Side-Necked Turtles (Testudines, Pleurodira) from the Ancient Gulf Coastal Plain of Florida During Middle Cenozoic Megathermals

Abstract

Abstract Fossils from paleocoastal deposits in northwestern Florida represent at least 3 pleurodire taxa. Biochronologic and paleoclimatic correlates suggest that the presence and absence of side-necked turtles in Florida was synchronous with global climatic shifts in the middle to late Paleogene and early Neogene. The oldest pleurodire record in Florida is from the end of the Greenhouse World in the middle to late Eocene, followed by a hiatus of ∼ 11 million yrs during the onset of the Icehouse World in the early Oligocene. Their sojourn in Florida during the latest Oligocene (25–24 Ma) was concurrent with a brief late Oligocene warming (LOW), and a subsequent hiatus in the early Miocene (∼ 24–18 Ma) was contemporaneous with global cooling. Their resettlement and most populous occurrences in Florida during the middle to late Hemingfordian through early Barstovian (∼ 18–15.5 Ma) coincided with the Middle Miocene Climatic Optimum (MMCO), a significant global warming event. Pleurodires are indicators that p...