Origins of endothermomy in synapses, including mammalian ancestry in mammals. The figure shows the evolution of the main groups by the triceps, and is a measure of the degree of warmth-hemorrhage reconstructed based on various indicators of bone formation and anatomy on a scale from blue to red. Credit: Mike Benton, University of Bristol. Animal images are from Nobu Tamura, Wikimedia
Mammals and birds are cozy today, and this is often taken as the reason for their great success.
University of Bristol Paleontologist Professor Mike Benton identifies in the journal Gondwana research That the ancestors of both mammals and birds became warm blood at the same time, about 250 million years ago, when life was returning from the greatest mass extinction.
Permian-Triassic Mass extinctions accounted for 95 percent of life, and very few survivors faced a volatile world, with frequent global warming and ocean acidification crises. No. The two main groups Tetrapods Survivors, including the ancestors of mammals and birds, respectively, are synapses and archos.
Paleontologists found signs of warm-bloodedness or technically endodermic in these triassic survivors, including evidence of possible whiskers in the diaphragm and synapses.
More recently, similar evidence has come to light for the early origins of the feathers of dinosaurs and bird ancestors. In both synapses and arcosomes of the triceps, the bone structure shows the characteristics of warm-bloodedness.
Evidence that the protective covering of the fetus in mammals from the beginning is doubtful has long been suspected, but the suggestion that there were feathers of archos auurs 250 million years ago is new.
Shifted into posture at the end of the Permian 252 million years ago. Before the crisis, most reptiles had scattered postures; Afterwards, they walked straight. This will probably be the first sign of a new pace of life in the Triassic. Credit: University of Bristol, Animal Pictures by Jim Robbins
But in 2009, at the exact time of the extinction of the Permian-Triassic mass, a strong indication for this sudden emergence was found in both synapses and archosores. Tai Kubo, a student studying for a master’s degree in paleobiology at Bristol and Professor Benton. Recognize that all medium-sized and large tetrapods have been turned to stand in a straight posture on the Permian-Triassic boundary.
His study was based on fossil footprints. They looked at a sample of hundreds of fossilized trackways, and as suggested, were surprised to see the Kubo and Benton postures shift immediately. It also happened in all groups, not just mammal ancestors or bird ancestors.
Professor Benten said: “Modern amphibians and reptiles are scattered, with their limbs partly side by side.
“Birds and mammals have asanas immediately under the body. This allows them to run faster and especially faster. There are many advantages to being in an upright posture and warm-blooded, but the price is that endotherms have to be eaten in greater quantities than cold-blooded animals to enhance their internal temperature control. “
Evidence of a change in posture and the early origin of hair and feathers, all occurring at the same time, suggests that this is the beginning of a kind of “arms race.” In ecology, arms races occur when the hunter and the prey have to compete with each other, and where adaptation increases. Lions evolve to run fast, but Wildbest also evolves to run fast or twist.
Something similar happened in the Triassic, 250 to 200 million years ago. Today, warm-blooded animals can live all over the earth, even in cold regions, and they stay active at night. They also demonstrate intensive parental care, feeding their children and teaching them complex and smart behaviors. This adaptation gives birds and mammals an edge over amphibians and reptiles and in the current cold world they are allowed to dominate more parts of the world.
Professor Benten added: “The Triassic was a significant time in the history of life on Earth. You will see birds and mammals everywhere on the ground today, while amphibians and reptiles are often hidden.
“This revolution in ecosystems was stimulated by the endogenous independent secretion in birds and mammals, but until recently we did not realize that these two events have been coordinated.
“It simply came to our notice then that the Permian-Triassic mass was the only endangered species in the world – surviving on the fierce competition of the tough world. Because some of the survivors were already primitively endothermic, everyone else had to become endothermic to survive in the new fast-paced world. “
Reference: Michael J. By Benton, 3 September 2020, “The Origin of Endothermomy in the Race of Weapons in Synapses and Archosource and the Triassic” Gondwana research.
DOI: 10.1016 / j.gr.2020.08.003
