Lance formation

Osborn, H.F. (1905): Tyrannosaurus and other Cretaceous carnivorous dinosaurs. Bulletin of the American Museum of Natural History 21: 259-265, DOI: 10.5281/zenodo.814935

@article{doi105281zenodo814935,
    author = "Osborn, Henry F.",
    title = "Tyrannosaurus And Other Cretaceous Carnivorous Dinosaurs",
    year = "1905",
    journal = "Zenodo (CERN European Organization for Nuclear Research)",
    abstract = "Osborn, H.F. (1905): Tyrannosaurus and other Cretaceous carnivorous dinosaurs. Bulletin of the American Museum of Natural History 21: 259-265, DOI: 10.5281/zenodo.814935",
    url = "https://doi.org/10.5281/zenodo.814935",
    doi = "10.5281/zenodo.814935",
    openalex = "W3113191843"
}

@article{bauer1925quartzite,
    author = "Bauer, C. Max",
    title = "Quartzite Pebbles at the Base of the Lance Formation in Montana: GEOLOGICAL NOTES",
    year = "1925",
    journal = "AAPG Bulletin",
    url = "https://doi.org/10.1306/3d9326bd-16b1-11d7-8645000102c1865d",
    doi = "10.1306/3d9326bd-16b1-11d7-8645000102c1865d",
    number = "2",
    openalex = "W2166941317",
    pages = "344-346",
    volume = "9"
}

Gilmore, C. W. (1946): New carnivorous dinosaur from the Lance formation of Montana. The Smithsonian Institution 106, No. 13: 1-19

@article{doi1015468yhxmzl,
    author = "Gilmore, Charles W.",
    title = "A new carnivorous dinosaur from the Lance Formation of Montana",
    year = "1946",
    journal = "Zenodo (CERN European Organization for Nuclear Research)",
    abstract = "Gilmore, C. W. (1946): New carnivorous dinosaur from the Lance formation of Montana. The Smithsonian Institution 106, No. 13: 1-19",
    url = "https://doi.org/10.15468/yhxmzl",
    doi = "10.15468/yhxmzl",
    openalex = "W2529936223"
}

Gilmore, Charles W. (1946): A new carnivorous dinosaur from the Lance Formation of Montana. Smithsonian Miscellaneous Collections 106: 1-19, DOI: 10.5281/zenodo.3239146

@article{gilmore1946a,
    author = "Gilmore, Charles W.",
    title = "A new carnivorous dinosaur from the Lance Formation of Montana",
    year = "1946",
    publisher = "Zenodo",
    abstract = "Gilmore, Charles W. (1946): A new carnivorous dinosaur from the Lance Formation of Montana. Smithsonian Miscellaneous Collections 106: 1-19, DOI: 10.5281/zenodo.3239146",
    url = "https://zenodo.org/record/3239146",
    doi = "10.5281/zenodo.3239146"
}

@misc{gilmore1946a1,
    author = "Gilmore, C. W",
    title = "A new carnivorous dinosaur from the Lance Formation of Montana",
    year = "1946",
    howpublished = "Smithsonian Miscellaneous Collections, v. 106, p. 1-19",
    note = "talkorigins\_source = {true}; raw\_reference = {Gilmore, C. W., 1946, A new carnivorous dinosaur from the Lance Formation of Montana: Smithsonian Miscellaneous Collections, v. 106, p. 1-19.}"
}

@article{doi1010160031018271900447,
    author = "Dodson, Peter",
    title = "Sedimentology and taphonomy of the Oldman Formation (Campanian), Dinosaur Provincial Park, Alberta (Canada)",
    year = "1971",
    journal = "Palaeogeography Palaeoclimatology Palaeoecology",
    url = "https://doi.org/10.1016/0031-0182(71)90044-7",
    doi = "10.1016/0031-0182(71)90044-7",
    openalex = "W1973699641",
    references = "doi1010079783662010204, doi101086626329, doi101111j136530911963tb01204x, doi101111j136530911964tb00459x, doi101111j136530911965tb01561x, doi101111j155856461968tb03995x, doi10113000167606195364381tfsaci20co2, doi101130spe40p1, doi102113gsrocky8specialpaper11, doi1023071934999, doi102475ajs2628975, doi105962bhltitle52089, doi105962p339375, openalexw2591879035, openalexw337536883, openalexw607142922"
}

The family Ornithomimidae is defined on the basis of the skeletal morphology of the three genera Ornithomimus, Struthiomimus, and Dromiceiomimus known in continental strata in Alberta, which are temporally equivalent to the Upper Campanian substage. At least two genera occur in Canadian Lance (Upper Maestrichtian) equivalent strata, but cannot be identified at present. A group of more primitive ornithomimoid theropods is represented else-where by the late Jurassic Elaphrosaurus and early Cretaceous Archaeornithomimus.Ornithomimid attributes include a general body form which parallels that of the ratites; elongate forelimbs, a kinetic skull, enormous eyes, a relatively highly evolved brain, and possibly a secondary palate and supertemporal fenestrae which were nearly encircled by alae of the squamosal. A reconstruction of the myology of the thigh indicates that ornithomimids were extremely fleet, but lacked the agility characteristic of modern large ground birds. They probably subsisted on small, soft-bodied animals.

@article{doi101139e72031,
    author = "Russell, Dale A.",
    title = "Ostrich Dinosaurs from the Late Cretaceous of Western Canada",
    year = "1972",
    journal = "Canadian Journal of Earth Sciences",
    abstract = "The family Ornithomimidae is defined on the basis of the skeletal morphology of the three genera Ornithomimus, Struthiomimus, and Dromiceiomimus known in continental strata in Alberta, which are temporally equivalent to the Upper Campanian substage. At least two genera occur in Canadian Lance (Upper Maestrichtian) equivalent strata, but cannot be identified at present. A group of more primitive ornithomimoid theropods is represented else-where by the late Jurassic Elaphrosaurus and early Cretaceous Archaeornithomimus.Ornithomimid attributes include a general body form which parallels that of the ratites; elongate forelimbs, a kinetic skull, enormous eyes, a relatively highly evolved brain, and possibly a secondary palate and supertemporal fenestrae which were nearly encircled by alae of the squamosal. A reconstruction of the myology of the thigh indicates that ornithomimids were extremely fleet, but lacked the agility characteristic of modern large ground birds. They probably subsisted on small, soft-bodied animals.",
    url = "https://doi.org/10.1139/e72-031",
    doi = "10.1139/e72-031",
    openalex = "W2140641637",
    references = "doi101002jmor1051140102, doi1010160031018271900447, doi105962bhltitle14474, openalexw1879660213, openalexw3208547338"
}

@article{doi101017cbo9780511608377011,
    author = "Currie, P. and Rigby, J. and Sloan, R. E.",
    title = "Dinosaur Systematics: Theropod teeth from the Judith River Formation of southern Alberta, Canada",
    year = "1990",
    booktitle = "Dinosaur Systematics",
    url = "https://www.semanticscholar.org/paper/fedead3cc1ae0ec35f3954946391d9906ed25ae7",
    doi = "10.1017/CBO9780511608377.011",
    is_oa = "true",
    pages = "107-126",
    semanticscholar_citation_count = "246",
    semanticscholar_id = "fedead3cc1ae0ec35f3954946391d9906ed25ae7"
}

The lithostratigraphic interval between the Taber and Lethbridge coal zones in the upper portion of the nonmarine Judith River Group of southeastern Alberta is divisible into two lithostratigraphic units separated by a regionally extensive and diachronous discontinuity. The lower unit, referred to here as the Oldman Formation, is characterized by very fine grained to fine-grained sandstones that contain fewer than 2% volcanic rock fragments; sandstone bodies with numerous sets of horizontally stratified sandstone, showing little or no evidence of lateral accretion; siliceous paleosols (ganisters); and a relatively high gamma-ray signal in the upper half of the formation. The Oldman Formation comprises deposits of a low-sinuosity, perhaps ephemeral fluvial system that originated in the southern Cordillera of Canada and northern Montana and flowed northeastward, perpendicular to the axis of the Alberta Basin.The upper unit is assigned to a new formation, the Dinosaur Park Formation, and is characterized by fine- to medium-grained sandstones with up to 10% volcanic rock fragments; sandstone bodies that exhibit lateral-accretion surfaces in the form of inclined heterolithic stratification; numerous articulated dinosaurs and dinosaur bone beds; and a relatively low gamma-ray signal in the lower half of the formation. The Dinosaur Park Formation comprises deposits of a high-sinuosity, fluvial-to-estuarine system that originated in the north and central Cordillera and flowed southeastward, subparallel to the axis of the Alberta Basin. 40 Ar/ 39 Ar and K–Ar dating of Judith River Group bentonites shows that the contact between the Oldman and Dinosaur Park formations becomes younger toward the south and southeast. These data also demonstrate that the Dinosaur Park Formation clastics migrated southeastward at a rate of approximately 130–140 km/Ma, gradually overstepping the Oldman Formation elastics.The widely recognized north-to-south increase in intensity of overthrust loading along the western margin of the Alberta Basin during the Late Cretaceous is thought to be responsible for (i) differences in accommodation space for the proximal portions of the Oldman and Dinosaur Park formations, and (ii) the establishment of a southerly tilt in the Alberta Basin leading to the southeastward migration of the Dinosaur Park Formation elastics. In the northern portion of the basin, relatively lower rates of subsidence, combined with periods of isostatic rebound in the foredeep, resulted in the southeastward migration of Dinosaur Park Formation elastics as sediment input exceeded accommodation space. In the southern portion of the basin, relatively higher rates of subsidence and little isostatic rebound acted to trap coarse-grained Oldman Formation elastics in the foredeep and may have led to periods of sediment starvation in more distal portions of the basin. An inferred lower depositional slope associated with the Dinosaur Park Formation (relative to the Oldman Formation) is thought to have resulted from gradual loading of the basin as Dinosaur Park Formation elastics migrated southeastward or some form of tectonically induced subsidence.

@article{doi101139e93016,
    author = "Eberth, David A. and Hamblin, A P",
    title = "Tectonic, stratigraphic, and sedimentologic significance of a regional discontinuity in the upper Judith River Group (Belly River wedge) of southern Alberta, Saskatchewan, and northern Montana",
    year = "1993",
    journal = "Canadian Journal of Earth Sciences",
    abstract = "The lithostratigraphic interval between the Taber and Lethbridge coal zones in the upper portion of the nonmarine Judith River Group of southeastern Alberta is divisible into two lithostratigraphic units separated by a regionally extensive and diachronous discontinuity. The lower unit, referred to here as the Oldman Formation, is characterized by very fine grained to fine-grained sandstones that contain fewer than 2\% volcanic rock fragments; sandstone bodies with numerous sets of horizontally stratified sandstone, showing little or no evidence of lateral accretion; siliceous paleosols (ganisters); and a relatively high gamma-ray signal in the upper half of the formation. The Oldman Formation comprises deposits of a low-sinuosity, perhaps ephemeral fluvial system that originated in the southern Cordillera of Canada and northern Montana and flowed northeastward, perpendicular to the axis of the Alberta Basin.The upper unit is assigned to a new formation, the Dinosaur Park Formation, and is characterized by fine- to medium-grained sandstones with up to 10\% volcanic rock fragments; sandstone bodies that exhibit lateral-accretion surfaces in the form of inclined heterolithic stratification; numerous articulated dinosaurs and dinosaur bone beds; and a relatively low gamma-ray signal in the lower half of the formation. The Dinosaur Park Formation comprises deposits of a high-sinuosity, fluvial-to-estuarine system that originated in the north and central Cordillera and flowed southeastward, subparallel to the axis of the Alberta Basin. 40 Ar/ 39 Ar and K–Ar dating of Judith River Group bentonites shows that the contact between the Oldman and Dinosaur Park formations becomes younger toward the south and southeast. These data also demonstrate that the Dinosaur Park Formation clastics migrated southeastward at a rate of approximately 130–140 km/Ma, gradually overstepping the Oldman Formation elastics.The widely recognized north-to-south increase in intensity of overthrust loading along the western margin of the Alberta Basin during the Late Cretaceous is thought to be responsible for (i) differences in accommodation space for the proximal portions of the Oldman and Dinosaur Park formations, and (ii) the establishment of a southerly tilt in the Alberta Basin leading to the southeastward migration of the Dinosaur Park Formation elastics. In the northern portion of the basin, relatively lower rates of subsidence, combined with periods of isostatic rebound in the foredeep, resulted in the southeastward migration of Dinosaur Park Formation elastics as sediment input exceeded accommodation space. In the southern portion of the basin, relatively higher rates of subsidence and little isostatic rebound acted to trap coarse-grained Oldman Formation elastics in the foredeep and may have led to periods of sediment starvation in more distal portions of the basin. An inferred lower depositional slope associated with the Dinosaur Park Formation (relative to the Oldman Formation) is thought to have resulted from gradual loading of the basin as Dinosaur Park Formation elastics migrated southeastward or some form of tectonically induced subsidence.",
    url = "https://doi.org/10.1139/e93-016",
    doi = "10.1139/e93-016",
    openalex = "W2037483301"
}

An embryonic skeleton of a nonavian theropod dinosaur was found preserved in an egg from Upper Cretaceous rocks in the Gobi Desert of Mongolia. Cranial features identify the embryo as a member of Oviraptoridae. Two embryo-sized skulls of dromaeosaurids, similar to that of Velociraptor, were also recovered in the nest. The eggshell microstructure is similar to that of ratite birds and is of a type common in the Djadokhta Formation at the Flaming Cliffs (Bayn Dzak). Discovery of a nest of such eggs at the Flaming Cliffs in 1923, beneath the Oviraptor philoceratops holotype, suggests that this dinosaur may have been a brooding adult.

@article{doi101126science2665186779,
    author = "Norell, Mark A. and Clark, James M. and Demberelyin, Dashzeveg and Rhinchen, Barsbold and Chiappe, Luis M. and Davidson, Amy R. and McKenna, Malcolm C. and Altangerel, Perle and Novacek, Michael J.",
    title = "A Theropod Dinosaur Embryo and the Affinities of the Flaming Cliffs Dinosaur Eggs",
    year = "1994",
    journal = "Science",
    abstract = "An embryonic skeleton of a nonavian theropod dinosaur was found preserved in an egg from Upper Cretaceous rocks in the Gobi Desert of Mongolia. Cranial features identify the embryo as a member of Oviraptoridae. Two embryo-sized skulls of dromaeosaurids, similar to that of Velociraptor, were also recovered in the nest. The eggshell microstructure is similar to that of ratite birds and is of a type common in the Djadokhta Formation at the Flaming Cliffs (Bayn Dzak). Discovery of a nest of such eggs at the Flaming Cliffs in 1923, beneath the Oviraptor philoceratops holotype, suggests that this dinosaur may have been a brooding adult.",
    url = "https://doi.org/10.1126/science.266.5186.779",
    doi = "10.1126/science.266.5186.779",
    openalex = "W2086035298",
    references = "doi101002jmor1051000302, doi1010160195667191900155, doi10108002724634198710011638, doi10108002724634199510011250, doi101111j174966321940tb57047x, doi101139e93196, doi1023073514816, doi105281zenodo16171435, openalexw2131558500, openalexw633579066, sues1977dentaries"
}

Late Cretaceous trace fossils from the Two Medicine Formation of Montana are interpreted as herbivorous dinosaur feces reworked by scarabaeine dung beetles. These irregular blocks of comminuted plant material occur in isolated patches in fluvial flood plain sediments near dinosaur bone beds and nesting grounds. Numerous burrows in and around the specimens indicate significant invertebrate activity which suggests intense competition for a rich food resource. Some of the burrows are backfilled with organic matter that had been translocated from the organic mass (dung pat) into the adjacent sediment. Paracoprid dung beetles are the only extant organisms known to make similar caches. These unique ichnofossils provide evidence for commensal interactions between dung beetles, herbivorous dinosaurs, and conifers. This find also reveals a pathway through which fecal resources were recycled and suggests that scarabs evolved coprophagy through association with dinosaurs.

@article{doi1023073515235,
    author = "Chin, Karen and Gill, Bruce D.",
    title = "Dinosaurs, Dung Beetles, and Conifers: Participants in a Cretaceous Food Web",
    year = "1996",
    journal = "Palaios",
    abstract = "Late Cretaceous trace fossils from the Two Medicine Formation of Montana are interpreted as herbivorous dinosaur feces reworked by scarabaeine dung beetles. These irregular blocks of comminuted plant material occur in isolated patches in fluvial flood plain sediments near dinosaur bone beds and nesting grounds. Numerous burrows in and around the specimens indicate significant invertebrate activity which suggests intense competition for a rich food resource. Some of the burrows are backfilled with organic matter that had been translocated from the organic mass (dung pat) into the adjacent sediment. Paracoprid dung beetles are the only extant organisms known to make similar caches. These unique ichnofossils provide evidence for commensal interactions between dung beetles, herbivorous dinosaurs, and conifers. This find also reveals a pathway through which fecal resources were recycled and suggests that scarabs evolved coprophagy through association with dinosaurs.",
    url = "https://doi.org/10.2307/3515235",
    doi = "10.2307/3515235",
    openalex = "W1966939491",
    references = "doi101038282296a0, doi101139e78109"
}

Fossils discovered in Lower Cretaceous (Aptian) rocks in the Tenere Desert of central Niger provide new information about spinosaurids, a peculiar group of piscivorous theropod dinosaurs. The remains, which represent a new genus and species, reveal the extreme elongation and transverse compression of the spinosaurid snout. The postcranial bones include blade-shaped vertebral spines that form a low sail over the hips. Phylogenetic analysis suggests that the enlarged thumb claw and robust forelimb evolved during the Jurassic, before the elongated snout and other fish-eating adaptations in the skull. The close phylogenetic relationship between the new African spinosaurid and Baryonyx from Europe provides evidence of dispersal across the Tethys seaway during the Early Cretaceous.

@article{doi101126science28253921298,
    author = "Sereno, Paul C. and Beck, Allison L. and Dutheil, Didier B. and Gado, Boubacar and Larsson, Hans C. E. and Lyon, Gabrielle H. and Marcot, Jonathan D. and Rauhut, Oliver W. M. and Sadleir, Rudyard W. and Sidor, Christian A. and Varricchio, David D. and Wilson, Gregory P. and Wilson, Jeffrey A.",
    title = "A Long-Snouted Predatory Dinosaur from Africa and the Evolution of Spinosaurids",
    year = "1998",
    journal = "Science",
    abstract = "Fossils discovered in Lower Cretaceous (Aptian) rocks in the Tenere Desert of central Niger provide new information about spinosaurids, a peculiar group of piscivorous theropod dinosaurs. The remains, which represent a new genus and species, reveal the extreme elongation and transverse compression of the spinosaurid snout. The postcranial bones include blade-shaped vertebral spines that form a low sail over the hips. Phylogenetic analysis suggests that the enlarged thumb claw and robust forelimb evolved during the Jurassic, before the elongated snout and other fish-eating adaptations in the skull. The close phylogenetic relationship between the new African spinosaurid and Baryonyx from Europe provides evidence of dispersal across the Tethys seaway during the Early Cretaceous.",
    url = "https://doi.org/10.1126/science.282.5392.1298",
    doi = "10.1126/science.282.5392.1298",
    openalex = "W2161814413",
    references = "doi101016s0195667105800199, doi101038324359a0, doi101093sysbio461195, doi101111j136531211989tb00328x, doi101126science2725264986, doi101127njgpa1991996151, doi101144gsjgs15310005, doi102113gssgfbulliv2335, doi105860choice331556, openalexw2989049194"
}

Histologic studies of embryonic and perinatal longbones of living birds, non-avian dinosaurs, and other reptiles show a strong phylogenetic signal in the distribution of tissues and patterns of vascularization in both the shafts and the bone ends. The embryonic bones of basal archosaurs and other reptiles have thin-walled cortices and large marrow cavities that are sometimes subdivided by erosion rooms in early stages of growth. The cortices of basal reptiles are poorly vascularized, and osteocyte lacunae are common but randomly organized. Additionally, there is no evidence of fibrolamellar tissue organization around the vascular spaces. Compared with turtles, basal archosaurs show an increase in vascularization, better organized osteocytes, and some fibrolamellar tissue organization. In dinosaurs, including birds, vascularization is greater than in basal archosaurs, as is cortical thickness, and the osteocyte lacunae are more abundant and less randomly organized. Fibrolamellar tissues are evident around vascular canals and form organized primary osteons in older perinates and juveniles. Metaphyseal (“epiphyseal”) morphology varies with the acquisition of new features in derived groups. The cartilage cone, persistent through the Reptilia (crown-group reptiles, including birds), is completely calcified in ornithischian dinosaurs before it is eroded by marrow processes; cartilage canals, absent in basal archosaurs, are present in Dinosauria; a thickened calcified hypertrophy zone in Dinosauria indicates an acceleration of longitudinal bone growth. Variations in this set of histological synapomorphies overlap between birds and non-avian dinosaurs. In birds, these variations are strongly correlated with life-history strategies. This overlap, plus independent evidence from nesting sites, reinforces the hypothesis that variations in bone growth strategies in Mesozoic dinosaurs reflect different life-history strategies, including nesting behavior of neonates and parental care.

@article{doi1016660094837320010270039coosea20co2,
    author = "Horner, John R. and Padian, Kevin and de Ricqlès, Armand",
    title = "Comparative osteohistology of some embryonic and perinatal archosaurs: developmental and behavioral implications for dinosaurs",
    year = "2001",
    journal = "Paleobiology",
    abstract = "Histologic studies of embryonic and perinatal longbones of living birds, non-avian dinosaurs, and other reptiles show a strong phylogenetic signal in the distribution of tissues and patterns of vascularization in both the shafts and the bone ends. The embryonic bones of basal archosaurs and other reptiles have thin-walled cortices and large marrow cavities that are sometimes subdivided by erosion rooms in early stages of growth. The cortices of basal reptiles are poorly vascularized, and osteocyte lacunae are common but randomly organized. Additionally, there is no evidence of fibrolamellar tissue organization around the vascular spaces. Compared with turtles, basal archosaurs show an increase in vascularization, better organized osteocytes, and some fibrolamellar tissue organization. In dinosaurs, including birds, vascularization is greater than in basal archosaurs, as is cortical thickness, and the osteocyte lacunae are more abundant and less randomly organized. Fibrolamellar tissues are evident around vascular canals and form organized primary osteons in older perinates and juveniles. Metaphyseal (“epiphyseal”) morphology varies with the acquisition of new features in derived groups. The cartilage cone, persistent through the Reptilia (crown-group reptiles, including birds), is completely calcified in ornithischian dinosaurs before it is eroded by marrow processes; cartilage canals, absent in basal archosaurs, are present in Dinosauria; a thickened calcified hypertrophy zone in Dinosauria indicates an acceleration of longitudinal bone growth. Variations in this set of histological synapomorphies overlap between birds and non-avian dinosaurs. In birds, these variations are strongly correlated with life-history strategies. This overlap, plus independent evidence from nesting sites, reinforces the hypothesis that variations in bone growth strategies in Mesozoic dinosaurs reflect different life-history strategies, including nesting behavior of neonates and parental care.",
    url = "https://doi.org/10.1666/0094-8373(2001)027<0039:coosea>2.0.co;2",
    doi = "10.1666/0094-8373(2001)027<0039:coosea>2.0.co;2",
    openalex = "W2192703335",
    references = "crossref1998encyclopedia, doi1010079781489953919, doi101016b9780125052559500298, doi101017s0094837300021308, doi101029sc005p0175, doi101038282296a0, doi101038378774a0, doi101038385247a0, doi10108002724634199510011271, doi101093clinids222240, doi101093oso97801951060840010001, doi101126science26251422020, doi101146annurevearth28119, doi1016710272463420000200115lbhoth20co2, doi1023071971635, openalexw563887495, reid1984primary"
}

@article{doi1016690883135120010160482ttoaco20co2,
    author = "Ryan, Michael J. and Russell, Anthony P. and Eberth, David A. and Currie, Philip J.",
    title = "The Taphonomy of a Centrosaurus (Ornithischia: Certopsidae) Bone Bed from the Dinosaur Park Formation (Upper Campanian), Alberta, Canada, with Comments on Cranial Ontogeny",
    year = "2001",
    journal = "Palaios",
    url = "https://doi.org/10.1669/0883-1351(2001)016<0482:ttoaco>2.0.co;2",
    doi = "10.1669/0883-1351(2001)016<0482:ttoaco>2.0.co;2",
    openalex = "W2179225693",
    references = "brinkman1990paleooecology, doi1010160031018288900855, doi101016003101829090202i, doi101017s0094837300005820, doi101038114085a0, doi101038282296a0, doi101093nqs5vi146318i, doi101111j109636421997tb00340x, doi101126science11282807, doi101139e93016, doi101306c1ea47bb16c911d78645000102c1865d, doi102113gsrocky8specialpaper11, doi1023071296618, doi1023072531613, doi1023075209, doi105962bhlpart22969, eberth1990stratigraphy, openalexw2259418280, openalexw2591879035, openalexw568618627, parrish1987late"
}

Patterns of bone microstructure have frequently been used to deduce dynamics and processes of growth in extant and fossil tetrapods. Often, the various types of primary bone tissue have been associated with different bone deposition rates and more recently such deductions have extended to patterns observed in dinosaur bone microstructure. These previous studies are challenged by the findings of the current research, which integrates an experimental neontological approach and a paleontological comparison. We use tetracycline labeling and morphometry to study the variability of bone deposition rates in Japanese quail (Coturnix japonica) growing under different experimental conditions. We compare resulting patterns in bone microstructure with those found in fossil birds and other dinosaurs. We found that a single type of primary bone varies significantly in rates of growth in response to environmental conditions. Ranging between 10-50 microm per day, rates of growth overlap with the full range of bone deposition rates that were previously associated with different patterns of bone histology. Bone formation rate was significantly affected by environmental/experimental conditions, skeletal element, and age. In the quail, the experimental conditions did not result in formation of lines of arrested growth (LAGs). Because of the observed variation of bone deposition rates in response to variation in environmental conditions, we conclude that bone deposition rates measured in extant birds cannot simply be extrapolated to their fossil relatives. Additionally, we observe the variable incidence of LAGs and annuli among several dinosaur species, including fossil birds, extant sauropsids, as well as nonmammalian synapsids, and some extant mammals. This suggests that the ancestral condition of the response of bone to environmental conditions was variable. We propose that such developmental plasticity in modern birds may be reduced in association with the shortened developmental time during the later evolution of the ornithurine birds.

@article{doi101002jmor10029,
    author = "Starck, J. Matthias and Chinsamy, Anusuya",
    title = "Bone microstructure and developmental plasticity in birds and other dinosaurs",
    year = "2002",
    journal = "Journal of Morphology",
    abstract = "Patterns of bone microstructure have frequently been used to deduce dynamics and processes of growth in extant and fossil tetrapods. Often, the various types of primary bone tissue have been associated with different bone deposition rates and more recently such deductions have extended to patterns observed in dinosaur bone microstructure. These previous studies are challenged by the findings of the current research, which integrates an experimental neontological approach and a paleontological comparison. We use tetracycline labeling and morphometry to study the variability of bone deposition rates in Japanese quail (Coturnix japonica) growing under different experimental conditions. We compare resulting patterns in bone microstructure with those found in fossil birds and other dinosaurs. We found that a single type of primary bone varies significantly in rates of growth in response to environmental conditions. Ranging between 10-50 microm per day, rates of growth overlap with the full range of bone deposition rates that were previously associated with different patterns of bone histology. Bone formation rate was significantly affected by environmental/experimental conditions, skeletal element, and age. In the quail, the experimental conditions did not result in formation of lines of arrested growth (LAGs). Because of the observed variation of bone deposition rates in response to variation in environmental conditions, we conclude that bone deposition rates measured in extant birds cannot simply be extrapolated to their fossil relatives. Additionally, we observe the variable incidence of LAGs and annuli among several dinosaur species, including fossil birds, extant sauropsids, as well as nonmammalian synapsids, and some extant mammals. This suggests that the ancestral condition of the response of bone to environmental conditions was variable. We propose that such developmental plasticity in modern birds may be reduced in association with the shortened developmental time during the later evolution of the ornithurine birds.",
    url = "https://doi.org/10.1002/jmor.10029",
    doi = "10.1002/jmor.10029",
    openalex = "W2064159002",
    references = "deklerk2000a, doi101016s0764446900001815, doi101017s0094837300013543, doi101017s0094837300021308, doi101038368196a0, doi10108002724634199310011490, doi101093clinids222240, doi101093oso97801951060840010001, doi1016660094837320000260466lhotts20co2, doi1016710272463420000200115lbhoth20co2, openalexw406909995"
}

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"
}

@article{doi105860choice434677,
    title = "The Carnivorous dinosaurs",
    year = "2006",
    journal = "Choice Reviews Online",
    url = "https://doi.org/10.5860/choice.43-4677",
    doi = "10.5860/choice.43-4677",
    openalex = "W4256719198"
}

Contributors Preface Acknowledgments I. Beaked Dinosaurs: The Ornithopods 1. Callovosaurus leedsi, the Earliest Dryosaurid Dinosaur (Ornithischia: Euornithopoda) from the Middle Jurassic of England Jose Ignacio Ruiz-Omenaca, Xabier Pereda Suberbiola, and Peter M. Galton 2. Teeth of Ornithischian Dinosaurs (Mostly Ornithopoda) from the Morrison Formation (Upper Jurassic) of the Western United States Peter M. Galton 3. A Description of a New Ornithopod from the Lytle Member of the Purgatoire Formation (Lower Cretaceous) and a Reassessment of the Skull of Camptosaurus Kathleen Brill and Kenneth Carpenter 4. Turning the Old into the New: A Separate Genus for the Gracile Iguanodont from the Wealden of England Gregory S. Paul 5. A Possible New Basal Hadrosaur from the Lower Cretaceous Cedar Mountain Formation of Eastern Utah David Gilpin, Tony DiCroce, and Kenneth Carpenter 6. Postcranial Osteology of the Hadrosaurid Dinosaur Brachylophosaurus canadensis from the Late Cretaceous of Montana Albert Prieto-Marquez 7. Leonardo, a Mummified Brachylophosaurus (Ornithischia: Hadrosauridae) from the Judith River Formation of Montana Nate L. Murphy, David Trexler, and Mark Thompson 8. Discussion of Character Analysis of the Appendicular Anatomy in Campanian and Maastrichtian North American Hadrosaurids-Variation and Ontogeny Michael K. Brett-Surman and Jonathan R. Wagner 9. Osteochondrosis in Late Cretaceous Hadrosauria: A Manifestation of Ontologic Failure Bruce Rothschild and Darren H. Tanke 10. Deciphering Duckbills: A History in Nomenclature Benjamin S. Creisler II. Horned Dinosaurs: Ceratopsians 11. Cranial Anatomy and Biogeography of the First Leptoceratops gracilis (Dinosauria: Ornithischia) Specimens from the Hell Creek Formation, Southeast Montana Christopher J. Ott 12. Cranial Osteology and Phylogenetic Relationships of the Chasmosaurine Ceratopsid Torosaurus latus Andrew A. Farke 13. Growth and Population Age Structure in the Horned Dinosaur Chasmosaurus Thomas M. Lehman 14. Bone Resorption, Bone Lesions, and Extracranial Fenestrae in Ceratopsid Dinosaurs: A Preliminary Assessment Darren H. Tanke and Andrew A. Farke 15. Bison alticornis and O. C. Marsh's Early Views on Ceratopsians Kenneth Carpenter Index

@article{s275130bec4b7de57fce9bef0ec8999fa1f29d33c4,
    author = "Carpenter, K.",
    title = "Horns and Beaks: Ceratopsian and Ornithopod Dinosaurs",
    year = "2006",
    booktitle = "Project Muse (Johns Hopkins University)",
    abstract = "Contributors Preface Acknowledgments I. Beaked Dinosaurs: The Ornithopods 1. Callovosaurus leedsi, the Earliest Dryosaurid Dinosaur (Ornithischia: Euornithopoda) from the Middle Jurassic of England Jose Ignacio Ruiz-Omenaca, Xabier Pereda Suberbiola, and Peter M. Galton 2. Teeth of Ornithischian Dinosaurs (Mostly Ornithopoda) from the Morrison Formation (Upper Jurassic) of the Western United States Peter M. Galton 3. A Description of a New Ornithopod from the Lytle Member of the Purgatoire Formation (Lower Cretaceous) and a Reassessment of the Skull of Camptosaurus Kathleen Brill and Kenneth Carpenter 4. Turning the Old into the New: A Separate Genus for the Gracile Iguanodont from the Wealden of England Gregory S. Paul 5. A Possible New Basal Hadrosaur from the Lower Cretaceous Cedar Mountain Formation of Eastern Utah David Gilpin, Tony DiCroce, and Kenneth Carpenter 6. Postcranial Osteology of the Hadrosaurid Dinosaur Brachylophosaurus canadensis from the Late Cretaceous of Montana Albert Prieto-Marquez 7. Leonardo, a Mummified Brachylophosaurus (Ornithischia: Hadrosauridae) from the Judith River Formation of Montana Nate L. Murphy, David Trexler, and Mark Thompson 8. Discussion of Character Analysis of the Appendicular Anatomy in Campanian and Maastrichtian North American Hadrosaurids-Variation and Ontogeny Michael K. Brett-Surman and Jonathan R. Wagner 9. Osteochondrosis in Late Cretaceous Hadrosauria: A Manifestation of Ontologic Failure Bruce Rothschild and Darren H. Tanke 10. Deciphering Duckbills: A History in Nomenclature Benjamin S. Creisler II. Horned Dinosaurs: Ceratopsians 11. Cranial Anatomy and Biogeography of the First Leptoceratops gracilis (Dinosauria: Ornithischia) Specimens from the Hell Creek Formation, Southeast Montana Christopher J. Ott 12. Cranial Osteology and Phylogenetic Relationships of the Chasmosaurine Ceratopsid Torosaurus latus Andrew A. Farke 13. Growth and Population Age Structure in the Horned Dinosaur Chasmosaurus Thomas M. Lehman 14. Bone Resorption, Bone Lesions, and Extracranial Fenestrae in Ceratopsid Dinosaurs: A Preliminary Assessment Darren H. Tanke and Andrew A. Farke 15. Bison alticornis and O. C. Marsh's Early Views on Ceratopsians Kenneth Carpenter Index",
    url = "https://www.semanticscholar.org/paper/75130bec4b7de57fce9bef0ec8999fa1f29d33c4",
    is_oa = "true",
    openalex = "W597685939",
    semanticscholar_citation_count = "72",
    semanticscholar_id = "75130bec4b7de57fce9bef0ec8999fa1f29d33c4"
}

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"
}

Recent histological studies suggest relatively rapid growth in dinosaurs. However, the timing of reproductive maturity (RM) in dinosaurs is poorly known because unambiguous indicators of RM are rare. One exception is medullary bone (MB), which is an ephemeral bony tissue that forms before ovulation in the marrow cavities of birds as a calcium source for eggshelling. Recently, MB also was described in a single specimen of the saurischian dinosaur Tyrannosaurus rex. Here, we report two other occurrences of MB: in another saurischian dinosaur, Allosaurus, and in the ornithischian dinosaur Tenontosaurus. We show by counting lines of arrested growth and performing growth curve reconstructions that Tenontosaurus, Allosaurus, and Tyrannosaurus were reproductively mature by 8, 10, and 18 years, respectively. RM in these dinosaurs coincided with a transition from growth acceleration to deceleration. It also far precedes predictions based on the growth rates of living reptiles scaled to similar size. Despite relatively rapid growth, dinosaurs were similar to reptiles in that RM developed before reaching asymptotic size. However, this reproductive strategy also occurs in medium- to large-sized mammals and correlates with a strategy of prolonged multiyear growth. RM in actively growing individuals suggests that these dinosaurs were born relatively precocial and experienced high adult mortality. The origin of the modern avian reproductive strategy in ornithuran birds likely coincided with their extreme elevations in growth rate and truncations to growth duration.

@article{doi101073pnas0708903105,
    author = "Lee, Andrew H. and Werning, Sarah",
    title = "Sexual maturity in growing dinosaurs does not fit reptilian growth models",
    year = "2008",
    journal = "Proceedings of the National Academy of Sciences",
    abstract = "Recent histological studies suggest relatively rapid growth in dinosaurs. However, the timing of reproductive maturity (RM) in dinosaurs is poorly known because unambiguous indicators of RM are rare. One exception is medullary bone (MB), which is an ephemeral bony tissue that forms before ovulation in the marrow cavities of birds as a calcium source for eggshelling. Recently, MB also was described in a single specimen of the saurischian dinosaur Tyrannosaurus rex. Here, we report two other occurrences of MB: in another saurischian dinosaur, Allosaurus, and in the ornithischian dinosaur Tenontosaurus. We show by counting lines of arrested growth and performing growth curve reconstructions that Tenontosaurus, Allosaurus, and Tyrannosaurus were reproductively mature by 8, 10, and 18 years, respectively. RM in these dinosaurs coincided with a transition from growth acceleration to deceleration. It also far precedes predictions based on the growth rates of living reptiles scaled to similar size. Despite relatively rapid growth, dinosaurs were similar to reptiles in that RM developed before reaching asymptotic size. However, this reproductive strategy also occurs in medium- to large-sized mammals and correlates with a strategy of prolonged multiyear growth. RM in actively growing individuals suggests that these dinosaurs were born relatively precocial and experienced high adult mortality. The origin of the modern avian reproductive strategy in ornithuran birds likely coincided with their extreme elevations in growth rate and truncations to growth duration.",
    url = "https://doi.org/10.1073/pnas.0708903105",
    doi = "10.1073/pnas.0708903105",
    openalex = "W2157017140",
    references = "doi101001archpedi194702020380122009, doi101002jmor10406, doi101007bf00344996, doi101017cbo9780511608483, doi10103835086500, doi101038nature02699, doi101086410622, doi101098rsbl20070254, doi101098rspb20042829, doi101111j146979981985tb04915x, doi101111j146979981990tb04316x, doi101111j155856461970tb01740x, doi101111j155856461986tb00560x, doi101146annureves18110187002103, doi101353book59141, doi1016660094837320000260466lhotts20co2, doi1016710272463420040240555gisdap20co2, doi1023073546065, doi10560219780801881206, hirsch1989upper"
}

Abstract Long bones (femora, humeri) are the most abundant remains of sauropod dinosaurs. Their length is a good proxy for body length and body mass, and their histology is informative about ontogenetic age. Here we provide a comparative assessment of histologic changes in growth series of several sauropod taxa, including diplodocids (Apatosaurus, Diplodocus, indeterminate Diplodocinae from the Tendaguru Beds and from the Morrison Formation), basal macronarians (Camarasaurus, Brachiosaurus, Europasaurus), and titanosaurs (Phuwiangosaurus, Ampelosaurus). A total of 167 long bones, mainly humeri and femora, and 18 limb girdle bones were sampled. Sampling was performed by core drilling at prescribed locations at midshaft, and 13 histologic ontogenetic stages (HOS stages) were recognized. Because growth of all sauropod long bones is quite uniform, with laminar fibrolamellar bone being the dominant tissue, HOS stages could be recognized across taxa, although with minor differences. Histologic ontogenetic stages generally correlate closely with body size and thus provide a means to resolve important issue like the ontogenetic status of questionable specimens. We hypothesize that sexual maturity was attained at HOS-8, well before maximum size was attained, but we did not find sexually differentiated growth trajectories subsequent to HOS-8. On the basis of HOS stages, we detected two morphotypes in the Camarasaurus sample, a small one (type 1) and a larger one (type 2), presumably representing different species or sexual dimorphism.

@article{doi1016660094837320080340247ositlb20co2,
    author = "Klein, Nicole and Sander, Martin",
    title = "Ontogenetic stages in the long bone histology of sauropod dinosaurs",
    year = "2008",
    journal = "Paleobiology",
    abstract = "Abstract Long bones (femora, humeri) are the most abundant remains of sauropod dinosaurs. Their length is a good proxy for body length and body mass, and their histology is informative about ontogenetic age. Here we provide a comparative assessment of histologic changes in growth series of several sauropod taxa, including diplodocids (Apatosaurus, Diplodocus, indeterminate Diplodocinae from the Tendaguru Beds and from the Morrison Formation), basal macronarians (Camarasaurus, Brachiosaurus, Europasaurus), and titanosaurs (Phuwiangosaurus, Ampelosaurus). A total of 167 long bones, mainly humeri and femora, and 18 limb girdle bones were sampled. Sampling was performed by core drilling at prescribed locations at midshaft, and 13 histologic ontogenetic stages (HOS stages) were recognized. Because growth of all sauropod long bones is quite uniform, with laminar fibrolamellar bone being the dominant tissue, HOS stages could be recognized across taxa, although with minor differences. Histologic ontogenetic stages generally correlate closely with body size and thus provide a means to resolve important issue like the ontogenetic status of questionable specimens. We hypothesize that sexual maturity was attained at HOS-8, well before maximum size was attained, but we did not find sexually differentiated growth trajectories subsequent to HOS-8. On the basis of HOS stages, we detected two morphotypes in the Camarasaurus sample, a small one (type 1) and a larger one (type 2), presumably representing different species or sexual dimorphism.",
    url = "https://doi.org/10.1666/0094-8373(2008)034[0247:ositlb]2.0.co;2",
    doi = "10.1666/0094-8373(2008)034[0247:ositlb]2.0.co;2",
    openalex = "W2177631336",
    references = "chinsamy1994dinosaur, doi101016jtree200508012, doi101029sc005p0175, doi101038nature04633, doi101046j10963642200200029x, doi101073pnas0708903105, doi10108002724634199310011490, doi101098rsbl20070254, doi101098rspb20042829, doi101111j109636422000tb02201x, doi1015159781400849505, doi1016660094837320000260466lhotts20co2, doi1016660094837320010270039coosea20co2, doi1016710272463420000200115lbhoth20co2, martinsander2006bone"
}

The oldest unequivocal records of Dinosauria were unearthed from Late Triassic rocks (approximately 230 Ma) accumulated over extensional rift basins in southwestern Pangea. The better known of these are Herrerasaurus ischigualastensis, Pisanosaurus mertii, Eoraptor lunensis, and Panphagia protos from the Ischigualasto Formation, Argentina, and Staurikosaurus pricei and Saturnalia tupiniquim from the Santa Maria Formation, Brazil. No uncontroversial dinosaur body fossils are known from older strata, but the Middle Triassic origin of the lineage may be inferred from both the footprint record and its sister-group relation to Ladinian basal dinosauromorphs. These include the typical Marasuchus lilloensis, more basal forms such as Lagerpeton and Dromomeron, as well as silesaurids: a possibly monophyletic group composed of Mid-Late Triassic forms that may represent immediate sister taxa to dinosaurs. The first phylogenetic definition to fit the current understanding of Dinosauria as a node-based taxon solely composed of mutually exclusive Saurischia and Ornithischia was given as "all descendants of the most recent common ancestor of birds and Triceratops". Recent cladistic analyses of early dinosaurs agree that Pisanosaurus mertii is a basal ornithischian; that Herrerasaurus ischigualastensis and Staurikosaurus pricei belong in a monophyletic Herrerasauridae; that herrerasaurids, Eoraptor lunensis, and Guaibasaurus candelariensis are saurischians; that Saurischia includes two main groups, Sauropodomorpha and Theropoda; and that Saturnalia tupiniquim is a basal member of the sauropodomorph lineage. On the contrary, several aspects of basal dinosaur phylogeny remain controversial, including the position of herrerasaurids, E. lunensis, and G. candelariensis as basal theropods or basal saurischians, and the affinity and/or validity of more fragmentary taxa such as Agnosphitys cromhallensis, Alwalkeria maleriensis, Chindesaurus bryansmalli, Saltopus elginensis, and Spondylosoma absconditum. The identification of dinosaur apomorphies is jeopardized by the incompleteness of skeletal remains attributed to most basal dinosauromorphs, the skulls and forelimbs of which are particularly poorly known. Nonetheless, Dinosauria can be diagnosed by a suite of derived traits, most of which are related to the anatomy of the pelvic girdle and limb. Some of these are connected to the acquisition of a fully erect bipedal gait, which has been traditionally suggested to represent a key adaptation that allowed, or even promoted, dinosaur radiation during Late Triassic times. Yet, contrary to the classical "competitive" models, dinosaurs did not gradually replace other terrestrial tetrapods over the Late Triassic. In fact, the radiation of the group comprises at least three landmark moments, separated by controversial (Carnian-Norian, Triassic-Jurassic) extinction events. These are mainly characterized by early diversification in Carnian times, a Norian increase in diversity and (especially) abundance, and the occupation of new niches from the Early Jurassic onwards. Dinosaurs arose from fully bipedal ancestors, the diet of which may have been carnivorous or omnivorous. Whereas the oldest dinosaurs were geographically restricted to south Pangea, including rare ornithischians and more abundant basal members of the saurischian lineage, the group achieved a nearly global distribution by the latest Triassic, especially with the radiation of saurischian groups such as "prosauropods" and coelophysoids.

@article{doi101111j1469185x200900094x,
    author = "Langer, Max C. and Ezcurra, Martín D. and Bittencourt, Jonathas S. and Novas, Fernando E.",
    title = "The origin and early evolution of dinosaurs",
    year = "2009",
    journal = "Biological reviews/Biological reviews of the Cambridge Philosophical Society",
    abstract = {The oldest unequivocal records of Dinosauria were unearthed from Late Triassic rocks (approximately 230 Ma) accumulated over extensional rift basins in southwestern Pangea. The better known of these are Herrerasaurus ischigualastensis, Pisanosaurus mertii, Eoraptor lunensis, and Panphagia protos from the Ischigualasto Formation, Argentina, and Staurikosaurus pricei and Saturnalia tupiniquim from the Santa Maria Formation, Brazil. No uncontroversial dinosaur body fossils are known from older strata, but the Middle Triassic origin of the lineage may be inferred from both the footprint record and its sister-group relation to Ladinian basal dinosauromorphs. These include the typical Marasuchus lilloensis, more basal forms such as Lagerpeton and Dromomeron, as well as silesaurids: a possibly monophyletic group composed of Mid-Late Triassic forms that may represent immediate sister taxa to dinosaurs. The first phylogenetic definition to fit the current understanding of Dinosauria as a node-based taxon solely composed of mutually exclusive Saurischia and Ornithischia was given as "all descendants of the most recent common ancestor of birds and Triceratops". Recent cladistic analyses of early dinosaurs agree that Pisanosaurus mertii is a basal ornithischian; that Herrerasaurus ischigualastensis and Staurikosaurus pricei belong in a monophyletic Herrerasauridae; that herrerasaurids, Eoraptor lunensis, and Guaibasaurus candelariensis are saurischians; that Saurischia includes two main groups, Sauropodomorpha and Theropoda; and that Saturnalia tupiniquim is a basal member of the sauropodomorph lineage. On the contrary, several aspects of basal dinosaur phylogeny remain controversial, including the position of herrerasaurids, E. lunensis, and G. candelariensis as basal theropods or basal saurischians, and the affinity and/or validity of more fragmentary taxa such as Agnosphitys cromhallensis, Alwalkeria maleriensis, Chindesaurus bryansmalli, Saltopus elginensis, and Spondylosoma absconditum. The identification of dinosaur apomorphies is jeopardized by the incompleteness of skeletal remains attributed to most basal dinosauromorphs, the skulls and forelimbs of which are particularly poorly known. Nonetheless, Dinosauria can be diagnosed by a suite of derived traits, most of which are related to the anatomy of the pelvic girdle and limb. Some of these are connected to the acquisition of a fully erect bipedal gait, which has been traditionally suggested to represent a key adaptation that allowed, or even promoted, dinosaur radiation during Late Triassic times. Yet, contrary to the classical "competitive" models, dinosaurs did not gradually replace other terrestrial tetrapods over the Late Triassic. In fact, the radiation of the group comprises at least three landmark moments, separated by controversial (Carnian-Norian, Triassic-Jurassic) extinction events. These are mainly characterized by early diversification in Carnian times, a Norian increase in diversity and (especially) abundance, and the occupation of new niches from the Early Jurassic onwards. Dinosaurs arose from fully bipedal ancestors, the diet of which may have been carnivorous or omnivorous. Whereas the oldest dinosaurs were geographically restricted to south Pangea, including rare ornithischians and more abundant basal members of the saurischian lineage, the group achieved a nearly global distribution by the latest Triassic, especially with the radiation of saurischian groups such as "prosauropods" and coelophysoids.},
    url = "https://doi.org/10.1111/j.1469-185x.2009.00094.x",
    doi = "10.1111/j.1469-185x.2009.00094.x",
    openalex = "W2121596487",
    references = "chatterjee2013a, crossref1998encyclopedia, currie2009stratigraphy, doi1010160031018281900924, doi1010160031018295000178, doi101016c20090644421, doi101016jjsames200504002, doi101016jpalaeo200606041, doi101016s0012825203000825, doi101016s0016699580800386, doi101016s0016699583800205, doi101016s0031018298001175, doi101017cbo9780511628948, doi101017s0094837300010575, doi101017s1477201906001970, doi101017s1477201907002040, doi101017s1477201907002246, doi101017s1477201907002271, doi101017s247526300000091x, doi10103820167, doi10106313060577, doi101073pnas0606028103, doi10108002724634199410011538, doi10108002724634199510011271, doi10108002724634199810011115, doi10108002724634199910011124, doi101098rspb20042692, doi101098rspb20080715, doi101098rspl18870117, doi101098rstb19990489, doi101111j109636421985tb01796x, doi101111j10963642200400130x, doi101126science1143325, doi101126science21545391501, doi101126science2645160828, doi101126science2845414616, doi101126science3616622, doi101127njgpa210199841, doi101144gsjgs14720321, doi1012060003009020073021taoeoa20co2, doi101525california97805202420980010001, doi1015468gbdyof, doi1016710272463420020220510toomka20co2, doi1016710272463420072773tclagn20co2, doi101671a1097, doi1023071292217, doi1023071441916, doi1023073889325, doi102475ajss319111253, doi102475ajss32313381, doi104202app20080415, doi10432497802030907329, doi105281zenodo16120887, doi105281zenodo16171435, doi105281zenodo16246150, doi105860choice325663, doi105860choice393984, doi105860choice465038, doi107146moggeosciv32i140904, doi10718895fylantbak30809522, openalexw114509570, openalexw1496509561, openalexw1535663436, openalexw205674743, openalexw2242116350, openalexw2788234611, openalexw2991310333, openalexw3208547338, openalexw3215057009, padian1989presence, rowe1989a, walker1964triassic"
}

BACKGROUND: A dinosaur census recorded during the Hell Creek Project (1999-2009) incorporates multiple lines of evidence from geography, taphohistory, stratigraphy, phylogeny and ontogeny to investigate the relative abundance of large dinosaurs preserved in the Upper Cretaceous Hell Creek Formation of northeastern Montana, USA. Overall, the dinosaur skeletal assemblages in the Hell Creek Formation (excluding lag-influenced records) consist primarily of subadult or small adult size individuals. Small juveniles and large adults are both extremely rare, whereas subadult individuals are relatively common. We propose that mature individuals of at least some dinosaur taxa either lived in a separate geographic locale analogous to younger individuals inhabiting an upland environment where sedimentation rates were relatively less, or these taxa experienced high mortality before reaching terminal size where late stage and often extreme cranial morphology is expressed. METHODOLOGY/PRINCIPAL FINDINGS: Tyrannosaurus skeletons are as abundant as Edmontosaurus, an herbivore, in the upper Hell Creek Formation and nearly twice as common in the lower third of the formation. Smaller, predatory dinosaurs (e.g., Troodon and dromaeosaurids) are primarily represented by teeth found in microvertebrate localities and their skeletons or identifiable lag specimens were conspicuously absent. This relative abundance suggests Tyrannosaurus was not a typical predator and likely benefited from much wider food choice opportunities than exclusively live prey and/or specific taxa. Tyrannosaurus adults may not have competed with Tyrannosaurus juveniles if the potential for selecting carrion increased with size during ontogeny. CONCLUSIONS/SIGNIFICANCE: Triceratops is the most common dinosaur and isolated skulls contribute to a significant portion of this census. Associated specimens of Triceratops consisting of both cranial and postcranial elements remain relatively rare. This rarity may be explained by a historical collecting bias influenced by facies and taphonomic factors. The limited discovery of postcranial elements may also depend on how extensive a fossil quarry is expanded after a skull is collected.

@article{doi101371journalpone0016574,
    author = "Horner, John R. and Goodwin, Mark B. and Myhrvold, Nathan",
    title = "Dinosaur Census Reveals Abundant Tyrannosaurus and Rare Ontogenetic Stages in the Upper Cretaceous Hell Creek Formation (Maastrichtian), Montana, USA",
    year = "2011",
    journal = "PLoS ONE",
    abstract = "BACKGROUND: A dinosaur census recorded during the Hell Creek Project (1999-2009) incorporates multiple lines of evidence from geography, taphohistory, stratigraphy, phylogeny and ontogeny to investigate the relative abundance of large dinosaurs preserved in the Upper Cretaceous Hell Creek Formation of northeastern Montana, USA. Overall, the dinosaur skeletal assemblages in the Hell Creek Formation (excluding lag-influenced records) consist primarily of subadult or small adult size individuals. Small juveniles and large adults are both extremely rare, whereas subadult individuals are relatively common. We propose that mature individuals of at least some dinosaur taxa either lived in a separate geographic locale analogous to younger individuals inhabiting an upland environment where sedimentation rates were relatively less, or these taxa experienced high mortality before reaching terminal size where late stage and often extreme cranial morphology is expressed. METHODOLOGY/PRINCIPAL FINDINGS: Tyrannosaurus skeletons are as abundant as Edmontosaurus, an herbivore, in the upper Hell Creek Formation and nearly twice as common in the lower third of the formation. Smaller, predatory dinosaurs (e.g., Troodon and dromaeosaurids) are primarily represented by teeth found in microvertebrate localities and their skeletons or identifiable lag specimens were conspicuously absent. This relative abundance suggests Tyrannosaurus was not a typical predator and likely benefited from much wider food choice opportunities than exclusively live prey and/or specific taxa. Tyrannosaurus adults may not have competed with Tyrannosaurus juveniles if the potential for selecting carrion increased with size during ontogeny. CONCLUSIONS/SIGNIFICANCE: Triceratops is the most common dinosaur and isolated skulls contribute to a significant portion of this census. Associated specimens of Triceratops consisting of both cranial and postcranial elements remain relatively rare. This rarity may be explained by a historical collecting bias influenced by facies and taphonomic factors. The limited discovery of postcranial elements may also depend on how extensive a fossil quarry is expanded after a skull is collected.",
    url = "https://doi.org/10.1371/journal.pone.0016574",
    doi = "10.1371/journal.pone.0016574",
    openalex = "W1982210430",
    references = "carr1999craniofacial, doi101038282296a0, doi101073pnas0708903105, doi101080027246342010483632, doi101098rspb20042829, doi101371journalpone0007626, doi1016660094837320010270039coosea20co2, doi1016710272463420000200115lbhoth20co2, doi1023072404970, openalexw1550433756"
}

@article{doi101016jpalaeo201206027,
    author = "Brown, Caleb M. and Evans, David C. and Campione, Nicolás E. and O’Brien, Lorna J. and Eberth, David A.",
    title = "Evidence for taphonomic size bias in the Dinosaur Park Formation (Campanian, Alberta), a model Mesozoic terrestrial alluvial‐paralic system",
    year = "2012",
    journal = "Palaeogeography Palaeoclimatology Palaeoecology",
    url = "https://doi.org/10.1016/j.palaeo.2012.06.027",
    doi = "10.1016/j.palaeo.2012.06.027",
    openalex = "W2079386558",
    references = "doi101007s1143001040949, doi1010160031018288900855, doi101016003101828890096x, doi101016jcretres200806007, doi101016jtree200504005, doi101017cbo9780511608551, doi101073pnas0606028103, doi10108002724634199510011575, doi101080027246342013746229, doi101093bioinformaticsbtg287, doi101093sysbio24137, doi101098rspb20091845, doi101111j109636421997tb00340x, doi101126science1116412, doi101126science1156963, doi101126science24148721441, doi101126science28454232137, doi101126science7701342, doi101144sp35813, doi101146annureves26110195002305, doi101186174170071060, doi101371journalpone0016574, doi101371journalpone0037122, doi1015468gcrned, doi1016690883135120010160482ttoaco20co2, doi1016710390290119, doi101890070037, doi105281zenodo1040973, doi105860choice331556, doi105860choice435902, doi107208chicago97802267237300010001, horner2011dinosaur, longrich2008a"
}

BACKGROUND: Sauropod dinosaurs were the largest animals ever to walk on land, and, as a result, the evolution of their remarkable adaptations has been of great interest. The braincase is of particular interest because it houses the brain and inner ear. However, only a few studies of these structures in sauropods are available to date. Because of the phylogenetic position of Spinophorosaurus nigerensis as a basal eusauropod, the braincase has the potential to provide key evidence on the evolutionary transition relative to other dinosaurs. METHODOLOGY/PRINCIPAL FINDINGS: The only known braincase of Spinophorosaurus ('Argiles de l'Irhazer', Irhazer Group; Agadez region, Niger) differs significantly from those of the Jurassic sauropods examined, except potentially for Atlasaurus imelakei (Tilougguit Formation, Morocco). The basisphenoids of Spinophorosaurus and Atlasaurus bear basipterygoid processes that are comparable in being directed strongly caudally. The Spinophorosaurus specimen was CT scanned, and 3D renderings of the cranial endocast and inner-ear system were generated. The endocast resembles that of most other sauropods in having well-marked pontine and cerebral flexures, a large and oblong pituitary fossa, and in having the brain structure obscured by the former existence of relatively thick meninges and dural venous sinuses. The labyrinth is characterized by long and proportionally slender semicircular canals. This condition recalls, in particular, that of the basal non-sauropod sauropodomorph Massospondylus and the basal titanosauriform Giraffatitan. CONCLUSIONS/SIGNIFICANCE: Spinophorosaurus has a moderately derived paleoneuroanatomical pattern. In contrast to what might be expected early within a lineage leading to plant-eating graviportal quadrupeds, Spinophorosaurus and other (but not all) sauropodomorphs show no reduction of the vestibular apparatus of the inner ear. This character-state is possibly a primitive retention in Spinophorosaurus, but due the scarcity of data it remains unclear whether it is also the case in the various later sauropods in which it is present or whether it has developed homoplastically in these taxa. Any interpretations remain tentative pending the more comprehensive quantitative analysis underway, but the size and morphology of the labyrinth of sauropodomorphs may be related to neck length and mobility, among other factors.

@article{doi101371journalpone0030060,
    author = "Knoll, Fabien and Witmer, Lawrence M. and Ortega, Francisco and Ridgely, Ryan C. and Schwarz, Daniela",
    title = "The Braincase of the Basal Sauropod Dinosaur Spinophorosaurus and 3D Reconstructions of the Cranial Endocast and Inner Ear",
    year = "2012",
    journal = "PLoS ONE",
    abstract = "BACKGROUND: Sauropod dinosaurs were the largest animals ever to walk on land, and, as a result, the evolution of their remarkable adaptations has been of great interest. The braincase is of particular interest because it houses the brain and inner ear. However, only a few studies of these structures in sauropods are available to date. Because of the phylogenetic position of Spinophorosaurus nigerensis as a basal eusauropod, the braincase has the potential to provide key evidence on the evolutionary transition relative to other dinosaurs. METHODOLOGY/PRINCIPAL FINDINGS: The only known braincase of Spinophorosaurus ('Argiles de l'Irhazer', Irhazer Group; Agadez region, Niger) differs significantly from those of the Jurassic sauropods examined, except potentially for Atlasaurus imelakei (Tilougguit Formation, Morocco). The basisphenoids of Spinophorosaurus and Atlasaurus bear basipterygoid processes that are comparable in being directed strongly caudally. The Spinophorosaurus specimen was CT scanned, and 3D renderings of the cranial endocast and inner-ear system were generated. The endocast resembles that of most other sauropods in having well-marked pontine and cerebral flexures, a large and oblong pituitary fossa, and in having the brain structure obscured by the former existence of relatively thick meninges and dural venous sinuses. The labyrinth is characterized by long and proportionally slender semicircular canals. This condition recalls, in particular, that of the basal non-sauropod sauropodomorph Massospondylus and the basal titanosauriform Giraffatitan. CONCLUSIONS/SIGNIFICANCE: Spinophorosaurus has a moderately derived paleoneuroanatomical pattern. In contrast to what might be expected early within a lineage leading to plant-eating graviportal quadrupeds, Spinophorosaurus and other (but not all) sauropodomorphs show no reduction of the vestibular apparatus of the inner ear. This character-state is possibly a primitive retention in Spinophorosaurus, but due the scarcity of data it remains unclear whether it is also the case in the various later sauropods in which it is present or whether it has developed homoplastically in these taxa. Any interpretations remain tentative pending the more comprehensive quantitative analysis underway, but the size and morphology of the labyrinth of sauropodomorphs may be related to neck length and mobility, among other factors.",
    url = "https://doi.org/10.1371/journal.pone.0030060",
    doi = "10.1371/journal.pone.0030060",
    openalex = "W2034908959",
    references = "doi101002ar20983, doi10100797844317693306, doi101017s0016756806002561, doi101046j10963642200200029x, doi101073pnas0704250104, doi101126science28654431342, doi101371journalpone0001230, doi101371journalpone0006924, doi1016710272463420072732caomct20co2, doi102475ajss31695411, doi102475ajss319111253, doi104202app20090007"
}

A high-resolution biostratigraphic analysis of 287 dinosaurian macrofossils and 138 bonebeds in the Edmonton Group (Upper Cretaceous) of southern Alberta provides evidence for at least three dinosaurian assemblage zones in the Horseshoe Canyon Formation (HCFm). From bottom to top the zones comprise unique assemblages of ornithischians and are named as follows: (1) Edmontosaurus regalis – Pachyrhinosaurus canadensis (lower zone); (2) Hypacrosaurus altispinus – Saurolophus osborni (middle zone); and (3) Eotriceratops xerinsularis (upper zone). Whereas the lower and middle zones are well defined and based on abundant specimens, the validity of the uppermost zone (E. xerinsularis) is tentative because it is based on a single specimen and the absence of dinosaur taxa from lower in section. The transition from the lower to the middle zone coincides with the replacement of a warm-and-wet saturated deltaic setting by a cooler, coastal-plain landscape, characterized by seasonal rainfall and better-drained substrates. Whereas changes in rainfall and substrate drainage appear to have influenced the faunal change, changes in mean annual temperature and proximity to shoreline appear to have had little influence on faunal change. We speculate that the faunal change between the middle and upper zones also resulted from a change in climate, with ornithischian dinosaurs responding to the re-establishment of wetter-and-warmer climates and poorly-drained substrates. Compared with the shorter-duration and climatically-consistent dinosaurian assemblage zones in the older Dinosaur Park Formation of southern Alberta, HCFm assemblage zones record long-term morphological stasis in dinosaurs. Furthermore, the coincidence of faunal and paleoenvironmental changes in the HCFm suggest climate-change-driven dinosaur migrations into and out of the region.

@article{doi101139cjes20120185,
    author = "Eberth, David A. and Evans, David C. and Brinkman, Donald B. and Therrien, François and Tanke, Darren H. and Russell, Loris S.",
    title = "Dinosaur biostratigraphy of the Edmonton Group (Upper Cretaceous), Alberta, Canada: evidence for climate influence",
    year = "2013",
    journal = "Canadian Journal of Earth Sciences",
    abstract = "A high-resolution biostratigraphic analysis of 287 dinosaurian macrofossils and 138 bonebeds in the Edmonton Group (Upper Cretaceous) of southern Alberta provides evidence for at least three dinosaurian assemblage zones in the Horseshoe Canyon Formation (HCFm). From bottom to top the zones comprise unique assemblages of ornithischians and are named as follows: (1) Edmontosaurus regalis – Pachyrhinosaurus canadensis (lower zone); (2) Hypacrosaurus altispinus – Saurolophus osborni (middle zone); and (3) Eotriceratops xerinsularis (upper zone). Whereas the lower and middle zones are well defined and based on abundant specimens, the validity of the uppermost zone (E. xerinsularis) is tentative because it is based on a single specimen and the absence of dinosaur taxa from lower in section. The transition from the lower to the middle zone coincides with the replacement of a warm-and-wet saturated deltaic setting by a cooler, coastal-plain landscape, characterized by seasonal rainfall and better-drained substrates. Whereas changes in rainfall and substrate drainage appear to have influenced the faunal change, changes in mean annual temperature and proximity to shoreline appear to have had little influence on faunal change. We speculate that the faunal change between the middle and upper zones also resulted from a change in climate, with ornithischian dinosaurs responding to the re-establishment of wetter-and-warmer climates and poorly-drained substrates. Compared with the shorter-duration and climatically-consistent dinosaurian assemblage zones in the older Dinosaur Park Formation of southern Alberta, HCFm assemblage zones record long-term morphological stasis in dinosaurs. Furthermore, the coincidence of faunal and paleoenvironmental changes in the HCFm suggest climate-change-driven dinosaur migrations into and out of the region.",
    url = "https://doi.org/10.1139/cjes-2012-0185",
    doi = "10.1139/cjes-2012-0185",
    openalex = "W2157353435",
    references = "doi101016jpalaeo201206024, doi101016jpalaeo201206027, doi101017cbo9780511536045020, doi101098rspb20090352, doi101126science1177265, doi1011270078042120120020, doi101139e10005, doi101139e11017, doi101139e72031, doi101139e93016, doi10130683d923ed16c711d78645000102c1865d, doi101371journalpone0016574, doi101371journalpone0025186, doi104202app20110033, doi105281zenodo3725717, horner2011dinosaur, openalexw2989049194, sternberg1926notes"
}

Isolated small theropod teeth are abundant in vertebrate microfossil assemblages, and are frequently used in studies of species diversity in ancient ecosystems. However, determining the taxonomic affinities of these teeth is problematic due to an absence of associated diagnostic skeletal material. Species such as Dromaeosaurus albertensis, Richardoestesia gilmorei, and Saurornitholestes langstoni are known from skeletal remains that have been recovered exclusively from the Dinosaur Park Formation (Campanian). It is therefore likely that teeth from different formations widely disparate in age or geographic position are not referable to these species. Tooth taxa without any associated skeletal material, such as Paronychodon lacustris and Richardoestesia isosceles, have also been identified from multiple localities of disparate ages throughout the Late Cretaceous. To address this problem, a dataset of measurements of 1183 small theropod teeth (the most specimen-rich theropod tooth dataset ever constructed) from North America ranging in age from Santonian through Maastrichtian were analyzed using multivariate statistical methods: canonical variate analysis, pairwise discriminant function analysis, and multivariate analysis of variance. The results indicate that teeth referred to the same taxon from different formations are often quantitatively distinct. In contrast, isolated teeth found in time equivalent formations are not quantitatively distinguishable from each other. These results support the hypothesis that small theropod taxa, like other dinosaurs in the Late Cretaceous, tend to be exclusive to discrete host formations. The methods outlined have great potential for future studies of isolated teeth worldwide, and may be the most useful non-destructive technique known of extracting the most data possible from isolated and fragmentary specimens. The ability to accurately assess species diversity and turnover through time based on isolated teeth will help illuminate patterns of evolution and extinction in these groups and potentially others in greater detail than has previously been thought possible without more complete skeletal material.

@article{doi101371journalpone0054329,
    author = "Larson, Derek W. and Currie, Philip J.",
    title = "Multivariate Analyses of Small Theropod Dinosaur Teeth and Implications for Paleoecological Turnover through Time",
    year = "2013",
    journal = "PLoS ONE",
    abstract = "Isolated small theropod teeth are abundant in vertebrate microfossil assemblages, and are frequently used in studies of species diversity in ancient ecosystems. However, determining the taxonomic affinities of these teeth is problematic due to an absence of associated diagnostic skeletal material. Species such as Dromaeosaurus albertensis, Richardoestesia gilmorei, and Saurornitholestes langstoni are known from skeletal remains that have been recovered exclusively from the Dinosaur Park Formation (Campanian). It is therefore likely that teeth from different formations widely disparate in age or geographic position are not referable to these species. Tooth taxa without any associated skeletal material, such as Paronychodon lacustris and Richardoestesia isosceles, have also been identified from multiple localities of disparate ages throughout the Late Cretaceous. To address this problem, a dataset of measurements of 1183 small theropod teeth (the most specimen-rich theropod tooth dataset ever constructed) from North America ranging in age from Santonian through Maastrichtian were analyzed using multivariate statistical methods: canonical variate analysis, pairwise discriminant function analysis, and multivariate analysis of variance. The results indicate that teeth referred to the same taxon from different formations are often quantitatively distinct. In contrast, isolated teeth found in time equivalent formations are not quantitatively distinguishable from each other. These results support the hypothesis that small theropod taxa, like other dinosaurs in the Late Cretaceous, tend to be exclusive to discrete host formations. The methods outlined have great potential for future studies of isolated teeth worldwide, and may be the most useful non-destructive technique known of extracting the most data possible from isolated and fragmentary specimens. The ability to accurately assess species diversity and turnover through time based on isolated teeth will help illuminate patterns of evolution and extinction in these groups and potentially others in greater detail than has previously been thought possible without more complete skeletal material.",
    url = "https://doi.org/10.1371/journal.pone.0054329",
    doi = "10.1371/journal.pone.0054329",
    openalex = "W2073560226",
    references = "carpenter2005the, crossref1998encyclopedia, doi1010029780470750711, doi101002ara20206, doi1010079780387217062, doi101016jpalaeo200902007, doi101017cbo9780511608377011, doi101098rspb20090352, doi101139e10005, doi101371journalpone0016574, doi101371journalpone0025186, doi1015468gcrned, doi1016660022336020010750208lcsdaf20co2, doi1016660022336020020760751stabtf20co2, doi105281zenodo3725717, doi105860choice393984, doi105860choice435902, horner2011dinosaur, openalexw2289748525, russell2002synopsis"
}

Three monodominant hadrosaurid bonebeds in the Horsethief Member of the Horseshoe Canyon Formation (uppermost Campanian) in southern Alberta, Canada, are documented. Each bonebed is hosted by a decimetre-thick deposit of poorly sorted and graded organic-fragment-rich mudstone. These fossil deposits are interpreted as having been carried and deposited by debris flows or hyperconcentrated mass sediment flows initiated by overbank flooding from local channels. Each bonebed is dominated (>50% of identifiable elements) by the disarticulated to occasionally associated remains of hadrosaurine hadrosaurids, inferred to be Edmontosaurus regalis. The majority of hadrosaurid elements at two of the sites (Bleriot Ferry and Prehistoric Park) are from large, presumably adult-sized individuals, whereas the majority of elements from the Fox Coulee site are from subadults and juveniles. Fossil elements from all the sites exhibit similar taphonomic signatures suggestive of a high degree of biostratinomic modification including: (i) thorough disarticulation of carcasses, (ii) a large amount of breakage, (iii) modest amounts of size sorting, and (iv) minimum to modest occurrences of abrasion, and scratch and tooth marks. These signatures indicate that carcasses were exposed for significant amounts of time on the floodplain, where they rotted, were scavenged and trampled, and were exposed to moving water prior to final burial. The size of each bonebed together with the density of bones suggest that the biocoenoses comprised large groups of hadrosaurids, and bone size distributions suggest the possibility of age-segregated populations. The monodominant nature of the assemblages combined with homogenous taphonomic signatures within and between sites suggests that these bonebed assemblages are best interpreted as the result of mass kills rather than attrition, with recurring tropical storm-induced coastal-plain flooding postulated as a likely mechanism for what killed and eventually buried these dinosaurs.

@article{doi101139cjes20140184,
    author = "Evans, David C. and Eberth, David A. and Ryan, Michael J.",
    title = "Hadrosaurid (Edmontosaurus) bonebeds from the Horseshoe Canyon Formation (Horsethief Member) at Drumheller, Alberta, Canada: geology, preliminary taphonomy, and significance",
    year = "2015",
    journal = "Canadian Journal of Earth Sciences",
    abstract = "Three monodominant hadrosaurid bonebeds in the Horsethief Member of the Horseshoe Canyon Formation (uppermost Campanian) in southern Alberta, Canada, are documented. Each bonebed is hosted by a decimetre-thick deposit of poorly sorted and graded organic-fragment-rich mudstone. These fossil deposits are interpreted as having been carried and deposited by debris flows or hyperconcentrated mass sediment flows initiated by overbank flooding from local channels. Each bonebed is dominated (>50\% of identifiable elements) by the disarticulated to occasionally associated remains of hadrosaurine hadrosaurids, inferred to be Edmontosaurus regalis. The majority of hadrosaurid elements at two of the sites (Bleriot Ferry and Prehistoric Park) are from large, presumably adult-sized individuals, whereas the majority of elements from the Fox Coulee site are from subadults and juveniles. Fossil elements from all the sites exhibit similar taphonomic signatures suggestive of a high degree of biostratinomic modification including: (i) thorough disarticulation of carcasses, (ii) a large amount of breakage, (iii) modest amounts of size sorting, and (iv) minimum to modest occurrences of abrasion, and scratch and tooth marks. These signatures indicate that carcasses were exposed for significant amounts of time on the floodplain, where they rotted, were scavenged and trampled, and were exposed to moving water prior to final burial. The size of each bonebed together with the density of bones suggest that the biocoenoses comprised large groups of hadrosaurids, and bone size distributions suggest the possibility of age-segregated populations. The monodominant nature of the assemblages combined with homogenous taphonomic signatures within and between sites suggests that these bonebed assemblages are best interpreted as the result of mass kills rather than attrition, with recurring tropical storm-induced coastal-plain flooding postulated as a likely mechanism for what killed and eventually buried these dinosaurs.",
    url = "https://doi.org/10.1139/cjes-2014-0184",
    doi = "10.1139/cjes-2014-0184",
    openalex = "W2165134975",
    references = "doi101016jpalaeo200906004, doi101139cjes20120185, doi102110palo2009p09103r, doi107208chicago97802267237300010001"
}

The small triangular posteriorly oriented nasal crest of Probrachylophosaurus is proposed to represent a transitional nasal morphology between that of a non-crested ancestor such as Acristavus and the large flat posteriorly oriented nasal crest of adult Brachylophosaurus. Because Probrachylophosaurus is stratigraphically and morphologically intermediate between these taxa, Probrachylophosaurus is hypothesized to be an intermediate member of the Acristavus-Brachylophosaurus evolutionary lineage.

@article{doi101371journalpone0141304,
    author = "Fowler, Elizabeth A. Freedman and Horner, John R.",
    title = "A New Brachylophosaurin Hadrosaur (Dinosauria: Ornithischia) with an Intermediate Nasal Crest from the Campanian Judith River Formation of Northcentral Montana",
    year = "2015",
    journal = "PLoS ONE",
    abstract = "The small triangular posteriorly oriented nasal crest of Probrachylophosaurus is proposed to represent a transitional nasal morphology between that of a non-crested ancestor such as Acristavus and the large flat posteriorly oriented nasal crest of adult Brachylophosaurus. Because Probrachylophosaurus is stratigraphically and morphologically intermediate between these taxa, Probrachylophosaurus is hypothesized to be an intermediate member of the Acristavus-Brachylophosaurus evolutionary lineage.",
    url = "https://doi.org/10.1371/journal.pone.0141304",
    doi = "10.1371/journal.pone.0141304",
    openalex = "W2114007970",
    references = "doi101016jgca201006017, doi101016s0009254197001599, doi101016s0195667105800308, doi101017pab201519, doi101038282296a0, doi101038nature11264, doi101073pnas1313334111, doi101080027246342011557116, doi101098rspb20090229, doi101371journalpone0016574, doi101371journalpone0018029, doi101371journalpone0029958, doi1016710272463420000200115lbhoth20co2, doi10167102724634200727373aarolm20co2, doi105860choice435902, doi105860choice514447, doi105962bhltitle101747, doi105962bhltitle115853, horner2011dinosaur, köhler2012seasonal, openalexw2904473752, openalexw3217097258, vanitterbeeck2005stratigraphy"
}

Despite long-standing significance in the annals of North American stratigraphy and paleontology, key aspects of the Upper Cretaceous Judith River Formation remain poorly understood. We re-evaluate Judith River stratigraphy and propose new reference sections that both document the range of lithologies present in the type area in north-central Montana and reveal dramatic changes in facies architecture, fossil content, and rock accumulation rates that can be mapped throughout the type area and into the plains of southern Alberta and Saskatchewan. One section spans the basal contact of the Judith River Formation with marine shales of the underlying Claggett Formation. This contact, which lies along the base of the Parkman Sandstone Member of the Judith River Formation, is erosional and consistent with an episode of forced regression, contrary to previous descriptions. A second reference section spans the entire Judith River Formation. This complete section hosts a lithologic discontinuity, herein referred to as the mid-Judith discontinuity, that reflects a regional reorganization of terrestrial and marine depositional systems associated with a turnaround from regressive to transgressive deposition. The mid-Judith discontinuity correlates with the base of three backstepping marine sequences in the eastern sector of the type area and is thus interpreted as the terrestrial expression of a maximum regressive surface. This mid-Judith discontinuity defines the boundary between the new McClelland Ferry and overlying Coal Ridge Members of the Judith River Formation. The shallow marine sandstones that form the backstepping sequences represent the leading edge of the Bearpaw transgression in this region and are formalized as the new Woodhawk Member of the Judith River Formation in a third reference section. New 40Ar/39Ar ages indicate (1) that the mid-Judith discontinuity formed ∼76.2 Ma, coincident with the onset of the Bearpaw transgression in central Montana; and (2) that the Bearpaw Sea had advanced westward beyond the Judith River type area by ∼75.2 Ma, on the basis of the dating of a bentonite bed at the base of the Bearpaw Formation. These new ages also provide more confident age control for important vertebrate fossil occurrences in the Judith River Formation. Facies analysis across the mid-Judith discontinuity reveals how alluvial systems respond to regional base-level rise, which is implicit with the increase in rock accumulation rates and marine transgression. With the increase in accommodation signaled by the mid-Judith discontinuity, the alluvial system shifted in dominance from fluvial channel to overbank deposits, with greater tidal influence in channel sands, more hydromorphic and carbonaceous overbank deposits, and a higher frequency of bentonites and skeletal concentrations, suggesting higher preservation rates. These features, along with the appearance of extraformational pebbles above the discontinuity, are consistent with an upstream tectonic explanation for the addition of accommodation.

@article{doi101086684289,
    author = "Rogers, Raymond R. and Kidwell, Susan M. and Deino, Alan L. and Mitchell, James P. and Nelson, Kenneth and Thole, Jeffrey T.",
    title = "Age, Correlation, and Lithostratigraphic Revision of the Upper Cretaceous (Campanian) Judith River Formation in Its Type Area (North-Central Montana), with a Comparison of Low- and High-Accommodation Alluvial Records",
    year = "2016",
    journal = "The Journal of Geology",
    abstract = "Despite long-standing significance in the annals of North American stratigraphy and paleontology, key aspects of the Upper Cretaceous Judith River Formation remain poorly understood. We re-evaluate Judith River stratigraphy and propose new reference sections that both document the range of lithologies present in the type area in north-central Montana and reveal dramatic changes in facies architecture, fossil content, and rock accumulation rates that can be mapped throughout the type area and into the plains of southern Alberta and Saskatchewan. One section spans the basal contact of the Judith River Formation with marine shales of the underlying Claggett Formation. This contact, which lies along the base of the Parkman Sandstone Member of the Judith River Formation, is erosional and consistent with an episode of forced regression, contrary to previous descriptions. A second reference section spans the entire Judith River Formation. This complete section hosts a lithologic discontinuity, herein referred to as the mid-Judith discontinuity, that reflects a regional reorganization of terrestrial and marine depositional systems associated with a turnaround from regressive to transgressive deposition. The mid-Judith discontinuity correlates with the base of three backstepping marine sequences in the eastern sector of the type area and is thus interpreted as the terrestrial expression of a maximum regressive surface. This mid-Judith discontinuity defines the boundary between the new McClelland Ferry and overlying Coal Ridge Members of the Judith River Formation. The shallow marine sandstones that form the backstepping sequences represent the leading edge of the Bearpaw transgression in this region and are formalized as the new Woodhawk Member of the Judith River Formation in a third reference section. New 40Ar/39Ar ages indicate (1) that the mid-Judith discontinuity formed ∼76.2 Ma, coincident with the onset of the Bearpaw transgression in central Montana; and (2) that the Bearpaw Sea had advanced westward beyond the Judith River type area by ∼75.2 Ma, on the basis of the dating of a bentonite bed at the base of the Bearpaw Formation. These new ages also provide more confident age control for important vertebrate fossil occurrences in the Judith River Formation. Facies analysis across the mid-Judith discontinuity reveals how alluvial systems respond to regional base-level rise, which is implicit with the increase in rock accumulation rates and marine transgression. With the increase in accommodation signaled by the mid-Judith discontinuity, the alluvial system shifted in dominance from fluvial channel to overbank deposits, with greater tidal influence in channel sands, more hydromorphic and carbonaceous overbank deposits, and a higher frequency of bentonites and skeletal concentrations, suggesting higher preservation rates. These features, along with the appearance of extraformational pebbles above the discontinuity, are consistent with an upstream tectonic explanation for the addition of accommodation.",
    url = "https://doi.org/10.1086/684289",
    doi = "10.1086/684289",
    openalex = "W2274198338",
    references = "doi101006cres19941022, doi1010079783642859168, doi1010160031018288900855, doi101016003101829090202i, doi1010160037073891901395, doi101016003707389390022w, doi101016jgca2006061563, doi101016s0016703799002045, doi101016s0195667105800308, doi101111j136530911979tb00935x, doi101126science1154339, doi1011270078042120110011, doi101139cjes20120185, doi1016660094837336180, doi101666080251, doi1018814epiiugs2013v36i3002, doi1023071005355, eberth1990stratigraphy"
}

@inproceedings{andmclain2017discovery,
    author = "McLain, Matthew A. and Snyder, Keith and Chadwick, Arthur V.",
    title = "DISCOVERY OF A UNIQUE MULTITAXIC DINOSAUR BONEBED FROM THE LANCE FORMATION (MAASTRICHTIAN) OF WYOMING",
    year = "2017",
    booktitle = "Geological Society of America Abstracts with Programs",
    url = "https://doi.org/10.1130/abs/2017am-304322",
    doi = "10.1130/abs/2017am-304322",
    openalex = "W2771509300"
}

Troodontids are known from Asia and North America, with the most complete specimens from the Jurassic of China and the Cretaceous of Mongolia. North American troodontids are poorly known, and specimens that have been described are isolated elements or partial skeletons with limited material. A new troodontid from the upper Dinosaur Park Formation (upper Campanian) is based on partial skulls, several vertebrae, ribs, gastralia, chevrons, a sacrum, partial pelvis, and partial fore and hind limbs. It is the largest troodontid known, with an estimated height of 180 cm and length of 350 cm. Like other troodontids, it possesses an elongated ambiens process and has a horizontal ventral margin of the postacetabular process. It differs from all other derived troodontids in that the slightly retroverted pubis has a shaft that curves anteroventrally. Some specimens from the Dinosaur Park Formation previously assigned to Troodon are reassigned to the new taxon, including multiple partial crania, an associated dentary and metatarsus, and a partial skeleton. Previously undescribed elements from the lower part of the Dinosaur Park Formation are assigned to the resurrected Stenonychosaurus inequalis. Distinct stratigraphic separation of Stenonychosaurus inequalis and the new taxon indicates a replacement in troodontid fauna, similar to the turnover of large ornithischians in the same formation. The new taxon is phylogenetically more closely related to Mongolian taxa, indicating the replacement of Stenonychosaurus may have been from an earlier Asian form immigrating into North America.

@article{doi101139cjes20170031,
    author = "van der Reest, Aaron J. and Currie, Philip J.",
    title = "Troodontids (Theropoda) from the Dinosaur Park Formation, Alberta, with a description of a unique new taxon: implications for deinonychosaur diversity in North America",
    year = "2017",
    journal = "Canadian Journal of Earth Sciences",
    abstract = "Troodontids are known from Asia and North America, with the most complete specimens from the Jurassic of China and the Cretaceous of Mongolia. North American troodontids are poorly known, and specimens that have been described are isolated elements or partial skeletons with limited material. A new troodontid from the upper Dinosaur Park Formation (upper Campanian) is based on partial skulls, several vertebrae, ribs, gastralia, chevrons, a sacrum, partial pelvis, and partial fore and hind limbs. It is the largest troodontid known, with an estimated height of 180 cm and length of 350 cm. Like other troodontids, it possesses an elongated ambiens process and has a horizontal ventral margin of the postacetabular process. It differs from all other derived troodontids in that the slightly retroverted pubis has a shaft that curves anteroventrally. Some specimens from the Dinosaur Park Formation previously assigned to Troodon are reassigned to the new taxon, including multiple partial crania, an associated dentary and metatarsus, and a partial skeleton. Previously undescribed elements from the lower part of the Dinosaur Park Formation are assigned to the resurrected Stenonychosaurus inequalis. Distinct stratigraphic separation of Stenonychosaurus inequalis and the new taxon indicates a replacement in troodontid fauna, similar to the turnover of large ornithischians in the same formation. The new taxon is phylogenetically more closely related to Mongolian taxa, indicating the replacement of Stenonychosaurus may have been from an earlier Asian form immigrating into North America.",
    url = "https://doi.org/10.1139/cjes-2017-0031",
    doi = "10.1139/cjes-2017-0031",
    openalex = "W2742325356",
    references = "doi101007s0011401411439, doi101007s1143400900096, doi101016jpalaeo201206024, doi101016jpalaeo201206027, doi101038415780a, doi101038nature02898, doi101038ncomms4289, doi101038ncomms4788, doi1010800272463420161269539, doi101139e93187, doi1012066481, doi1012067481, doi101371journalpone0024487, doi101371journalpone0054329, doi101371journalpone0093190, doi1016710272463420072787antdtf20co2, doi105860choice435902, doi105962p339375, openalexw2597671315"
}

Interbasinal stratigraphic correlation provides the foundation for all consequent continental-scale geological and paleontological analyses. Correlation requires synthesis of lithostratigraphic, biostratigraphic and geochronologic data, and must be periodically updated to accord with advances in dating techniques, changing standards for radiometric dates, new stratigraphic concepts, hypotheses, fossil specimens, and field data. Outdated or incorrect correlation exposes geological and paleontological analyses to potential error. The current work presents a high-resolution stratigraphic chart for terrestrial Late Cretaceous units of North America, combining published chronostratigraphic, lithostratigraphic, and biostratigraphic data. 40Ar / 39Ar radiometric dates are newly recalibrated to both current standard and decay constant pairings. Revisions to the stratigraphic placement of most units are slight, but important changes are made to the proposed correlations of the Aguja and Javelina formations, Texas, and recalibration corrections in particular affect the relative age positions of the Belly River Group, Alberta; Judith River Formation, Montana; Kaiparowits Formation, Utah; and Fruitland and Kirtland formations, New Mexico. The stratigraphic ranges of selected clades of dinosaur species are plotted on the chronostratigraphic framework, with some clades comprising short-duration species that do not overlap stratigraphically with preceding or succeeding forms. This is the expected pattern that is produced by an anagenetic mode of evolution, suggesting that true branching (speciation) events were rare and may have geographic significance. The recent hypothesis of intracontinental latitudinal provinciality of dinosaurs is shown to be affected by previous stratigraphic miscorrelation. Rapid stepwise acquisition of display characters in many dinosaur clades, in particular chasmosaurine ceratopsids, suggests that they may be useful for high resolution biostratigraphy.

@article{doi101371journalpone0188426,
    author = "Fowler, Denver Warwick",
    title = "Revised geochronology, correlation, and dinosaur stratigraphic ranges of the Santonian-Maastrichtian (Late Cretaceous) formations of the Western Interior of North America.",
    year = "2017",
    journal = "PloS one",
    abstract = "Interbasinal stratigraphic correlation provides the foundation for all consequent continental-scale geological and paleontological analyses. Correlation requires synthesis of lithostratigraphic, biostratigraphic and geochronologic data, and must be periodically updated to accord with advances in dating techniques, changing standards for radiometric dates, new stratigraphic concepts, hypotheses, fossil specimens, and field data. Outdated or incorrect correlation exposes geological and paleontological analyses to potential error. The current work presents a high-resolution stratigraphic chart for terrestrial Late Cretaceous units of North America, combining published chronostratigraphic, lithostratigraphic, and biostratigraphic data. 40Ar / 39Ar radiometric dates are newly recalibrated to both current standard and decay constant pairings. Revisions to the stratigraphic placement of most units are slight, but important changes are made to the proposed correlations of the Aguja and Javelina formations, Texas, and recalibration corrections in particular affect the relative age positions of the Belly River Group, Alberta; Judith River Formation, Montana; Kaiparowits Formation, Utah; and Fruitland and Kirtland formations, New Mexico. The stratigraphic ranges of selected clades of dinosaur species are plotted on the chronostratigraphic framework, with some clades comprising short-duration species that do not overlap stratigraphically with preceding or succeeding forms. This is the expected pattern that is produced by an anagenetic mode of evolution, suggesting that true branching (speciation) events were rare and may have geographic significance. The recent hypothesis of intracontinental latitudinal provinciality of dinosaurs is shown to be affected by previous stratigraphic miscorrelation. Rapid stepwise acquisition of display characters in many dinosaur clades, in particular chasmosaurine ceratopsids, suggests that they may be useful for high resolution biostratigraphy.",
    url = "https://pmc.ncbi.nlm.nih.gov/articles/PMC5699823/",
    doi = "10.1371/journal.pone.0188426",
    openalex = "W2544476050",
    pmcid = "PMC5699823",
    pmid = "29166406",
    references = "doi1010160012821x77900607, doi101016016896228790025x, doi101016037594749090598g, doi101016jgca201006017, doi101016jgca201106021, doi101016jsedgeo200610001, doi101016s0009254197001599, doi101016s0016703799002045, doi101016s0375947497006131, doi101126science1154339, doi101130001676061952631011cotcfo20co2, doi101130b310761, doi101139e93016, doi101371journalpone0012292, doi101371journalpone0024487, doi101371journalpone0025186, doi101371journalpone0141304, doi10167102724634200727373aarolm20co2, doi105860choice514447, lehman1987late, openalexw2025327988"
}

The Late Jurassic Tendaguru Formation of Tanzania, southeastern Africa, records a diverse and abundant sauropod fauna, including the flagellicaudatan diplodocoids Dicraeosaurus and Tornieria, and the brachiosaurid titanosauriform Giraffatitan. However, the taxonomic affinities of other sympatric sauropod taxa and remains are poorly understood. Here, we critically reassess and redescribe these problematic taxa, and present the largest phylogenetic analysis for sauropods (117 taxa scored for 542 characters) to explore their placement within Eusauropoda. A full re-description of the holotype of Janenschia, and all referable remains, supports its validity and placement as a nonneosauropod eusauropod. New information on the internal pneumatic tissue structure of the anterior dorsal vertebrae of the enigmatic Tendaguria tanzaniensis, coupled with a full re-description, results in its novel placement as a turiasaur. A previously referred caudal sequence cannot be assigned to Janenschia and displays several features that indicate a close relationship with Middle–Late Jurassic East Asian mamenchisaurids. It can be diagnosed by six autapomorphies, and we erect the new taxon Wamweracaudia keranjei n. gen. n. sp. The Tendaguru Formation shares representatives of nearly all sauropod lineages with Middle Jurassic–earliest Cretaceous global faunas, but displays a greater range of diversity than any of those faunas considered individually.

@article{doi101093zoolinneanzly068,
    author = "Mannion, Philip D. and Upchurch, Paul and Schwarz, Daniela and Wings, Oliver",
    title = "Taxonomic affinities of the putative titanosaurs from the Late Jurassic Tendaguru Formation of Tanzania: phylogenetic and biogeographic implications for eusauropod dinosaur evolution",
    year = "2018",
    journal = "Zoological Journal of the Linnean Society",
    abstract = "The Late Jurassic Tendaguru Formation of Tanzania, southeastern Africa, records a diverse and abundant sauropod fauna, including the flagellicaudatan diplodocoids Dicraeosaurus and Tornieria, and the brachiosaurid titanosauriform Giraffatitan. However, the taxonomic affinities of other sympatric sauropod taxa and remains are poorly understood. Here, we critically reassess and redescribe these problematic taxa, and present the largest phylogenetic analysis for sauropods (117 taxa scored for 542 characters) to explore their placement within Eusauropoda. A full re-description of the holotype of Janenschia, and all referable remains, supports its validity and placement as a nonneosauropod eusauropod. New information on the internal pneumatic tissue structure of the anterior dorsal vertebrae of the enigmatic Tendaguria tanzaniensis, coupled with a full re-description, results in its novel placement as a turiasaur. A previously referred caudal sequence cannot be assigned to Janenschia and displays several features that indicate a close relationship with Middle–Late Jurassic East Asian mamenchisaurids. It can be diagnosed by six autapomorphies, and we erect the new taxon Wamweracaudia keranjei n. gen. n. sp. The Tendaguru Formation shares representatives of nearly all sauropod lineages with Middle Jurassic–earliest Cretaceous global faunas, but displays a greater range of diversity than any of those faunas considered individually.",
    url = "https://doi.org/10.1093/zoolinnean/zly068",
    doi = "10.1093/zoolinnean/zly068",
    openalex = "W2911482806",
    references = "doi101002mmng19994860020102, doi101002mmng19994860020109, doi101002mmng200900004, doi101016jcretres201603008, doi101016jearscirev201203002, doi101016jgr201403014, doi101017s0016756804000330, doi101038ncomms3929, doi101038s41467018051281, doi101038srep19165, doi101038srep34467, doi101080027246342011557116, doi101080027246342012671204, doi101080027246342013776562, doi101093sysbiosyu056, doi101093zoolinneanzlx103, doi101098rspb20120660, doi101098rspb20171219, doi101111cla12160, doi101111j10960031200800217x, doi101111j10963642201000620x, doi101111pala12142, doi101111zoj12029, doi101111zoj12425, doi101144001676492006032, doi101371journalpone0006924, doi101371journalpone0017114, doi101371journalpone0037122, doi101371journalpone0079420, doi101371journalpone0125819, doi1018814epiiugs2013v36i3002, doi1021425f55419694, doi1022179revmacn7344, doi1023073802723, doi1026879529, doi10274700206814489791, doi105281zenodo16171435, doi105710amegh261210131889, doi105860choice331556, doi107717peerj857, heinrich1998late, openalexw1545181283"
}

Perinatal specimens of hadrosaurids discovered in the late 1970's by field crews from Princeton University were significant in providing evidence of the early ontogenetic stages in North American dinosaurs. These specimens from the Campanian (Upper Cretaceous) Two Medicine Formation of Montana consist of over a dozen skeletons referable to the saurolophine hadrosaurid Maiasaura peeblesorum, but never fully figured or described. Here, we provide a more complete documentation of the morphology of these specimens, along with an examination of variation during a large span of the development of saurolophine hadrosaurids. Many ontogenetic changes in the available facial and mandibular elements are associated with the progressive elongation of the preorbital region of the skull and mandible. In the postcranium, limb bones change nearly isometrically, with exception of certain elements of the forelimb. Some cranial and postcranial characters commonly used for inferring hadrosaurid phylogenetic relationships remain invariable during the ontogeny of M. peeblesorum. This indicates that early ontogenetic stages may still provide a limited amount of character information useful for systematics and phylogenetic inference.

@article{doi107717peerj4734,
    author = "Prieto‐Márquez, Albert and Guenther, Merrilee F.",
    title = "Perinatal specimens of Maiasaura from the Upper Cretaceous of Montana (USA): insights into the early ontogeny of saurolophine hadrosaurid dinosaurs",
    year = "2018",
    journal = "PeerJ",
    abstract = "Perinatal specimens of hadrosaurids discovered in the late 1970's by field crews from Princeton University were significant in providing evidence of the early ontogenetic stages in North American dinosaurs. These specimens from the Campanian (Upper Cretaceous) Two Medicine Formation of Montana consist of over a dozen skeletons referable to the saurolophine hadrosaurid Maiasaura peeblesorum, but never fully figured or described. Here, we provide a more complete documentation of the morphology of these specimens, along with an examination of variation during a large span of the development of saurolophine hadrosaurids. Many ontogenetic changes in the available facial and mandibular elements are associated with the progressive elongation of the preorbital region of the skull and mandible. In the postcranium, limb bones change nearly isometrically, with exception of certain elements of the forelimb. Some cranial and postcranial characters commonly used for inferring hadrosaurid phylogenetic relationships remain invariable during the ontogeny of M. peeblesorum. This indicates that early ontogenetic stages may still provide a limited amount of character information useful for systematics and phylogenetic inference.",
    url = "https://doi.org/10.7717/peerj.4734",
    doi = "10.7717/peerj.4734",
    openalex = "W2803572907",
    references = "doi101371journalpone0141304"
}

Modern megaherbivore community richness is limited by bottom-up controls, such as resource limitation and resultant dietary competition. However, the extent to which these same controls impacted the richness of fossil megaherbivore communities is poorly understood. The present study investigates the matter with reference to the megaherbivorous dinosaur assemblage from the middle to upper Campanian Dinosaur Park Formation of Alberta, Canada. Using a meta-analysis of 21 ecomorphological variables measured across 14 genera, contemporaneous taxa are demonstrably well-separated in ecomorphospace at the family/subfamily level. Moreover, this pattern is persistent through the approximately 1.5 Myr timespan of the formation, despite continual species turnover, indicative of underlying structural principles imposed by long-term ecological competition. After considering the implications of ecomorphology for megaherbivorous dinosaur diet, it is concluded that competition structured comparable megaherbivorous dinosaur communities throughout the Late Cretaceous of western North America.

@article{doi101038s41598019517095,
    author = "Mallon, Jordan C.",
    title = "Competition structured a Late Cretaceous megaherbivorous dinosaur assemblage",
    year = "2019",
    journal = "Scientific Reports",
    abstract = "Modern megaherbivore community richness is limited by bottom-up controls, such as resource limitation and resultant dietary competition. However, the extent to which these same controls impacted the richness of fossil megaherbivore communities is poorly understood. The present study investigates the matter with reference to the megaherbivorous dinosaur assemblage from the middle to upper Campanian Dinosaur Park Formation of Alberta, Canada. Using a meta-analysis of 21 ecomorphological variables measured across 14 genera, contemporaneous taxa are demonstrably well-separated in ecomorphospace at the family/subfamily level. Moreover, this pattern is persistent through the approximately 1.5 Myr timespan of the formation, despite continual species turnover, indicative of underlying structural principles imposed by long-term ecological competition. After considering the implications of ecomorphology for megaherbivorous dinosaur diet, it is concluded that competition structured comparable megaherbivorous dinosaur communities throughout the Late Cretaceous of western North America.",
    url = "https://doi.org/10.1038/s41598-019-51709-5",
    doi = "10.1038/s41598-019-51709-5",
    openalex = "W2981425882",
    references = "doi101007978146124018114, doi101017cbo9780511565441, doi101017cbo9780511608551, doi101017cbo9780511735011, doi101086653688, doi101093biomet301281, doi101098rsos161086, doi101111j15023931200900187x, doi101139cjes20120185, doi101139e10005, doi101139e78109, doi101186147267851314, doi1012060003008220023660001aitrou20co2, doi101371journalpone0098605, doi101371journalpone0175253, doi101371journalpone0188426, doi1023073545850, doi1023075663, doi102475ajs2628975, openalexw2183707334"
}

The non-marine Horseshoe Canyon Formation (HCFm, southern Alberta) yields taxonomically diverse, late Campanian to middle Maastrichtian dinosaur assemblages that play a central role in documenting dinosaur evolution, paleoecology, and paleobiogeography leading up to the end-Cretaceous extinction. Here, we present high-precision U–Pb CA–ID–TIMS ages and the first calibrated chronostratigraphy for the HCFm using zircon grains from (1) four HCFm bentonites distributed through 129 m of section, (2) one bentonite from the underlying Bearpaw Formation, and (3) a bentonite from the overlying Battle Formation that we dated previously. In its type area, the HCFm ranges in age from 73.1–68.0 Ma. Significant paleoenvironmental and climatic changes are recorded in the formation, including (1) a transition from a warm-and-wet deltaic setting to a cooler, seasonally wet-dry coastal plain at 71.5 Ma, (2) maximum transgression of the Drumheller Marine Tongue at 70.896 ± 0.048 Ma, and (3) transition to a warm-wet alluvial plain at 69.6 Ma. The HCFm’s three mega-herbivore dinosaur assemblage zones track these changes and are calibrated as follows: Edmontosaurus regalis – Pachyrhinosaurus canadensis zone, 73.1–71.5 Ma; Hypacrosaurus altispinus – Saurolophus osborni zone, 71.5–69.6 Ma; and Eotriceratops xerinsularis zone, 69.6–68.2 Ma. The Albertosaurus Bonebed — a monodominant assemblage of tyrannosaurids in the Tolman Member — is assessed an age of 70.1 Ma. The unusual triceratopsin, Eotriceratops xerinsularis, from the Carbon Member, is assessed an age of 68.8 Ma. This chronostratigraphy is useful for refining correlations with dinosaur-bearing upper Campanian–middle Maastrichtian units in Alberta and elsewhere in North America.

@article{doi101139cjes20190019,
    author = "Eberth, David A. and Kamo, Sandra L.",
    title = "High-precision U–Pb CA–ID–TIMS dating and chronostratigraphy of the dinosaur-rich Horseshoe Canyon Formation (Upper Cretaceous, Campanian–Maastrichtian), Red Deer River valley, Alberta, Canada",
    year = "2019",
    journal = "Canadian Journal of Earth Sciences",
    abstract = "The non-marine Horseshoe Canyon Formation (HCFm, southern Alberta) yields taxonomically diverse, late Campanian to middle Maastrichtian dinosaur assemblages that play a central role in documenting dinosaur evolution, paleoecology, and paleobiogeography leading up to the end-Cretaceous extinction. Here, we present high-precision U–Pb CA–ID–TIMS ages and the first calibrated chronostratigraphy for the HCFm using zircon grains from (1) four HCFm bentonites distributed through 129 m of section, (2) one bentonite from the underlying Bearpaw Formation, and (3) a bentonite from the overlying Battle Formation that we dated previously. In its type area, the HCFm ranges in age from 73.1–68.0 Ma. Significant paleoenvironmental and climatic changes are recorded in the formation, including (1) a transition from a warm-and-wet deltaic setting to a cooler, seasonally wet-dry coastal plain at 71.5 Ma, (2) maximum transgression of the Drumheller Marine Tongue at 70.896 ± 0.048 Ma, and (3) transition to a warm-wet alluvial plain at 69.6 Ma. The HCFm’s three mega-herbivore dinosaur assemblage zones track these changes and are calibrated as follows: Edmontosaurus regalis – Pachyrhinosaurus canadensis zone, 73.1–71.5 Ma; Hypacrosaurus altispinus – Saurolophus osborni zone, 71.5–69.6 Ma; and Eotriceratops xerinsularis zone, 69.6–68.2 Ma. The Albertosaurus Bonebed — a monodominant assemblage of tyrannosaurids in the Tolman Member — is assessed an age of 70.1 Ma. The unusual triceratopsin, Eotriceratops xerinsularis, from the Carbon Member, is assessed an age of 68.8 Ma. This chronostratigraphy is useful for refining correlations with dinosaur-bearing upper Campanian–middle Maastrichtian units in Alberta and elsewhere in North America.",
    url = "https://doi.org/10.1139/cjes-2019-0019",
    doi = "10.1139/cjes-2019-0019",
    openalex = "W2979872101",
    references = "andeberth2016new, doi101007springerreference4923, doi1010160016703773902135, doi101016jchemgeo200503011, doi101016jgca200509007, doi101016jgca201006017, doi101016s0009254196000332, doi101016s0195667105800308, doi101073pnas1313334111, doi101103physrevc41889, doi101126science1154339, doi101126science1230492, doi101139cjes20120185, doi101371journalpone0188426, doi104202app20110033, doi105860choice435902, openalexw2989049194"
}

In the mid-19th century, the discovery that bone microstructure in fossils could be preserved with fidelity provided a new avenue for understanding the evolution, function, and physiology of long extinct organisms. This resulted in the establishment of paleohistology as a subdiscipline of vertebrate paleontology, which has contributed greatly to our current understanding of dinosaurs as living organisms. Dinosaurs are part of a larger group of reptiles, the Archosauria, of which there are only two surviving lineages, crocodilians and birds. The goal of this review is to document progress in the field of archosaur paleohistology, focusing in particular on the Dinosauria. We briefly review the "growth age" of dinosaur histology, which has encompassed new and varied directions since its emergence in the 1950s, resulting in a shift in the scientific perception of non-avian dinosaurs from "sluggish" reptiles to fast-growing animals with relatively high metabolic rates. However, fundamental changes in growth occurred within the sister clade Aves, and we discuss this major evolutionary transition as elucidated by histology. We then review recent innovations in the field, demonstrating how paleohistology has changed and expanded to address a diversity of non-growth related questions. For example, dinosaur skull histology has elucidated the formation of curious cranial tissues (e.g., "metaplastic" tissues), and helped to clarify the evolution and function of oral adaptations, such as the dental batteries of duck-billed dinosaurs. Lastly, we discuss the development of novel techniques with which to investigate not only the skeletal tissues of dinosaurs, but also less-studied soft-tissues, through molecular paleontology and paleohistochemistry-recently developed branches of paleohistology-and the future potential of these methods to further explore fossilized tissues. We suggest that the combination of histological and molecular methods holds great potential for examining the preserved tissues of dinosaurs, basal birds, and their extant relatives. This review demonstrates the importance of traditional bone paleohistology, but also highlights the need for innovation and new analytical directions to improve and broaden the utility of paleohistology, in the pursuit of more diverse, highly specific, and sensitive methods with which to further investigate important paleontological questions.

@article{doi107717peerj7764,
    author = "Bailleul, Alida M. and O’Connor, Jingmai K. and Schweitzer, Mary H.",
    title = "Dinosaur paleohistology: review, trends and new avenues of investigation",
    year = "2019",
    journal = "PeerJ",
    abstract = {In the mid-19th century, the discovery that bone microstructure in fossils could be preserved with fidelity provided a new avenue for understanding the evolution, function, and physiology of long extinct organisms. This resulted in the establishment of paleohistology as a subdiscipline of vertebrate paleontology, which has contributed greatly to our current understanding of dinosaurs as living organisms. Dinosaurs are part of a larger group of reptiles, the Archosauria, of which there are only two surviving lineages, crocodilians and birds. The goal of this review is to document progress in the field of archosaur paleohistology, focusing in particular on the Dinosauria. We briefly review the "growth age" of dinosaur histology, which has encompassed new and varied directions since its emergence in the 1950s, resulting in a shift in the scientific perception of non-avian dinosaurs from "sluggish" reptiles to fast-growing animals with relatively high metabolic rates. However, fundamental changes in growth occurred within the sister clade Aves, and we discuss this major evolutionary transition as elucidated by histology. We then review recent innovations in the field, demonstrating how paleohistology has changed and expanded to address a diversity of non-growth related questions. For example, dinosaur skull histology has elucidated the formation of curious cranial tissues (e.g., "metaplastic" tissues), and helped to clarify the evolution and function of oral adaptations, such as the dental batteries of duck-billed dinosaurs. Lastly, we discuss the development of novel techniques with which to investigate not only the skeletal tissues of dinosaurs, but also less-studied soft-tissues, through molecular paleontology and paleohistochemistry-recently developed branches of paleohistology-and the future potential of these methods to further explore fossilized tissues. We suggest that the combination of histological and molecular methods holds great potential for examining the preserved tissues of dinosaurs, basal birds, and their extant relatives. This review demonstrates the importance of traditional bone paleohistology, but also highlights the need for innovation and new analytical directions to improve and broaden the utility of paleohistology, in the pursuit of more diverse, highly specific, and sensitive methods with which to further investigate important paleontological questions.},
    url = "https://doi.org/10.7717/peerj.7764",
    doi = "10.7717/peerj.7764",
    openalex = "W2975364321",
    references = "doi101002jmor10372, doi101017pab201519, doi101029sc005p0175, doi101038362709a0, doi101038nature01420, doi101038s4146701909259x, doi1010719781486300679, doi101093sysbiosyw033, doi101098rsbl20090310, doi101098rspb20042813, doi1011111475475400064, doi101111j1469185x201000142x, doi101111j1474919x1968tb00058x, doi101126science26251422020, doi101242dev1172409, doi101371journalpone0029958, doi101371journalpone0088834, doi1016660094837320040300253chopom20co2, doi1016660094837320050310291teafot20co2, doi1016690883135120030180286rpoumt20co2, doi1016710272463420000200115lbhoth20co2, doi1031610680390210, doi10560219780801881206, doi107717peerj4129, garilli2009first"
}

Inferring the body mass of fossil taxa, such as non-avian dinosaurs, provides a powerful tool for interpreting physiological and ecological properties, as well as the ability to study these traits through deep time and within a macroevolutionary context. As a result, over the past 100 years a number of studies advanced methods for estimating mass in dinosaurs and other extinct taxa. These methods can be categorized into two major approaches: volumetric-density (VD) and extant-scaling (ES). The former receives the most attention in non-avian dinosaurs and advanced appreciably over the last century: from initial physical scale models to three-dimensional (3D) virtual techniques that utilize scanned data obtained from entire skeletons. The ES approach is most commonly applied to extinct members of crown clades but some equations are proposed and utilized in non-avian dinosaurs. Because both approaches share a common goal, they are often viewed in opposition to one another. However, current palaeobiological research problems are often approach specific and, therefore, the decision to utilize a VD or ES approach is largely question dependent. In general, biomechanical and physiological studies benefit from the full-body reconstruction provided through a VD approach, whereas large-scale evolutionary and ecological studies require the extensive data sets afforded by an ES approach. This study summarizes both approaches to body mass estimation in stem-group taxa, specifically non-avian dinosaurs, and provides a comparative quantitative framework to reciprocally illuminate and corroborate VD and ES approaches. The results indicate that mass estimates are largely consistent between approaches: 73% of VD reconstructions occur within the expected 95% prediction intervals of the ES relationship. However, almost three quarters of outliers occur below the lower 95% prediction interval, indicating that VD mass estimates are, on average, lower than would be expected given their stylopodial circumferences. Inconsistencies (high residual and per cent prediction deviation values) are recovered to a varying degree among all major dinosaurian clades along with an overall tendency for larger deviations between approaches among small-bodied taxa. Nonetheless, our results indicate a strong corroboration between recent iterations of the VD approach based on 3D specimen scans suggesting that our current understanding of size in dinosaurs, and hence its biological correlates, has improved over time. We advance that VD and ES approaches have fundamentally (metrically) different advantages and, hence, the comparative framework used and advocated here combines the accuracy afforded by ES with the precision provided by VD and permits the rapid identification of discrepancies with the potential to open new areas of discussion.

@article{doi101111brv12638,
    author = "Campione, Nicolás E. and Evans, David C.",
    title = "The accuracy and precision of body mass estimation in non‐avian dinosaurs",
    year = "2020",
    journal = "Biological reviews/Biological reviews of the Cambridge Philosophical Society",
    abstract = "Inferring the body mass of fossil taxa, such as non-avian dinosaurs, provides a powerful tool for interpreting physiological and ecological properties, as well as the ability to study these traits through deep time and within a macroevolutionary context. As a result, over the past 100 years a number of studies advanced methods for estimating mass in dinosaurs and other extinct taxa. These methods can be categorized into two major approaches: volumetric-density (VD) and extant-scaling (ES). The former receives the most attention in non-avian dinosaurs and advanced appreciably over the last century: from initial physical scale models to three-dimensional (3D) virtual techniques that utilize scanned data obtained from entire skeletons. The ES approach is most commonly applied to extinct members of crown clades but some equations are proposed and utilized in non-avian dinosaurs. Because both approaches share a common goal, they are often viewed in opposition to one another. However, current palaeobiological research problems are often approach specific and, therefore, the decision to utilize a VD or ES approach is largely question dependent. In general, biomechanical and physiological studies benefit from the full-body reconstruction provided through a VD approach, whereas large-scale evolutionary and ecological studies require the extensive data sets afforded by an ES approach. This study summarizes both approaches to body mass estimation in stem-group taxa, specifically non-avian dinosaurs, and provides a comparative quantitative framework to reciprocally illuminate and corroborate VD and ES approaches. The results indicate that mass estimates are largely consistent between approaches: 73\% of VD reconstructions occur within the expected 95\% prediction intervals of the ES relationship. However, almost three quarters of outliers occur below the lower 95\% prediction interval, indicating that VD mass estimates are, on average, lower than would be expected given their stylopodial circumferences. Inconsistencies (high residual and per cent prediction deviation values) are recovered to a varying degree among all major dinosaurian clades along with an overall tendency for larger deviations between approaches among small-bodied taxa. Nonetheless, our results indicate a strong corroboration between recent iterations of the VD approach based on 3D specimen scans suggesting that our current understanding of size in dinosaurs, and hence its biological correlates, has improved over time. We advance that VD and ES approaches have fundamentally (metrically) different advantages and, hence, the comparative framework used and advocated here combines the accuracy afforded by ES with the precision provided by VD and permits the rapid identification of discrepancies with the potential to open new areas of discussion.",
    url = "https://doi.org/10.1111/brv.12638",
    doi = "10.1111/brv.12638",
    openalex = "W3082346069",
    references = "doi101016jcub201706071, doi101016jpalaeo201206027, doi101017cbo9780511608551, doi101038417070a, doi101038srep06196, doi101086303327, doi101098rsbl20120263, doi101098rspb20060443, doi101098rspb20171219, doi1011112041210x12226, doi101111evo12150, doi101111j17447429200700272x, doi101111j2041210x201100153x, doi101111pala12329, doi101126science1061967, doi101152physrev1947274511, doi101371journalpone0044318, doi101371journalpone0051925, doi101371journalpone0081917, doi101371journalpone0082000, doi107717peerj857, openalexw1558456135, openalexw195142154, openalexw2593733766, openalexw260994251, pontzer2009biomechanics"
}

Spinosaurids are among the most distinctive and yet poorly-known of large-bodied theropod dinosaurs, a situation exacerbated by their mostly fragmentary fossil record and competing views regarding their palaeobiology. Here, we report two new Early Cretaceous spinosaurid specimens from the Wessex Formation (Barremian) of the Isle of Wight. Large-scale phylogenetic analyses using parsimony and Bayesian techniques recover the pair in a new clade within Baryonychinae that also includes the hypodigm of the African spinosaurid Suchomimus. Both specimens represent distinct and novel taxa, herein named Ceratosuchops inferodios gen. et sp. nov. and Riparovenator milnerae gen. et sp. nov. A palaeogeographic reconstruction suggests a European origin for Spinosauridae, with at least two dispersal events into Africa. These new finds provide welcome information on poorly sampled areas of spinosaurid anatomy, suggest that sympatry was present and potentially common in baryonychines and spinosaurids as a whole, and contribute to updated palaeobiogeographic reconstructions for the clade.

@article{doi101038s41598021978708,
    author = "Barker, Chris T. and Hone, David W. E. and Naish, Darren and Cau, Andrea and Lockwood, Jeremy A. F. and Foster, Brian and Clarkin, Claire and Schneider, Philipp and Gostling, Neil J.",
    title = "New spinosaurids from the Wessex Formation (Early Cretaceous, UK) and the European origins of Spinosauridae",
    year = "2021",
    journal = "Scientific Reports",
    abstract = "Spinosaurids are among the most distinctive and yet poorly-known of large-bodied theropod dinosaurs, a situation exacerbated by their mostly fragmentary fossil record and competing views regarding their palaeobiology. Here, we report two new Early Cretaceous spinosaurid specimens from the Wessex Formation (Barremian) of the Isle of Wight. Large-scale phylogenetic analyses using parsimony and Bayesian techniques recover the pair in a new clade within Baryonychinae that also includes the hypodigm of the African spinosaurid Suchomimus. Both specimens represent distinct and novel taxa, herein named Ceratosuchops inferodios gen. et sp. nov. and Riparovenator milnerae gen. et sp. nov. A palaeogeographic reconstruction suggests a European origin for Spinosauridae, with at least two dispersal events into Africa. These new finds provide welcome information on poorly sampled areas of spinosaurid anatomy, suggest that sympatry was present and potentially common in baryonychines and spinosaurids as a whole, and contribute to updated palaeobiogeographic reconstructions for the clade.",
    url = "https://doi.org/10.1038/s41598-021-97870-8",
    doi = "10.1038/s41598-021-97870-8",
    openalex = "W3203271713",
    references = "doi101016jcretres201103005, doi101038s4159802066261w, doi101073pnas1613813113, doi1010800272463420201877151, doi101111brv12666, doi104202app20110144, doi107717peerj5976, doi107717peerj9192, sánchezhernández2007dinosaurs"
}

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"
}

@article{doi101016jcub202205057,
    author = "Canale, Juan I. and Apesteguı́a, Sebastián and Gallina, Pablo A. and Mitchell, Jonathan S. and Smith, Nathan D. and Cullen, Thomas M. and Shinya, Akiko and Haluza, Alejandro and Gianechini, Federico A. and Makovicky, Peter J.",
    title = "New giant carnivorous dinosaur reveals convergent evolutionary trends in theropod arm reduction",
    year = "2022",
    journal = "Current Biology",
    url = "https://doi.org/10.1016/j.cub.2022.05.057",
    doi = "10.1016/j.cub.2022.05.057",
    openalex = "W4284892786",
    references = "doi101038ncomms12931, doi101098rspb20202258, doi101371journalpone0088905, doi103897zookeys92847517"
}

@article{doi101038s41586022045280,
    author = "Fabbri, Matteo and Navalón, Guillermo and Benson, Roger and Pol, Diego and O’Connor, Jingmai K. and Bhullar, Bhart‐Anjan S. and Erickson, Gregory M. and Norell, Mark A. and Orkney, Andrew and Lamanna, Matthew C. and Zouhri, Samir and Becker, Justine and Emke, Amanda R and Sasso, Cristiano Dal and Bindellini, Gabriele and Maganuco, Simone and Auditore, Marco and Ibrahim, Nizar",
    title = "Subaqueous foraging among carnivorous dinosaurs",
    year = "2022",
    journal = "Nature",
    url = "https://doi.org/10.1038/s41586-022-04528-0",
    doi = "10.1038/s41586-022-04528-0",
    openalex = "W4220981938",
    references = "doi101111brv12666, doi101111brv12790, doi101126science1258750, doi103897zookeys92847517"
}

A new spinosaurid genus and species is described based on the right maxilla and five caudal vertebrae of a single specimen from the Arcillas de Morella Formation (Early Cretaceous) at the locality of Cinctorres (Castellón, Spain). Protathlitis cinctorrensis gen. et sp. nov. is diagnosed by one autapomorphic feature as well as by a unique combination of characters. The autapomorphy includes a subcircular depression in the anterior corner of the antorbital fossa in the maxilla. The new Iberian species is recovered as a basal baryonychine. The recognition of Protathlitis cinctorrensis gen. et sp. nov. as the first baryonychine dinosaur species identified from the Arcillas de Morella Formation (late Barremian) from the same time as Vallibonavenatrix cani, the first spinosaurine dinosaur from the same formation in the Morella subbasin (Maestrat Basin, eastern Spain), indicates that the Iberian Peninsula was home to a highly diverse assemblage of medium-to-large bodied spinosaurid dinosaurs. It seems that spinosaurids appeared during the Early Cretaceous in Laurasia, with the two subfamilies occupying the western part of Europe during this period. Later, during the Barremian-Aptian, they migrated to Africa and Asia, where they would diversify. In Europe, baryonychines were dominant, while in Africa, spinosaurines were most abundant.

@article{doi101038s41598023334182,
    author = "Cubedo, Andrés Santos and de Santisteban, Carlos and Poza, Begoña and Meseguer, Sergi",
    title = "A new spinosaurid dinosaur species from the Early Cretaceous of Cinctorres (Spain)",
    year = "2023",
    journal = "Scientific Reports",
    abstract = "A new spinosaurid genus and species is described based on the right maxilla and five caudal vertebrae of a single specimen from the Arcillas de Morella Formation (Early Cretaceous) at the locality of Cinctorres (Castellón, Spain). Protathlitis cinctorrensis gen. et sp. nov. is diagnosed by one autapomorphic feature as well as by a unique combination of characters. The autapomorphy includes a subcircular depression in the anterior corner of the antorbital fossa in the maxilla. The new Iberian species is recovered as a basal baryonychine. The recognition of Protathlitis cinctorrensis gen. et sp. nov. as the first baryonychine dinosaur species identified from the Arcillas de Morella Formation (late Barremian) from the same time as Vallibonavenatrix cani, the first spinosaurine dinosaur from the same formation in the Morella subbasin (Maestrat Basin, eastern Spain), indicates that the Iberian Peninsula was home to a highly diverse assemblage of medium-to-large bodied spinosaurid dinosaurs. It seems that spinosaurids appeared during the Early Cretaceous in Laurasia, with the two subfamilies occupying the western part of Europe during this period. Later, during the Barremian-Aptian, they migrated to Africa and Asia, where they would diversify. In Europe, baryonychines were dominant, while in Africa, spinosaurines were most abundant.",
    url = "https://doi.org/10.1038/s41598-023-33418-2",
    doi = "10.1038/s41598-023-33418-2",
    openalex = "W4377092856",
    references = "doi103897zookeys92847517, sánchezhernández2007dinosaurs"
}

The end of the Cretaceous saw the Western Interior Seaway divide North America into two land masses, Laramidia in the west and Appalachia in the east. Laramidian dinosaurs inhabited a narrow strip of land extending from Mexico to Alaska. Within this geographically restricted area, dinosaurs evolved high diversity and endemism, with distinct species in the north and south. Here, we report a new tyrannosaurid from the Late Campanian-aged Cerro del Pueblo Formation of Coahuila, Mexico, which is part of a tribe of tyrannosaurs originating in southern Laramidia. Phylogenetic analysis recovers the new tyrannosaur as part of a clade including Labocania anomala from the La Bocana Roja Formation of Baja California Norte, Bistahieversor sealeyi from the Kirtland Formation of New Mexico, Teratophoneus curriei from the Kaiparowits Formation in Utah, and Dynamoterror dynastes from the Menefee Formation of New Mexico. Distinct frontal morphology and the younger age (~72.5–73 Ma versus >75.8 Ma for L. anomala) support recognition of the new tyrannosaur as a distinct species of Labocania, Labocania aguillonae. The Labocania clade dominated southern Laramidia at a time when the north was dominated by daspletosaurins and albertosaurines. The high endemism seen in tyrannosaurids is remarkable, given that modern apex predators have large geographic ranges and hints that the diversity of carnivorous dinosaurs has been underestimated.

@article{doi103390fossils2040012,
    author = "Rivera-Sylva, Héctor E. and Longrich, Nicholas R.",
    title = "A New Tyrant Dinosaur from the Late Campanian of Mexico Reveals a Tribe of Southern Tyrannosaurs",
    year = "2024",
    journal = "Fossil Studies",
    abstract = "The end of the Cretaceous saw the Western Interior Seaway divide North America into two land masses, Laramidia in the west and Appalachia in the east. Laramidian dinosaurs inhabited a narrow strip of land extending from Mexico to Alaska. Within this geographically restricted area, dinosaurs evolved high diversity and endemism, with distinct species in the north and south. Here, we report a new tyrannosaurid from the Late Campanian-aged Cerro del Pueblo Formation of Coahuila, Mexico, which is part of a tribe of tyrannosaurs originating in southern Laramidia. Phylogenetic analysis recovers the new tyrannosaur as part of a clade including Labocania anomala from the La Bocana Roja Formation of Baja California Norte, Bistahieversor sealeyi from the Kirtland Formation of New Mexico, Teratophoneus curriei from the Kaiparowits Formation in Utah, and Dynamoterror dynastes from the Menefee Formation of New Mexico. Distinct frontal morphology and the younger age (\textasciitilde 72.5–73 Ma versus >75.8 Ma for L. anomala) support recognition of the new tyrannosaur as a distinct species of Labocania, Labocania aguillonae. The Labocania clade dominated southern Laramidia at a time when the north was dominated by daspletosaurins and albertosaurines. The high endemism seen in tyrannosaurids is remarkable, given that modern apex predators have large geographic ranges and hints that the diversity of carnivorous dinosaurs has been underestimated.",
    url = "https://doi.org/10.3390/fossils2040012",
    doi = "10.3390/fossils2040012",
    openalex = "W4402898593",
    references = "doi101007s11692022095731, doi101007s1254202100555w, doi101016jcretres2021105034, doi101017s1755691013000261, doi102110001c37652, doi103390fossils2010001"
}

@article{doi1010800891296320252532735,
    author = "Coppock, Colton C. and Powers, Mark B. and Voris, Jared T. and Currie, Philip J.",
    title = "First occurrence of Daspletosaurus horneri (Tyrannosauridae, Tyrannosaurinae) in the Dinosaur Park Formation of Dinosaur Provincial Park, Alberta (Treaty 7 Territory)",
    year = "2025",
    journal = "Historical Biology",
    url = "https://doi.org/10.1080/08912963.2025.2532735",
    doi = "10.1080/08912963.2025.2532735",
    openalex = "W4412673825",
    references = "doi101007s11692022095731, doi101139cjes20230037"
}

@misc{gilmore2025a,
    author = "Gilmore, Charles W.",
    title = "A new carnivorous dinosaur from the Lance Formation of Montana",
    year = "2025",
    publisher = "Plazi",
    url = "https://www.checklistbank.org/dataset/31643/imports/89",
    doi = "10.48580/d3bn6.v89"
}

@misc{openalexw7130264215,
    title = "A new carnivorous dinosaur from the Lance Formation of Montana",
    year = "2025",
    booktitle = "Open MIND",
    url = "https://openalex.org/W7130264215",
    openalex = "W7130264215"
}

Because teeth can be taxonomically distinct, particularly for non-mammalian carnivores such as non-avian dinosaurs, teeth that have broken off in the bone of another animal during feeding, predation or antagonism can provide direct information on carnivore behaviour. Here, we report on a semi-complete, articulated adult Edmontosaurus skull (MOR 1627) from the Hell Creek Formation with an embedded theropod tooth in the nasal. To ascertain taxonomic identity of the preserved tooth tip, we compare standardized crown and denticle measurements as well as denticle descriptions of the embedded tooth to known non-avian theropods recovered from the Hell Creek Formation. We also use computed tomography (CT) scans to investigate the full extent and orientation of the embedded tooth. The apicobasal, labiolingual and mesiodistal dimensions of the tip as well as measured denticle densities and observed denticle characteristics indicate the embedded tooth is from a medium to large bodied tyrannosaurid. The curvature and ovoid cross-sectional shape of the tooth further suggests that the tooth is a maxillary tooth from a middle or posterior tooth position. The lack of reactive bone in the region surrounding the tooth suggests the animal died around the time the tooth became embedded in the nasal. Combined, this information suggests the tooth broke off when a tyrannosaurid bit the snout of the Edmontosaurus from the front at or near the time of death of the animal. Comparing observations of hunting and feeding behaviors of modern carnivores specializing in large-bodied prey, the scenario captured by MOR 1627 is most consistent with a bite inflicted during an attempt to control the struggling Edmontosaurus or deliver a killing blow followed by carcass consumption.

@article{doi107717peerj20796,
    author = "Wyenberg-Henzler, Taia C A and Scannella, John B",
    title = "Behavioral implications of an embedded tyrannosaurid tooth and associated tooth marks on an articulated skull of Edmontosaurus from the Hell Creek Formation, Montana.",
    year = "2026",
    journal = "PeerJ",
    abstract = "Because teeth can be taxonomically distinct, particularly for non-mammalian carnivores such as non-avian dinosaurs, teeth that have broken off in the bone of another animal during feeding, predation or antagonism can provide direct information on carnivore behaviour. Here, we report on a semi-complete, articulated adult Edmontosaurus skull (MOR 1627) from the Hell Creek Formation with an embedded theropod tooth in the nasal. To ascertain taxonomic identity of the preserved tooth tip, we compare standardized crown and denticle measurements as well as denticle descriptions of the embedded tooth to known non-avian theropods recovered from the Hell Creek Formation. We also use computed tomography (CT) scans to investigate the full extent and orientation of the embedded tooth. The apicobasal, labiolingual and mesiodistal dimensions of the tip as well as measured denticle densities and observed denticle characteristics indicate the embedded tooth is from a medium to large bodied tyrannosaurid. The curvature and ovoid cross-sectional shape of the tooth further suggests that the tooth is a maxillary tooth from a middle or posterior tooth position. The lack of reactive bone in the region surrounding the tooth suggests the animal died around the time the tooth became embedded in the nasal. Combined, this information suggests the tooth broke off when a tyrannosaurid bit the snout of the Edmontosaurus from the front at or near the time of death of the animal. Comparing observations of hunting and feeding behaviors of modern carnivores specializing in large-bodied prey, the scenario captured by MOR 1627 is most consistent with a bite inflicted during an attempt to control the struggling Edmontosaurus or deliver a killing blow followed by carcass consumption.",
    url = "https://pmc.ncbi.nlm.nih.gov/articles/PMC12922588/",
    doi = "10.7717/peerj.20796",
    openalex = "W7129700407",
    pmcid = "PMC12922588",
    pmid = "41727239",
    references = "doi101007s11692022095731, doi101016s0047248486800021, doi101017cbo9780511608377011, doi101017s0094837300005820, doi101017s0094837300006849, doi101034j16000706200312378x, doi10108002724634199910011161, doi10108002724634200310010947, doi1010802766964520252539638, doi101093icbicm016, doi101111j146979982000tb01076x, doi101515mamm19673111, doi107717peerj5748"
}