Evidence for mesothermy in dinosaurs

  title={Evidence for mesothermy in dinosaurs},
  author={John M. Grady and Brian J. Enquist and Eva Dettweiler‐Robinson and Natalie A. Wright and Felisa A. Smith},
  pages={1268 - 1272}
Not too fast, not too slow, somewhere in between In early depictions, dinosaurs lumbered slowly, dragging their tails. More recently, we have imagined them lifting their tails and running. The question boils down to whether dinosaurs had energetic systems closer to those of rapidly metabolizing mammals and birds, or to those of slower reptiles that do not internally regulate their body temperature. However, determining the metabolic rate of extinct organisms is no easy task. Grady et al… 
Shrinking dinosaurs and the evolution of endothermy in birds
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.
Eggshell geochemistry reveals ancestral metabolic thermoregulation in Dinosauria
Applying this method to well-preserved fossil eggshells demonstrates that the three major clades of dinosaurs, Ornithischia, Sauropodomorpha, and Theropoda, were characterized by warm body temperatures, and that metabolically controlled thermoregulation was the ancestral condition for Dinosauria.
Polar and K/Pg nonavian dinosaurs were low-metabolic rate reptiles vulnerable to cold-induced extinction, rather than more survivable tachyenergetic bird relatives: comment on an obsolete hypothesis
  • G. Paul
  • Environmental Science, Geography
    International Journal of Earth Sciences
  • 2017
High- as well as low-latitude dinosaurs add to the growing evidence that high-energy endothermy has been a common adaptation in a wide variety of vertebrates and flying insects since the late Paleozoic.
Isotopic ordering in eggshells reflects body temperatures and suggests differing thermophysiology in two Cretaceous dinosaurs.
Clumped isotope analysis of eggshells can be used to determine body temperatures of females during periods of ovulation and indicates 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.
Theropod dinosaurs had primate-like numbers of telencephalic neurons
This procedure indicates that theropods such as Tyrannosaurus rex and Allosaurus had monkey-like numbers of telencephalic neurons, which would make these animals not only giant but also long-lived and endowed with flexible cognition, and thus even more magnificent predators than previously thought.
Dinosaur paleohistology: review, trends and new avenues of investigation
It is suggested that the combination of histological and molecular methods holds great potential for examining the preserved tissues of dinosaurs, basal birds, and their extant relatives, and the development of novel techniques with which to further investigate important paleontological questions are discussed.
Palaeohistological Evidence for Ancestral High Metabolic Rate in Archosaurs.
The results show that Mesozoic theropod dinosaurs exhibit metabolic rates very close to those found in modern birds, that archosaurs share a higher ancestral metabolic rate than that of extant ectotherms, and that this derived high metabolic rate was acquired at a much more inclusive level of the phylogenetic tree, among non-archosaurian archosauromorphs.
Dinosaur demise in light of their alleged perennial polar residency
  • Z. Lewy
  • Environmental Science, Geography
    International Journal of Earth Sciences
  • 2016
The end-Cretaceous biological crisis is represented by the demise of the non-avian dinosaurs. However, most crucial biologically was the elimination of the photosynthesizing marine phyto- and
Osteohistological analyses reveal diverse strategies of theropod dinosaur body-size evolution
The first evidence of a lack of strong mechanistic or physiological constraints on size evolution in the largest bipeds in the fossil record is provided and evidence of one of the longest-living individual dinosaurs ever documented is provided.


Dinosaur body temperatures: the occurrence of endothermy and ectothermy
  • F. Seebacher
  • Environmental Science, Geography
  • 2003
The commonly asked question whether dinosaurs were ectotherms or endotherms is inappropriate, and it is more constructive to ask which dinosaurs were likely to have been endothermic and which ones ectothermic, which suggests endothermy most likely evolved among the Coelurosauria and, to a lesser extent, among the Hypsilophodontidae.
Gigantism and comparative life-history parameters of tyrannosaurid dinosaurs
Growth patterns within the Tyrannosauridae are studied and it is determined that Tyrannosaurus rex's great stature was primarily attained by accelerating growth rates beyond that of its closest relatives.
Sexual maturity in growing dinosaurs does not fit reptilian growth models
It is shown by counting lines of arrested growth and performing growth curve reconstructions that Tenontosaurus, Allosaurus, and Tyrannosaurus were reproductively mature by 8, 10, and 18 years, respectively, which suggests that these dinosaurs were born relatively precocial and experienced high adult mortality.
Dinosaurian growth patterns and rapid avian growth rates
It is shown that dinosaurs exhibited sigmoidal growth curves similar to those of other vertebrates, but had unique growth rates with respect to body mass.
Dinosaurian growth rates and bird origins
Dinosaurs, like other tetrapods, grew more quickly just after hatching than later in life. However, they did not grow like most other non-avian reptiles, which grow slowly and gradually through life.
Metabolism of leatherback turtles, gigantothermy, and thermoregulation of dinosaurs
It is indicated that leatherbacks can use large body size, peripheral tissues as insulation, and circulatory changes, to maintain warm temperatures in the North Atlantic and to avoid overheating in the tropics.
Was Dinosaurian Physiology Inherited by Birds? Reconciling Slow Growth in Archaeopteryx
These findings dispute the hypothesis that non-avialan dinosaur growth and physiology were inherited in totality by the first birds and demonstrate the presence of a scale-dependent maniraptoran histological continuum that Archaeopteryx and other basalmost birds follow.
Modeling growth rates for sauropod dinosaurs
Alternative method of estimating limb length and body mass for each growth line, and fitting the resulting age/ mass data to the von Bertalanffy growth equation, yields a revised growth curve suggesting that sauropods grew at rates similar to other dinosaurs in spite of their great size.
Thermoregulation in monotremes: riddles in a mosaic
A comparison of the thermoregulation of three extant genera of the Monotremata reveals a diversity of physiology that might represent both plesiomorphic and apomorphic elements within this mosaic, making it difficult to determine which aspects of monotreme thermoreGulation are plesiomorph and which are apomorphic.
Respiration of antarctic fish from McMurdo Sound.
  • R. Wells
  • Environmental Science
    Comparative biochemistry and physiology. A, Comparative physiology
  • 1987