Brasilodon quadrangularis was a small, regarding 20 cm long, shrew-like creature that walked the earth 225 million years ago According to a team of Brazilian and British scientists, it coincides with some of the oldest dinosaurs and sheds light on the evolution of modern mammals.
The discovery was made by researchers from the Natural History Museum in London, King’s College London and the Federal University of Rio Grande do Sul in Porto Alegre.
The scientists relied on evidence provided by fossils of hard tissues such as bones and teeth. Because the milk-producing glands of mammals have not been preserved in any fossil found so far.
So far, Morganucodon has been thought to be the first mammal whose isolated teeth show it to be around 205 million years old. Morganucodon had a small body resembling a jerboa and a long face resembling that of a shrew or civet cat.
wrong identity
Martha Richter, a research fellow at the museum and the paper’s lead author, told CNN that Brazil was previously thought to be an “advanced reptile,” but an examination of its teeth “conclusively” shows it is a mammal.
“If you think regarding reptiles, they have many, many replacement teeth throughout their lives, but we mammals only have two. First the milk teeth, then the second teeth that replace the original set of teeth. That’s what distinguishes mammals,” says Richter. .
The press release said Prazilodon is the oldest extinct vertebrate with two consecutive teeth – milk teeth and one permanent set – also known as diphyodonts.
The first group begins to develop during the embryonic stage and the second group develops following birth.
Richter and her colleagues studied three mandibles from species living in what is now the surveyed area of southern Brazil. Under a microscope, she said, they discovered “the kind of dentures only found in mammals.”
“This was a very, very small mammal that was probably a burrowing animal that lived in the shadow of the oldest dinosaurs we know of from that time,” added Richter.
She said the team has been working on the project for more than five years and described their discovery as “extremely significant”.
In the press release, Richter said the results “contributed to our understanding of the ecological landscape of that time and the evolution of modern mammals.”
Moya Meredith Smith, contributing author and Professor of Structural Biology of Evolutionary Teeth at Kings College London, said in the statement: “Our article increases controversy regarding what defines mammals and shows that it was a much earlier fossil record than previously known.” .”
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