Les empreintes de dinosaures du Jurassique inférieur de Peyre (Aveyron, France) : fouille récente et nouvelles données ichnologiques révélées par imagerie 3D

Abstract

At the end of the 20th century, dinosaur footprints were discovered at Peyre, in Aveyron (Causses Basin, southern France). At that time, the tracksite was limited to a single fossiliferous surface bearing a dozen of Lower Jurassic footprints. Recent excavations (2022–2024), led along a 23 m thick stratigraphic section revealed six additional track-bearing surfaces. Dinosaur tracksites showing such a high density of track-bearing surfaces along such a short section are uncommon in the fossil record and extremely rare in the Causses Basin. Today, the tracksite displays 126 footprints some of which reach 49 cm in length. Tracks are preserved in situ as concave epireliefs on the surface of dolomitic beds. Some footprints are well-preserved, showing details of digit, pad and claw marks. The excavation and 3D modelling by photogrammetry revealed several morphologies of tridactyl footprints. Biometric analyses combined with photogrammetric imaging indicated the co-occurrence of three ichnotaxa: Eubrontes giganteus, Grallator variabilis and Kayentapus isp. The high density of footprints unidirectionally oriented suggests repeated passages of theropods whose migrations were restricted by local physical barriers (coastlines, topography). Tracks are preserved in dolomite with cryptalgal laminites, mud cracks and ripple marks. The depositional environment is interpreted as a tidal flat periodically flooded then emerged.