Upper Maastrichtian bivalve faunas from the Crimea, Maastricht and Mangyshlak

Upper (but not uppermost) Maastrichtian bivalve faunas in the stratotypical Maastrichtian area and in the Crimea are extremely diverse and species rich, and represent a very littoral shallow and warm environment. Uppermost Maastrichtian bivalve faunas and in the Maastrichtan stratotypical area and in the Crimea indícate a somewhat deeper, cooler environment. The Upper Maastrichtian bivalves from Mangyshlak are much less diversified and indícale a cold environment, comparable wilh the "upper shelf" in today's seas.