EVOLUTION OF CORAL GENUS STYLOPHORA: RECONSTRUCTING FAUNAL TURNOVER

Prior to about 3 Ma species of the genus Stylophora were among the dominant corals in the Caribbean. As many as 9 different species of Stylophora are known to have inhabited the Caribbean and Western Atlantic during the Miocene and Pliocene (11.6-1.8Ma). By ~1 Ma Stylophora were completely extinct in this region. This extinction coincides with a spike in extinctions that followed a pulse of origination in the region. The combination of origination and subsequent extinction events caused a major faunal turnover and the emergence of the modern assemblage of Caribbean coral species. The turnover has been tied to the closure of the Central American Seaway (CAS) which triggered major physical and chemical changes in the Caribbean. The aim of this project is to use Stylophora to provide some insight and a finer scale resolution into the ecologic impacts of CAS closure prior to the major Pleistocene extinction pulse. Approximately 1500 Stylophora specimens from the Northern Dominican Republic (6.5-3.5 Ma) were morphometrically analyzed. All specimens were placed into morpho-species which were traced strategraphically through the section to determine the pattern of origination and extinction events during the last stages of CAS closure.