Palaeontology, taxonomic revision and variability of some species of the genus Gassendiceras Bert et al., 2006 (Ammonitina, Upper Barremian) from southeastern Franc

Abstract

Abstract Bed-by-bed sampling of twelve Barremian sections in southeastern France from pelagic basin (Vocontian Basin) to neritic platforms (Arc of Castellane, Arc of Nice and Provencal Domain) has enabled the collection of isochronous samples of the ammonite genus Gassendiceras. Three poorly known species of the Toxancyloceras vandenheckei Zone (Upper Barremian) are revised: G. alpinum, G. multicostatum and G. hoheneggeri; two new species are described (G. rebouleti nov. sp. and G. bosellii nov. sp.). The intraspecific variability of particular species was recognised. This variability is between slender peramorphic and robust paedomorphic extreme morphologies, with the presence of all intermediates.