Recent study revealed a high correlation potential of inoceramid bivalves across the Campanian Maastrichtian (Upper Cretaceous) boundary within the Euroamerican biogeographical region. In inoceramid terms the Campanian/Maastricthian boundary as currently defined, lies in the topmost part of the "Inoceramus" redbirdensis Zone, close to the base of the Endocostea typica Zone. Both zones, as well as the whole late Campanian and early Maastrichtian inoceramid succession is well recognisable across the European sections and across the Atlantic to the US Western Interior succession.