What evolved endothermy?
Endothermy in vertebrates evolved at least twice in the vertebrate lineage – leading to birds and mammals – along separate, but parallel lines from different groups of reptilian ancestors.
When did endothermy evolve in birds?
As proposed in Section IV, endothermy probably evolved first in therapsids and archosaurs during the Permian and Triassic in large-sized animals, perhaps larger than 5 kg.
Did endothermy evolve independently with birds mammals?
Furthermore, while there is strong evidence that endothermy must have arisen independently in birds and mammals, the mechanisms underlying torpor/hibernation in both groups could well be monophyletic in origin.
Did hair and endothermy evolve simultaneously in mammals?
Both features occurred at the time of the origin of mammals (McNab, 1978). Thus, a hairy, insulative covering in mammals may have evolved in association with endothermic homeothermy, but long after mammal-like metabolic rates had evolved in therapsids.
Are endotherms cold blooded?
Although most endotherms appear “warm-blooded” and most ectotherms appear “cold-blooded,” some animals display characteristics of both groups. They are called heterotherms.
Do reptiles have endothermy?
Endotherms (like us) are able to create their own heat through metabolic reactions (these use energy to create heat). As reptiles are unable to do this, they have to maintain their body temperature another way, mostly by changing behaviour.
Is endothermy convergent evolution?
Birds and mammals share a number of features that are remarkably similar but have evolved convergently. Although endothermy has been proposed to have been a cardinal character that led to much of this convergent evolution, selection for extensive parental care behaviors is a more compelling explaination.
How did birds evolve?
Birds evolved from a group of meat-eating dinosaurs called theropods. The oldest bird fossils are about 150 million years old. These ancient birds looked quite a lot like small, feathered dinosaurs and they had much in common. Their mouths still contained sharp teeth.
Why was hair first evolved?
The evolution of hair was an essential step for that of endothermy or warm-bloodedness. As I’ve said, the earliest mammals were nocturnal and couldn’t rely on their eyes to feel their environment.