New Ostracoda species from an Upper Cretaceous oyster reef, northern Gulf Coastal Plain, U.S.A.

Abstract

This paper describes new species of Ostracoda from Late Cretaceous (late Santonian) oyster reefs of the Eutaw Formation of eastern Alabama. The reefs are composed almost exclusively ofOstrea cretaceaMorton, with rarer occurrences of the oystersExogyra upatoiensisStephenson andLopha ucheensis(Stephenson) and the bivalveAnomia preolmstediStephenson. Total thickness of the reefs is about 30 m, and the reefs are a major topographic feature across most of Macon and Russell Counties, Alabama, a distance of about 60 km. The reefs are interpreted to have been backbarrier sediments deposited under brackish conditions.Eight species of ostracodes are identified, including five new species described herein. The fauna is typically well preserved, and includes males, females, and juveniles. New species includeHaplocytheridea?eutawensis, Antibythocypris dimorphicus, A. nephotrema, Brachycythere asymmetrica, andEocytheropteron mutafoveata.Also discussed and illustrated areCytherella tuberculiferaAlexander,Haplocytheridea renfroensis renfroensisCrane, andFissocarinocythere gapensis(Alexander).