By Will Dunham
June 21 (Reuters) – More than 250 million years ago, Scotland was not covered in fog and rain, as is often the case today, but rather a desert covered in sand dunes.
One of the inhabitants of this challenging landscape was a stocky, vaguely pig-like mammalian precursor called Gordonia, with a pug-like face and two fangs protruding from its beaked jaws.
Using high-resolution three-dimensional images of a fossil of this creature from the Permian Period, researchers have been able to see its brain cavity and make a digital replica of the brain, providing information about the size and composition of this crucial organ at an early stage. in the evolution of mammals.
Gordonia’s brain was a far cry from that of a modern mammal, but the relative size of its brain compared to its body seemed to presage the intelligence that later helped mammals, including humans, dominate the Earth.
Gordonia, which lived about 254-252 million years ago, was a type of animal called a proto-mammal, a predecessor of mammals that still retained traits from its reptilian ancestors.
“Overall, Gordonia’s brain is more reptile-like than mammal-like despite being more closely related to us than to any modern living reptile,” said paleontology PhD student Hady George of the University of Bristol. lead author of the study published this week in the Zoological Journal of the Linnean Society.
The front part of Gordonia’s brain – the forebrain – is proportionally much smaller than that of any mammal, George said. While Gordonia’s brain is generally typical of an ancient mammalian relative, an organ called the pineal body, dedicated to metabolic functions, was greatly enlarged, George added.
But there appear to be some first glimpses of what was to come.
“We see a brain that looks very different from our own, not a large balloon-like orb, but rather a long, arched tube. But although its shape seems strange, when we measure its volume we can see that it was quite large compared to body size,” said University of Edinburgh paleontologist and lead author of the study, Steve Brusatte.
“It is very difficult to measure intelligence in modern animals, and even more so in long-extinct species that we can never directly observe. But at least we can say in general that it would have been an intelligent creature for its time,” he said.
“By increasing their brain size relative to other animals of the time, we can feel the first evolutionary roots of our huge brains,” Brusatte added.
Gordonia was approximately one meter long and weighed about 20 kilos. Her head was tall and wide. Although he had a stocky, pig-like build, his legs were not as long as those of that animal.
“The combination of beak and fangs facilitated a herbivorous lifestyle, especially pulling up juicy roots from the desert it made its home,” George said.
It was a type of proto-mammal called dicynodont, which appeared about 265 million years ago and became extinct 200 million years ago. As a group, dicynodonts survived Earth’s worst mass extinction 252 million years ago at the end of the Permian, which is believed to have been caused by immense volcanic activity in Siberia, although Gordonia did not.
After that calamity the first dinosaurs appeared, about 230 million years ago. Mammals appeared about 210 million years ago, when they scurried under the paws of dinosaurs. Only after an asteroid impact 66 million years ago wiped out the competition did mammals have a chance to dominate.
Discovered in 1997, the Gordonia fossil is a block of sandstone containing a void that perfectly captures the skull and lower jaw.
“Gordonia’s brain bears little resemblance to the brain of modern mammals and does not possess any of the unique features that characterize mammalian brains. This highlights how much more the brain had to change to become one we would recognize today.” like a real mammal,” George said.
(Reporting by Will Dunham in Washington; Editing in Spanish by Natalia Ramos)
