A Berriasian actinopterygian fauna from Cherves-de-Cognac, France: Biodiversity and palaeoenvironmental implications

The paleontological site of Cherves-de-Cognac (Charente, southwestern France) is an 81-levels sedimentary series, which records deposits from a coastal lagoon to a continental lake, reflecting the general regressive context of the Upper Jurassic-Lower Cretaceous. This site has yielded a rich and diversified vertebrate fauna from the Lower Cretaceous, including numerous actinopterygian remains described here. Cranial bones and scales have been found as macro-remains during excavations, and are all referable to the ginglymodian Scheenstia mantelli. In parallel, an important program for extracting and sorting vertebrate dental micro-remains from the 63 fossiliferous levels of the series, has led to a collection of more than 26,000 actinopterygian isolated teeth. Among these specimens, eleven tooth morphotypes can be distinguished. Tooth morphotypes 1 and 2 are the more commonly found and are identified as respectively “oral” and “pharyngeal” teeth of S. mantelli. Tooth morphotypes 3 to 5 are less frequent and referred to Caturus sp., Belonostomus sp. and Thrissops sp. respectively. Tooth morphotypes 6 to 11 correspond to Pycnodontiformes morphologies, morphotype 6 being the most represented in the sedimentary series after morphotype 1. Review of known ecologies of these taxa, together with palaeoenvironmental data available for the site of Cherves-de-Cognac, indicate a fresh to brackish life environment for S. mantelli and Pycnodontiformes.