Researchers uncovered what may be the earliest known ancestor of mammals, a gorgonopsian fossil, in Mallorca, Spain, dating back an estimated 270 to 280 million years. The discovery is significant not only because of the fossil's age but also because it was found in an unexpected location, challenging previous understandings of the geographical distribution of these ancient creatures.
"We have found everything from fragments of skull, vertebrae, and ribs to a very well-preserved femur," said Rafel Matamales, the principal investigator and curator of the Museu Balear de Ciències Naturals, according to El Mundo. "In fact, when we started this excavation, we never thought we would find so many remains of an animal of this type in Mallorca."
The excavation began in 2019 as part of Matamales' doctoral thesis and continued through a series of campaigns until 2022. The remains were found at a site in the municipality of Banyalbufar, part of the Serra de Tramuntana in Mallorca. The fossilized bones have been more than enough to affirm that the 'saber-tooth' of Banyalbufar is the oldest known ancestor of mammals on the planet.
"This is probably the oldest gorgonopsian on the planet," stated Josep Fortuny, a co-author of the study from the Catalan Institute of Paleontology Miquel Crusafont, as reported by El Confidencial. The gorgonopsian lived almost 60 million years before those that we would later call mammals, highlighting its significance in understanding the eventual human evolution.
Gorgonopsians are an extinct group of predatory therapsids that lived during the Permian period, approximately 299 to 252 million years ago. They are considered evolutionary ancestors that later led to the emergence of mammals. The newly discovered fossil predates previous records by at least five million years, making it the oldest known specimen.
"Gorgonopsians are more closely related to mammals than they are to any other living animals. They don't have any modern descendants, and while they're not our direct ancestors, they're related to species that were our direct ancestors," said Ken Angielczyk, a paleomammalogist at the Field Museum in Chicago and co-author of the study, as reported by Newsweek.
The fossil remains provide valuable information about the creature's appearance and lifestyle. The gorgonopsian was about one meter long, resembling a medium-sized dog but without fur or canine ears. "If you saw this animal walking down the street, it would look a little bit like a medium-sized dog, maybe about the size of a husky, but it wouldn't be quite right," Angielczyk said.
One of the most distinctive features of the gorgonopsian was its long, saber-like canine teeth, which suggest the animal was a top predator in its ecosystem. These saber teeth made gorgonopsians among the first animals to adopt a predation strategy using long fangs. "It was the first opportunity to have this type of tool to prey on herbivores," Fortuny said, according to New Scientist.
The discovery is also notable because gorgonopsians were previously thought to have inhabited primarily high-latitude regions such as Russia and South Africa. The finding in Mallorca, which was part of the supercontinent Pangaea and located near the equator during the Permian period, challenges this understanding. "The origin of the line that gives rise to mammals is found in more tropical and arid environments than we suspected," Fortuny said, according to El Confidencial.
The fossils also reveal insights into the locomotion of the gorgonopsian. The animal had limbs positioned more vertically under its body, allowing for more efficient movement, especially when running. This arrangement is considered a transitional stage between the locomotion of primitive reptiles and modern mammals.
During the Permian period, Mallorca had a monsoonal climate with alternating very humid and very dry seasons, similar to present-day conditions in Southeast Asia. The site where the remains were found was a floodplain with temporary ponds and lagoons, where gorgonopsians and other fauna came to drink and feed. An ancient group of herbivorous reptiles, such as the tramuntanasaurus discovered earlier at the same site, was probably among the animals that the gorgonopsian preyed upon.
The study was published in the journal Nature Communications and involved an international team of researchers, including participation from institutions such as the North Carolina Museum of Natural Sciences, Princeton University, and the Field Museum of Chicago.
"Before the time of dinosaurs, there was an age of ancient mammal relatives," Angielczyk said, according to Interesting Engineering. "Most of those ancient mammal relatives looked really different from what we think of mammals looking like today. But they were really diverse and played lots of different ecological roles. The discovery of this new fossil is another piece of the puzzle for how mammals evolved."
This article was written in collaboration with generative AI company Alchemiq