The first mammals evolved around 200 million years agoin the early days of the dinosaurs. They are related to an even older group called the therapsids.
Therapsids were not very similar to mammals in appearancebut had certain characteristics that are still found in mammals, such as a hole in the side of their skull for the jaw muscles to come togetheror parts of their jaw bones that would evolve into the middle ear bones of mammals.
Scientists have discovered what may be the oldest therapsid fossil. Oddly enough, it looks like a dog but has saber teeth. The fossil does not yet have a species name. It is part of a group called the gorgonopsians who lived around 265 million years ago. This unidentified species probably lived around 270 to 280 million years ago.
« It is most likely the oldest gorgonopsian on the planet. ”, said Josep Fortuny, head of the group of computational biomechanics and evolution of life history at the Catalan Institute of Paleontologia Miquel Crusafont (ICP) in Spain.
After the discovery of the fossils in Mallorca, Spain, the discovery was published in the journal Nature Communications. Mallorca was once part of the supercontinent Pangea. The discovered fossil site was “surprising” for the team. There were so many remains of this animal, including pieces of skull, vertebrae and ribs as well as a femur in very good condition.
Dogs versus Gorgonopsians
This particular animal could have looked like a medium sized dog, such as a Labrador, Husky or Collie. However, he didn't look like a dog at all, with no fur and no dog ears. His likeness is actually hidden from outside view – in his teeth. “ It's the oldest animal scientists have ever discovered with long, blade-like canines,” explained co-author Angielczyk.
Existing between the Middle and Late Permian, Gorgonopsia is an extinct clade of four-legged saber-toothed animals. This was a type of synapsid – a large evolutionary group that includes all mammals and their extinct relatives. The University of Berkeley indicates that the only synapsids alive today are mammals (the only surviving branch of synapsid).
Although they seem enigmatic, gorgonopsians are more closely related to mammals than any other animal group. No clear descendants are observed today. Although they are not a direct ancestor of our mammals, they are directly related to many modern mammal species. This new discovery of fossils adds a piece to the puzzle of their evolution.
