225-million-year-old mammal is the oldest confirmed mammal ever

Brasilodon quadrangularis was a small shrew-like creature about 20 centimeters (8 inches) long that roamed the earth 225 million years ago. It sheds light on the evolution of modern mammals alongside some of the oldest dinosaurs, according to a team of Brazilian and British scientists.

The discovery was made by researchers at the Natural History Museum in London, King’s College London and the Federal University of Rio Grande do Sul in Porto Alegre.

Scientists relied on clues from fossils of hard tissues such as bones and teeth. This is because the milk-producing glands of mammals are not preserved in any fossils discovered so far.

Previously, Morganucodon was thought to be the first mammal, with isolated teeth indicating that it dates back to about 205 million years ago. Morganucodon had a small body like a gerbil and a long face like a shrew or a civet cat.

The tooth record in the study, published Tuesday in the Journal of Anatomy, is dated 225 million years ago, 25 million years after the Permian-Triassic mass extinction event. The third and largest mass extinction in which more than 90% of marine life became extinct and 70% of land animals became extinct.

wrong identity

Martha Richter, the museum’s associate of science and lead author of the paper, told CNN that Brasilodon quadrangularis was previously thought to be an “advanced reptile,” but examination of its teeth revealed that it was not a mammal. He said one thing was “conclusively” shown.

“If you think about reptiles, they have so many different replacement teeth throughout their lives, whereas we mammals have only two: first the milk teeth, then the second teeth that replace the original set. Column.This is what defines a mammal.

Brasilodon is the oldest extinct vertebrate animal with two sets of consecutive teeth, primary and permanent, also known as twin teeth, the news release said.

The first set begins to develop during the fetal period and the second set after birth.

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Richter and her colleagues examined three mandibles of this species that lived in what is now the southernmost part of Brazil. Under the microscope, they discovered “a type of replacement tooth that exists only in mammals.”

Richter added, “This was a very small mammal, a burrowing animal that probably lived in the shadow of the oldest known dinosaurs from that era.”

She said the team had been working on the project for more than five years and called their findings “very significant.”

In a news release, Richter said the discovery “contributed to our understanding of the ecological landscape and the evolution of modern mammals during this period.”

Contributor and professor of evolutionary skeletal biology at King’s College London, Moya Meredith Smith, said in this release: than previously known. ”

Source: www.cnn.com

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