Les ammonites du Toarcien de Chantonnay (Vendée, France) : analyse paléontologique, biostratigraphie et réflexion sur les Hildoceratinae

Toarcian ammonites from the Chantonnay section (Vendée, France) are analyzed (taxonomy and biostratigraphy). This section supplements a nearby one published by Gabilly (1976a, b). Shape variability and evolutionary patterns of species of the genus Hildoceras Hyatt, 1867 are discussed and compared with the faunas described here. Previously published phylogenetic reconstitutions for the Hildoceratinae are analyzed and criticized. It appears that authors use both morphological and stratigraphic arguments when attempting phylogenetic reconstitutions. We suggest that it would be preferable to base phylogenetic reconstitutions on morphological arguments alone.