Comparison of Gulf Coast Late Jurassic Ostracoda with Those of Western Europe: ABSTRACT

Abstract

More than 30 genera of Ostracoda are represented in the Upper Jurassic rocks of the central Gulf region, United States. Most of these occur in the Schuler Formation, Dorcheat Member (Portlandian-Tithonian). About 12 of the genera are of European origin and, of these, several (e.g., Nophrecythere, Galliaecytheridea) began in earlier Late Jurassic or in Middle Jurassic of the European province. Emigration to the Gulf of Mexico region probably occurred around the northern margin of the opening Atlantic Ocean. About 10 of the other Jurassic ostracode genera were endemic to the northern Gulf of Mexico or the western Atlantic. Most of these remained in those areas, some extending into the Cretaceous. Only a few Gulf forms, particularly Hutsonia and Paraschuleridea dispersed sparsely eastward to Europe. Schuleridea, which became abundant on both sides of the Atlantic, may have migrated eastward from the Gulf region in the Oxfordian or Kimmeridgian, as indicated from occurrences in offshore wells in the western Atlantic where it is associated with index foraminifera. End_of_Article - Last_Page 791------------