Sunday, August 7, 2022

Ear fossils reveal origin of warm-blooded mammals

Before becoming warm-blooded animals, the ancestors of mammals were cold-blooded creatures.

But while the ancestors of these mammals evolved later, just the timing of the transition is still debated.

Warm-blooded or endothermic animals are themselves animals that can maintain a consistently high body temperature due to their fast metabolism.

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

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

According to the researchers, this evolutionary step of warming allowed this diverse class of animals to thrive in many environments around the world.

derive from science alertFriday (22/7/2022) An international team of scientists led by paleontologist Ricardo Araujo of the University of Lisbon has found evidence that endotherms originated about 230 million years ago, during the Late Triassic, the geological epoch that marked the age of dinosaurs. marks the. ,

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

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

But in fact it is logical, because body temperature affects the viscosity or thinness of the fluid that circulates around the small semicircular canals in 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 estimate body temperature,” explains Romain David, one of the study’s authors.

gather Nature, The research team hypothesized that as body temperature rises and animals become more active, the shape of the ear canal will evolve into a less viscous fluid to maintain balance and movement.

So to track these adaptations, the team compared the inner ear structure and physiology of 50 living vertebrates, including reptiles, fish, birds and mammals.

The researchers then developed a thermo-motility index based on the size of the inner ear which, when adjusted for body size, allowed them to predict the animal’s body temperature.

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When they analyzed the inner ear canals of 56 extinct synapsids—the ancestors of reptile-like mammals—and included them in the index, the authors found that the shape of the canals had changed abruptly in the late Triassic period, which lasted 237 million years. . Last year to 201 million.

This suggests that the ancestors of mammals began to be warm-blooded, where there was an increase in body temperature of 5–9 °C and an increase in metabolism as well.

The researchers concluded that this adaptation gave early endotherms an advantage in dealing with a Triassic climate that was cooler than the previous Permian period.

According to Jose Eduardo Bicudo, a comparative physiologist at the University of So Paulo in Brazil, this approach is new to looking at the emergence of endotherms.

This is because the origins of endotherms have been intensely debated over the past 60 years and there are several theories each with evidence to support it.

Nation World News Desk
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