PLATE TECTONICS AND MARGINAL MARINE OSTRACODA

Marginal and shallow marine ostracode taxa are unsurpassed as paleogeographic indicators because of their low potential for dispersion, particularly across deep-water barriers, and are thus useful for deciphering evolving plate tectonic configurations. The Mesozoic breakup of Pangea offers an excellent setting in which to relate the Earth processes of plate tectonics to biological evolution.

The Late Cretaceous ostracode fauna of North America extends from New Jersey to Texas. The Late Cretaceous faunas of South America are completely different than those of North America. Cuba was selected for study because of its paleogeographically intermediate position between the rifting North and South American faunal realms.

Samples were collected during a reconnaissance trip to Cuba. Ostracodes were observed rarely, due mainly to diagenesis and harsh paleoenvironmental conditions (including high rates of sedimentation associated with the tectonically-active island arc setting). Planktonic foraminifera indicate the samples are of Campanian and Maastrichtian age.

Essentially all of the ostracodes collected from Cuba are undescribed, and most species cannot be readily assigned to any known genera. Only one species, Schuleridea cf. S. travisensis, was a recognized as a North American species, and none were recognized as South American species. Only four other species can be assigned to described genera, which are Amphicytherura, Brachycythere, Paracypris, and Cytherelloidea. Each of these genera is known to occur widely. Most of the Cuban faunas include sighted ostracodes, indicating relatively shallow marine conditions. These observations indicate that faunal barriers existed between North America, Cuba and South America during the Late Cretaceous.