Ear fossils reveal origins of warm-blooded mammals

KOMPAS.com – Before becoming warm-blooded animals, ancestors mammal are cold blooded creatures.

But the ancestor of these mammals later evolved, it’s just that the timing of the transition is still being debated.

Warm-blooded or endothermic animals themselves are animals that can maintain a constant high body temperature because of their fast metabolism.

Also read: Eggshell reveals dinosaurs were warm-blooded, how come?

While ectotherms or cold blooded have a low metabolic rate and depend on the environment to stay warm.

Now in a new study, researchers are using fossils of the inner ear canal to show that the adaptation occurred some 230 million to 200 million years ago.

This evolutionary step into warm-bloodedness, according to researchers, allowed this diverse class of animals to thrive in many environments around the world.

Quoted from Science AlertFriday (22/7/2022) an international team of scientists led by University of Lisbon paleontologist Ricardo Araújo has found evidence suggesting that endotherms originated about 230 million years ago, during the Late Triassic, the geological age that marks the age of the dinosaurs.

The evidence was not found in blood, but in the petrified inner ear of an ancient mammalian ancestor.

The inner ear may seem like an unlikely place to look for clues to body temperature.

But actually that’s logical, because body temperature affects the viscosity or thinness of the fluid that gushes around the tiny semicircular canals of the inner ear.

The main job of these fluid-filled structures of the inner ear is to help detect head movement, which is important for balance, vision, and coordinated movement.

“But looking at their biomechanics, we found that it was used to infer body temperature,” explains Romain David, one of the study’s authors.

Also read: 42 million-year-old tooth fossil reveals first sword-toothed mammal

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