By Will Dunham
(Reuters) – More than 250 million years ago, Scotland was not shrouded 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 precursor mammal called Gordonia, with a pug face and two tusks jutting from pointed jaws.
Using high-resolution, three-dimensional images of a fossil of this Permian Period creature, researchers were able to view 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. stage of mammalian evolution.
To be clear, the Gordonia brain was a far cry from a modern mammal’s brain. But the relative size of its brain compared to its body seemed to presage the intelligence that later helped mammals — including people — dominate the Earth.
Gordonia, which lived about 254-252 million years ago, was a type of animal called a protomammal – a predecessor of mammals that still retained characteristics of its reptilian ancestors.
“Overall, the brain of Gordonia looks more like a reptile than a mammal, despite being closer 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 Jornal Zoológico da Sociedade Linneana.
The front part of Gordonia’s brain — the forebrain — is proportionally much smaller than that of any mammal, George said. Although Gordonia’s brain is generally typical of an ancient mammal relative, an organ called the pineal body, dedicated to metabolic functions, was greatly enlarged, George added.
But there seemed to be some glimpses of what was to come.
“What we see is a brain that looks very different from our own, not a large balloon-like sphere, but rather a long, arched tube. But even though its shape seems strange, when we measure its volume we can see that it was very large compared to the size of the body,” said Steve Brusatte, a paleontologist at the University of Edinburgh and senior author of the study.
“It is so difficult to measure intelligence in modern animals, and even more so in extinct species that we can never observe directly. But we can at least say generally that it would have been an intelligent creature for its time. By increasing the size of its brain relative to to other animals of the time, we can feel the first evolutionary roots of our enormous brains,” Brusatte added.
Gordonia was about three feet long and weighed approximately 45 pounds. Her head was tall and wide. Although she had a stocky, pig-like build, her legs were not as long as a pig’s.
“The combination of beak and tusks facilitated a herbivorous lifestyle and especially pulling up succulent roots from the desert that made it home,” George said.
It was a type of proto-mammal called a dicynodont, which first appeared about 265 million years ago and became extinct about 200 million years ago. As a group, dicynodonts survived the worst mass extinction in Earth’s history, 252 million years ago at the end of the Permian – thought to have been caused by immense volcanic activity in Siberia – although Gordonia did not.
It was after this calamity that the first dinosaurs appeared, around 230 million years ago. Later, mammals appeared about 210 million years ago, when they ran under the feet of dinosaurs. Only after an asteroid strike 66 million years ago eliminated competition did mammals have the opportunity to dominate.
Discovered in 1997, the Gordonia fossil is a block of sandstone containing a void that perfectly captures the skull and jaw.
“The Gordonia brain bears very little resemblance to the brains of modern mammals and lacks any of the unique features that characterize mammalian brains. This highlights how much more the brain had to change to become one that we would recognize today as a true mammal.” , George said.
(Reporting by Will Dunham in Washington; Editing by Daniel Wallis)
