Cenomanian–Turonian (Cretaceous) heterodont bivalves from the Sergipe Basin, Brazil

Fifty heterodont bivalve species, belonging to 35 genera, 15 families and six orders, from the Cenomanian–Coniacian Cotinguiba Formation of the Sergipe Basin, north-eastern Brazil, are systematically described and figured. Thirty-three species are recorded from the basin for the first time. The new species Callucina (C.) itaporangensis sp. nov. from the lower Cenomanian is characterised by its heart-shaped to sublanceolate and slightly asymmetric lunule, narrow, shallow and elongated escutcheon, widely spaced commarginal ribs crossed by faint radial striations, rod-like anterior adductor muscle scar (separated ventrally from the pallial line) and straight postero-dorsal and posterior margins with an angular junction. The fauna shows little endemism, which indicates that the larvae were long-lived and possessed a high dispersal potential. The fauna occurred across a wide geographic area, from the Middle East, northern Africa and southern Europe to western Africa and the Pacific rim of South America, with some taxa also known from India. The biogeographic pattern suggests that many groups migrated via the trans-Saharan seaway, which connected the southern Tethys with the incipient South Atlantic Ocean.