Latest Maastrichtian species-rich rudist associations of the Apulian Margin of Salento (S Italy) and the Ionian Islands (Greece)

Numerical ages have been derived from the 87Sr/86Sr values of well-preserved rudist shells from localities in Salento (S Italy) and Lefkas (Ionian Islands, Greece). Samples are from the platform margin (Salento) and from the toe of slope (Lefkas) of the former Apulian carbonate platform. Rudists from both localities yielded a latest Maastrichtian age (66.4 Ma), and their rudist associations are the most species-rich so far reported from the Mediterranean region so close to the Cretaceous–Paleogene (K–P) boundary. The abundance of largesize recumbent morphotypes of a taxon similar to Pseudosabinia is remarkable. Generally, the latest Maastrichtian rudist morphotypes of the Caribbean and of the Mediterranean region are very similar, although the faunas are highly endemic on the genus level. When compared to the Turonian–Campanian, the increased abundance of aragonite in the shells of the dominant rudist taxa, and the higher abundance of other originally aragonitic skeletal components, is discussed with respect to the major-ion composition of Cretaceous seawater. The now well-documented existence of species-rich rudist associations on both sides of the Atlantic argues for a catastrophic rather than a gradual extinction of the group.