Maastricthtian ammonite and inoceramid ranges from Bay of Biscay Cretaceous-Tertiary boundary sections

Abstract

New collecting of ammonites and inoceramid bivalves from Cretaceous-Tertiary boundary sections exposed al Sopelana and Zumaya, Spain, and Hendaye and Bidart (Biarritz), France, has led to better understanding of molluscan biostratigraphy in each of these coastal exposures. Ali of these sections can be lithologically correlated. At all of the sections, ammonites have now been found within the last meter of the Cretaceous. Also, in all of the sections, inoceramid bivalves disappear near the base A. mayaronensis planktonic foram zone, the only exception being the small, enigmatic bivalve genus Tenuipteria, which ranges up to the Cretaceous-Tertiary boundary.