday (an academic “grandson” of Peter) of the University of Missouri School of Medicine and Emma R. Schachner (another PhD student of Peter) then of Louisiana State University Health Sciences Center (Holliday \& Schachner, 2022; Laitman \& Smith, 2022), was also done largely as an homage to Peter. Just the mention of something that will say a “thanks” to Peter has colleagues and former students and grand-students coming out of the rock pile to contribute. Attesting to Peter's broad influence, the contributions do not focus solely upon his own particular interests/scholarship charting the rise and distribution of ceratopsian dinosaurs (he is their undisputed horned king!). Rather, to name just some, they span a glorious gamut: from detailed descriptions of unusual Therapods from New Jersey (really? hadrosaurs, Jimmy Hoffa…who knew Jersey was actually interesting; sorry, JL is a native New Yorker and has little control when commenting on New Jersey; Gallagher, 2023); reports on a new iguanodontian dinosaur from South Africa (Forster et al., 2023); new insights on evolutionary relationships from analyses of the hyolaryngeal apparatus in extant archosaurs (i.e., birds and crocodilians; Yoshida et al., 2023); new reconstructions of the pectoral girdle and forelimb musculature of Megaraptora (Rolando et al., 2023); insights from osteohistology of Dromornis stironi with implications for understanding the histology of Australian mihirung birds (Chinsamy et al., 2023); insightful observations on fracture and disease in a large-bodied ornithomimosaur with insights into identifying unusual endosteal bone in the fossil record (Chinzorig et al., 2023); a comprehensive assessment of the history and future of the study of morphometrics in the study on non-avian dinosaurs (Hedrick, 2023); detailed modeling to assess and predict the abundance of large carnivorous dinosaurs of the Upper Jurassic Morrison Formation and the Upper Cretaceous Dinosaur Park formation (by Peter and JL's Yale classmate, the ever-creative James Farlow; JL is still in awe at all the super-bright dino dudes that surrounded him at Yale “back in the day”; Farlow et al., 2023); to a number of papers—naturally—on Peter's great love, the ceratopsians, including those by lead Guest Editor Fiorillo (Fiorillo \& Tykoski, 2023) and Peter's successor teaching anatomy at Penn, Ali Nabavizadeh (Nabavizadeh, 2023). Even the cover of this Special Issue has been a creative homage to Peter, lovingly created by Anatomical Record Associate Editor (and artist extraordinaire) Adam Hartstone-Rose (Hartstone-Rose et al., 2023). What an incredible smorgasbord of new ideas from the minds of some of today's best dinosaur workers. “Hurry up, Jeff,” Peter exhorts, “our appointment is for 10:00 sharp and the curator is expecting us.” Along with JL's accommodating wife Leila (who was pressed into service as our photographer; if it was not for her adoring Peter—who does not?—not a chance she would spend hours taking photos of poor JL!), we bundled into our Uber and headed to the glorious Mütter Museum and Professor Leidy. The first time Peter and JL tried to visit Professor Leidy was back in 2009 when he was then in residence at the Wistar Institute on Penn's campus (they were turned away as they did not have an appropriate appointment and told “the Professor did not receive just anyone”). Since then, Leidy's domicile has changed (fortunately) to the extraordinary Mütter Museum, named after surgeon Thomas Dent Mütter who in 1856 donated his extensive collections of anatomical and pathological specimens to the College of Physicians of Philadelphia, wherein they have both grown and been lovingly cared for (btw, this is a really cool place, and if you had to choose between some cracked Liberty Bell and the Mütter, go Mütter!; see Worden, 2002). For Peter and JL, visiting Professor Leidy was almost a religious experience, as the Professor was their direct ancestor in so many ways: For PD, as Professor of Anatomy at Penn Veterinary School, and the comparative anatomist and vertebrate paleontologist at Penn, the line is direct; for JL, also, as an anatomy professor and fossil aficionado, but also as a past President of the American Association for Anatomy, the society of which Leidy was the first President, the bond is also powerful. Both PD and JL were well aware that they were coming into the presence of both their past and present (Figure 4). Professor Leidy was brought to PD and JL in his permanent home, a thick and heavy glass jar. What remained of the Professor was his brain. While this may seem odd, it was not uncommon in the 19th century to preserve the brains of great people (when JL told his daughter of this custom, Miss Snarky responded “do not worry, dad, you are safe”). The Professor's brain had turned a rather eerie shade of green, probably due to the preservatives used. Green or not, encased or not, this extraordinary anatomical remain was the repository of arguably more scientific knowledge than was held by any other mortal in the latter half of the 19th century. Within lay the secrets of anatomy and the founding of dinosaur paleontology in the United States. Peter and JL were in the presence of greatness, a most special and rare moment. As the group left the Mütter that day—and headed to our next stop, Peter's second home, his beloved Philadelphia Academy of Natural Sciences—JL could not stop pondering the gravity of the encounter. There were two of the rarest gems in the history of American Paleontology, Professors Joseph Leidy and Peter Dodson, together. As JL's kids would say, “two heavy dudes.” As Peter, JL, and JL's wife Leila (our sometimes complaining photographer) came into the main hall of the Academy staring us in the face were exhibit after exhibit that Peter had lovingly created. His name and images were everywhere. One, in particular, caught JL's attention as it so accurately summarized the moment and the person of appreciation: there was a picture of Peter with his reconstruction of Avaceratops with a bold banner that read “A Rare Find” (Figure 5). It clearly identified both the fossil and the scientist. HS and JL are very proud, on behalf of The Anatomical Record, to share both the wonderful science and scientists that have come together to offer new ideas from old bones, and to give a heartfelt thanks to our “Rare Find” of a colleague, Peter Dodson. We hope that you will explore the articles within and enjoy and learn from them as much as we have. And give a smile and thanks when you think of our most dear colleague, Peter Dodson. Jeffrey T. Laitman: Conceptualization; writing – original draft; writing – review and editing; visualization. Heather F. Smith: Conceptualization; writing – original draft; writing – review and editing; visualization.",
    url = "https://doi.org/10.1002/ar.25233",
    doi = "10.1002/ar.25233",
    openalex = "W4375844442",
    references = "doi101002ar20989, doi101002ar21439, doi101002ar24099, doi101002ar25038, doi101002ar25047, doi101002ar25069, doi101002ar25104, doi101002ar25128, doi101002ar25196, doi101002ar25205, doi101002ar25241, farlow2023dragons"
}

Ankylosaurs were important megaherbivores of Jurassic and Cretaceous ecosystems. Their distinctive craniodental anatomy and mechanics differentiated them from coexisting hadrosaurs and ceratopsians, and morphological evidence suggests dietary niche partitioning between sympatric ankylosaurids and nodosaurids. Here, we investigate the skull biomechanics of ankylosaurs relative to feeding function. First, we compare feeding functional performance between nodosaurids and ankylosaurids applying finite element analysis and lever mechanics to the skulls of Panoplosaurus mirus (Nodosauridae) and Euoplocephalus tutus (Ankylosauridae). We also compare jaw performance across a wider sample of ankylosaurs through lever mechanics and phylogenetic comparative methods. Mandibular stress levels are higher in Euoplocephalus, supporting the view that Panoplosaurus consumed tougher foodstuffs. Bite force and mechanical advantage (MA) estimates indicate that Panoplosaurus had a relatively more forceful and efficient bite than Euoplocephalus. There is little support for a role of the secondary palate in resisting feeding loads in the two ankylosaur clades. Several ankylosaurs converged on similar jaw mechanics, while some nodosaurids specialised towards high MA and some ankylosaurids evolved low MA jaws. Our study supports the hypothesis that ankylosaurs partitioned dietary niches in Late Cretaceous ecosystems and reveals that the two main ankylosaur clades evolved divergent evolutionary pathways in skull biomechanics and feeding habits.

@article{doi101038s41598023454441,
    author = "Ballell, Antonio and Mai, Bohao and Benton, Michael J.",
    title = "Divergent strategies in cranial biomechanics and feeding ecology of the ankylosaurian dinosaurs",
    year = "2023",
    journal = "Scientific Reports",
    abstract = "Ankylosaurs were important megaherbivores of Jurassic and Cretaceous ecosystems. Their distinctive craniodental anatomy and mechanics differentiated them from coexisting hadrosaurs and ceratopsians, and morphological evidence suggests dietary niche partitioning between sympatric ankylosaurids and nodosaurids. Here, we investigate the skull biomechanics of ankylosaurs relative to feeding function. First, we compare feeding functional performance between nodosaurids and ankylosaurids applying finite element analysis and lever mechanics to the skulls of Panoplosaurus mirus (Nodosauridae) and Euoplocephalus tutus (Ankylosauridae). We also compare jaw performance across a wider sample of ankylosaurs through lever mechanics and phylogenetic comparative methods. Mandibular stress levels are higher in Euoplocephalus, supporting the view that Panoplosaurus consumed tougher foodstuffs. Bite force and mechanical advantage (MA) estimates indicate that Panoplosaurus had a relatively more forceful and efficient bite than Euoplocephalus. There is little support for a role of the secondary palate in resisting feeding loads in the two ankylosaur clades. Several ankylosaurs converged on similar jaw mechanics, while some nodosaurids specialised towards high MA and some ankylosaurids evolved low MA jaws. Our study supports the hypothesis that ankylosaurs partitioned dietary niches in Late Cretaceous ecosystems and reveals that the two main ankylosaur clades evolved divergent evolutionary pathways in skull biomechanics and feeding habits.",
    url = "https://doi.org/10.1038/s41598-023-45444-1",
    doi = "10.1038/s41598-023-45444-1",
    openalex = "W4387933579",
    references = "doi101002ar23988, doi101002ar24283, doi101098rsos220519"
}

@incollection{crossref2024horned,
    title = "HORNED DINOSAURS",
    year = "2024",
    booktitle = "The Little Book of Dinosaurs",
    url = "https://doi.org/10.2307/jj.14284458.35",
    doi = "10.2307/jj.14284458.35",
    openalex = "W4403630886",
    pages = "72-73"
}

Dinosaurs thrived for over 160 million years in Mesozoic ecosystems, displaying diverse ecological and evolutionary adaptations. Their ecology was shaped by large-scale climatic and biogeographic changes, calling for a 'deep-time' macroecological investigation. These factors include temperature fluctuations and the break up of Pangaea, influencing species richness, ecological diversity and biogeographic history. Recent improvements in the dinosaur fossil record have enabled large-scale studies of their responses to tectonic, geographic and climatic shifts. Trends in species diversity, body size and reproductive traits can now be analysed using quantitative approaches like phylogenetic comparative methods, machine learning and Bayesian inference. These patterns sometimes align with, but also deviate from, first-order macroecological rules (e.g. species-area relationship, latitudinal biodiversity gradient, Bergmann's rule). Accurate reconstructions of palaeobiodiversity and niche partitioning require ongoing taxonomic revisions and detailed anatomical descriptions. Interdisciplinary research combining sedimentology, geochemistry and palaeoclimatology helps uncover the environmental conditions driving dinosaur adaptations. Fieldwork in under-sampled regions, particularly at latitudinal extremes, is crucial for understanding the spatial heterogeneity of dinosaur ecosystems across the planet. Open science initiatives and online databases play a key role in advancing this field, enriching our understanding of deep-time ecological processes, and offering new insights into dinosaur macroecology and its broader implications.

@article{doi101098rsbl20240392,
    author = "Chiarenza, Alfio Alessandro",
    title = "The macroecology of Mesozoic dinosaurs",
    year = "2024",
    journal = "Biology Letters",
    abstract = "Dinosaurs thrived for over 160 million years in Mesozoic ecosystems, displaying diverse ecological and evolutionary adaptations. Their ecology was shaped by large-scale climatic and biogeographic changes, calling for a 'deep-time' macroecological investigation. These factors include temperature fluctuations and the break up of Pangaea, influencing species richness, ecological diversity and biogeographic history. Recent improvements in the dinosaur fossil record have enabled large-scale studies of their responses to tectonic, geographic and climatic shifts. Trends in species diversity, body size and reproductive traits can now be analysed using quantitative approaches like phylogenetic comparative methods, machine learning and Bayesian inference. These patterns sometimes align with, but also deviate from, first-order macroecological rules (e.g. species-area relationship, latitudinal biodiversity gradient, Bergmann's rule). Accurate reconstructions of palaeobiodiversity and niche partitioning require ongoing taxonomic revisions and detailed anatomical descriptions. Interdisciplinary research combining sedimentology, geochemistry and palaeoclimatology helps uncover the environmental conditions driving dinosaur adaptations. Fieldwork in under-sampled regions, particularly at latitudinal extremes, is crucial for understanding the spatial heterogeneity of dinosaur ecosystems across the planet. Open science initiatives and online databases play a key role in advancing this field, enriching our understanding of deep-time ecological processes, and offering new insights into dinosaur macroecology and its broader implications.",
    url = "https://doi.org/10.1098/rsbl.2024.0392",
    doi = "10.1098/rsbl.2024.0392",
    openalex = "W4404328467",
    references = "chiarenza2024early, doi101002spp21487, doi101016jearscirev2023104537, doi101038s41467024468432, doi1010801477201920242346577, doi101111pala12591, doi101139cjes20200145, doi101371journalpone0235078, doi102110palo2016041, doi104202app001522015"
}

Abstract The Campanian Two Medicine Formation of northwestern Montana, USA, is richly fossiliferous, and discoveries made within the unit over the past century have greatly advanced our appreciation of dinosaur paleobiology and evolution. Previously undifferentiated from a lithostratigraphic perspective, the formation is now subdivided into four new members that include (from base to top) (1) the Rock City Member, (2) the Shields Crossing Member, (3) the Hagans Crossing Member, and (4) the Flag Butte Member. These new formal units and their associated fossil occurrences are also now included in an age model founded on eight high-resolution chemical abrasion–isotope dilution–thermal ionization mass spectrometry (CA-ID-TIMS) U-Pb ages. New age data confirm that the Two Medicine Formation accumulated during much of the Campanian, with deposition spanning ca. 82.4 Ma to 74.4 Ma. New age data further indicate that a major reorganization of depositional systems, marked by a shift from predominantly lacustrine to alluvial facies and accompanied by a dramatic increase in accommodation, transpired near the base of the new Flag Butte Member at ca. 76.3 Ma. This change in depositional regime correlates in age with the Judith River–Belly River discontinuity, which marks the contact between the McClelland Ferry and Coal Ridge Members in the Judith River Formation and coincides with the onset of the Bearpaw transgression in north-central Montana. The new lithostratigraphic and chronostratigraphic framework for the Two Medicine Formation serves to contextualize and calibrate the formation’s rich dinosaur fossil record, which can now be interrogated with increased clarity and precision. These results also provide ground truth for numerical models that explore the structure of the fossil record in relation to alluvial architecture and terrestrial sequence stratigraphy.

@article{doi101130b374981,
    author = "Rogers, Raymond R. and Horner, John R. and Ramezani, Jahandar and Roberts, Eric M. and Varricchio, David J.",
    title = "Updating the Upper Cretaceous (Campanian) Two Medicine Formation of Montana: Lithostratigraphic revisions, new CA-ID-TIMS U-Pb ages, and a calibrated framework for dinosaur occurrences",
    year = "2024",
    journal = "Geological Society of America Bulletin",
    abstract = "Abstract The Campanian Two Medicine Formation of northwestern Montana, USA, is richly fossiliferous, and discoveries made within the unit over the past century have greatly advanced our appreciation of dinosaur paleobiology and evolution. Previously undifferentiated from a lithostratigraphic perspective, the formation is now subdivided into four new members that include (from base to top) (1) the Rock City Member, (2) the Shields Crossing Member, (3) the Hagans Crossing Member, and (4) the Flag Butte Member. These new formal units and their associated fossil occurrences are also now included in an age model founded on eight high-resolution chemical abrasion–isotope dilution–thermal ionization mass spectrometry (CA-ID-TIMS) U-Pb ages. New age data confirm that the Two Medicine Formation accumulated during much of the Campanian, with deposition spanning ca. 82.4 Ma to 74.4 Ma. New age data further indicate that a major reorganization of depositional systems, marked by a shift from predominantly lacustrine to alluvial facies and accompanied by a dramatic increase in accommodation, transpired near the base of the new Flag Butte Member at ca. 76.3 Ma. This change in depositional regime correlates in age with the Judith River–Belly River discontinuity, which marks the contact between the McClelland Ferry and Coal Ridge Members in the Judith River Formation and coincides with the onset of the Bearpaw transgression in north-central Montana. The new lithostratigraphic and chronostratigraphic framework for the Two Medicine Formation serves to contextualize and calibrate the formation’s rich dinosaur fossil record, which can now be interrogated with increased clarity and precision. These results also provide ground truth for numerical models that explore the structure of the fossil record in relation to alluvial architecture and terrestrial sequence stratigraphy.",
    url = "https://doi.org/10.1130/b37498.1",
    doi = "10.1130/b37498.1",
    openalex = "W4400724459",
    references = "doi101139cjes20200169, doi101139cjes20230037"
}

Despite paying concerted attention to evolutionary mechanisms, literary scholars have rarely focused on forms of “directed evolution” like orthogenesis (evolution along a linear track) and phylogeronty—the parallel between the lifespan of an animal group and the lifespan of an aging individual—analogical concepts reflecting a paleontological manifestation of a wider interest in human decadence. This essay analyzes how these concepts are explored in three areas: popular adventure fiction, social reform novels by Marie Stopes and H. G. Wells, and writings by paleontologists. Across these texts, the essay argues that directed evolution offered a recognizable trajectory with which to render the complexity and strangeness of prehistoric and modern life alike into a familiar linear shape by reading certain extinct animals as moral exemplars of evolutionary failure. While reformers hoped that humans could escape the orthogenetic grooves confining nonhuman animals to extinction, this optimism was shadowed both with fears that humans might inevitably face decadence and with a sense that survival meant mediocrity.

@article{doi1012150041462x11098327,
    author = "Fallon, Richard H.",
    title = "Decadent Dinosaurs: Directed Evolution in British and North American Literature, 1890s–1970s",
    year = "2024",
    journal = "Twentieth Century Literature",
    abstract = "Despite paying concerted attention to evolutionary mechanisms, literary scholars have rarely focused on forms of “directed evolution” like orthogenesis (evolution along a linear track) and phylogeronty—the parallel between the lifespan of an animal group and the lifespan of an aging individual—analogical concepts reflecting a paleontological manifestation of a wider interest in human decadence. This essay analyzes how these concepts are explored in three areas: popular adventure fiction, social reform novels by Marie Stopes and H. G. Wells, and writings by paleontologists. Across these texts, the essay argues that directed evolution offered a recognizable trajectory with which to render the complexity and strangeness of prehistoric and modern life alike into a familiar linear shape by reading certain extinct animals as moral exemplars of evolutionary failure. While reformers hoped that humans could escape the orthogenetic grooves confining nonhuman animals to extinction, this optimism was shadowed both with fears that humans might inevitably face decadence and with a sense that survival meant mediocrity.",
    url = "https://doi.org/10.1215/0041462x-11098327",
    doi = "10.1215/0041462x-11098327",
    openalex = "W4398786472",
    references = "doi101017cbo9780511770401, doi1010800890549520181395802, doi101093acprofoso97801996065970010001, doi101093oxfordhb97801953731410010001, doi1023073508689, doi1023073824699, doi105860choice304570, doi105962bhltitle25509, doi107208chicago97802266167040010001, openalexw2164113877"
}

Yinlong downsi, the earliest known ceratopsian, is represented by dozens of specimens of different sizes collected from the Upper Jurassic of the Junggar Basin, northwestern China. Here, we present the first comprehensive study on the bone histology of Yinlong downsi based on ten specimens varying in size. Four ontogenetic stages are recognized: early juvenile, late juvenile, subadult, and adult. The reconstructed growth curve suggests that Yinlong may reach sexual maturity at 6 years old, which is earlier than that of the well-studied early-diverging ceratopsian Psittacosaurus (9 years old) but later than ceratopsids (about 3 to 5 years old). This may indicate that sexual maturity begins earlier during the evolution of ceratopsians, and that the giant size of ceratopsids is acquired by accelerating growth rates. The cortex of the tibia mainly consists of fibrolamellar bone tissues, but parallel-fibered bone and lines of arrested growth (LAGs) are very common throughout ontogeny, suggesting a moderate growth rate. Quantitative analysis indicates that Yinlong has a maximum growth rate similar to those of other small-sized dinosaurs such as Psittacosaurus, Dysalotosaurus, and Troodon, and their maximum growth rates are higher than those of extant squamates and crocodiles but lower than those of extant mammals and large dinosaurs. This suggests that body size plays a more important role in growth rate than other factors such as phylogenetic position and/or diet among non-avian dinosaurs.

@article{doi107717peerj18761,
    author = "Han, Fenglu and Zhao, Qi and Hu, Jinfeng and Xu, Xing",
    title = "Bone histology and growth curve of the earliest ceratopsian Yinlong downsi from the Upper Jurassic of Junggar Basin, Northwest China",
    year = "2024",
    journal = "PeerJ",
    abstract = "Yinlong downsi, the earliest known ceratopsian, is represented by dozens of specimens of different sizes collected from the Upper Jurassic of the Junggar Basin, northwestern China. Here, we present the first comprehensive study on the bone histology of Yinlong downsi based on ten specimens varying in size. Four ontogenetic stages are recognized: early juvenile, late juvenile, subadult, and adult. The reconstructed growth curve suggests that Yinlong may reach sexual maturity at 6 years old, which is earlier than that of the well-studied early-diverging ceratopsian Psittacosaurus (9 years old) but later than ceratopsids (about 3 to 5 years old). This may indicate that sexual maturity begins earlier during the evolution of ceratopsians, and that the giant size of ceratopsids is acquired by accelerating growth rates. The cortex of the tibia mainly consists of fibrolamellar bone tissues, but parallel-fibered bone and lines of arrested growth (LAGs) are very common throughout ontogeny, suggesting a moderate growth rate. Quantitative analysis indicates that Yinlong has a maximum growth rate similar to those of other small-sized dinosaurs such as Psittacosaurus, Dysalotosaurus, and Troodon, and their maximum growth rates are higher than those of extant squamates and crocodiles but lower than those of extant mammals and large dinosaurs. This suggests that body size plays a more important role in growth rate than other factors such as phylogenetic position and/or diet among non-avian dinosaurs.",
    url = "https://doi.org/10.7717/peerj.18761",
    doi = "10.7717/peerj.18761",
    openalex = "W4405595414",
    references = "doi101002ar24099, doi101016jcretres2023105738, doi1010800272463420181509866, doi101111joa13679"
}

Two hundred years after the naming of the first dinosaur, taxonomic studies remain an important component of dinosaur research. Around 50 new dinosaurs are named each year and are discovered from across the globe. The rate of new dinosaur discovery shows no signs of slowing, but not all geographical areas and temporal windows have been equally investigated. The potential for new dinosaur discoveries in India and Africa seems particularly high, while the Carnian, when dinosaurs probably originated, and the Middle Jurassic, when the major clades diversified, offer the best opportunities to make discoveries that will fundamentally change our understanding of dinosaur evolution. A major challenge to the discovery of new dinosaurs is funding. Frontier fieldwork is sometimes viewed as too risky to fund, while basic taxonomic work is considered to lack impact. As a consequence, we risk an 'extinction of experience', where researchers have limited training in the basic field- and specimen-based research that underpins our discipline. Going forward, new remote sensing techniques may help to find prospective areas, while three-dimensional scanning apps on smartphones will allow us to quickly record field data. Artificial intelligence is likely to be used increasingly for computed tomography segmentation and identification of problematic fossils.

@article{doi101098rsbl20250045,
    author = "Maidment, Susannah C. R. and Butler, Richard J.",
    title = "New frontiers in dinosaur exploration",
    year = "2025",
    journal = "Biology Letters",
    abstract = "Two hundred years after the naming of the first dinosaur, taxonomic studies remain an important component of dinosaur research. Around 50 new dinosaurs are named each year and are discovered from across the globe. The rate of new dinosaur discovery shows no signs of slowing, but not all geographical areas and temporal windows have been equally investigated. The potential for new dinosaur discoveries in India and Africa seems particularly high, while the Carnian, when dinosaurs probably originated, and the Middle Jurassic, when the major clades diversified, offer the best opportunities to make discoveries that will fundamentally change our understanding of dinosaur evolution. A major challenge to the discovery of new dinosaurs is funding. Frontier fieldwork is sometimes viewed as too risky to fund, while basic taxonomic work is considered to lack impact. As a consequence, we risk an 'extinction of experience', where researchers have limited training in the basic field- and specimen-based research that underpins our discipline. Going forward, new remote sensing techniques may help to find prospective areas, while three-dimensional scanning apps on smartphones will allow us to quickly record field data. Artificial intelligence is likely to be used increasingly for computed tomography segmentation and identification of problematic fossils.",
    url = "https://doi.org/10.1098/rsbl.2025.0045",
    doi = "10.1098/rsbl.2025.0045",
    openalex = "W4409965177",
    references = "doi101016jtree201309012, doi1010801477201920242345333, doi101093zoolinneanzlab072, doi101098rsbl20240443, doi101098rsbl20250045, doi101098rspb20080715, doi101098rspb20121745, doi101111j1469185x200900094x, doi101111j2041210x201200223x, doi101126science28253921298, doi101139cjes20230037, doi10157900447447200837114ecitbs20co2, doi1054991jop202115, openalexw3215057009, sereno1997the"
}

Unlike mammals, reptiles typically lack large muscles and ligaments that connect the zygoma to the mandible. Dinosaur craniomandibular soft tissue reconstructions, often based on the rationale of extant phylogenetic bracketing, follow this general rule. However, descending flanges from the zygomata of hadrosaurs, heterodontosaurids, and psittacosaurids have been used to argue for a masseter-like muscle in these dinosaur taxa. We examined dinosauriform skulls for osteological indicators of connective tissue entheses on the zygoma and mandible, and subsequently sectioned 10 specimens for histological evidence. Osteological indicators were found on the zygoma in most sampled dinosauriforms, which range from rugosities to large descending processes, and morphologically resemble known muscular and ligamentous entheses. Similarly, rugose features oriented towards the zygoma were found on the mandible in sampled dinosauriforms, many having previously been interpreted as entheses for the adductor mandibulae muscle group. Serial histological sectioning of ceratopsid, hadrosaurid, and tyrannosaurid jugal and surangular rugosities reveals an external cortex rich in collagen fibres, strongly resembling entheseal fibres. Jugal entheseal fibres are usually oriented ventrally towards the surangular, and in hadrosaurids and tyrannosaurids these are parallel to macroscopic striations on the surfaces of the jugal flange. Histological sections of extant chicken buccal regions show similar entheseal fibres in the attachments of the jugomandibular ligament on the jugal and of the adductor musculature on the mandible. We hypothesise a strong connective tissue structure bridging the zygoma and mandible in dinosaurs, termed the 'exoparia'. This structure's size and proximity to the craniomandibular joint would be advantageous in stabilising the mandible relative to the cranium during jaw movement, particularly in dinosaurs thought to process their masticate. A ligamentous or muscular identity for the exoparia cannot be determined with the available data, but the size and shape of the zygomatic entheses in many dinosaurs are more consistent with a muscular attachment. Possible antecedents in non-dinosauriform archosaurs and derivations in modern birds may exist, but the homology of the exoparia is currently unknown. These results highlight the complex soft tissue evolution of dinosaurs and caution against simplified phylogenetic model-based approaches to tissue reconstruction that ignore contrasting osteological signals.

@article{doi101111joa14242,
    author = "Sharpe, Henry S. and Yan-yin, Wang and Dudgeon, Thomas W. and Powers, Mark J. and Whitebone, S. Amber and Coppock, Colton C. and Dyer, Aaron D. and Sullivan, Corwin",
    title = "Skull morphology and histology indicate the presence of an unexpected buccal soft tissue structure in dinosaurs",
    year = "2025",
    journal = "Journal of Anatomy",
    abstract = "Unlike mammals, reptiles typically lack large muscles and ligaments that connect the zygoma to the mandible. Dinosaur craniomandibular soft tissue reconstructions, often based on the rationale of extant phylogenetic bracketing, follow this general rule. However, descending flanges from the zygomata of hadrosaurs, heterodontosaurids, and psittacosaurids have been used to argue for a masseter-like muscle in these dinosaur taxa. We examined dinosauriform skulls for osteological indicators of connective tissue entheses on the zygoma and mandible, and subsequently sectioned 10 specimens for histological evidence. Osteological indicators were found on the zygoma in most sampled dinosauriforms, which range from rugosities to large descending processes, and morphologically resemble known muscular and ligamentous entheses. Similarly, rugose features oriented towards the zygoma were found on the mandible in sampled dinosauriforms, many having previously been interpreted as entheses for the adductor mandibulae muscle group. Serial histological sectioning of ceratopsid, hadrosaurid, and tyrannosaurid jugal and surangular rugosities reveals an external cortex rich in collagen fibres, strongly resembling entheseal fibres. Jugal entheseal fibres are usually oriented ventrally towards the surangular, and in hadrosaurids and tyrannosaurids these are parallel to macroscopic striations on the surfaces of the jugal flange. Histological sections of extant chicken buccal regions show similar entheseal fibres in the attachments of the jugomandibular ligament on the jugal and of the adductor musculature on the mandible. We hypothesise a strong connective tissue structure bridging the zygoma and mandible in dinosaurs, termed the 'exoparia'. This structure's size and proximity to the craniomandibular joint would be advantageous in stabilising the mandible relative to the cranium during jaw movement, particularly in dinosaurs thought to process their masticate. A ligamentous or muscular identity for the exoparia cannot be determined with the available data, but the size and shape of the zygomatic entheses in many dinosaurs are more consistent with a muscular attachment. Possible antecedents in non-dinosauriform archosaurs and derivations in modern birds may exist, but the homology of the exoparia is currently unknown. These results highlight the complex soft tissue evolution of dinosaurs and caution against simplified phylogenetic model-based approaches to tissue reconstruction that ignore contrasting osteological signals.",
    url = "https://doi.org/10.1111/joa.14242",
    doi = "10.1111/joa.14242",
    openalex = "W4408725133",
    references = "doi101002ar24283, doi101093zoolinneanzlab039"
}

. Here we describe new material of Ajkaceratops and conduct phylogenetic analyses that support its ceratopsian affinities. Our results unexpectedly demonstrate that some 'rhabdodontid' taxa are not, in fact, iguanodontians but actually ceratopsians. This suggests a substantial but previously hidden diversity and evolutionary history of European horned dinosaurs, and co-occurrence of iguanodontians and ceratopsians indicates greater similarity than previously appreciated to other Laurasian ecosystems. Our results challenge conventional understanding of ornithischian dinosaur evolution and indicate the need for a fundamental re-evaluation of the Late Cretaceous herbivorous dinosaur assemblages of Europe.

@article{doi101038s4158602509897w,
    author = "Maidment, Susannah C. R. and Butler, Richard J. and Brusatte, Stephen L. and Meade, Luke E. and Augustin, Felix J. and Csiki-Sava, Zoltán. and Ősi, Attila",
    title = "A hidden diversity of ceratopsian dinosaurs in Late Cretaceous Europe",
    year = "2026",
    journal = "Nature",
    abstract = ". Here we describe new material of Ajkaceratops and conduct phylogenetic analyses that support its ceratopsian affinities. Our results unexpectedly demonstrate that some 'rhabdodontid' taxa are not, in fact, iguanodontians but actually ceratopsians. This suggests a substantial but previously hidden diversity and evolutionary history of European horned dinosaurs, and co-occurrence of iguanodontians and ceratopsians indicates greater similarity than previously appreciated to other Laurasian ecosystems. Our results challenge conventional understanding of ornithischian dinosaur evolution and indicate the need for a fundamental re-evaluation of the Late Cretaceous herbivorous dinosaur assemblages of Europe.",
    url = "https://doi.org/10.1038/s41586-025-09897-w",
    doi = "10.1038/s41586-025-09897-w",
    openalex = "W7119146319",
    references = "doi1010800272463420181509866, doi107717peerj17224, longrich2016a"
}