Late Cretaceous bivalves from the A 10 exposures in Northern Aquitaine

Abstract

Fifty taxa of Late Cretaceous bivalves, collected between Saintes and Mirambeau during the construction of the A 10 motorway, have been identified. The pectinids, spondylids, limids and oysters are of better preservation and more diverse than the other groups. The faunas of Cenomanian age are from warm temperate to Tethyan seas. The assemblages collected from the Turonian-Coniacian strata are small and not diagnostic. Faunas of Santonian and Campanian age are diversified and the many Plagiostoma and Pycnodonte species indicate an upper shelf environment. These faunas have strong affinities with those from white chalks and other deposits from N.W. Europe. The fauna from the uppermost Campanian (equivalent to the top of the Aubeterre section, stratotype of the Campanian) indicates a much shallower environment and has many elements in common with the fauna from the Maastrichtian stratotype.