The Grande Coupure in Southern France

Investigating fossil layers in the Luberon – With Pauline Coster

Oligocene fossil tracks in the Luberon

Understanding the climatic drivers of late Paleogene European faunal turnover

The Grande Coupure corresponds to a major episode of faunal turnover around the Eocene-Oligocene boundary: the disappearance of endemic Eocene animals in western Europe and the appearance of new Asian immigrants, including the ancestors of modern families of rodents and ungulates. The European paleontological record indicates that the Grande Coupure is synchronous with the Oi-1 glaciation 33.5 million years ago, the most dramatic episode of ice-sheet growth, sea-level drop, and global cooling associated with the fall into the Oligocene Icehouse. The sea-level drop would have favored landmass connectivity, dried out part of the epicontinental seaways separating Europe and Asia, and favored the westward dispersal of Asian mammals; climatic deterioration and competition following the dispersal would have caused the extinction of the European fauna.

This simple story of dispersal controlled by sea-level and climate change has been challenged in recent years in multiple ways. Paleogeographic studies have shown that the Turgai Strait, connecting the Arctic Sea to the Paratethys and frequently proposed as the main biogeographic barrier between Europe and East Asia during the Paleogene, completely dried out by 37 Ma, well before the Oi-1 glaciation, and experienced earlier events of closure. Paleoenvironmental studies have shown that the Oi-1 glaciation had a dramatic effect on Asian ecosystems but had only a weak impact in Europe.

Most of the sites where the Grande Coupure is defined in southern Europe are still poorly dated and have been barely investigated since the early XXth century. This project aims at revisiting historical paleontological sites in one of the places where the Grande Coupure was originally studied, in the Parc Naturel Régional du Luberon of southern France. Our goal is to precise the timing of the faunal turnover and study the evolution of continental ecosystems associated with the changing fauna, in order to highlight how and when environmental changes took place. This work uses magnetostratigraphic and geochronological proxies for dating, and combines paleontology with paleobotanical, sedimentological and geochemical tools to reconstruct past environments.

Collaborators: Pauline Coster (Parc Naturel Régional du Luberon), Anaïs Boura & André Néel (MNHN, Paris), Séverine Fauquette (Université de Montpellier), Alexis Nutz (CEREGE), Mustafa Kaya (METU, Ankara).

This project was started in 2021 and has not been featured in any publication yet. Nine minutes on this French radio podcast are dedicated to our work in the Luberon (in French).