A new paper with free pdf:
Free pdf:
Highlights
Birds and mammals likely acquired endothermy (warm-bloodedness) at the same time
This time was the Early Triassic, as suggested by phylogenetic macroevolutionary studies of both archosaurs and synapsids
The Early Triassic was the time when life remodelled itself most significantly in the aftermath of the devastating end-Permian mass extinction
The switchover happened in parallel with an already-noted shift in posture from sprawling to parasagittal in both major lineages
We can envisage cynodonts and avemetatarsalian archosaurs in ecological arms races through the Triassic, as their metabolic rates speeded up
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.