An exceptionally well-preserved fossil deposit discovered in southern France

A new fossil deposit has been unearthed in the Hérault region thanks to the long-term work of a couple of amateur paleontology enthusiasts, whose discoveries have been studied by an international team involving scientists from the CNRS⁽¹⁾ and the University of Lausanne. With over 400 fossils dating back 470 million years, the Cabrières site near Pézenas bears witness to the closest environment ever observed to the South Pole at that time. This makes it one of the richest and most diverse Ordovician deposits in the world. Its exceptional level of preservation has led to the extremely rare discovery of soft-bodied organisms. In particular, the discovery of a wide range of algae and sponges contributes to a better understanding of their pivotal role in the ecosystem of the period.

These observations cast doubt on the earlier idea of a decline in biodiversity or biological extinction between the Cambrian and Ordovician periods some 485 million years ago. On the other hand, the high biodiversity observed confirms the hypothesis that species migrated to the southern hemisphere as a refuge zone, to escape the excessively high temperatures of tropical zones at that time.

This first study of the site, published in Nature Ecology & Evolution , is the starting point for a research program that will extend over several years, with large-scale excavations followed by in-depth analysis of the fossils using innovative imaging techniques. The aim is to reveal in detail their external and internal anatomy, their kinship relationships and their way of life.

1. Working at the Laboratoire de Géologie de Lyon : Terre, Planètes, Environnement LGL-TPE (CNRS/Université Claude Bernard Lyon 1/ENS de Lyon/Université Jean Monnet) and at the Institut photonique d’analyse non-destructive européen des matériaux anciens IPANEMA (CNRS/Université Paris-Saclay).

Reference

The Cabrières Biota (France) provides insights into Ordovician polar ecosystems. Farid Saleh, Lorenzo Lustri, Pierre Gueriau, Gaëtan J.-M. Potin, Francesc Pérez-Peris, Luká? Laibl, Valentin Jamart, Antoine Vite, Jonathan B. Antcliffe, Allison C. Daley, Martina Nohejlová, Christophe Dupichaud, Sebastian Schöder, Emilie Bérard, Sinéad Lynch, Harriet B. Drage, Romain Vaucher, Muriel Vidal, Eric Monceret, Sylvie Monceret and Bertrand Lefebvre. Nature Ecology and Evolution , February 9.
DOI : 10.1038/s41559’024 -02331-w

Chercheur CNRS

Bertrand Lefebvre

Email Übertrand.lefebvre [at] univ-lyon1.fr

CNRS technical engineer

Pierre Gueriau

E-mail: pierre.gueriau [at] synchrotron-soleil.fr

Press CNRS

Clémence Ribette

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Email : clemence.ribette [at] cnrs.fr