TAPHONOMY AND DIVERSITY OF MOLLUSCAN FAUNAS FROM THE LOWER WACCAMAW FORMATION AT PRINCE'S QUARRY IN SOUTHEASTERN NORTH CAROLINA

Students in a paleontology class at Georgia State University examined molluscan assemblages from the lower Waccamaw Formation at Prince’s Quarry as part of a broader study on episodes of extinction in marine faunas across the Plio-Pleistocene. The entire class participated in sample processing by sieving, sorting, picking, and identifying over 1650 specimens for paleoecological research. Only specimens >5mm with intact umbos (bivalves) and apices (gastropods) were retained for study. Shells were divided into “whole” specimens (if ~85% of the shell remained) and fragments. Taxa were categorized at the genus level and “whole” specimens placed in 5mm size bins.

Bivalves were represented by 46 genera and nearly 1500 specimens. Gastropods were represented by 17 genera and over 150 specimens. Plotting of diversity curves using Holland’s Analytic Rarefaction program revealed that additional sampling is not needed to capture the genera that make up the majority of individuals at Prince’s Quarry. Ten genera (Glycymeris, Plicatula, Lirophora, Chama, Caryocorbula, Pecten, Pleuromeris, Arcinella, Anadara, and Diplodonta) made up almost 80% of all bivalves. Five genera (Olivella, Crepidula, Conus, Prunum, and Turritella) made up over 80% of all gastropods. Most bivalve and gastropod genera were documented only by a few specimens. Other fossils recorded from this sample included the remains of corals, bryozoans, barnacles, crab claws, sand dollars, sea urchin spines, serpulids, and shark teeth.

Many genera were represented by both “whole” and fragmented shells; however, several genera were reported exclusively as either “whole” or fragmented. Over 80% of all bivalves were marked as “whole” compared to 60% of gastropods. Taxa that were limited to fragmented pieces comprised 9% of bivalves and 12% of gastropods. Genera in which only “whole” specimens were observed included 41% of bivalves and 29% of gastropods. The distribution of size classes for all “whole” specimens indicated that 95% of shells were <30mm. Data on additional rare genera and several small specimens have yet to be incorporated into this work, but once complete, our results will be used in comparison to other localities in the region for examining changes in molluscan faunas through the Plio-Pleistocene.