There are rudists in Brazil! Derived examples of cf. Amphitriscoelus Harris and Hodson, 1922, in the Araripe Basin, north-east Brazil: Implications for dating of the fossil Lagerstätten of the Santana and Crato formations

Abstract

Internal moulds of rudist bivalves from the basal Exu Formation of the western Araripe Basin, northeastern Brazil, are identified as the Early Cretaceous (Barremian to Aptian) radiolitidin caprinuloideid genus cf. Amphitriscoelus Harris and Hodson. The rudists occur as part of a sparse assemblage of remané fossils in the Exu Formation, a fluvial sandstone resting disconformably on the Santana Formation of the Araripe Group and are likely to have been derived from the shallow marine upper parts of that formation. The presence of caprinuloideid rudists in the Exu Formation suggests that the underlying Santana Formation can be no younger than lower Aptian. These are the first rudist bivalves found in Brazil and are the furthest south occurrence of caprinuloideid rudists, confirming suspected faunal links for the Araripe Basin with the Caribbean province of the Tethyan realm.