Mystery solved: when mammals’ ancestors became warm-blooded


Mammals and birds produce their own body heat and control their body temperatures. This process is known as endothermy, or warm-bloodedness, and it may be one of the reasons why mammals tend to dominate almost every global ecosystem. Warm-blooded animals are more active during both days and nights than their cold-blooded counterparts and they reproduce faster.

Tritylodon, a therapsid, reconstructed as a night dwelling warm blooded animal. Note the steam coming out of its lungs. Illustrated by Luzia Soares

But until now it hasn’t been known exactly when endothermy originated in mammalian ancestry. Our new study, just published in Nature, changes that. A combination of scientists’ intuition, fossils from South Africa’s Karoo region and cutting-edge technology has provided the answer: endothermy developed in mammalian ancestors about 233 million years ago during the Late Triassic period.


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