Early Cretaceous non-marine ostracods from the Recôncavo Basin, Northeast of Brazil

Abstract

The Early Cretaceous chronostratigraphic positioning of the northeast Brazilian basins is mainly based on ostracod distribution, including a biozoning proposal of local stages. The ostracod species were recovered from shales and siltstones samples along Gameleira, Manguinhos and Praia da Falha outcrops of the Maracangalha Formation (Recôncavo Basin). In the analyzed samples, six genera were recognized, out of a total of 1036 specimens. The non-marine ostracod fauna consists of the species Cypridea lunula Krömmelbein, 1962, Cypridea ellipsoidea Krömmelbein and Weber, 1971, Cypridea aff. C. vulgaris Krömmelbein, 1962, Cypridea sp. 1, Cypridea sp. 2, Cypridea sp. 3, Cypridea spp., Reconcavona? polita Viana, 1966, Reconcavona sp., Ilhasina amphotera Krömmelbein, 1963, Ilhasina sp. aff. I. remanei cuneiformis Krömmelbein, 1963, Ilhasina sp., Candona? condensa Krömmelbein, 1962, Brasacypris sp. and Alicenula sp. The biochronostratigraphic position of the Manguinhos outcrop in the Rio da Serra Stage (Berriasian–Valanginian) was possible through the identification of the guide species Reconcavona? polita, index in subzone RT-004.2. In the Praia da Falha outcrop the faunal association suggests an age range between the late Rio da Serra to Aratu Stage (Valanginian-Hauterivian), through the recording of the species Ilhasina amphotera and Cypridea lunula.