In the Oligocene Ashley and Chandler Bridge formations near Charleston, South Carolina, remains of three species of pancheloniid sea turtle are common. In their relative order of abundance, they are Carolinochelys wilsoni, Ashleychelys palmeri, gen. et sp. nov., and Procolpochelys charlestonensis, sp. nov. Unlike the other two Oligocene South Carolina genera, Procolpochelys persisted into the middle Miocene. An isolated skull, referable to the Miocene species Procolpochelys grandaeva, is described here to supplement description of the poorly known skull of the Oligocene species P. charlestonensis. These turtles, all referable to Pancheloniidae, represent an endemic, moderately advanced sea turtle assemblage that occupied the Oligocene coastal waters of the southeastern United States. This tendency toward endemism also is seen in some parts of the co-occurring cetacean assemblage, which included at least two endemic families. Regionally restricted endemic assemblages appear to have been the norm among pre-Miocene pancheloniid sea turtles. It is not until the Miocene that crown cheloniids appear and begin to achieve very widespread to global distributions.

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