Fossocytheridea Swain & Brown and Perissocytheridea Stephenson (Ostracoda): insights into paleosalinity gradients of Late Cretaceous deposits from Brazil and Portugal

Fossocytheridea Swain & Brown and Perissocytheridea Stephenson are genera characteristic of brackish water environments. In 51 samples from the Santonian-Campanian, from the well 9-MO-13-RN, Potiguar Basin, Brazil, Fossocytheridea potiguarensis Piovesan, Cabral & Colin, Fossocytheridea POT 1 Piovesan, Cabral & Colin and Perissocytheridea jandairensis Piovesan, Cabral & Colin have been identified. In the Sao Joao das Lampas section (middle Cenomanian), Lusitanian Basin, Portugal, 25 samples were studied and Fossocytheridea merlensis (Babinot & Colin) and Perissocytheridea estribeirensis Andreu have been recognized. The distributional pattern of the Fossocytheridea-Perissocytheridea assemblage, combined with analysis of the abundance and diversity of marine ostracodes, suggests that in the Late Cretaceous Fossocytheridea and Perissocytheridea were euryhaline genera, and that the tolerance to salinity gradients is related to the ecology of each species and not strictly to that of the genus.