Artist’s rendering of a mammalian ancestor (Source: Luzia Soares) © ANSA / Ansa
animals & warm blood are older than expected: the first ones have appeared at least 233 million years ago and they were the ancestors of mammals. Evidence for this fundamental evolutionary step was found by the research group coordinated by Ricardo Araújo from the University of Lisbon and Romain David from the Natural History Museum in Paris, who published the analyzes of the fossils found in the journal Nature.important site in Karoo, South Africa.
L’endothermy, that is, the ability to heat one’s body and control its temperature, is one of the evolutionary solutions that has allowed mammals to adapt to virtually any ecosystem and spread everywhere. Until now, there has been great uncertainty in precisely dating the appearance of this major evolutionary novelty, but examining the Karoo fossils may provide new temporal references.
In particular, the study focused on the changes that have occurred to the structures found over millions of yearsinner ear and which, above all, serve to balance, but are also, according to the researchers, an excellent indicator for measuring the development of endothermic abilities. In fact, the ducts that make up these structures have different properties in animals, where the internal temperature varies greatly.
Based on this intuition, the researchers examined the many fossils that are present in Karoo, a kind of giant time window that spans 100 million years. After the evolution of the internal auditory canals, researchers found that the first warm-blooded animals appeared at least 30 million years before the first mammals, and very quickly, at just 1 million years.
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