Evolution: Warm-hearted crocs

  title={Evolution: Warm-hearted crocs},
  author={Adam P. Summers},
  • A. Summers
  • Published 14 April 2005
  • Biology, Medicine
  • Nature
Our ideas about how crocodiles evolved have just taken a battering. It seems that these cold-blooded creatures, with their limited capacity for prolonged activity, might have had active, warm-blooded ancestors. 
A review of the taxonomy of the living Crocodiles including the description of three new tribes, a new genus, and two new species.
The taxonomy of the living Crocodilians is reviewed and the nomenclature of most living species is updated.
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.
Oxygen isotopes suggest elevated thermometabolism within multiple Permo-Triassic therapsid clades
It is concluded that mammalian endothermy originated in the Epicynodontia during the middle-late Permian, and major global climatic and environmental fluctuations were the most likely selective pressures on the success of such elevated thermometabolism.
Thermophysiologies of Jurassic marine crocodylomorphs inferred from the oxygen isotope composition of their tooth apatite
Endothermy in metriorhynchids might have been a by-product of their ecological adaptations to active pelagic hunting, and it probably allowed them to survive the global cooling of the Late Jurassic, thus explaining the selective extinction affecting Thalattosuchia at the Jurassic–Cretaceous boundary.
First and most northern occurrence of a thalattosuchian crocodylomorph from the Jurassic of the Isle of Skye, Scotland
The Jurassic was a key interval for the evolution of dinosaurs, crocodylomorphs and many other vertebrate groups. In recent years, new vertebrate fossils have emerged from the Early–Middle Jurassic
DNA methylation in reptiles.
The craniomandibular anatomy of the early archosauriform Euparkeria capensis and the dawn of the archosaur skull
The skull of Euparkeria epitomizes a major evolutionary transition, and places crown Archosaur morphology in an evolutionary context, corresponding to increases in brain size, visual sensitivity, upright locomotion and metabolism around this point in archosauriform evolution.
The evolution of the avian genome as revealed by comparative molecular cytogenetics
Speculating as to the reasons for the strange behaviour of these chromosomes as well as the role of telomeres and nuclear organisation in avian evolution is suggested.
Evidence for High Bone Growth Rate in Euparkeria Obtained Using a New Paleohistological Inference Model for the Humerus
New evidence is provided for the hypothesis of an ancestral endothermic state for the last common ancestor of archosaurs, and it is shown that non-archosaurian archosauromorphs and Triassic crurotarsans may have been characterized by a thermometabolism more similar to that of dinosaurs rather than that of lepidosaurs and turtles.
Bone histology of Iberosuchus macrodon (Sebecosuchia, Crocodylomorpha)
Bone histology in the femora of two specimens attributed to I. macrodon suggests that Iberosuchus basically had a slow, cyclical growth indicative of an ecto-poikilothermic, lizard-like, resting metabolic rate, however, it might also have retained a limited capacity for fast periosteal accretion in relation to local morphogenetic requirements as, for instance, the development of crests or trochanters.


Evidence for Endothermic Ancestors of Crocodiles at the Stem of Archosaur Evolution
Developmental studies show that all of these uniquely crocodilian features are secondarily derived, indicating a shift from the complete separation of blood flow of endotherms to the controlled shunting of ectotherms.
Getting Warmer, Getting Colder: Reconstructing Crocodylomorph Physiology
The authors argue not merely that crocodilian biology was modified from that of their Triassic and Early Jurassic ancestors but explicitly that these ancestors had attained full endothermic status, and provide no compelling evidence that endothermy was in fact present in the ancestral forms.
The complete mitochondrial genome of Alligator mississippiensis and the separation between recent archosauria (birds and crocodiles).
The complete mitochondrial genome of the alligator, Alligator mississippiensis, was sequenced and maximum-likelihood branch length data of amino acid sequences suggest that the divergence between the avian and crocodilian lineages took place at approximately equal to 254 MYA.
The evolution of activity capacity.
The capacities of animals for activity (burst speed, maximal exertion, endurance) are examined in relation to their selective importance in extant populations and the pattern of their evolution in
The integration of ventilation and locomotion in archosaurs
It is suggested that an ischiotruncus muscle pulled the medial aspect of the gastralia caudally, and thereby helped to produce inspiration by increasing the volume of the cuirassal basket in non-avian theropods.