WASHINGTON: By analysing the ear structure of current and extinct mammals as well as their close relatives, researchers were able to pinpoint the origin of warm-bloodedness, a characteristic crucial to the success of the lineage.
On Wednesday, scientists reported that the reduced size of inner ear structures called semicircular canals in the remains of mammal ancestors demonstrated that endothermy, or warm-bloodedness, emerged around 233 million years ago during the Triassic Period.
Mammaliamorph synapsids, the first organisms to reach this milestone, are not officially categorised as mammals because actual mammals didn’t emerge until some 30 million years later. However, they had started to develop characteristics common to mammals.
