They discover the oldest ancestor of mammals in the world

Scientists have identified and described a fossil animal that lived between 270 and 280 million years ago in modern-day Mallorca, one of the Balearic Islands. The find is exceptional not only because of the amount of fossil remains located but also because it is the oldest known gorgonopsian on the planet. Gorgonopsians are the lineage that would end up giving rise to mammals.

The work has been carried out by an international team led by the Miquel Crusafont Catalan Institute of Paleontology (ICP) and the Balearic Museum of Natural Sciences (MBCN).

Gorgonopsians are an extinct group of synapsids that lived during the Permian period between 270 and 250 million years ago. They belong to the evolutionary line that gave rise to the first mammals 50 million years later. They were warm-blooded animals like modern mammals, but, unlike most of these, they laid eggs. They were carnivores and were the first animals to develop the characteristic saber teeth. They were often the top predators of the ecosystems where they lived and their appearance must have been similar to that of a dog, but without ears or hair.

The remains found in Mallorca belong to a small-medium sized animal, approximately one meter in length, and come from a paleontological site located in the municipality of Banyalbufar (Serra de Tramuntana, Mallorca). Excavation tasks were carried out in three different campaigns during which a large amount of material was unearthed. “The large number of bone remains is surprising. We have found everything from skull fragments, vertebrae, ribs, to a very well preserved femur. Really, when we started this excavation, we never thought that we would find so many remains of an animal of this type in Mallorca,” explains Rafel Matamales, curator of the Balearic Museum of Natural Sciences, associate researcher at the ICP and first signatory of the study.

Recreation of what a typical adult individual of the oldest known gorgonopsian on Earth must have looked like in life. (Illustration: © Henry Sutherland Sharpe)

Its location in the Balearic Islands is an unusual fact in itself. The known remains of gorgonopsians before the discovery belonged to very high latitudes such as those of Russia or South Africa. Its age has also surprised the authors of the study. “It is, most likely, the oldest gorgonopsian on the planet. The one we found in Mallorca is at least 270 million years old and the other records of this group worldwide are slightly younger,” comments Josep Fortuny, co-author of the study and head from the Computational Biomechanics and Life History Evolution group of the Miquel Crusafont Catalan Institute of Paleontology.

Among the fossil remains unearthed, an almost complete leg stands out, which has made it possible to study how the animal moved. Unlike reptiles, which have a more ancestral locomotion with their legs spread further apart, gorgonopsians had their legs arranged more vertically and, therefore, moved in a way that would be halfway between that of reptiles and of mammals. This system is more efficient for walking and especially running.

The saber teeth that have been unearthed confirm their diet. “We know that it is a carnivorous animal, a characteristic that gorgonopsians share throughout the world. Saber teeth are a common feature in large predators in ecosystems, and the one we have found was surely the same in the environment in which it lived,” highlights Àngel Galobart, ICP researcher and director of the Conca Dellà Museum.

When Mallorca was not an island

During the Permian, approximately 270 million years ago, Mallorca was not an island, but was part of the supercontinent Pangea. It was located at an equatorial latitude, where today you can find countries like the Congo or Guinea. The climate was monsoonal, alternating wet seasons with very dry seasons. It is believed that the site where the fossils were found was a floodplain with temporary pools where gorgonopsians and the rest of the fauna drank. Among the animals that cohabited in this ecosystem are moradisaurin captorhinids, an ancient group of herbivorous reptiles to which the well-known Tramuntanasaurus tiai belongs, which perhaps was part of the gorgonopsians’ diet.

Despite the small area they occupy, the Balearic Islands have an exceptional fossil record. The most studied and known fossils are those from the Pleistocene and Holocene. However, the fossil record from other periods is much more unknown. Despite everything, notable fossils have been found, such as that of the oldest mosquito in the world, nearly a thousand species of ammonoids (cephalopods related to squid), ancestors of horses and hippopotamuses, giant sharks and large coral reefs.

In addition to Matamales, Fortuny and Galobart, Eudald Mujal, a researcher at the SMN (Staatliches Museum für Naturkun) in Stuttgart (Germany), Tiago Simões, from Princeton University (USA), Christian Kammerer, from the North Carolina Museum of Natural Sciences (USA) and Kenneth Angielczyk, Field Museum of Natural History (USA). The study has had the support of the project “Mallorca abans dels dinosaures: estudi dels ecosystemes continentales del Permià i Triásic amb especial èmfasi en les restes de vertebrats” of the Catalan Institute of Paleontology Miquel Crusafont.

The study is titled “Early–middle Permian Mediterranean gorgonopsian suggests an equatorial origin of therapsids.” And it has been published in the academic journal Nature Communications. (Source: Catalan Institute of Paleontology Miquel Crusafont)