Mammals grew big at first and then got smarter after the extinction of the dinosaurs
This is according to research by the University of Edinburgh. Skull Arctocyonan archaic mammal from the Archaic period from the collections of the Royal Belgian Institute of Natural Sciences, plays a key role in the study.
During the first 10 million years after the extinction of the dinosaurs, the body size of mammals increased. The researchers said this was an adaptation to drastic shifts in the composition of the animal kingdom on Earth.
Their findings show that the size of mammalian brains, compared to their body weight, decreased only after the catastrophic impact of an asteroid 66 million years ago, which ended the era of the dinosaurs. Until now, it was believed that the relative size of mammalian brains increased only after the demise of the dinosaurs.
While much is known about the evolution of the brains of modern mammals, it is not yet clear how they evolved in the first million years after the mass extinction.
An international team led by the University of Edinburgh has shed new light on this evolution by conducting a tomographic survey of newly discovered fossils from 10 million years after the mass extinction, a period we call the Paleocene.
The main fossil for the study was a skull Arctocyon, an ancient Paleocene mammal from the collections of the Royal Belgian Institute of Natural Sciences. Paleontologist Thierry Smith (KBIN), co-author of the study:Arctocyon It was a mammal weighing between 30 and 50 kg, the size of a large dog. But his brain volume was only 24 cubic centimeters, at least five times smaller than the brain of a dog of this weight. Really impressive how young his mind was!
Their findings show that the relative brain size of mammals decreased first, as their body size increased at a much faster rate. The results of the scans also indicate that the animals relied heavily on their sense of smell, and that their eyesight and other senses were less developed. The team said this indicated that it was more important to be big first than downright smart to survive in the post-dinosaur era.
After about 10 million years, the first representatives of modern mammalian groups, such as primates, began to develop larger brains and a more complex set of senses and motor skills. The researchers say this would improve their chances of surviving at a time when competition for resources was much greater.
The idea that big brains are always better at colonizing new territories or surviving extinctions is misleading.
Paleontologist Ornella Bertrand from the University of Edinburgh’s School of Earth Sciences explains: “Big brains are difficult to maintain and if there is no need to gain resources, potentially detrimental to the survival of early placental mammals in the chaos and turmoil that followed. Asteroid impact.
Because today’s mammals are so intelligent, it’s easy to assume that large brains helped our ancestors survive the days of the dinosaurs and escape extinction — but that didn’t happen, the researchers show.
‘The mammals that succeeded the dinosaurs were pretty dumb,’ says Steve Brusatte, also from the University of Edinburgh and one of the study’s authors, and it wasn’t until millions of years later that many species of mammals developed bigger brains while competing for new ecosystems.
Arctocyon He lived at the end of the Paleocene, 8 to 9 million years after the extinction of the dinosaurs. “The skull in question was discovered in the 1980s in the Reims area, near the vineyards in the Champaign area,” says Thierry Smith.
Other fossils studied in the study come from the Badlands of northwest New Mexico, one of the few places where scientists can find complete skulls and skeletons of mammals that lived after the dinosaurs’ mass extinction.
“Thanks to the collection and tomography of these beautiful fossil skulls, we now have a better understanding of these strange animals and the evolution of the mammalian brain,” said Thomas Williamson, curator of the New Mexico Museum of Natural History and Science.
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