Aptian ostracods from the Santana Group, Araripe Basin, Brazil

Abstract

The Class Ostracoda provides a well preserved and diverse microfossil succession throughout the Aptian Santana Group, Araripe Basin, Brazil. The Santana Group, consisting of the Barbalha, Crato, Ipubi and Romualdo formations, records the post-rift sequence (Alagoas local stage) of the Gondwana break-up. The Alagoas Stage is characterised by ostracods grouped as Cytheridea? spp. 201–218 of which several have been identified as belonging to Pattersoncypris Bate and Damonella Anderson. From 2 well cores and 10 outcrops of the Santana Group, 25 taxa were identified, 5 of which are here newly described. Throughout the Santana Group, Pattersoncypris micropapillosa Bate and Damonella grandiensis Tomé, Lima Filho and Neumann were recovered. Restricted to the Barbalha Formation, Candonopsis? alagoensis Tomé, Lima Filho and Neumann and Pattersoncypris cucurves nov. sp are abundant. The Crato Formation shows higher ostracod diversity with Damonella grandiensis being the most abundant and associated with Cypridea araripensis Silva, Brasacypris subovatum Do Carmo, Coimbra, Whatley, Antonietto and Citon, Damonella pumila nov. sp., Pattersoncypris alta (Antonietto, Gobbo, Do Carmo, Assine, Fernandes and Silva), Zonocypris berthoui Piovesan, Melo, Cabral and Guzmán, Zonocypris dorsoconvexa Piovesan, Melo, Cabral and Guzmán, Ilyocypris coimbrai nov. sp., Neuquenocypris berthoui Colin and Dépêche, Neuquenocypris sp., Rhinocypris spinata nov. sp., Theriosynoecum silvai (Silva), Theriosynoecum sp., Timiriasevia? sp. and Alicenula martinsi (Silva). The Ipubi and Romualdo formations record abundant Pattersoncypris crepata (Do Carmo, Coimbra, Whatley, Antonietto and Citon) in association with P. alta, Pattersoncypris kroemmelbeini nov. sp., P. symmetrica (Krömmelbein and Weber) and Alicenula martinsi (Silva). Theriosynoecum colini Do Carmo, Coimbra, Whatley, Antonietto and Citon, Ilyocypris coimbrai nov. sp. and Rhinocypris spinata nov. sp. also occur in the Ipubi Formation.