An unequivocally Hemphillian fauna of the Bone Valley type is described from the Manatee County dam site. Three habitats (savannah, stream, and estuary) are present. Sharks are the most abundant; these today range into estuarine and fresh-water streams. If the land has been stable tectonically since at least Miocene, then the sea dropped as low as the level of the Manatee site, 6 feet above present sea level. Evidence of eustatic fluctuations of over 90 feet during Hemphillian time is present. A horse species and a tortoise are reported from the eastern U.S. for the first time, and other genera and species are discussed and described.