A NEW LATE CRETACEOUS MARINE VERTEBRATE ASSEMBLAGE FROM ALLISONS FERRY, FLORENCE COUNTY, SOUTH CAROLINA

A late Cretaceous (Maastrichtian) marine vertebrate fauna has been recovered from rocks of the Pee Dee Formation exposed along the west bank of the Great Pee Dee River at Allisons Ferry, Florence County, South Carolina. Some fossils were obtained by surface collecting, but most were recovered through the disaggregation of bulk matrix, either through dissolving limestone samples in dilute acetic acid or soaking clay/shale matrix in household detergent. Resulting concentrates were sorted with a binocular microscope up to 40x magnification, and to date twenty-nine taxa have been identified. These include a mosasuar, six osteichthyans and twenty-two elasmobranchs. Although some species have previously been reported from the Peedee Formation at the Burches Ferry site in Florence County (Lawrence and Hall, 1987), most were heretofore not known to occur in the state. New elasmobranch records for South Carolina include Squatina sp., Cantioscyllium sp., Galeorhinus sp., ?Columbusia sp., Scylliorhinus sp. cf. S. ivagrantae, Squatigaleus sp. cf. S. sulphurensis, Plicatoscyllium derameei, Serratolamna serrata, Hamrabatis weltoni, Rhombodus binkhorsti, Raja farishi, Rhinobatos uvulatus, Texabatus corrugatus, Pseudohypolophus sp., Ptychotrygon vermiculata, Ptychotrygon sp. aff. P. winni, and Dasyatis sp. In addition, five osteichthyans are new records, including Paralbula casei, Anomoeodus phaseolus, Hadrodus sp., Ostraciidae indet., Dercetidae indet. Most of the species listed above have been reported from Texas and North Carolina, and their discovery in SC may therefore not be surprising. However, the SC material provides additional data on the paleoenvironments inhabited by these taxa, as well as the paleobiogeographic ranges for the species.

Further investigation of the vertebrate paleontology of the Peedee Formation will focus on sampling the entire vertical exposure at Burches Ferry as well as at Cains Landing, a site that is geographically between Burches Ferry (older) and Allisons Ferry (younger). Comparison of paleofaunas occurring at each of these sites will provide a better understanding of any changes in marine vertebrate assemblages, laterally (geographically) and vertically (temporally), that occurred during the Maastrichtian.