Hot/cold blood

Maintenance of constant body temperature in a homoiothermic animal depends upon a balance between heat production and heat dissipation, and there are consequently three possible main avenues for climatic adaptation, (1) by body-to-air gradient, (2) by heat dissipation, and (3) by metabolic rate. There is no evidence of adaptive low body temperature in arctic mammals and birds, or high body temperature in tropical mammals and birds. The body-to-air gradient can be adapted only by means of behavioral thermoregulation (nest building, avoidance of direct sunshine, etc.). With few exceptions our adult arctic and tropical mammals and birds have a basal metabolic rate that fits the standard mouse to elephant curve, i.e., the basal metabolic rate is determined by an exponential relation to size; evidently fundamental to most animals, warm-blooded or not. The basal metabolic rate is consequently not influenced by such factors as temperature gradient and insulation which largely determine the heat loss, and is hence inadaptive to climate. Equally inadaptive is the body temperature, and the phylogenetic adaptation to cold or hot climate therefore has taken place only through factors that regulate the heat dissipation, notably the fur and skin insulation. For any temperature gradient where the body temperature is maintained, the over-all insulation and the metabolic rate must be so adjusted that their product is proportional to the gradient. This is confirmed by our material inasmuch as the observed critical gradients can be approximately predicted from fur insulation and basal metabolic rate. Under the same climatic conditions there may be an inverse relation between metabolic rate and fur insulation.

@article{doi1023071538742,
    author = "Scholander, P. F. and Hock, Raymond J. and Walters, Vladimir and Irving, Laurence",
    title = "ADAPTATION TO COLD IN ARCTIC AND TROPICAL MAMMALS AND BIRDS IN RELATION TO BODY TEMPERATURE, INSULATION, AND BASAL METABOLIC RATE",
    year = "1950",
    journal = "Biological Bulletin",
    abstract = "Maintenance of constant body temperature in a homoiothermic animal depends upon a balance between heat production and heat dissipation, and there are consequently three possible main avenues for climatic adaptation, (1) by body-to-air gradient, (2) by heat dissipation, and (3) by metabolic rate. There is no evidence of adaptive low body temperature in arctic mammals and birds, or high body temperature in tropical mammals and birds. The body-to-air gradient can be adapted only by means of behavioral thermoregulation (nest building, avoidance of direct sunshine, etc.). With few exceptions our adult arctic and tropical mammals and birds have a basal metabolic rate that fits the standard mouse to elephant curve, i.e., the basal metabolic rate is determined by an exponential relation to size; evidently fundamental to most animals, warm-blooded or not. The basal metabolic rate is consequently not influenced by such factors as temperature gradient and insulation which largely determine the heat loss, and is hence inadaptive to climate. Equally inadaptive is the body temperature, and the phylogenetic adaptation to cold or hot climate therefore has taken place only through factors that regulate the heat dissipation, notably the fur and skin insulation. For any temperature gradient where the body temperature is maintained, the over-all insulation and the metabolic rate must be so adjusted that their product is proportional to the gradient. This is confirmed by our material inasmuch as the observed critical gradients can be approximately predicted from fur insulation and basal metabolic rate. Under the same climatic conditions there may be an inverse relation between metabolic rate and fur insulation.",
    url = "https://doi.org/10.2307/1538742",
    doi = "10.2307/1538742",
    openalex = "W1832973567",
    references = "doi101086physzool17130151829"
}

@misc{bakker1968the1,
    author = "Bakker, R. T",
    title = "The superiority of dinosaurs",
    year = "1968",
    howpublished = "Discovery, v. 3, p. 11-22",
    note = "talkorigins\_source = {true}; raw\_reference = {Bakker, R. T., 1968, The superiority of dinosaurs: Discovery, v. 3, p. 11-22.}"
}

Journal Article DINOSAUR PHYSIOLOGY AND THE ORIGIN OF MAMMALS Get access Robert T. Barker Robert T. Barker Department of Vertebrate Paleontology, Museum of Comparative Zoology Harvard University Cambridge Massachusetts 02138 Search for other works by this author on: Oxford Academic Google Scholar Evolution, Volume 25, Issue 4, 1 December 1971, Pages 636–658, https://doi.org/10.1111/j.1558-5646.1971.tb01922.x Published: 01 December 1971 Article history Received: 09 September 1970 Published: 01 December 1971

@article{doi101111j155856461971tb01922x,
    author = "Barker, Robert T.",
    title = "DINOSAUR PHYSIOLOGY AND THE ORIGIN OF MAMMALS",
    year = "1971",
    journal = "Evolution",
    abstract = "Journal Article DINOSAUR PHYSIOLOGY AND THE ORIGIN OF MAMMALS Get access Robert T. Barker Robert T. Barker Department of Vertebrate Paleontology, Museum of Comparative Zoology Harvard University Cambridge Massachusetts 02138 Search for other works by this author on: Oxford Academic Google Scholar Evolution, Volume 25, Issue 4, 1 December 1971, Pages 636–658, https://doi.org/10.1111/j.1558-5646.1971.tb01922.x Published: 01 December 1971 Article history Received: 09 September 1970 Published: 01 December 1971",
    url = "https://doi.org/10.1111/j.1558-5646.1971.tb01922.x",
    doi = "10.1111/j.1558-5646.1971.tb01922.x",
    openalex = "W2073972884",
    references = "doi101098rstb19700028, doi101111j109636421961tb00220x, doi101111j174966321912tb55164x, doi1023071441916, doi1023071932171, doi104095105049, doi105962bhltitle118972, doi107208chicago97802267365700010001, openalexw2089359955, openalexw337536883"
}

@article{bakker1972anatomical,
    author = "BAKKER, ROBERT T.",
    title = "Anatomical and Ecological Evidence of Endothermy in Dinosaurs",
    year = "1972",
    journal = "Nature",
    url = "https://doi.org/10.1038/238081a0",
    doi = "10.1038/238081a0",
    number = "5359",
    openalex = "W2021172872",
    pages = "81-85",
    volume = "238",
    references = "doi101001jama196203050110085031, doi101111j155856461971tb01922x, doi101152ajplegacy197021941104, doi101515mamm19673111, doi1023071365733, doi1023071933240, doi1023072406945, doi1023073250, doi1023073799111, doi107208chicago97802267365700010001"
}

Journal Article REPLY TO “DINOSAURS AS REPTILES” Get access John H. Ostrom John H. Ostrom Department of Geology and Geophysics and Peabody Museum of Natural History Yale University New Haven Connecticut Search for other works by this author on: Oxford Academic Google Scholar Evolution, Volume 28, Issue 3, 1 September 1974, Pages 491–493, https://doi.org/10.1111/j.1558-5646.1974.tb00776.x Published: 01 September 1974 Article history Received: 20 August 1973 Published: 01 September 1974

@article{doi101111j155856461974tb00776x,
    author = "Ostrom, John H.",
    title = "REPLY TO “DINOSAURS AS REPTILES”",
    year = "1974",
    journal = "Evolution",
    abstract = "Journal Article REPLY TO “DINOSAURS AS REPTILES” Get access John H. Ostrom John H. Ostrom Department of Geology and Geophysics and Peabody Museum of Natural History Yale University New Haven Connecticut Search for other works by this author on: Oxford Academic Google Scholar Evolution, Volume 28, Issue 3, 1 September 1974, Pages 491–493, https://doi.org/10.1111/j.1558-5646.1974.tb00776.x Published: 01 September 1974 Article history Received: 20 August 1973 Published: 01 September 1974",
    url = "https://doi.org/10.1111/j.1558-5646.1974.tb00776.x",
    doi = "10.1111/j.1558-5646.1974.tb00776.x",
    openalex = "W2333683586",
    references = "feduccia1974endothermy"
}

@article{feduccia1974endothermy,
    author = "Feduccia, Alan",
    title = "Endothermy, Dinosaurs, and Archaeopteryx",
    year = "1974",
    journal = "Evolution",
    url = "https://doi.org/10.2307/2407180",
    doi = "10.2307/2407180",
    number = "3",
    openalex = "W4236695320",
    pages = "503",
    volume = "28"
}

@article{seymour1976dinosaurs,
    author = "SEYMOUR, ROGER S.",
    title = "Dinosaurs, endothermy and blood pressure",
    year = "1976",
    journal = "Nature",
    url = "https://doi.org/10.1038/262207a0",
    doi = "10.1038/262207a0",
    number = "5565",
    openalex = "W1982587162",
    pages = "207-208",
    volume = "262",
    references = "doi101001jama196103040510042019, doi1010160031018275900279, doi101016003456877190020x, doi101038scientificamerican047558, doi1010970000044119620600000017, doi101111j155856461971tb01922x, doi10116101res13291, doi1023071375442, doi1023072406945, doi107326000348197311521"
}

@book{seymour1976dinosaurs7,
    author = "Seymour, R. S",
    title = "Dinosaurs, endothermy and blood pressure",
    year = "1976",
    publisher = "Nature, v. 262, p. 207-208",
    note = "talkorigins\_source = {true}; raw\_reference = {Seymour, R. S., 1976, Dinosaurs, endothermy and blood pressure: Nature, v. 262, p. 207-208.}"
}

@article{bouvier1977dinosaur,
    author = "Bouvier, Marianne",
    title = "DINOSAUR HAVERSIAN BONE AND ENDOTHERMY",
    year = "1977",
    journal = "Evolution",
    url = "https://doi.org/10.1111/j.1558-5646.1977.tb01028.x",
    doi = "10.1111/j.1558-5646.1977.tb01028.x",
    number = "2",
    openalex = "W2325766925",
    pages = "449-450",
    volume = "31",
    references = "bakker1972anatomical, doi1010160021929074900645, doi101017s0021859600040491, doi101242jcss310361111, doi1021060000462319705208000005, openalexw2247544283"
}

@misc{marx1978warmblooded4,
    author = "Marx, J. L",
    title = "Warm-blooded dinosaurs",
    year = "1978",
    howpublished = "Evidence pro and con: Science, v. 199, p. 1424-1426",
    note = "talkorigins\_source = {true}; raw\_reference = {Marx, J. L., 1978, Warm-blooded dinosaurs: Evidence pro and con: Science, v. 199, p. 1424-1426.}"
}

The ratio of carnivorous to herbivorous dinosaur skeletons from Dinosaur Provincial Park has been cited as evidence of endothermy in dinosaurs. In living populations of large endothermic mammals, carnivore biomass represents approximately 1% of total biomass. Two models describing energy flow from herbivores to carnivores indicate that tyrannosaurids are three to four times more abundant in the fossil sample than would have been the case if they were endothermic. Either the fossil sample does not adequately reflect relative abundances of large dinosaurs in the ancient community, or large dinosaurs were ectothermic.

@article{béland1979ectothermy,
    author = "Béland, P. and Russell, D. A.",
    title = "Ectothermy in dinosaurs: paleoecological evidence from Dinosaur Provincial Park, Alberta",
    year = "1979",
    journal = "Canadian Journal of Earth Sciences",
    abstract = "The ratio of carnivorous to herbivorous dinosaur skeletons from Dinosaur Provincial Park has been cited as evidence of endothermy in dinosaurs. In living populations of large endothermic mammals, carnivore biomass represents approximately 1\% of total biomass. Two models describing energy flow from herbivores to carnivores indicate that tyrannosaurids are three to four times more abundant in the fossil sample than would have been the case if they were endothermic. Either the fossil sample does not adequately reflect relative abundances of large dinosaurs in the ancient community, or large dinosaurs were ectothermic.",
    url = "https://doi.org/10.1139/e79-024",
    doi = "10.1139/e79-024",
    number = "2",
    pages = "250-255",
    volume = "16"
}

Resting and maximal levels of oxygen consumption of endothermic vertebrates exceed those of ectotherms by an average of five- to tenfold. Endotherms have a much broader range of activity that can be sustained by this augmented aerobic metabolism. Ectotherms are more reliant upon, and limited by, anaerobic metabolism during activity. A principal factor in the evolution of endothermy was the increase in aerobic capacities to support sustained activity.

@article{doi101126science493968,
    author = "Bennett, Albert F. and Ruben, John A.",
    title = "Endothermy and Activity in Vertebrates",
    year = "1979",
    journal = "Science",
    abstract = "Resting and maximal levels of oxygen consumption of endothermic vertebrates exceed those of ectotherms by an average of five- to tenfold. Endotherms have a much broader range of activity that can be sustained by this augmented aerobic metabolism. Ectotherms are more reliant upon, and limited by, anaerobic metabolism during activity. A principal factor in the evolution of endothermy was the increase in aerobic capacities to support sustained activity.",
    url = "https://doi.org/10.1126/science.493968",
    doi = "10.1126/science.493968",
    openalex = "W2171422564",
    references = "bakker1972anatomical, doi101016s0003347280801357, doi101038272333a0, doi101086283249, doi101086physzool36330152307, doi101086physzool37430152753, doi101111j1474919x1969tb02566x, doi101111j155856461971tb01922x, doi101126science1774045222, doi101139f64103, doi101146annurevph40030178002311, doi101152ajplegacy197021941104, doi101242jeb631273, doi1023071366368, spotila1973a"
}

The relationship between half time of the O2 uptake on-response (t1/2 VO2on, seconds) and early blood lactate accumulation (delta Lab, mmol.1(-1) at the onset of submaximal arm and/or leg exercise was the object of a cross-sectional study of sedentary subjects (S,n = 3), and kayakers (K, n = 8), and of a longitudinal study on 11 untrained subjects of specific arm vs. leg training. In supine arm cranking (W = 125 watts) S had an average t1/2 VO2on of 82 s and a delta Aab of 9.2 mmol.1(-1) compared to 47 +/- 7 s and 4 +/- 1.4 mmol.1(-1), respectively, for K. In longitudinal trainees shorter t1/2 VO2on was accompanied by lower Lab for the trained limbs. Specific limb conditioning in swimmers and runners resulted in shorter t1/2 VO2on. A linear relationship was observed between delta Lab and t1/2 VO2on having an intercept on the time axis at congruent to 20 s and a slope proportional to muscle mass. Trained muscles were grouped closest to the intercept indicating local acceleration of the rate of O2 transfer approaching the t1/2 VO2on for isolated perfused muscle at the onset of work. Since t1/2 VO2on, we conclude that factors distal to the capillary are specifically involved in the local training response.

@article{doi101152jappl1979474761,
    author = "Cerretelli, P. and Pendergast, D. R. and Paganelli, William C. and Rennie, D. W.",
    title = "Effects of specific muscle training on VO2 on-response and early blood lactate",
    year = "1979",
    journal = "Journal of Applied Physiology",
    abstract = "The relationship between half time of the O2 uptake on-response (t1/2 VO2on, seconds) and early blood lactate accumulation (delta Lab, mmol.1(-1) at the onset of submaximal arm and/or leg exercise was the object of a cross-sectional study of sedentary subjects (S,n = 3), and kayakers (K, n = 8), and of a longitudinal study on 11 untrained subjects of specific arm vs. leg training. In supine arm cranking (W = 125 watts) S had an average t1/2 VO2on of 82 s and a delta Aab of 9.2 mmol.1(-1) compared to 47 +/- 7 s and 4 +/- 1.4 mmol.1(-1), respectively, for K. In longitudinal trainees shorter t1/2 VO2on was accompanied by lower Lab for the trained limbs. Specific limb conditioning in swimmers and runners resulted in shorter t1/2 VO2on. A linear relationship was observed between delta Lab and t1/2 VO2on having an intercept on the time axis at congruent to 20 s and a slope proportional to muscle mass. Trained muscles were grouped closest to the intercept indicating local acceleration of the rate of O2 transfer approaching the t1/2 VO2on for isolated perfused muscle at the onset of work. Since t1/2 VO2on, we conclude that factors distal to the capillary are specifically involved in the local training response.",
    url = "https://doi.org/10.1152/jappl.1979.47.4.761",
    doi = "10.1152/jappl.1979.47.4.761",
    openalex = "W1894577697"
}

@incollection{hopson1980relative2,
    author = "Hopson, J. A",
    editor = "Thomas, D. K. and Olson, E. C.",
    title = "Relative Brainsize in Dinosaurs: Implications for Dinosaur Endothermy",
    year = "1980",
    booktitle = "A Cold Look at the Warm Blooded Dinosaurs",
    publisher = "Washington, D.C., American Association for the Advancement of Science, p. 287-310",
    note = "talkorigins\_source = {true}; raw\_reference = {Hopson, J. A., 1980, Relative Brainsize in Dinosaurs: Implications for Dinosaur Endothermy, in Thomas, D. K., and Olson, E. C., eds., A Cold Look at the Warm Blooded Dinosaurs: Washington, D.C., American Association for the Advancement of Science, p. 287-310.}"
}

@incollection{hotton1980an3,
    author = "Hotton, N",
    editor = "Thomas, D. K. and Olson, E. C.",
    title = "An Alternative to Dinosaur Endothermy: The Happy Wanderers",
    year = "1980",
    booktitle = "A Cold Look at the Warm Blooded Dinosaurs",
    publisher = "Washington, D.C., American Association for the Advancement of Science, p. 311-350",
    note = "talkorigins\_source = {true}; raw\_reference = {Hotton, N., 1980, An Alternative to Dinosaur Endothermy: The Happy Wanderers, in Thomas, D. K., and Olson, E. C., eds., A Cold Look at the Warm Blooded Dinosaurs: Washington, D.C., American Association for the Advancement of Science, p. 311-350.}"
}

@incollection{ricqles1980tissue6,
    author = "Ricqles, A. R",
    editor = "Thomas, D. K. and Olson, E. C.",
    title = "Tissue Structures of Dinosaur Bones: Functional Significance and Possible Relation to Dinosaur Physiology",
    year = "1980",
    booktitle = "A Cold Look at the Warm Blooded Dinosaurs",
    publisher = "Washington, D.C., American Association for the Advancement of Science, p. 103-140",
    note = "talkorigins\_source = {true}; raw\_reference = {Ricqles, A. R., 1980, Tissue Structures of Dinosaur Bones: Functional Significance and Possible Relation to Dinosaur Physiology, in Thomas, D. K., and Olson, E. C., eds., A Cold Look at the Warm Blooded Dinosaurs: Washington, D.C., American Association for the Advancement of Science, p. 103-140.}"
}

The mid‐shaft circumferences of the humerus and femur are closely related to body weight in living terrestrial vertebrates. Because these elements are frequently preserved in subfossil and fossil vertebrate skeletal materials, the relationship can be used to estimate body weight in extinct vertebrates. When the allometric equations are applied to the mid‐shaft circumferences of these elements in dinosaurs, the weights calculated for some giant sauropods (Brachiosaurus) are found to be lighter than previous estimates.

@article{doi101111j146979981985tb04915x,
    author = "Anderson, John F. and Hall-Martin, A.J. and Russell, Dale A.",
    title = "Long‐bone circumference and weight in mammals, birds and dinosaurs",
    year = "1985",
    journal = "Journal of Zoology",
    abstract = "The mid‐shaft circumferences of the humerus and femur are closely related to body weight in living terrestrial vertebrates. Because these elements are frequently preserved in subfossil and fossil vertebrate skeletal materials, the relationship can be used to estimate body weight in extinct vertebrates. When the allometric equations are applied to the mid‐shaft circumferences of these elements in dinosaurs, the weights calculated for some giant sauropods (Brachiosaurus) are found to be lighter than previous estimates.",
    url = "https://doi.org/10.1111/j.1469-7998.1985.tb04915.x",
    doi = "10.1111/j.1469-7998.1985.tb04915.x",
    openalex = "W2160621949",
    references = "bakker1972anatomical, crossref1976allosaurus, doi101017s0094837300004322, doi101038238081a0, doi101086410790, doi101111j136520281979tb00256x, doi101111j146979981979tb03940x, doi101111j146979981979tb03964x, doi101111j146979981983tb05785x, doi1023072987996, openalexw654491377"
}

Dinosaur extinction in Montana, Alberta, and Wyoming was a gradual process that began 7 million years before the end of the Cretaceous and accelerated rapidly in the final 0.3 million years of the Cretaceous, during the interval of apparent competition from rapidly evolving immigrating ungulates. This interval involves rapid reduction in both diversity and population density of dinosaurs. The last dinosaurs known are from a channel that contains teeth of Mantuan mammals, seven species of dinosaurs, and Paleocene pollen. The top of this channel is 1.3 meters above the likely position of the iridium anomaly, the Cretaceous/Tertiary boundary.

@article{sloan1986gradual,
    author = "Sloan, Robert E. and Rigby, J. Keith and Van Valen, Leigh M. and Gabriel, Diane",
    title = "Gradual Dinosaur Extinction and Simultaneous Ungulate Radiation in the Hell Creek Formation",
    year = "1986",
    journal = "Science",
    abstract = "Dinosaur extinction in Montana, Alberta, and Wyoming was a gradual process that began 7 million years before the end of the Cretaceous and accelerated rapidly in the final 0.3 million years of the Cretaceous, during the interval of apparent competition from rapidly evolving immigrating ungulates. This interval involves rapid reduction in both diversity and population density of dinosaurs. The last dinosaurs known are from a channel that contains teeth of Mantuan mammals, seven species of dinosaurs, and Paleocene pollen. The top of this channel is 1.3 meters above the likely position of the iridium anomaly, the Cretaceous/Tertiary boundary.",
    url = "https://doi.org/10.1126/science.232.4750.629",
    doi = "10.1126/science.232.4750.629",
    number = "4750",
    pages = "629-633",
    volume = "232"
}

@misc{morell1987the5,
    author = "Morell, V",
    title = "The birth of a heresy",
    year = "1987",
    howpublished = "Discover, v. 8, p. 26-50",
    note = "talkorigins\_source = {true}; raw\_reference = {Morell, V., 1987, The birth of a heresy: Discover, v. 8, p. 26-50.}"
}

Histological and ultrastructural evaluation of the ends of long bones of juvenile dinosaurs from the Upper Cretaceous Two Medicine Formation of Montana revealed the preservation of growth plates. Growth plates are discs of cartilage present near the ends of growing long bones that generate bone elongation. Comparison of the fossils with modern taxa demonstrated homology of the growth plate in birds and dinosaurs. The presence of an avian-type growth plate in dinosaurs adds a shared derived anatomical character corroborating inclusion of birds within the Dinosauria. Additionally, possession of a growth plate, which in birds is capable of producing rapid determinate long bone growth, implies that an avian developmental pattern may have been present in these dinosaurs.

@article{doi101126science26251422020,
    author = "Barreto, Claudia and Albrecht, Ralph M. and Bjorling, Dale E. and Horner, John R. and Wilsman, Norman J.",
    title = "Evidence of the Growth Plate and the Growth of Long Bones in Juvenile Dinosaurs",
    year = "1993",
    journal = "Science",
    abstract = "Histological and ultrastructural evaluation of the ends of long bones of juvenile dinosaurs from the Upper Cretaceous Two Medicine Formation of Montana revealed the preservation of growth plates. Growth plates are discs of cartilage present near the ends of growing long bones that generate bone elongation. Comparison of the fossils with modern taxa demonstrated homology of the growth plate in birds and dinosaurs. The presence of an avian-type growth plate in dinosaurs adds a shared derived anatomical character corroborating inclusion of birds within the Dinosauria. Additionally, possession of a growth plate, which in birds is capable of producing rapid determinate long bone growth, implies that an avian developmental pattern may have been present in these dinosaurs.",
    url = "https://doi.org/10.1126/science.262.5142.2020",
    doi = "10.1126/science.262.5142.2020",
    openalex = "W2007794110",
    references = "bouvier1977dinosaur, doi101002jor1100090306, doi101017s247526300000091x, doi101038248168a0, doi101038282296a0, doi101038297675a0, doi101038361064a0, doi1010970124139819921100000022, doi1021060000462319876902000002, doi1023071443592, openalexw575222456"
}

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"
}

The debate over the origins of endothermy—and whether or not dinosaurs were warm-blooded—has blown hot and cold for years, hampered by the lack of clear-cut evidence. But bones in the nose that are essential for conserving water and heat in endotherms seem completely lacking in dinosaurs, and many researchers say this indicates the extinct animals couldn't have been warm-blooded.

@article{doi101126science2705237735,
    author = "Fischman, Joshua",
    title = "Were Dinos Cold-Blooded After All? The Nose Knows",
    year = "1995",
    journal = "Science",
    abstract = "The debate over the origins of endothermy—and whether or not dinosaurs were warm-blooded—has blown hot and cold for years, hampered by the lack of clear-cut evidence. But bones in the nose that are essential for conserving water and heat in endotherms seem completely lacking in dinosaurs, and many researchers say this indicates the extinct animals couldn't have been warm-blooded.",
    url = "https://doi.org/10.1126/science.270.5237.735",
    doi = "10.1126/science.270.5237.735",
    openalex = "W1641318940"
}

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

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

Among local faunas, the maximum body size and taxonomic affiliation of the top terrestrial vertebrate vary greatly. Does this variation reflect how food requirements differ between trophic levels (herbivores vs. carnivores) and with taxonomic affiliation (mammals and birds vs. reptiles)? We gathered data on the body size and food requirements of the top terrestrial herbivores and carnivores, over the past 65,000 years, from oceanic islands and continents. The body mass of the top species was found to increase with increasing land area, with a slope similar to that of the relation between body mass and home range area, suggesting that maximum body size is determined by the number of home ranges that can fit into a given land area. For a given land area, the body size of the top species decreased in the sequence: ectothermic herbivore > endothermic herbivore > ectothermic carnivore > endothermic carnivore. When we converted body mass to food requirements, the food consumption of a top herbivore was about 8 times that of a top carnivore, in accord with the factor expected from the trophic pyramid. Although top ectotherms were heavier than top endotherms at a given trophic level, lower metabolic rates per gram of body mass in ectotherms resulted in endotherms and ectotherms having the same food consumption. These patterns explain the size of the largest-ever extinct mammal, but the size of the largest dinosaurs exceeds that predicted from land areas and remains unexplained.

@article{doi101073pnas251548698,
    author = "Burness, Gary and Diamond, Jared M. and Flannery, Timothy F.",
    title = "Dinosaurs, dragons, and dwarfs: The evolution of maximal body size",
    year = "2001",
    journal = "Proceedings of the National Academy of Sciences",
    abstract = "Among local faunas, the maximum body size and taxonomic affiliation of the top terrestrial vertebrate vary greatly. Does this variation reflect how food requirements differ between trophic levels (herbivores vs. carnivores) and with taxonomic affiliation (mammals and birds vs. reptiles)? We gathered data on the body size and food requirements of the top terrestrial herbivores and carnivores, over the past 65,000 years, from oceanic islands and continents. The body mass of the top species was found to increase with increasing land area, with a slope similar to that of the relation between body mass and home range area, suggesting that maximum body size is determined by the number of home ranges that can fit into a given land area. For a given land area, the body size of the top species decreased in the sequence: ectothermic herbivore > endothermic herbivore > ectothermic carnivore > endothermic carnivore. When we converted body mass to food requirements, the food consumption of a top herbivore was about 8 times that of a top carnivore, in accord with the factor expected from the trophic pyramid. Although top ectotherms were heavier than top endotherms at a given trophic level, lower metabolic rates per gram of body mass in ectotherms resulted in endotherms and ectotherms having the same food consumption. These patterns explain the size of the largest-ever extinct mammal, but the size of the largest dinosaurs exceeds that predicted from land areas and remains unexplained.",
    url = "https://doi.org/10.1073/pnas.251548698",
    doi = "10.1073/pnas.251548698",
    openalex = "W1974031613",
    references = "ciofi1999the, doi101016016953479090113r, doi101046j14698137199800221x, doi101086320621, doi1012019781420064452, doi101353book59141, doi1023072403875, doi102475ajs29910805, doi105860choice325665, doi105962bhltitle60647, doi107208chicago97802265867480010001"
}

Wilson, Jeffrey A. (2002): Sauropod dinosaur phylogeny: critique and cladistic analysis. Zoological Journal of the Linnean Society 136 (2): 217-276, DOI: 10.1046/j.1096-3642.2002.00029.x, URL: https://academic.oup.com/zoolinnean/article-lookup/doi/10.1046/j.1096-3642.2002.00029.x

@article{doi101046j10963642200200029x,
    author = "Wilson, Jeffrey A.",
    title = "Sauropod dinosaur phylogeny: critique and cladistic analysis",
    year = "2002",
    journal = "Zoological Journal of the Linnean Society",
    abstract = "Wilson, Jeffrey A. (2002): Sauropod dinosaur phylogeny: critique and cladistic analysis. Zoological Journal of the Linnean Society 136 (2): 217-276, DOI: 10.1046/j.1096-3642.2002.00029.x, URL: https://academic.oup.com/zoolinnean/article-lookup/doi/10.1046/j.1096-3642.2002.00029.x",
    url = "https://doi.org/10.1046/j.1096-3642.2002.00029.x",
    doi = "10.1046/j.1096-3642.2002.00029.x",
    openalex = "W2018305891",
    references = "doi101002mmng19994860020102, doi101007978140206754912413, doi101017s0094837300026543, doi10108002724634199410011523, doi10108002724634199410011524, doi10108002724634199510011575, doi10108002724634199810011115, doi101098rstb19950125, doi101111j109636421998tb00569x, doi101111j155856461983tb05533x, doi101126science28053661048, doi101126science28454232137, doi101242dev1212333, doi1023071292217, doi1023072408332, doi1023072992353, doi102475ajss319111253, doi102475ajss321125417, doi102475ajss32313381, doi105281zenodo16171435, doi107312crac92306005, openalexw1025856234, openalexw3114518543, ostrom2019osteology"
}

Within developmental biology, the digits of the wing of birds are considered on embryological grounds to be digits 2, 3 and 4. In contrast, within paleontology, wing digits are named 1, 2, 3 as a result of phylogenetic analysis of fossil taxa indicating that birds descended from theropod dinosaurs that had lost digits 4 and 5. It has been argued that the development of the wing does not support the conclusion that birds are theropods, and that birds must have descended from ancestors that had lost digits 1 and 5. Here we use highly conserved gene expression patterns in the developing limbs of mouse and chicken, including the chicken talpid(2)mutant and polydactylous Silkie breed (Silkie mutant), to aid the assessment of digital identity in the wing. Digit 1 in developing limbs does not express Hoxd12, but expresses Hoxd13. All other digits express both Hoxd12and Hoxd13. We found this signature expression pattern identifies the anteriormost digit of the wing as digit 1, in accordance with the hypothesis these digits are 1, 2 and 3, as in theropod dinosaurs. Our evidence contradicts the long-standing argument that the development of the wing does not support the hypothesis that birds are living dinosaurs.

@article{doi101002jezb21023,
    author = "Vargas, Alexander O. and Fallon, John F.",
    title = "Birds have dinosaur wings: The molecular evidence",
    year = "2004",
    journal = "Journal of Experimental Zoology Part B Molecular and Developmental Evolution",
    abstract = "Within developmental biology, the digits of the wing of birds are considered on embryological grounds to be digits 2, 3 and 4. In contrast, within paleontology, wing digits are named 1, 2, 3 as a result of phylogenetic analysis of fossil taxa indicating that birds descended from theropod dinosaurs that had lost digits 4 and 5. It has been argued that the development of the wing does not support the conclusion that birds are theropods, and that birds must have descended from ancestors that had lost digits 1 and 5. Here we use highly conserved gene expression patterns in the developing limbs of mouse and chicken, including the chicken talpid(2)mutant and polydactylous Silkie breed (Silkie mutant), to aid the assessment of digital identity in the wing. Digit 1 in developing limbs does not express Hoxd12, but expresses Hoxd13. All other digits express both Hoxd12and Hoxd13. We found this signature expression pattern identifies the anteriormost digit of the wing as digit 1, in accordance with the hypothesis these digits are 1, 2 and 3, as in theropod dinosaurs. Our evidence contradicts the long-standing argument that the development of the wing does not support the hypothesis that birds are living dinosaurs.",
    url = "https://doi.org/10.1002/jez.b.21023",
    doi = "10.1002/jez.b.21023",
    openalex = "W2107569688"
}

The crystal structure of a subtilisin-like serine proteinase from the psychrotrophic marine bacterium, Vibrio sp. PA-44, was solved by means of molecular replacement and refined at 1.84 A. This is the first structure of a cold-adapted subtilase to be determined and its elucidation facilitates examination of the molecular principles underlying temperature adaptation in enzymes. The cold-adapted Vibrio proteinase was compared with known three-dimensional structures of homologous enzymes of meso- and thermophilic origin, proteinase K and thermitase, to which it has high structural resemblance. The main structural features emerging as plausible determinants of temperature adaptation in the enzymes compared involve the character of their exposed and buried surfaces, which may be related to temperature-dependent variation in the physical properties of water. Thus, the hydrophobic effect is found to play a significant role in the structural stability of the meso- and thermophile enzymes, whereas the cold-adapted enzyme has more of its apolar surface exposed. In addition, the cold-adapted Vibrio proteinase is distinguished from the more stable enzymes by its strong anionic character arising from the high occurrence of uncompensated negatively charged residues at its surface. Interestingly, both the cold-adapted and thermophile proteinases differ from the mesophile enzyme in having more extensive hydrogen- and ion pair interactions in their structures; this supports suggestions of a dual role of electrostatic interactions in the adaptation of enzymes to both high and low temperatures. The Vibrio proteinase has three calcium ions associated with its structure, one of which is in a calcium-binding site not described in other subtilases.

@article{doi101111j17424658200504523x,
    author = "Arnórsdóttir, Jóhanna and Kristjánsson, Magnús M. and Ficner, Ralf",
    title = "Crystal structure of a subtilisin‐like serine proteinase from a psychrotrophic Vibrio species reveals structural aspects of cold adaptation",
    year = "2005",
    journal = "FEBS Journal",
    abstract = "The crystal structure of a subtilisin-like serine proteinase from the psychrotrophic marine bacterium, Vibrio sp. PA-44, was solved by means of molecular replacement and refined at 1.84 A. This is the first structure of a cold-adapted subtilase to be determined and its elucidation facilitates examination of the molecular principles underlying temperature adaptation in enzymes. The cold-adapted Vibrio proteinase was compared with known three-dimensional structures of homologous enzymes of meso- and thermophilic origin, proteinase K and thermitase, to which it has high structural resemblance. The main structural features emerging as plausible determinants of temperature adaptation in the enzymes compared involve the character of their exposed and buried surfaces, which may be related to temperature-dependent variation in the physical properties of water. Thus, the hydrophobic effect is found to play a significant role in the structural stability of the meso- and thermophile enzymes, whereas the cold-adapted enzyme has more of its apolar surface exposed. In addition, the cold-adapted Vibrio proteinase is distinguished from the more stable enzymes by its strong anionic character arising from the high occurrence of uncompensated negatively charged residues at its surface. Interestingly, both the cold-adapted and thermophile proteinases differ from the mesophile enzyme in having more extensive hydrogen- and ion pair interactions in their structures; this supports suggestions of a dual role of electrostatic interactions in the adaptation of enzymes to both high and low temperatures. The Vibrio proteinase has three calcium ions associated with its structure, one of which is in a calcium-binding site not described in other subtilases.",
    url = "https://doi.org/10.1111/j.1742-4658.2005.04523.x",
    doi = "10.1111/j.1742-4658.2005.04523.x",
    openalex = "W1865157307"
}

In the early 1990s some isolated finds of strange bird-like dinosaurs from Argentina and Mongolia threw a spanner in the works of determining bird origins. The discovery of partial skeletons of Alvarezsaurus from Argentina and Mononykus from Mongolia revealed that the boundary between bipedal running dinosaurs and flightless birds was totally blurred. Then the discovery of more complete remains of a similar beast, Shuvuuia from Mongolia, revealed the true nature of these strange beasts. They had long legs, curved, delicate necks, small, gracile heads with tiny teeth, and short, powerful arms each with one very large claw and two remnant smaller claws.

@incollection{crossref2008bird,
    title = "Bird Dinosaurs And Dinosaur Birds",
    year = "2008",
    booktitle = "Feathered Dinosaurs",
    abstract = "In the early 1990s some isolated finds of strange bird-like dinosaurs from Argentina and Mongolia threw a spanner in the works of determining bird origins. The discovery of partial skeletons of Alvarezsaurus from Argentina and Mononykus from Mongolia revealed that the boundary between bipedal running dinosaurs and flightless birds was totally blurred. Then the discovery of more complete remains of a similar beast, Shuvuuia from Mongolia, revealed the true nature of these strange beasts. They had long legs, curved, delicate necks, small, gracile heads with tiny teeth, and short, powerful arms each with one very large claw and two remnant smaller claws.",
    url = "https://doi.org/10.1093/oso/9780195372663.003.0009",
    doi = "10.1093/oso/9780195372663.003.0009",
    pages = "25-28"
}

Abstract Among eubacteria and archeabacteria, amino acid composition is correlated with habitat temperatures. In particular, species living at high temperatures have proteins enriched in the amino acids E-R-K and depleted in D-N-Q-T-S-H-A. Here, we show that this bias is a proteome-wide effect in prokaryotes, and that the same trend is observed in fully sequenced mammals and chicken compared to cold-blooded vertebrates (Reptilia, Amphibia and fish). Thus, warm-blooded vertebrates likely experienced genome-wide weak positive selection on amino acid composition to increase protein thermostability.

@article{doi101038npre200929741,
    author = "Wang, Guang‐Zhong and Lercher, Martin J.",
    title = "Biased amino acid composition in warm-blooded animals",
    year = "2009",
    journal = "Nature Precedings",
    abstract = "Abstract Among eubacteria and archeabacteria, amino acid composition is correlated with habitat temperatures. In particular, species living at high temperatures have proteins enriched in the amino acids E-R-K and depleted in D-N-Q-T-S-H-A. Here, we show that this bias is a proteome-wide effect in prokaryotes, and that the same trend is observed in fully sequenced mammals and chicken compared to cold-blooded vertebrates (Reptilia, Amphibia and fish). Thus, warm-blooded vertebrates likely experienced genome-wide weak positive selection on amino acid composition to increase protein thermostability.",
    url = "https://doi.org/10.1038/npre.2009.2974.1",
    doi = "10.1038/npre.2009.2974.1",
    openalex = "W55137705",
    references = "doi101016jbbrc200505039"
}

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

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

Endothermy has evolved at least twice, in the precursors to modern mammals and birds. The most widely accepted explanation for the evolution of endothermy has been selection for enhanced aerobic capacity. We review this hypothesis in the light of advances in our understanding of ATP generation by mitochondria and muscle performance. Together with the development of isotope-based techniques for the measurement of metabolic rate in free-ranging vertebrates these have confirmed the importance of aerobic scope in the evolution of endothermy: absolute aerobic scope, ATP generation by mitochondria and muscle power output are all strongly temperature-dependent, indicating that there would have been significant improvement in whole-organism locomotor ability with a warmer body. New data on mitochondrial ATP generation and proton leak suggest that the thermal physiology of mitochondria may differ between organisms of contrasting ecology and thermal flexibility. Together with recent biophysical modelling, this strengthens the long-held view that endothermy originated in smaller, active eurythermal ectotherms living in a cool but variable thermal environment. We propose that rather than being a secondary consequence of the evolution of an enhanced aerobic scope, a warmer body was the means by which that enhanced aerobic scope was achieved. This modified hypothesis requires that the rise in metabolic rate and the insulation necessary to retain metabolic heat arose early in the lineages leading to birds and mammals. Large dinosaurs were warm, but were not endotherms, and the metabolic status of pterosaurs remains unresolved.

@article{doi101111j1469185x201000122x,
    author = "Clarke, Andrew and Pörtner, Hans‐Otto",
    title = "Temperature, metabolic power and the evolution of endothermy",
    year = "2010",
    journal = "Biological reviews/Biological reviews of the Cambridge Philosophical Society",
    abstract = "Endothermy has evolved at least twice, in the precursors to modern mammals and birds. The most widely accepted explanation for the evolution of endothermy has been selection for enhanced aerobic capacity. We review this hypothesis in the light of advances in our understanding of ATP generation by mitochondria and muscle performance. Together with the development of isotope-based techniques for the measurement of metabolic rate in free-ranging vertebrates these have confirmed the importance of aerobic scope in the evolution of endothermy: absolute aerobic scope, ATP generation by mitochondria and muscle power output are all strongly temperature-dependent, indicating that there would have been significant improvement in whole-organism locomotor ability with a warmer body. New data on mitochondrial ATP generation and proton leak suggest that the thermal physiology of mitochondria may differ between organisms of contrasting ecology and thermal flexibility. Together with recent biophysical modelling, this strengthens the long-held view that endothermy originated in smaller, active eurythermal ectotherms living in a cool but variable thermal environment. We propose that rather than being a secondary consequence of the evolution of an enhanced aerobic scope, a warmer body was the means by which that enhanced aerobic scope was achieved. This modified hypothesis requires that the rise in metabolic rate and the insulation necessary to retain metabolic heat arose early in the lineages leading to birds and mammals. Large dinosaurs were warm, but were not endotherms, and the metabolic status of pterosaurs remains unresolved.",
    url = "https://doi.org/10.1111/j.1469-185x.2010.00122.x",
    doi = "10.1111/j.1469-185x.2010.00122.x",
    openalex = "W2110669729",
    references = "amiot2006oxygen, doi101016s1095643302000454, doi101017s0094837300007557, doi101017s0094837300021321, doi10103835007527, doi101038nature07447, doi101038nature07856, doi101086283249, doi101086284325, doi101086425185, doi101093oso97801985464120010001, doi101126science1061967, doi101126science24248841403, doi101146annurevph57030195000441, doi101152physrev1997773731, doi101371journalpone0003303, doi1016660094837320030290105dbttoo20co2, doi1016660094837320030290243vpasat20co2, doi101890039000, doi1023071223169, doi105860choice295104, openalexw2983381470"
}

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

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

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

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

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

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

Inertial homeothermy, the maintenance of a relatively constant body temperature that occurs simply because of large size, is often applied to large dinosaurs. Moreover, biophysical modelling and actual measurements show that large crocodiles can behaviourally achieve body temperatures above 30°C. Therefore it is possible that some dinosaurs could achieve high and stable body temperatures without the high energy cost of typical endotherms. However it is not known whether an ectothermic dinosaur could produce the equivalent amount of muscular power as an endothermic one. To address this question, this study analyses maximal power output from measured aerobic and anaerobic metabolism in burst exercising estuarine crocodiles, Crocodylusporosus, weighing up to 200 kg. These results are compared with similar data from endothermic mammals. A 1 kg crocodile at 30°C produces about 16 watts from aerobic and anaerobic energy sources during the first 10% of exhaustive activity, which is 57% of that expected for a similarly sized mammal. A 200 kg crocodile produces about 400 watts, or only 14% of that for a mammal. Phosphocreatine is a minor energy source, used only in the first seconds of exercise and of similar concentrations in reptiles and mammals. Ectothermic crocodiles lack not only the absolute power for exercise, but also the endurance, that are evident in endothermic mammals. Despite the ability to achieve high and fairly constant body temperatures, therefore, large, ectothermic, crocodile-like dinosaurs would have been competitively inferior to endothermic, mammal-like dinosaurs with high aerobic power. Endothermy in dinosaurs is likely to explain their dominance over mammals in terrestrial ecosystems throughout the Mesozoic.

@article{doi101371journalpone0069361,
    author = "Seymour, Roger S.",
    title = "Maximal Aerobic and Anaerobic Power Generation in Large Crocodiles versus Mammals: Implications for Dinosaur Gigantothermy",
    year = "2013",
    journal = "PLoS ONE",
    abstract = "Inertial homeothermy, the maintenance of a relatively constant body temperature that occurs simply because of large size, is often applied to large dinosaurs. Moreover, biophysical modelling and actual measurements show that large crocodiles can behaviourally achieve body temperatures above 30°C. Therefore it is possible that some dinosaurs could achieve high and stable body temperatures without the high energy cost of typical endotherms. However it is not known whether an ectothermic dinosaur could produce the equivalent amount of muscular power as an endothermic one. To address this question, this study analyses maximal power output from measured aerobic and anaerobic metabolism in burst exercising estuarine crocodiles, Crocodylusporosus, weighing up to 200 kg. These results are compared with similar data from endothermic mammals. A 1 kg crocodile at 30°C produces about 16 watts from aerobic and anaerobic energy sources during the first 10\% of exhaustive activity, which is 57\% of that expected for a similarly sized mammal. A 200 kg crocodile produces about 400 watts, or only 14\% of that for a mammal. Phosphocreatine is a minor energy source, used only in the first seconds of exercise and of similar concentrations in reptiles and mammals. Ectothermic crocodiles lack not only the absolute power for exercise, but also the endurance, that are evident in endothermic mammals. Despite the ability to achieve high and fairly constant body temperatures, therefore, large, ectothermic, crocodile-like dinosaurs would have been competitively inferior to endothermic, mammal-like dinosaurs with high aerobic power. Endothermy in dinosaurs is likely to explain their dominance over mammals in terrestrial ecosystems throughout the Mesozoic.",
    url = "https://doi.org/10.1371/journal.pone.0069361",
    doi = "10.1371/journal.pone.0069361",
    openalex = "W2009770728",
    references = "doi101016jresp200401006, doi101016s0034568799000833, doi101042bst0311095, doi101073pnas89167521, doi101098rsbl20050378, doi101111j146979981983tb02087x, doi101126science493968, doi101146annurevphysiol621207, doi101152physrev1997773731, openalexw656806957"
}

Sauropod dinosaurs are a group of herbivorous dinosaurs which exceeded all other terrestrial vertebrates in mean and maximal body size. Sauropod dinosaurs were also the most successful and long-lived herbivorous tetrapod clade, but no abiological factors such as global environmental parameters conducive to their gigantism can be identified. These facts justify major efforts by evolutionary biologists and paleontologists to understand sauropods as living animals and to explain their evolutionary success and uniquely gigantic body size. Contributions to this research program have come from many fields and can be synthesized into a biological evolutionary cascade model of sauropod dinosaur gigantism (sauropod gigantism ECM). This review focuses on the sauropod gigantism ECM, providing an updated version based on the contributions to the PLoS ONE sauropod gigantism collection and on other very recent published evidence. The model consist of five separate evolutionary cascades ("Reproduction", "Feeding", "Head and neck", "Avian-style lung", and "Metabolism"). Each cascade starts with observed or inferred basal traits that either may be plesiomorphic or derived at the level of Sauropoda. Each trait confers hypothetical selective advantages which permit the evolution of the next trait. Feedback loops in the ECM consist of selective advantages originating from traits higher in the cascades but affecting lower traits. All cascades end in the trait "Very high body mass". Each cascade is linked to at least one other cascade. Important plesiomorphic traits of sauropod dinosaurs that entered the model were ovipary as well as no mastication of food. Important evolutionary innovations (derived traits) were an avian-style respiratory system and an elevated basal metabolic rate. Comparison with other tetrapod lineages identifies factors limiting body size.

@article{doi101371journalpone0078573,
    author = "Sander, P. Martin",
    title = "An Evolutionary Cascade Model for Sauropod Dinosaur Gigantism - Overview, Update and Tests",
    year = "2013",
    journal = "PLoS ONE",
    abstract = {Sauropod dinosaurs are a group of herbivorous dinosaurs which exceeded all other terrestrial vertebrates in mean and maximal body size. Sauropod dinosaurs were also the most successful and long-lived herbivorous tetrapod clade, but no abiological factors such as global environmental parameters conducive to their gigantism can be identified. These facts justify major efforts by evolutionary biologists and paleontologists to understand sauropods as living animals and to explain their evolutionary success and uniquely gigantic body size. Contributions to this research program have come from many fields and can be synthesized into a biological evolutionary cascade model of sauropod dinosaur gigantism (sauropod gigantism ECM). This review focuses on the sauropod gigantism ECM, providing an updated version based on the contributions to the PLoS ONE sauropod gigantism collection and on other very recent published evidence. The model consist of five separate evolutionary cascades ("Reproduction", "Feeding", "Head and neck", "Avian-style lung", and "Metabolism"). Each cascade starts with observed or inferred basal traits that either may be plesiomorphic or derived at the level of Sauropoda. Each trait confers hypothetical selective advantages which permit the evolution of the next trait. Feedback loops in the ECM consist of selective advantages originating from traits higher in the cascades but affecting lower traits. All cascades end in the trait "Very high body mass". Each cascade is linked to at least one other cascade. Important plesiomorphic traits of sauropod dinosaurs that entered the model were ovipary as well as no mastication of food. Important evolutionary innovations (derived traits) were an avian-style respiratory system and an elevated basal metabolic rate. Comparison with other tetrapod lineages identifies factors limiting body size.},
    url = "https://doi.org/10.1371/journal.pone.0078573",
    doi = "10.1371/journal.pone.0078573",
    openalex = "W2144687291",
    references = "doi101016jpalaeo201206008, doi101017cbo9780511565441, doi10103846266, doi101046j10963642200200029x, doi101086410622, doi101098rsbl20120263, doi101111j15585646201000960x, doi101126science1118806, doi101126science1177265, doi101186174170071060, doi101371journalpone0016574, doi101371journalpone0030060, doi101371journalpone0051925, doi101371journalpone0054991, doi101371journalpone0069361, doi103184175815508x402482, doi107717peerj36, horner2011dinosaur, openalexw1534787790"
}

Thermogenesis is one of the most important homeostatic mechanisms that evolved during vertebrate evolution. Despite its importance for the survival of the organism, the mechanistic details behind various thermogenic processes remain incompletely understood. Although heat production from muscle has long been recognized as a thermogenic mechanism, whether muscle can produce heat independently of contraction remains controversial. Studies in birds and mammals suggest that skeletal muscle can be an important site of non-shivering thermogenesis (NST) and can be recruited during cold adaptation, although unequivocal evidence is lacking. Much research on thermogenesis during the last two decades has been focused on brown adipose tissue (BAT). These studies clearly implicate BAT as an important site of NST in mammals, in particular in newborns and rodents. However, BAT is either absent, as in birds and pigs, or is only a minor component, as in adult large mammals including humans, bringing into question the BAT-centric view of thermogenesis. This review focuses on the evolution and emergence of various thermogenic mechanisms in vertebrates from fish to man. A careful analysis of the existing data reveals that muscle was the earliest facultative thermogenic organ to emerge in vertebrates, long before the appearance of BAT in eutherian mammals. Additionally, these studies suggest that muscle-based thermogenesis is the dominant mechanism of heat production in many species including birds, marsupials, and certain mammals where BAT-mediated thermogenesis is absent or limited. We discuss the relevance of our recent findings showing that uncoupling of sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA) by sarcolipin (SLN), resulting in futile cycling and increased heat production, could be the basis for NST in skeletal muscle. The overall goal of this review is to highlight the role of skeletal muscle as a thermogenic organ and provide a balanced view of thermogenesis in vertebrates.

@article{doi101111brv12157,
    author = "Rowland, Leslie A. and Bal, Naresh C. and Periasamy, Muthu",
    title = "The role of skeletal‐muscle‐based thermogenic mechanisms in vertebrate endothermy",
    year = "2014",
    journal = "Biological reviews/Biological reviews of the Cambridge Philosophical Society",
    abstract = "Thermogenesis is one of the most important homeostatic mechanisms that evolved during vertebrate evolution. Despite its importance for the survival of the organism, the mechanistic details behind various thermogenic processes remain incompletely understood. Although heat production from muscle has long been recognized as a thermogenic mechanism, whether muscle can produce heat independently of contraction remains controversial. Studies in birds and mammals suggest that skeletal muscle can be an important site of non-shivering thermogenesis (NST) and can be recruited during cold adaptation, although unequivocal evidence is lacking. Much research on thermogenesis during the last two decades has been focused on brown adipose tissue (BAT). These studies clearly implicate BAT as an important site of NST in mammals, in particular in newborns and rodents. However, BAT is either absent, as in birds and pigs, or is only a minor component, as in adult large mammals including humans, bringing into question the BAT-centric view of thermogenesis. This review focuses on the evolution and emergence of various thermogenic mechanisms in vertebrates from fish to man. A careful analysis of the existing data reveals that muscle was the earliest facultative thermogenic organ to emerge in vertebrates, long before the appearance of BAT in eutherian mammals. Additionally, these studies suggest that muscle-based thermogenesis is the dominant mechanism of heat production in many species including birds, marsupials, and certain mammals where BAT-mediated thermogenesis is absent or limited. We discuss the relevance of our recent findings showing that uncoupling of sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA) by sarcolipin (SLN), resulting in futile cycling and increased heat production, could be the basis for NST in skeletal muscle. The overall goal of this review is to highlight the role of skeletal muscle as a thermogenic organ and provide a balanced view of thermogenesis in vertebrates.",
    url = "https://doi.org/10.1111/brv.12157",
    doi = "10.1111/brv.12157",
    openalex = "W2160105048",
    references = "doi101016jcell201205016, doi101016jcmet200812014, doi10103835007527, doi101038387090a0, doi101038nature07182, doi101038nature11264, doi101038nm3361, doi101086425185, doi101111j1469185x201000122x, doi101152physrev000152003, doi101152physrev000312010, doi101152physrev1997773731, doi101172jci114857, doi101242jeb029009, doi101371journalpone0069361, doi103382ps0490621, köhler2012seasonal, pontzer2009biomechanics"
}

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

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

Our understanding of the evolutionary transitions leading to the modern endothermic state of birds and mammals is incomplete, partly because tools available to study the thermophysiology of extinct vertebrates are limited. Here we show that clumped isotope analysis of eggshells can be used to determine body temperatures of females during periods of ovulation. Late Cretaceous titanosaurid eggshells yield temperatures similar to large modern endotherms. In contrast, oviraptorid eggshells yield temperatures lower than most modern endotherms but ∼ 6 °C higher than co-occurring abiogenic carbonates, implying that this taxon did not have thermoregulation comparable to modern birds, but was able to elevate its body temperature above environmental temperatures. Therefore, we observe no strong evidence for end-member ectothermy or endothermy in the species examined. Body temperatures for these two species indicate that variable thermoregulation likely existed among the non-avian dinosaurs and that not all dinosaurs had body temperatures in the range of that seen in modern birds.

@article{doi101038ncomms9296,
    author = "Eagle, Robert A. and Enriquez, Marcus and Grellet‐Tinner, Gerald and Pérez‐Huerta, Alberto and Hu, David L. and Tütken, Thomas and Montanari, Shaena and Loyd, S. J. and Ramírez, Pedro Dueñas and Tripati, Aradhna and Kohn, Matthew J. and Cerling, Thure E. and Chiappe, Luis M. and Eiler, John M.",
    title = "Isotopic ordering in eggshells reflects body temperatures and suggests differing thermophysiology in two Cretaceous dinosaurs",
    year = "2015",
    journal = "Nature Communications",
    abstract = "Our understanding of the evolutionary transitions leading to the modern endothermic state of birds and mammals is incomplete, partly because tools available to study the thermophysiology of extinct vertebrates are limited. Here we show that clumped isotope analysis of eggshells can be used to determine body temperatures of females during periods of ovulation. Late Cretaceous titanosaurid eggshells yield temperatures similar to large modern endotherms. In contrast, oviraptorid eggshells yield temperatures lower than most modern endotherms but ∼ 6 °C higher than co-occurring abiogenic carbonates, implying that this taxon did not have thermoregulation comparable to modern birds, but was able to elevate its body temperature above environmental temperatures. Therefore, we observe no strong evidence for end-member ectothermy or endothermy in the species examined. Body temperatures for these two species indicate that variable thermoregulation likely existed among the non-avian dinosaurs and that not all dinosaurs had body temperatures in the range of that seen in modern birds.",
    url = "https://doi.org/10.1038/ncomms9296",
    doi = "10.1038/ncomms9296",
    openalex = "W1942246699",
    references = "doi101002jms1614, doi1010160168962291900552, doi101016030096299190122s, doi101016jchemgeo200708005, doi101016jgca200405035, doi101016jgca200511014, doi101016jgca201109025, doi101016s0016703797001695, doi101073pnas1001824107, doi101126science2665186779"
}

Titanosauria is a globally distributed clade of sometimes extremely large Mesozoic herbivorous sauropod dinosaurs. On the basis of current evidence these giant dinosaurs seem to have reproduced in specific and localized nesting sites. However, no investigations have been performed to understand the possible ecological and geological biases that acted for the selection of these nesting sites worldwide. In this study, observations were performed on the best-known Cretaceous nesting sites around the world. Our observations strongly suggest their eggs were incubated with environmental sources of heat, in burial conditions. Taking into account the clutch composition and geometry, the nature and properties of the sediments, the eggshells' structures and conductance, it would appear that titanosaurs adopted nesting behaviors comparable to the modern Australasian megapodes, using burrow-nesting in diverse media and mound-building strategies.

@article{doi107717peerj1341,
    author = "Hechenleitner, E. Martín and Grellet‐Tinner, Gerald and Fiorelli, Lucas E.",
    title = "What do giant titanosaur dinosaurs and modern Australasian megapodes have in common?",
    year = "2015",
    journal = "PeerJ",
    abstract = "Titanosauria is a globally distributed clade of sometimes extremely large Mesozoic herbivorous sauropod dinosaurs. On the basis of current evidence these giant dinosaurs seem to have reproduced in specific and localized nesting sites. However, no investigations have been performed to understand the possible ecological and geological biases that acted for the selection of these nesting sites worldwide. In this study, observations were performed on the best-known Cretaceous nesting sites around the world. Our observations strongly suggest their eggs were incubated with environmental sources of heat, in burial conditions. Taking into account the clutch composition and geometry, the nature and properties of the sediments, the eggshells' structures and conductance, it would appear that titanosaurs adopted nesting behaviors comparable to the modern Australasian megapodes, using burrow-nesting in diverse media and mound-building strategies.",
    url = "https://doi.org/10.7717/peerj.1341",
    doi = "10.7717/peerj.1341",
    openalex = "W1811641504",
    references = "doi101038ncomms9296"
}

Recent palaeontological data and novel physiological hypotheses now allow a timescaled reconstruction of the evolution of endothermy in birds and mammals. A three-phase iterative model describing how endothermy evolved from Permian ectothermic ancestors is presented. In Phase One I propose that the elevation of endothermy - increased metabolism and body temperature (T b) - complemented large-body-size homeothermy during the Permian and Triassic in response to the fitness benefits of enhanced embryo development (parental care) and the activity demands of conquering dry land. I propose that Phase Two commenced in the Late Triassic and Jurassic and was marked by extreme body-size miniaturization, the evolution of enhanced body insulation (fur and feathers), increased brain size, thermoregulatory control, and increased ecomorphological diversity. I suggest that Phase Three occurred during the Cretaceous and Cenozoic and involved endothermic pulses associated with the evolution of muscle-powered flapping flight in birds, terrestrial cursoriality in mammals, and climate adaptation in response to Late Cenozoic cooling in both birds and mammals. Although the triphasic model argues for an iterative evolution of endothermy in pulses throughout the Mesozoic and Cenozoic, it is also argued that endothermy was potentially abandoned at any time that a bird or mammal did not rely upon its thermal benefits for parental care or breeding success. The abandonment would have taken the form of either hibernation or daily torpor as observed in extant endotherms. Thus torpor and hibernation are argued to be as ancient as the origins of endothermy itself, a plesiomorphic characteristic observed today in many small birds and mammals.

@article{doi101111brv12280,
    author = "Lovegrove, Barry G.",
    title = "A phenology of the evolution of endothermy in birds and mammals",
    year = "2016",
    journal = "Biological reviews/Biological reviews of the Cambridge Philosophical Society",
    abstract = "Recent palaeontological data and novel physiological hypotheses now allow a timescaled reconstruction of the evolution of endothermy in birds and mammals. A three-phase iterative model describing how endothermy evolved from Permian ectothermic ancestors is presented. In Phase One I propose that the elevation of endothermy - increased metabolism and body temperature (T b) - complemented large-body-size homeothermy during the Permian and Triassic in response to the fitness benefits of enhanced embryo development (parental care) and the activity demands of conquering dry land. I propose that Phase Two commenced in the Late Triassic and Jurassic and was marked by extreme body-size miniaturization, the evolution of enhanced body insulation (fur and feathers), increased brain size, thermoregulatory control, and increased ecomorphological diversity. I suggest that Phase Three occurred during the Cretaceous and Cenozoic and involved endothermic pulses associated with the evolution of muscle-powered flapping flight in birds, terrestrial cursoriality in mammals, and climate adaptation in response to Late Cenozoic cooling in both birds and mammals. Although the triphasic model argues for an iterative evolution of endothermy in pulses throughout the Mesozoic and Cenozoic, it is also argued that endothermy was potentially abandoned at any time that a bird or mammal did not rely upon its thermal benefits for parental care or breeding success. The abandonment would have taken the form of either hibernation or daily torpor as observed in extant endotherms. Thus torpor and hibernation are argued to be as ancient as the origins of endothermy itself, a plesiomorphic characteristic observed today in many small birds and mammals.",
    url = "https://doi.org/10.1111/brv.12280",
    doi = "10.1111/brv.12280",
    openalex = "W2346237294",
    references = "doi101002ara20206, doi101016jcub201408034, doi101016jcub201508003, doi101038nature11146, doi101038nature12424, doi101038nature12973, doi101038nature13467, doi101038nature13718, doi101073pnas1203238109, doi101073pnas1519387112, doi101086422766, doi101086425185, doi101098rspb20110238, doi101098rspb20130508, doi101111brv12157, doi101111j1469185x201100190x, doi101126science1180219, doi101126science1200043, doi101126science1206196, doi101126science1213780, doi101126science1228753, doi101126science1253143, doi101126science1253293, doi101371journalpone0068714, doi1016660094837320030290605etatoo20co2, doi1016710272463420050250865hitrif20co2"
}

Extant crocodilians are a highly apomorphic archosaur clade that is ectothermic, yet often achieve large body sizes that can be subject to higher heat loads. Therefore, the anatomical and physiological roles that blood vessels play in crocodilian thermoregulation need further investigation to better understand how crocodilians establish and maintain cephalic temperatures and regulate neurosensory tissue temperatures during basking and normal activities. The cephalic vascular anatomy of extant crocodilians, particularly American alligator (Alligator mississippiensis) was investigated using a differential-contrast, dual-vascular injection technique and high resolution X-ray micro-computed tomography (μCT). Blood vessels were digitally isolated to create representations of vascular pathways. The specimens were then dissected to confirm CT results. Sites of thermal exchange, consisting of the oral, nasal, and orbital regions, were given special attention due to their role in evaporative cooling and cephalic thermoregulation in other diapsids. Blood vessels to and from sites of thermal exchange were studied to detect conserved vascular patterns and to assess their ability to deliver cooled blood to neurosensory tissues. Within the orbital region, both the arteries and veins demonstrated consistent branching patterns, with the supraorbital, infraorbital, and ophthalmotemporal vessels supplying and draining the orbit. The venous drainage of the orbital region showed connections to the dural sinuses via the orbital veins and cavernous sinus. The palatal region demonstrated a vast plexus that comprised both arteries and veins. The most direct route of venous drainage of the palatal plexus was through the palatomaxillary veins, essentially bypassing neurosensory tissues. Anastomotic connections with the nasal region, however, may provide an alternative route for palatal venous blood to reach neurosensory tissues. The nasal region in crocodilians is probably the most prominent site of thermal exchange, as it offers a substantial surface area and is completely surrounded by blood vessels. The venous drainage routes from the nasal region offer routes directly to the dural venous sinuses and the orbit, offering evidence of the potential to directly affect neurosensory tissue temperatures. The evolutionary history of crocodilians is complex, with large-bodied, terrestrial, and possibly endothermic taxa that may have had to deal with thermal loads that likely provided the anatomical building-blocks for such an extensive vascularization of sites of thermal exchange. A clear understanding of the physiological abilities and the role of blood vessels in the thermoregulation of crocodilians neurosensory tissues is not available but vascular anatomical patterns of crocodilian sites of thermal exchange indicate possible physiological abilities that may be more sophisticated than in other extant diapsids.

@article{doi101111joa12539,
    author = "Porter, William Ruger and Sedlmayr, Jayc C. and Witmer, Lawrence M.",
    title = "Vascular patterns in the heads of crocodilians: blood vessels and sites of thermal exchange",
    year = "2016",
    journal = "Journal of Anatomy",
    abstract = "Extant crocodilians are a highly apomorphic archosaur clade that is ectothermic, yet often achieve large body sizes that can be subject to higher heat loads. Therefore, the anatomical and physiological roles that blood vessels play in crocodilian thermoregulation need further investigation to better understand how crocodilians establish and maintain cephalic temperatures and regulate neurosensory tissue temperatures during basking and normal activities. The cephalic vascular anatomy of extant crocodilians, particularly American alligator (Alligator mississippiensis) was investigated using a differential-contrast, dual-vascular injection technique and high resolution X-ray micro-computed tomography (μCT). Blood vessels were digitally isolated to create representations of vascular pathways. The specimens were then dissected to confirm CT results. Sites of thermal exchange, consisting of the oral, nasal, and orbital regions, were given special attention due to their role in evaporative cooling and cephalic thermoregulation in other diapsids. Blood vessels to and from sites of thermal exchange were studied to detect conserved vascular patterns and to assess their ability to deliver cooled blood to neurosensory tissues. Within the orbital region, both the arteries and veins demonstrated consistent branching patterns, with the supraorbital, infraorbital, and ophthalmotemporal vessels supplying and draining the orbit. The venous drainage of the orbital region showed connections to the dural sinuses via the orbital veins and cavernous sinus. The palatal region demonstrated a vast plexus that comprised both arteries and veins. The most direct route of venous drainage of the palatal plexus was through the palatomaxillary veins, essentially bypassing neurosensory tissues. Anastomotic connections with the nasal region, however, may provide an alternative route for palatal venous blood to reach neurosensory tissues. The nasal region in crocodilians is probably the most prominent site of thermal exchange, as it offers a substantial surface area and is completely surrounded by blood vessels. The venous drainage routes from the nasal region offer routes directly to the dural venous sinuses and the orbit, offering evidence of the potential to directly affect neurosensory tissue temperatures. The evolutionary history of crocodilians is complex, with large-bodied, terrestrial, and possibly endothermic taxa that may have had to deal with thermal loads that likely provided the anatomical building-blocks for such an extensive vascularization of sites of thermal exchange. A clear understanding of the physiological abilities and the role of blood vessels in the thermoregulation of crocodilians neurosensory tissues is not available but vascular anatomical patterns of crocodilian sites of thermal exchange indicate possible physiological abilities that may be more sophisticated than in other extant diapsids.",
    url = "https://doi.org/10.1111/joa.12539",
    doi = "10.1111/joa.12539",
    openalex = "W2526585154",
    references = "doi101002jmor1052250304, doi101016s109649590200012x, doi101038eye199132, doi101038nature02802, doi10108002724634199710011027, doi101086422766, doi101086physzool37330152398, doi101098rstb19850092, doi101371journalpone0062806, doi101371journalpone0069361, doi105860choice326223, openalexw197683541"
}

Cardiovascular function in dinosaurs can be inferred from fossil evidence with knowledge of how metabolic rate, blood flow rate, blood pressure, and heart size are related to body size in living animals. Skeletal stature and nutrient foramen size in fossil femora provide direct evidence of a high arterial blood pressure, a large four-chambered heart, a high aerobic metabolic rate, and intense locomotion. But was the heart of a huge, long-necked sauropod dinosaur able to pump blood up 9 m to its head?

@article{doi101152physiol000162016,
    author = "Seymour, Roger S.",
    title = "Cardiovascular Physiology of Dinosaurs",
    year = "2016",
    journal = "Physiology",
    abstract = "Cardiovascular function in dinosaurs can be inferred from fossil evidence with knowledge of how metabolic rate, blood flow rate, blood pressure, and heart size are related to body size in living animals. Skeletal stature and nutrient foramen size in fossil femora provide direct evidence of a high arterial blood pressure, a large four-chambered heart, a high aerobic metabolic rate, and intense locomotion. But was the heart of a huge, long-necked sauropod dinosaur able to pump blood up 9 m to its head?",
    url = "https://doi.org/10.1152/physiol.00016.2016",
    doi = "10.1152/physiol.00016.2016",
    openalex = "W2529499608",
    references = "doi1010160002934380904714, doi101016000368709290318p, doi101038262207a0, doi101038417166a, doi101126science2765309122, doi101146annurevbioeng8061505095721, doi101152physiol000222014, doi101152physiol000612014, doi101242jeb01501, doi101371journalpone0069361, doi101371journalpone0078573, doi107717peerj36, openalexw1558456135, openalexw1581028088, openalexw623886000, seymour1976dinosaurs"
}

mice adapted to mild cold up-regulated muscle-based thermogenesis, indicated by increases in muscle succinate dehydrogenase activity, SLN expression, mitochondrial content, and neovascularization, compared with WT mice. These results further confirm that SLN-based thermogenesis is a key player in muscle non-shivering thermogenesis (NST) and can compensate for loss of BAT activity. We also present evidence that the increased reliance on BAT-based NST depends on increased autonomic input, as indicated by abundant levels of tyrosine hydroxylase and neuropeptide Y. Our findings demonstrate that both BAT and muscle-based NST are equally recruited during mild and severe cold adaptation and that loss of heat production from one thermogenic pathway leads to increased recruitment of the other, indicating a functional interplay between these two thermogenic processes.

@article{doi101074jbcm117790451,
    author = "Bal, Naresh C. and Singh, Sushant and Reis, Felipe C.G. and Maurya, Santosh K. and Pani, Sunil and Rowland, Leslie A. and Periasamy, Muthu",
    title = "Both brown adipose tissue and skeletal muscle thermogenesis processes are activated during mild to severe cold adaptation in mice",
    year = "2017",
    journal = "Journal of Biological Chemistry",
    abstract = "mice adapted to mild cold up-regulated muscle-based thermogenesis, indicated by increases in muscle succinate dehydrogenase activity, SLN expression, mitochondrial content, and neovascularization, compared with WT mice. These results further confirm that SLN-based thermogenesis is a key player in muscle non-shivering thermogenesis (NST) and can compensate for loss of BAT activity. We also present evidence that the increased reliance on BAT-based NST depends on increased autonomic input, as indicated by abundant levels of tyrosine hydroxylase and neuropeptide Y. Our findings demonstrate that both BAT and muscle-based NST are equally recruited during mild and severe cold adaptation and that loss of heat production from one thermogenic pathway leads to increased recruitment of the other, indicating a functional interplay between these two thermogenic processes.",
    url = "https://doi.org/10.1074/jbc.m117.790451",
    doi = "10.1074/jbc.m117.790451",
    openalex = "W2742463962",
    references = "doi101111brv12157"
}

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

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

The development of sustained, long-term endothermy was one of the major transitions in the evolution of vertebrates. Thermogenesis in endotherms does not only occur via shivering or activity, but also via non-shivering thermogenesis (NST). Mammalian NST is mediated by the uncoupling protein 1 in the brown adipose tissue (BAT) and possibly involves an additional mechanism of NST in skeletal muscle. This alternative mechanism is based on Ca 2+ -slippage by a sarcoplasmatic reticulum Ca 2+ -ATPase (SERCA) and is controlled by the protein sarcolipin. The existence of muscle based NST has been discussed for a long time and is likely present in all mammals. However, its importance for thermoregulation was demonstrated only recently in mice. Interestingly, birds, which have evolved from a different reptilian lineage than mammals and lack UCP1-mediated NST, also exhibit muscle based NST under the involvement of SERCA, though likely without the participation of sarcolipin. In this review we summarize the current knowledge on muscle NST and discuss the efficiency of muscle NST and BAT in the context of the hypothesis that muscle NST could have been the earliest mechanism of heat generation during cold exposure in vertebrates that ultimately enabled the evolution of endothermy. We suggest that the evolution of BAT in addition to muscle NST was related to heterothermy being predominant among early endothermic mammals. Furthermore, we argue that, in contrast to small mammals, muscle NST is sufficient to maintain high body temperature in birds, which have enhanced capacities to fuel muscle NST by high rates of fatty acid import.

@article{doi103389fphys201700889,
    author = "Nowack, Julia and Giroud, Sylvain and Arnold, Walter and Ruf, Thomas",
    title = "Muscle Non-shivering Thermogenesis and Its Role in the Evolution of Endothermy",
    year = "2017",
    journal = "Frontiers in Physiology",
    abstract = "The development of sustained, long-term endothermy was one of the major transitions in the evolution of vertebrates. Thermogenesis in endotherms does not only occur via shivering or activity, but also via non-shivering thermogenesis (NST). Mammalian NST is mediated by the uncoupling protein 1 in the brown adipose tissue (BAT) and possibly involves an additional mechanism of NST in skeletal muscle. This alternative mechanism is based on Ca 2+ -slippage by a sarcoplasmatic reticulum Ca 2+ -ATPase (SERCA) and is controlled by the protein sarcolipin. The existence of muscle based NST has been discussed for a long time and is likely present in all mammals. However, its importance for thermoregulation was demonstrated only recently in mice. Interestingly, birds, which have evolved from a different reptilian lineage than mammals and lack UCP1-mediated NST, also exhibit muscle based NST under the involvement of SERCA, though likely without the participation of sarcolipin. In this review we summarize the current knowledge on muscle NST and discuss the efficiency of muscle NST and BAT in the context of the hypothesis that muscle NST could have been the earliest mechanism of heat generation during cold exposure in vertebrates that ultimately enabled the evolution of endothermy. We suggest that the evolution of BAT in addition to muscle NST was related to heterothermy being predominant among early endothermic mammals. Furthermore, we argue that, in contrast to small mammals, muscle NST is sufficient to maintain high body temperature in birds, which have enhanced capacities to fuel muscle NST by high rates of fatty acid import.",
    url = "https://doi.org/10.3389/fphys.2017.00889",
    doi = "10.3389/fphys.2017.00889",
    openalex = "W2767572094",
    references = "doi101093oso97801985660380010001, doi101111brv12157"
}

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

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

Birds and mammals are key elements of modern ecosystems, and many biologists explain their great success by their endothermy, or warm-bloodedness. New palaeontological discoveries point to the origins of endothermy in the Triassic, and that birds (archosaurs) and mammals (synapsids) likely acquired endothermy in parallel. Here, a further case is made, that the emergence of endothermy in a stepwise manner began in the Late Permian but accelerated in the Early Triassic. The trigger was the profound destruction wrought by the Permian-Triassic mass extinction (PTME). In the oceans, this was the beginning of the Mesozoic Marine Revolution (MMR), and a similar revolution occurred on land, termed here the Triassic Terrestrial Revolution (TTR). Among tetrapods, both synapsids and archosaurs survived into the Triassic, but numbers were heavily depleted. However, the survivors were marked by the acquisition of endothermy, as shown by bone histology, isotopic analyses, and the acquisition of insulating pelage. Both groups before the PTME had been sprawlers; after the event they adopted parasagittal (erect) gait. The new posture and the new physiology enabled both groups to compete in their ecosystems at a faster rate than before the PTME. The new world of the Triassic was characterised by a fast-paced arms race between synapsids and archosauromorphs in which the latter, as both dinosaurs and pterosaurs, initially prevailed.

@article{doi101016jgr202008003,
    author = "Benton, Michael J.",
    title = "The origin of endothermy in synapsids and archosaurs and arms races in the Triassic",
    year = "2020",
    journal = "Gondwana Research",
    abstract = "Birds and mammals are key elements of modern ecosystems, and many biologists explain their great success by their endothermy, or warm-bloodedness. New palaeontological discoveries point to the origins of endothermy in the Triassic, and that birds (archosaurs) and mammals (synapsids) likely acquired endothermy in parallel. Here, a further case is made, that the emergence of endothermy in a stepwise manner began in the Late Permian but accelerated in the Early Triassic. The trigger was the profound destruction wrought by the Permian-Triassic mass extinction (PTME). In the oceans, this was the beginning of the Mesozoic Marine Revolution (MMR), and a similar revolution occurred on land, termed here the Triassic Terrestrial Revolution (TTR). Among tetrapods, both synapsids and archosaurs survived into the Triassic, but numbers were heavily depleted. However, the survivors were marked by the acquisition of endothermy, as shown by bone histology, isotopic analyses, and the acquisition of insulating pelage. Both groups before the PTME had been sprawlers; after the event they adopted parasagittal (erect) gait. The new posture and the new physiology enabled both groups to compete in their ecosystems at a faster rate than before the PTME. The new world of the Triassic was characterised by a fast-paced arms race between synapsids and archosauromorphs in which the latter, as both dinosaurs and pterosaurs, initially prevailed.",
    url = "https://doi.org/10.1016/j.gr.2020.08.003",
    doi = "10.1016/j.gr.2020.08.003",
    openalex = "W3082265010",
    references = "doi1010079781461417439, doi1010160031018274900194, doi10103831635, doi10103834356, doi101038ngeo1475, doi101038s41467018039961, doi101038s41598020678541, doi101093sysbiosyw033, doi101098rspb20180361, doi101098rstb20190136, doi101111j2041210x201100169x, doi101126sciadvaaw4486, doi101126science1097023, doi101126science493968, doi101152physiol000162016, doi1012063521, doi105281zenodo16171435, doi107312kiel11918, owen1857monograph"
}

Endothermy, i.e. the endogenous production of metabolic heat, has evolved multiple times among vertebrates, and several strategies of heat production have been studied extensively by physiologists over the course of the twentieth century. The independent acquisition of endothermy by mammals and birds has been the subject of many hypotheses regarding their origin and associated evolutionary constraints. Many groups of vertebrates, however, are thought to possess other mechanisms of heat production, and alternative ways to regulate thermogenesis that are not always considered in the palaeontological literature. Here, we perform a review of the mechanisms involved in heat production, with a focus on cellular and molecular mechanisms, in a phylogenetic context encompassing the entire vertebrate diversity. We show that endothermy in mammals and birds is not as well defined as commonly assumed by evolutionary biologists and consists of a vast array of physiological strategies, many of which are currently unknown. We also describe strategies found in other vertebrates, which may not always be considered endothermy, but nonetheless correspond to a process of active thermogenesis. We conclude that endothermy is a highly plastic character in vertebrates and provides a guideline on terminology and occurrences of the different types of heat production in vertebrate evolution. This article is part of the theme issue 'Vertebrate palaeophysiology'.

@article{doi101098rstb20190136,
    author = "Legendre, Lucas J. and Davesne, Donald",
    title = "The evolution of mechanisms involved in vertebrate endothermy",
    year = "2020",
    journal = "Philosophical Transactions of the Royal Society B Biological Sciences",
    abstract = "Endothermy, i.e. the endogenous production of metabolic heat, has evolved multiple times among vertebrates, and several strategies of heat production have been studied extensively by physiologists over the course of the twentieth century. The independent acquisition of endothermy by mammals and birds has been the subject of many hypotheses regarding their origin and associated evolutionary constraints. Many groups of vertebrates, however, are thought to possess other mechanisms of heat production, and alternative ways to regulate thermogenesis that are not always considered in the palaeontological literature. Here, we perform a review of the mechanisms involved in heat production, with a focus on cellular and molecular mechanisms, in a phylogenetic context encompassing the entire vertebrate diversity. We show that endothermy in mammals and birds is not as well defined as commonly assumed by evolutionary biologists and consists of a vast array of physiological strategies, many of which are currently unknown. We also describe strategies found in other vertebrates, which may not always be considered endothermy, but nonetheless correspond to a process of active thermogenesis. We conclude that endothermy is a highly plastic character in vertebrates and provides a guideline on terminology and occurrences of the different types of heat production in vertebrate evolution. This article is part of the theme issue 'Vertebrate palaeophysiology'.",
    url = "https://doi.org/10.1098/rstb.2019.0136",
    doi = "10.1098/rstb.2019.0136",
    openalex = "W2999733722",
    references = "doi101016b9780444820334500015, doi101038nature11264, doi101038nature15697, doi101038nature19417, doi101038nm2897, doi101073pnas1616702114, doi101093sysbiosyw033, doi101098rspb20111778, doi101111brv12137, doi101111evo13680, doi101126science1187443, doi101126science493968, doi101152physiol000162016, doi101152physrev000152003, doi101186s1286201709583, doi101371journalpone0069361, doi101371journalpone0081917, doi101371journalpone0088834, doi101371journalpone0185185, doi107717peerj1358, köhler2012seasonal, pontzer2009biomechanics"
}

The evolution of endothermy represents a major transition in vertebrate history, yet how and why endothermy evolved in birds and mammals remains controversial. Here, we combine a heat transfer model with theropod body size data to reconstruct the evolution of metabolic rates along the bird stem lineage. Results suggest that a reduction in size constitutes the path of least resistance for endothermy to evolve, maximizing thermal niche expansion while obviating the costs of elevated energy requirements. In this scenario, metabolism would have increased with the miniaturization observed in the Early-Middle Jurassic (~180 to 170 million years ago), resulting in a gradient of metabolic levels in the theropod phylogeny. Whereas basal theropods would exhibit lower metabolic rates, more recent nonavian lineages were likely decent thermoregulators with elevated metabolism. These analyses provide a tentative temporal sequence of the key evolutionary transitions that resulted in the emergence of small, endothermic, feathered flying dinosaurs.

@article{doi101126sciadvaaw4486,
    author = "Rezende, Enrico L. and Bacigalupe, Leonardo D. and Nespolo, Roberto F. and Bozinovic, Francisco",
    title = "Shrinking dinosaurs and the evolution of endothermy in birds",
    year = "2020",
    journal = "Science Advances",
    abstract = "The evolution of endothermy represents a major transition in vertebrate history, yet how and why endothermy evolved in birds and mammals remains controversial. Here, we combine a heat transfer model with theropod body size data to reconstruct the evolution of metabolic rates along the bird stem lineage. Results suggest that a reduction in size constitutes the path of least resistance for endothermy to evolve, maximizing thermal niche expansion while obviating the costs of elevated energy requirements. In this scenario, metabolism would have increased with the miniaturization observed in the Early-Middle Jurassic (\textasciitilde 180 to 170 million years ago), resulting in a gradient of metabolic levels in the theropod phylogeny. Whereas basal theropods would exhibit lower metabolic rates, more recent nonavian lineages were likely decent thermoregulators with elevated metabolism. These analyses provide a tentative temporal sequence of the key evolutionary transitions that resulted in the emergence of small, endothermic, feathered flying dinosaurs.",
    url = "https://doi.org/10.1126/sciadv.aaw4486",
    doi = "10.1126/sciadv.aaw4486",
    openalex = "W2997429867",
    references = "doi101038272333a0, doi101038nature13272, doi101073pnas251548698, doi101098rsbl20050378, doi101111j1469185x201000122x, doi101111j1469185x201000137x, doi101126science1253293, doi101126science493968, doi101371journalpbio1001853, doi101371journalpone0069361, doi101371journalpone0088834, doi1022179revmacn14372, doi1023071538742, doi107717peerj2159"
}

The question why non-avian dinosaurs went extinct 66 million years ago (Ma) remains unresolved because of the coarseness of the fossil record. A sudden extinction caused by an asteroid is the most accepted hypothesis but it is debated whether dinosaurs were in decline or not before the impact. We analyse the speciation-extinction dynamics for six key dinosaur families, and find a decline across dinosaurs, where diversification shifted to a declining-diversity pattern ~76 Ma. We investigate the influence of ecological and physical factors, and find that the decline of dinosaurs was likely driven by global climate cooling and herbivorous diversity drop. The latter is likely due to hadrosaurs outcompeting other herbivores. We also estimate that extinction risk is related to species age during the decline, suggesting a lack of evolutionary novelty or adaptation to changing environments. These results support an environmentally driven decline of non-avian dinosaurs well before the asteroid impact.

@article{doi101038s41467021237540,
    author = "Condamine, Fabien L. and Guinot, Guillaume and Benton, Michael J. and Currie, Philip J.",
    title = "Dinosaur biodiversity declined well before the asteroid impact, influenced by ecological and environmental pressures",
    year = "2021",
    journal = "Nature Communications",
    abstract = "The question why non-avian dinosaurs went extinct 66 million years ago (Ma) remains unresolved because of the coarseness of the fossil record. A sudden extinction caused by an asteroid is the most accepted hypothesis but it is debated whether dinosaurs were in decline or not before the impact. We analyse the speciation-extinction dynamics for six key dinosaur families, and find a decline across dinosaurs, where diversification shifted to a declining-diversity pattern \textasciitilde 76 Ma. We investigate the influence of ecological and physical factors, and find that the decline of dinosaurs was likely driven by global climate cooling and herbivorous diversity drop. The latter is likely due to hadrosaurs outcompeting other herbivores. We also estimate that extinction risk is related to species age during the decline, suggesting a lack of evolutionary novelty or adaptation to changing environments. These results support an environmentally driven decline of non-avian dinosaurs well before the asteroid impact.",
    url = "https://doi.org/10.1038/s41467-021-23754-0",
    doi = "10.1038/s41467-021-23754-0",
    openalex = "W3160661672",
    references = "alvarez1980extraterrestrial, close2020the, doi101016jcub202006105, doi101016jgloplacha201804004, doi101016jpalaeo201602033, doi101016jtree202009001, doi101038307360a0, doi101038nature06588, doi101038nature24679, doi101038ncomms9296, doi101038s41467019089972, doi101038s41598019517095, doi101046j14610248200200354x, doi101073pnas1521478113, doi101073pnas1902693116, doi101073pnas2006087117, doi1010801477201920151059985, doi101093sysbiosyy032, doi101098rsos161086, doi101111nph13264, doi101126sciadvaaw4486, doi101126science1059412, doi101126science1116412, doi101126science1177265, doi101126science1211028, doi101126scienceabd9220, doi101139cjes20170031, doi10120639651, doi101371journalpone0028964, doi101371journalpone0032623, doi101371journalpone0067182, doi101371journalpone0108804, doi103389feart201800252, doi107717peerj1032, doi107717peerj5749, doi107717peerj7247, doi107717peerj8672, openalexw2145250129"
}

Endothermy is a typical convergent phenomenon which has evolved independently at least eight times in vertebrates, and is of significant advantage to organisms in extending their niches. However, how vertebrates other than mammals or birds, especially teleosts, achieve endothermy has not previously been fully understood. In this study, we sequenced the genomes of two billfishes (swordfish and sailfish), members of a representative lineage of endothermic teleosts. Convergent amino acid replacements were observed in proteins related to heat production and the visual system in two endothermic teleost lineages, billfishes and tunas. The billfish-specific genetic innovations were found to be associated with heat exchange, thermoregulation, and the specialized morphology, including elongated bill, enlarged dorsal fin in sailfish and loss of the pelvic fin in swordfish.

@article{doi101093molbevmsab035,
    author = "Wu, Baosheng and Feng, Chenguang and Zhu, Chenglong and Xu, Wenjie and Yuan, Yuan and Hu, Mingliang and Yuan, Ke and Li, Yongxin and Ren, Yandong and Zhou, Yang and Jiang, Haifeng and Qiu, Qiang and Wen, Wang and He, Shunping and Wang, Kun",
    title = "The Genomes of Two Billfishes Provide Insights into the Evolution of Endothermy in Teleosts",
    year = "2021",
    journal = "Molecular Biology and Evolution",
    abstract = "Endothermy is a typical convergent phenomenon which has evolved independently at least eight times in vertebrates, and is of significant advantage to organisms in extending their niches. However, how vertebrates other than mammals or birds, especially teleosts, achieve endothermy has not previously been fully understood. In this study, we sequenced the genomes of two billfishes (swordfish and sailfish), members of a representative lineage of endothermic teleosts. Convergent amino acid replacements were observed in proteins related to heat production and the visual system in two endothermic teleost lineages, billfishes and tunas. The billfish-specific genetic innovations were found to be associated with heat exchange, thermoregulation, and the specialized morphology, including elongated bill, enlarged dorsal fin in sailfish and loss of the pelvic fin in swordfish.",
    url = "https://doi.org/10.1093/molbev/msab035",
    doi = "10.1093/molbev/msab035",
    openalex = "W3126532908",
    references = "doi101126sciadvaaw4486"
}

-ATPase (SERCA) in skeletal muscle, similar to a process seen in some fishes. This similarity prompted our realisation that the capacity for whole-body endothermy could even have pre-dated the divergence of Amniota into Synapsida and Sauropsida, leading us to hypothesise the homology of whole-body endothermy in birds and mammals, in contrast to the current assumption of their independent (convergent) evolution. To explore the extent of similarity between muscle NST in mammals and birds we undertook a detailed review of these processes and their control in each group. We found considerable but not complete similarity between them: in extant mammals the 'slippage' is controlled by the protein sarcolipin (SLN), in birds the SLN is slightly different structurally and its role in NST is not yet proved. However, considering the multi-millions of years since the separation of synapsids and diapsids, we consider that the similarity between NST production in birds and mammals is consistent with their whole-body endothermy being homologous. If so, we should expect to find evidence for it much earlier and more widespread among extinct amniotes than is currently recognised. Accordingly, we conducted an extensive survey of the palaeontological literature using established proxies. Fossil bone histology reveals evidence of sustained rapid growth rates indicating tachymetabolism. Large body size and erect stature indicate high systemic arterial blood pressures and four-chambered hearts, characteristic of tachymetabolism. Large nutrient foramina in long bones are indicative of high bone perfusion for rapid somatic growth and for repair of microfractures caused by intense locomotion. Obligate bipedality appeared early and only in whole-body endotherms. Isotopic profiles of fossil material indicate endothermic levels of body temperature. These proxies led us to compelling evidence for the widespread occurrence of whole-body endothermy among numerous extinct synapsids and sauropsids, and very early in each clade's family tree. These results are consistent with and support our hypothesis that tachymetabolic endothermy is plesiomorphic in Amniota. A hypothetical structure for the heart of the earliest endothermic amniotes is proposed. We conclude that there is strong evidence for whole-body endothermy being ancient and widespread among amniotes and that the similarity of biochemical processes driving muscle NST in extant birds and mammals strengthens the case for its plesiomorphy.

@article{doi101111brv12822,
    author = "Grigg, Gordon C. and Nowack, Julia and Bicudo, J. Eduardo P. W. and Bal, Naresh C. and Woodward, Holly N. and Seymour, Roger S.",
    title = "Whole‐body endothermy: ancient, homologous and widespread among the ancestors of mammals, birds and crocodylians",
    year = "2021",
    journal = "Biological reviews/Biological reviews of the Cambridge Philosophical Society",
    abstract = "-ATPase (SERCA) in skeletal muscle, similar to a process seen in some fishes. This similarity prompted our realisation that the capacity for whole-body endothermy could even have pre-dated the divergence of Amniota into Synapsida and Sauropsida, leading us to hypothesise the homology of whole-body endothermy in birds and mammals, in contrast to the current assumption of their independent (convergent) evolution. To explore the extent of similarity between muscle NST in mammals and birds we undertook a detailed review of these processes and their control in each group. We found considerable but not complete similarity between them: in extant mammals the 'slippage' is controlled by the protein sarcolipin (SLN), in birds the SLN is slightly different structurally and its role in NST is not yet proved. However, considering the multi-millions of years since the separation of synapsids and diapsids, we consider that the similarity between NST production in birds and mammals is consistent with their whole-body endothermy being homologous. If so, we should expect to find evidence for it much earlier and more widespread among extinct amniotes than is currently recognised. Accordingly, we conducted an extensive survey of the palaeontological literature using established proxies. Fossil bone histology reveals evidence of sustained rapid growth rates indicating tachymetabolism. Large body size and erect stature indicate high systemic arterial blood pressures and four-chambered hearts, characteristic of tachymetabolism. Large nutrient foramina in long bones are indicative of high bone perfusion for rapid somatic growth and for repair of microfractures caused by intense locomotion. Obligate bipedality appeared early and only in whole-body endotherms. Isotopic profiles of fossil material indicate endothermic levels of body temperature. These proxies led us to compelling evidence for the widespread occurrence of whole-body endothermy among numerous extinct synapsids and sauropsids, and very early in each clade's family tree. These results are consistent with and support our hypothesis that tachymetabolic endothermy is plesiomorphic in Amniota. A hypothetical structure for the heart of the earliest endothermic amniotes is proposed. We conclude that there is strong evidence for whole-body endothermy being ancient and widespread among amniotes and that the similarity of biochemical processes driving muscle NST in extant birds and mammals strengthens the case for its plesiomorphy.",
    url = "https://doi.org/10.1111/brv.12822",
    doi = "10.1111/brv.12822",
    openalex = "W4200490813",
    references = "cubo2020were, doi101016jgr202008003, doi101016s0092867400814105, doi101017pab201519, doi101038262207a0, doi101038nature11264, doi101038ncomms9296, doi101038s4155901910473, doi101038srep06196, doi1010719781486300679, doi101073pnas1206625109, doi101086283547, doi101093biolinneanblw044, doi101093sysbiosyw033, doi101096fj020367com, doi101098rstb20190136, doi101098rstb20190142, doi101111brv12137, doi101111j10958312201001431x, doi101126sciadvaaw4486, doi101126science1187443, doi101126science493968, doi101126scienceaal4853, doi101152physiol000162016, doi101152physrev000152003, doi1012063521, doi101210er20020012, doi101371journalpone0011613, doi101371journalpone0033539, doi101371journalpone0069361, doi105860choice355657, doi107717peerj1778, doi107717peerj7764, köhler2012seasonal, pontzer2009biomechanics, seymour1976dinosaurs, zhao2019ontogenetic"
}

and NVC. In addition to our focus on effects of perfusion pressure (or blood pressure), we describe the impact of select stimuli on regulation of CBF (i.e., arterial blood gases, cerebral metabolism, neural mechanisms, and specific vascular cells), the interrelationships between these stimuli, and implications for regulation of CBF at the level of large arteries and the microcirculation. We review clinical implications of autoregulation in aging, hypertension, stroke, mild cognitive impairment, anesthesia, and dementias. Finally, we discuss autoregulation in the context of common daily physiological challenges, including changes in posture (e.g., orthostatic hypotension, syncope) and physical activity.

@article{doi101152physrev000222020,
    author = "Claassen, Jurgen A.H.R. and Thijssen, Dick H. J. and Panerai, Ronney B. and Faraci, Frank M.",
    title = "Regulation of cerebral blood flow in humans: physiology and clinical implications of autoregulation",
    year = "2021",
    journal = "Physiological Reviews",
    abstract = "and NVC. In addition to our focus on effects of perfusion pressure (or blood pressure), we describe the impact of select stimuli on regulation of CBF (i.e., arterial blood gases, cerebral metabolism, neural mechanisms, and specific vascular cells), the interrelationships between these stimuli, and implications for regulation of CBF at the level of large arteries and the microcirculation. We review clinical implications of autoregulation in aging, hypertension, stroke, mild cognitive impairment, anesthesia, and dementias. Finally, we discuss autoregulation in the context of common daily physiological challenges, including changes in posture (e.g., orthostatic hypotension, syncope) and physical activity.",
    url = "https://doi.org/10.1152/physrev.00022.2020",
    doi = "10.1152/physrev.00022.2020",
    openalex = "W3139496128",
    references = "doi101113jphysiol2004070409, doi101152physiol000162016"
}

The Early Jurassic Jenkyns Event (∼183 Ma) was characterized in terrestrial environments by global warming, perturbation of the carbon cycle, enhanced weathering and wildfires. Heating and acid rain on land caused a loss of forests and affected diversity and composition of land plant assemblages and the rest of the trophic web. We suggest that the Jenkyns Event, triggered by the activity of the Karoo-Ferrar Large Igneous Province, was pivotal in remodelling terrestrial ecosystems, including plants and dinosaurs. Macroplant assemblages and palynological data show reductions in diversity and richness of conifers, cycadophytes, ginkgophytes, bennetitaleans, and ferns, and continuation of seasonally dry and warm conditions. Major changes occurred to sauropodomorph dinosaurs, with extinction of diverse basal families formerly called ‘prosauropods’ as well as some basal sauropods, and diversification of the derived Eusauropoda in the Toarcian in South America, Africa, and Asia, and wider diversification of new families, including Mamenchisauridae, Cetiosauridae and Neosauropoda (Dicraeosauridae and Macronaria) in the Middle Jurassic, showing massive increase in size and diversification of feeding modes. Ornithischian dinosaurs show patchy records; some heterodontosaurids and scelidosaurids disappeared, and major new clades (Stegosauridae, Ankylosauridae, Nodosauridae) emerged soon after the Jenkyns Event, in the Bajocian and Bathonian worldwide. Among theropod dinosaurs, Coelophysidae and Dilophosauridae died out during the Jenkyns Event and a diversification of theropods (Megalosauroidea, Allosauroidea, Tyrannosauroidea) occurred after this event with substantial increases in size. We suggest then that the Jenkyns Event terrestrial crisis was marked especially by floral changes and origins of major new sauropodomorph and theropod clades, characterized by increasing body size. Comparison with the end Triassic Mass Extinction helps to understand the incidence of climatic changes driven by activity of large igneous provinces on land ecosystems and their great impacts on early dinosaur evolution.

@article{doi101016jearscirev2022104196,
    author = "Reolid, Matías and Ruebsam, Wolfgang and Benton, Michael J.",
    title = "Impact of the Jenkyns Event (early Toarcian) on dinosaurs: Comparison with the Triassic/Jurassic transition",
    year = "2022",
    journal = "Earth-Science Reviews",
    abstract = "The Early Jurassic Jenkyns Event (∼183 Ma) was characterized in terrestrial environments by global warming, perturbation of the carbon cycle, enhanced weathering and wildfires. Heating and acid rain on land caused a loss of forests and affected diversity and composition of land plant assemblages and the rest of the trophic web. We suggest that the Jenkyns Event, triggered by the activity of the Karoo-Ferrar Large Igneous Province, was pivotal in remodelling terrestrial ecosystems, including plants and dinosaurs. Macroplant assemblages and palynological data show reductions in diversity and richness of conifers, cycadophytes, ginkgophytes, bennetitaleans, and ferns, and continuation of seasonally dry and warm conditions. Major changes occurred to sauropodomorph dinosaurs, with extinction of diverse basal families formerly called ‘prosauropods’ as well as some basal sauropods, and diversification of the derived Eusauropoda in the Toarcian in South America, Africa, and Asia, and wider diversification of new families, including Mamenchisauridae, Cetiosauridae and Neosauropoda (Dicraeosauridae and Macronaria) in the Middle Jurassic, showing massive increase in size and diversification of feeding modes. Ornithischian dinosaurs show patchy records; some heterodontosaurids and scelidosaurids disappeared, and major new clades (Stegosauridae, Ankylosauridae, Nodosauridae) emerged soon after the Jenkyns Event, in the Bajocian and Bathonian worldwide. Among theropod dinosaurs, Coelophysidae and Dilophosauridae died out during the Jenkyns Event and a diversification of theropods (Megalosauroidea, Allosauroidea, Tyrannosauroidea) occurred after this event with substantial increases in size. We suggest then that the Jenkyns Event terrestrial crisis was marked especially by floral changes and origins of major new sauropodomorph and theropod clades, characterized by increasing body size. Comparison with the end Triassic Mass Extinction helps to understand the incidence of climatic changes driven by activity of large igneous provinces on land ecosystems and their great impacts on early dinosaur evolution.",
    url = "https://doi.org/10.1016/j.earscirev.2022.104196",
    doi = "10.1016/j.earscirev.2022.104196",
    openalex = "W4297473149",
    references = "doi101016jgr202008003, doi101016jjsames2021103341, doi101017jpa202014, doi102307jctt1zxz1md6, doi103389feart2022899541, doi107717peerj5976"
}

levels inside avian myofibres. The endocrine control of avian muscle NST is still poorly defined. A better understanding of the mechanistic details of avian muscle NST will provide insights into the roles of these processes in regulatory thermogenesis, which could further inform our understanding of the evolution of endothermy among vertebrates.

@article{doi101111brv12885,
    author = "Pani, Punyadhara and Bal, Naresh C.",
    title = "Avian adjustments to cold and non‐shivering thermogenesis: whats, wheres and hows",
    year = "2022",
    journal = "Biological reviews/Biological reviews of the Cambridge Philosophical Society",
    abstract = "levels inside avian myofibres. The endocrine control of avian muscle NST is still poorly defined. A better understanding of the mechanistic details of avian muscle NST will provide insights into the roles of these processes in regulatory thermogenesis, which could further inform our understanding of the evolution of endothermy among vertebrates.",
    url = "https://doi.org/10.1111/brv.12885",
    doi = "10.1111/brv.12885",
    openalex = "W4288080962",
    references = "doi1010160300962989901576, doi101016jcell201205016, doi101016jcmet201811002, doi101038299818a0, doi101056nejmoa0808949, doi101111brv12137, doi101111brv12822, doi101146annurevph56030194002413, doi101152physrev000262013, doi101152physrev20018131097, doi101210er201700211, doi103382ps0490621, openalexw619493784"
}

). In conclusion, cold exposure altered the expression level of genes involved in heat production in muscle tissue. Some potential mechanisms were revealed, including calcium ion transport in the calcium signaling pathway, fatty acid metabolism in the PPAR signaling pathway, and cAMP biosynthesis in the cAMP signaling pathway. This study implied that skeletal muscle plays an important role in thermoregulation in lambs.

@article{doi103389fgene20221017458,
    author = "Ji, Kaixi and Jiao, Dan and Yang, Guo and Degen, A. Allan and Zhou, Jianwei and Liu, Hu and Wang, Wenqiang and Cong, Haitao",
    title = "Transcriptome analysis revealed potential genes involved in thermogenesis in muscle tissue in cold-exposed lambs",
    year = "2022",
    journal = "Frontiers in Genetics",
    abstract = "). In conclusion, cold exposure altered the expression level of genes involved in heat production in muscle tissue. Some potential mechanisms were revealed, including calcium ion transport in the calcium signaling pathway, fatty acid metabolism in the PPAR signaling pathway, and cAMP biosynthesis in the cAMP signaling pathway. This study implied that skeletal muscle plays an important role in thermoregulation in lambs.",
    url = "https://doi.org/10.3389/fgene.2022.1017458",
    doi = "10.3389/fgene.2022.1017458",
    openalex = "W4307047947",
    references = "doi101006meth20011262, doi101007s004240031106z, doi101016jcell200511026, doi101016jmam201207010, doi101016jmolcel201705032, doi101016jplipres201312001, doi101016s0005276097002051, doi10103836285, doi101073pnas1530509100, doi101093bioinformaticsbtp612, doi101111brv12822"
}

In amniotes, the predominant developmental strategy underlying body size evolution is thought to be adjustments to the rate of growth rather than its duration. However, most theoretical and experimental studies supporting this axiom focus on pairwise comparisons and/or lack an explicit phylogenetic framework. We present the first large-scale phylogenetic comparative analysis examining developmental strategies underlying the evolution of body size, focusing on non-avialan theropod dinosaurs. We reconstruct ancestral states of growth rate and body mass in a taxonomically rich dataset, finding that contrary to expectations, changes in the rate and duration of growth played nearly equal roles in the evolution of the vast body size disparity present in non-avialan theropods-and perhaps that of amniotes in general.

@article{doi101126scienceadc8714,
    author = "D’Emic, Michael D. and O’Connor, Patrick M. and Sombathy, Riley S. and Cerda, Ignacio A. and Pascucci, Thomas R. and Varricchio, David J. and Pol, Diego and Dave, Anjali and Coria, Rodolfo A. and Rogers, Kristina A. Curry",
    title = "Developmental strategies underlying gigantism and miniaturization in non-avialan theropod dinosaurs",
    year = "2023",
    journal = "Science",
    abstract = "In amniotes, the predominant developmental strategy underlying body size evolution is thought to be adjustments to the rate of growth rather than its duration. However, most theoretical and experimental studies supporting this axiom focus on pairwise comparisons and/or lack an explicit phylogenetic framework. We present the first large-scale phylogenetic comparative analysis examining developmental strategies underlying the evolution of body size, focusing on non-avialan theropod dinosaurs. We reconstruct ancestral states of growth rate and body mass in a taxonomically rich dataset, finding that contrary to expectations, changes in the rate and duration of growth played nearly equal roles in the evolution of the vast body size disparity present in non-avialan theropods-and perhaps that of amniotes in general.",
    url = "https://doi.org/10.1126/science.adc8714",
    doi = "10.1126/science.adc8714",
    openalex = "W4321749260",
    references = "doi101017s0094837300006588, doi101038nature02699, doi101038s41598019453069, doi101073pnas0611235104, doi10108002724634199610011283, doi101080147720192011630927, doi101086410622, doi101093oso97801951060840010001, doi101098rspb20202258, doi101111brv12822, doi101111j2041210x201100169x, doi101371journalpbio1001853, doi101371journalpone0121476, doi1016710272463420000200115lbhoth20co2"
}

@article{chiarenza2024early,
    author = "Chiarenza, Alfio Alessandro and Cantalapiedra, Juan L. and Jones, Lewis A. and Gamboa, Sara and Galván, Sofía and Farnsworth, Alexander J. and Valdes, Paul J. and Sotelo, Graciela and Varela, Sara",
    title = "Early Jurassic origin of avian endothermy and thermophysiological diversity in dinosaurs",
    year = "2024",
    journal = "Current Biology",
    url = "https://doi.org/10.1016/j.cub.2024.04.051",
    doi = "10.1016/j.cub.2024.04.051",
    number = "11",
    openalex = "W4396921380",
    pages = "2517-2527.e4",
    volume = "34",
    references = "barta2022osteohistology, doi101002ar24130, doi101016jcub202105041, doi101016jcub202111061, doi101016jgr202008003, doi101017s0094837300004310, doi10103844766, doi101038ncomms12931, doi101038sdata2018214, doi101073pnas2213987120, doi10108003610927808827599, doi101086284325, doi101086426002, doi101093aesa383396, doi101093bioinformaticsbtu181, doi101111j2041210x201100169x, doi101111pala12514, doi101126sciadvaaw4486, doi101371journalpone0235078, doi105281zenodo16171435, doi107717peerj12362, doi107717peerj7764"
}

A recent study showed evidence that endothermy was ancestral for amniotes using a variety of proxies and a large sample of taxa. However, it did not include numerous crucial taxa. We reevaluated this hypothesis using a large sample of early amniotes and tetrapodomorphs. We inferred the probability of endothermy for each taxon using a model constructed through phylogenetic logistic regressions and using the size of their bone vascular cavities. An ancestral state reconstruction, based on these inferences, was performed to assess the probability of an ancestral endothermy at the node Amniota. Most outgroups were recovered as ectothermic, as is the node Amniota. Our results contradict the hypothesis of an ancestral endothermy and support several independent acquisitions. We discuss that endothermy should be regarded as a collection of acquisitions forming an "endothermic engine" and that studies aimed at inferring endothermy should consider as many of these features as possible.

@article{doi101016jisci2024109375,
    author = "Faure‐Brac, Mathieu G. and Woodward, Holly N. and Aubier, Paul and Cubo, Jorge",
    title = "On the origins of endothermy in amniotes",
    year = "2024",
    journal = "iScience",
    abstract = {A recent study showed evidence that endothermy was ancestral for amniotes using a variety of proxies and a large sample of taxa. However, it did not include numerous crucial taxa. We reevaluated this hypothesis using a large sample of early amniotes and tetrapodomorphs. We inferred the probability of endothermy for each taxon using a model constructed through phylogenetic logistic regressions and using the size of their bone vascular cavities. An ancestral state reconstruction, based on these inferences, was performed to assess the probability of an ancestral endothermy at the node Amniota. Most outgroups were recovered as ectothermic, as is the node Amniota. Our results contradict the hypothesis of an ancestral endothermy and support several independent acquisitions. We discuss that endothermy should be regarded as a collection of acquisitions forming an "endothermic engine" and that studies aimed at inferring endothermy should consider as many of these features as possible.},
    url = "https://doi.org/10.1016/j.isci.2024.109375",
    doi = "10.1016/j.isci.2024.109375",
    openalex = "W4392345591",
    references = "doi101017pab202134, doi101017pab202228"
}