This Saber-Toothed Predator is the oldest mammal ancestor ever found

The origin of mammals is shrouded in mystery, but every fossil clue helps to rewrite history. A new discovery on a Mediterranean island is challenging what we know when – and where – mammal ancestors emerged.

A team of paleontologists has discovered the oldest known mammal ancestor in a pile of fossilized bones from Mallorca, a Spanish island in the Mediterranean Sea. The animal is a roughly 280-million-year-old gorgonopsian, a group of saber-toothed predators that roamed the Earth before modern mammals. The discovery of the team, published today in Communications of naturepush back the chronology and geography of some of the earliest ancestors of mammals.

Most people write the rise of mammals goes back to the death of the dinosaurs about 66 million years ago. When the asteroid Chicxulub put about 75% of Earth’s species to the sword, including all the dinosaurs, but the ancestors of the birds, runty mammals, scorrying were the survivors left to inherit the planet. But the life of mammals began much earlier, with fundamental evolutionary splits that gave animals with spines, unique holes in their heads, and other differences that distinguish their branch on the tree of life from all others.

The recently studied specimen is fragmentary – it consists of several vertebrae, ribs, a leg bone and parts of the animal’s skull – so the team was unable to identify the animal more precisely than a limb of Gorgonopsia. The specimen dates back to at least 270 million years ago, making it the oldest known gorgonopsia to date. For context, dinosaurs did not appear for another 25 million years, rising to prominence during the Triassic Period after the catastrophic mass extinction that marked the end of the Permian.

Like mammals, gorgonopsians were tetrapods – four-legged spinal creatures – and more specifically, part of a group of synapsids known as therapsids.

“There is a large time gap in the fossil record of therapsids, between when they are expected to have evolved based on our understanding of synapsid relationships and when they actually appear in the fossil record,” said Josep Fortuny, a paleontologist in the doctor. Institut Català de Paleontologia Miquel Crusafont in Spain is senior author of the study, in an email to Gizmodo. “The new specimen helps fill some of that gap.”

“Our discovery is particularly relevant for two reasons: first, because it is the first gorgonopsian found in low latitudes,” said Fortuny.

Previously, all known gorgonops were found in higher latitudes – places including Russia and South Africa. They lived when the continents were all part of the supercontinent Pangea, and Mallorca was located towards the center of the land mass.

“Second, and even more important, it is the oldest in the world,” said Fortuny. “Thus, finding the oldest gorgonopsian in the Mediterranean suggests an equatorial origin for this group of animals.”

The fossil was found in what was an ancient floodplain in the center of Pangea, where precursor mammals and other creatures came to drink.

Mammals are the only living synapsids, but the team’s recent paper shows how early the four-legged vertebrate playbook has been written. It also raises questions about exactly where on Earth’s supercontinent our ancestors were first, and why. Specimens like the gorgonopsian investigated by the team shed some light on these fundamental questions of our origins, but there is still a long way to go towards a complete understanding.