This saber-toothed predator is the oldest mammalian ancestor ever found

The origin of mammals is shrouded in mystery, but each fossil clue helps rewrite the story. A new discovery on a Mediterranean island challenges what we know about when and where the ancestors of mammals appeared.

A team of paleontologists has discovered the oldest known ancestor of mammals in a pile of fossilized bones from Majorca, a Spanish island in the Mediterranean. This animal is about 280 million years old, and is a group of saber-toothed predators that roamed the Earth before modern mammals. Team discovery published Today in Nature Communicationspushes back the timeline and geography of some of the oldest mammalian ancestors.

Most people chalk it up The rise of mammals It dates back to the extinction of dinosaurs about 66 million years ago. When the asteroid Chicxulub was placed About 75% of the species found on Earth To the sword, including all dinosaurs except the ancestors of birds, and the scurrying mammals, are the survivors left to inherit the planet. But mammalian life began much earlier, with fundamental evolutionary splits that gave rise to animals with spines, unique holes in their heads, and other differences that distinguished 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 it identified the Gorgonopsia member. This specimen dates back to at least 270 million years ago, making it the oldest Gorgonopsian known to date. For context, dinosaurs would not appear for another 25 million years, having risen to prominence during the Triassic after the catastrophic mass extinction that marked the end of the Permian.

Like mammals, gorgonopsians were tetrapods—creatures with a backbone on four legs—and, more specifically, were part of a group of synapsids known as therapsids.

“There is a large gap in time in the fossil record of therapsids, between the time when they are predicted to have evolved based on our knowledge of the relationships between synapsids, and the time when they actually appear in the fossil record,” said Giuseppe Fortuny, a paleontologist at the University of California, California. Instituto Catala de Paleontologia Miquel Crosafonte in Spain and the study’s senior author said in an email to Gizmodo. “The new sample helps fill part of this gap.”

“Our discovery is particularly relevant for two reasons: First, because it is the first Gorgonopsi to be found at low latitudes,” Fortuny said.

Previously, all known gorgonopsians were found in high latitude regions, including Russia and South Africa. They lived when all the continents were part of the supercontinent Pangea, and Majorca was located towards the center of the land mass.

“Secondly, and more importantly, it is the oldest in the world,” Fortuny said. “Thus, the finding of the oldest Gorgonopsi in the Mediterranean indicates a tropical origin for this group of animals.”

The fossil was found in an ancient floodplain in central Pangea, where ancestors of mammals and other creatures would have come to drink.

Mammals have the only living synapses, but the team’s latest paper shows how the rules of the game for four-legged vertebrates were established early on. It also raises questions about exactly where our ancestors first appeared on Earth’s then-giant continent, and why. Specimens like Gorgonops that the team studied shed some light on these fundamental questions about our origins, but there is still a long way to go toward full understanding.