Gigantic dog-bears lived in France 12 million years ago

A team of paleontologists describes a new species of large hypercarnivore of the Amphicyonidae family, called dog-bears, from a fossilized mandible isolated in the south of France. Details of the study are published in the journal PeerJ.

A new top predator in France

The Amphicyonidae represent one of the most characteristic groups of predators of past European faunas. They are often colloquially referred to as bear-dogs due to their resemblance to these two cross-breed species. According to the fossil record, these animals first appeared during the Eocene around thirty-six million years before dying out before the end of this era, about 7.5 million years old.

These bear dogs were also ecologically diverse and varied in body mass. Some could weigh only nine kilos, while others imposed much more with more than three hundred kilos on the scale. Their diets also differed. Some were mesocarnivores, while others were hypercarnivores.

The species is here described from a fossilized lower jaw discovered in the Commune of Sallespisse, in the Pyrénées-Atlantiques. The fossil consists of a lower fourth premolar unique. This is a particularly important tooth in the determination of species and genera.

Although this new taxon is close in size to some European Miocene amphicyonids (such as Amphicyon or Megamphicyon), the unique morphology of its tooth, unknown in this clade, allowed the team of researchers led by paleontologist Bastien Mennecart, from Basel Natural History Museum, determined that it was a “new animal” for science. The species is named Tartarocyon cazanavei. This newly identified animal had an estimated body mass of about two hundred kilos and live there is between 12.8 and 12 million years old.

The fossilized jawbone. Credits: Floréal Solé et al. (2022), Peerj.

Why is discovery important?

The Middle Miocene (15.97 – 11.63 Ma) is a period of great interest regarding climate change and the dispersal of fauna in Eurasia and Africa. The Langhian (ca. 15.97-13.65 Ma) encompasses the Middle Miocene climatic optimum, an overall temperature increase of about 5°C, while cooler temperatures set in during the Serravallian (13. 82 – 11.63 Ma).

These events have resulted in significant environmental changes and wildlife renewals and exchanges. Despite the extensive invertebrate fossil record, little is currently known about the faunal connections between the northern and southern part of the Pyrenees range during the Middle Miocene due to a lack of continental salvage remains. Indeed, France was flooded by the sea several times during the Lower and Middle Miocene. Also, the continued uplift of the Pyrenees forming a natural barrier between the Iberian Peninsula and the rest of Europe did not help either.

The last transgression in the Southwest region occurred in the Serravallian (13.82 – 11.63 Ma). This sea has deposited in the region of Orthez, including at Sallespisse, a marine fauna particularly abundant isolated in sandy shell deposits. However, the discoveries of land evolving on the northern edge of the Pyrenees there are thirteen to eleven million years are very rare.

This fossil therefore offers researchers the opportunity to explore the development of European bear dogs in the context of environmental events, some of which we hear today.

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