Paleoenvironmental context and significance of a partial elasmosaurid skeleton from the Albian of Haute-Provence, France

Peggy Vincent (1) , Anne-Sabine Grosjean (2) , Didier Bert (3) , Jorge Ferreira , Baptiste Suchéras-Marx (4) , Guillaume C Suan (5) , Guillaume Guinot (6) , Vincent Perrier (5) , Kévin Janneau (7) , Jean-Michel Brazier (8) , Estel Sarroca (2) , Myette Guiomar (3) , Jérémy E. Martin (5)

1 CR2P - Centre de recherche sur la Paléobiodiversité et les Paléoenvironnements
2 Paleorhodania
3 Réserve naturelle nationale géologique de Haute-Provence
4 CEREGE - Centre européen de recherche et d'enseignement des géosciences de l'environnement
5 LGL-TPE - Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement
6 UMR ISEM - Institut des Sciences de l'Evolution de Montpellier
7 UNISTRA - Université de Strasbourg
8 TU Graz - Graz University of Technology [Graz]

The Early-Late Cretaceous transition (late Albian-early Cenomanian; ~100 Ma) witnessed marked environmental changes and a deep reorganization of the marine fauna. The impact of these environmental and biotic changes on Tethyan marine vertebrates is poorly understood, due to a fragmentary fossil record. Here we report upper Albian marine vertebrate remains, including a partially articulated plesiosaurian skeleton, from a fossiliferous glauconite-rich bed in the Alpes de Haute-Provence, France. The fossiliferous horizon produced a diversified invertebrate fauna including ammonoids and belemnoids. The ammonite fauna is abundant and diversified, indicating the Mortoniceras fallax ammonite Zone. The calcareous nannofossil biomarkers date the bed to the NC10a Zone. The fossiliferous bed consists of glauconitic marls enriched in planktic foraminifera and occurs amongst a monotonous succession of alternating marlstones and limestone beds. The vertebrate fauna consists of chondrichthyans and marine reptiles. Chondrichthyans are represented by five Lamniformes species (dominated by Sphenodus) and comprise predator taxa probably living in open marine temperate waters. The site yielded a large, partial post-cranial plesiosaurian skeleton with articulated elements belonging to an elasmosaurid and representing one of the most complete Albian plesiosaurian specimens known from Europe. The abundance and preservation of the collected fossil remains are best explained by their concentration during a basin-scale episode of very low sedimentation corresponding to a major episode of marine transgression, associated with a lower oxygenation of bottom waters. These findings indicate that the newly 2 discovered fossiliferous bed holds promising clues about the evolutionary history of major groups of marine vertebrates and ammonites near the Early-Late Cretaceous transition.

Mots clés: marine reptiles; southeastern France; Cretaceous; Albian; Réserve Naturelle Nationale Géologique de Haute-Provence; glauconite bed; Konzentrat-Lagerstätte; Plesiosauria

Domaines: Sciences de la Terre; Paléontologie

Peggy Vincent, Anne-Sabine Grosjean, Didier Bert, Jorge Ferreira, Baptiste Suchéras-Marx, et al.. Paleoenvironmental context and significance of a partial elasmosaurid skeleton from the Albian of Haute-Provence, France. Cretaceous Research, 2020, 108, ⟨10.1016/j.cretres.2019.104293⟩. ⟨hal-02358719⟩