Statistical analyses of occurrence data based on collections made from scattered Caribbean sections over the past 20 years indicate that turnover occurred in the Caribbean reef coral fauna between the late Miocene and early Pleistocene. The collections have been identified using standardized procedures, and age-dates assigned using high-resolution chronostratigraphic methods. During turnover, ~80% of the > 100 species and 17 of the 41 genera that were living in the Caribbean during the early Pliocene became extinct, and > 60% of the species now living in the Caribbean originated. Turnover involved increased speciation beginning in the late Miocene and ended with a pulse of extinction in Plio-Pleistocene time. Turnover was preceded by faunal collapse during the late Oligocene to early Miocene, and it was followed by stasis during the late Pleistocene to Recent. During these preceding and succeeding intervals, reef development was at a maximum, although reef coral diversity was relatively low. As a consequence of origination preceding extinction during turnover, most modern Caribbean reef coral species originated before the Plio-Pleistocene peak of extinction, under quite different ecological conditions from those in which they have lived over the past million years. The unusual relationship between origination and extinction may have been caused by changes in productivity associated with emergence of the Central American Isthmus, followed by the onset of Northern Hemisphere glaciation.
During turnover, faunal change was stepwise or gradual. Local assemblages consisted of a mix of extinct and living species, which varied in composition but not in richness. Important reef dominants such as Acropora palmata and A. cervicornis arose in the southern Caribbean and appear to have migrated northward. Faunal change took place in shallow exposed environments, before it occurred in deep protected environments that served as refuges. Plio-Pleistocene extinction was selective for corals with small colonies, and resulted in a faunal shift to the large, fast-growing species that dominate Caribbean reefs today.