THE OTHER 82%: INCREASING THE DIVERSITY OF THE WACCAMAW FORMATION

The lower Waccamaw Formation is a basal Pleistocene shelly sand found in southeastern North Carolina and eastern South Carolina. Extensive field sampling and examination of museum collections has produced a near doubling in the number of mollusk species known from the Waccamaw Formation, from 650 to 1150 species. The field sampling has included over 1000 kg of bulk material from a single quarry. This sampling contained 850 species of mollusk, 470 of which were new to the formation, and 300 of which were undescribed. All species have been photographed for documentation. The increased diversity significantly affects assessments of patterns of extinction. Examination of museum collections enables reassessment of published records which do not include illustrations.

Two families are reported for the first time as fossils, Tjaernoeidae and Alacuppidae. Higher taxa with the most dramatic rise in number of species known from the formation include Eulimidae, Marginellidae, Conoidea, Pyramidelloidea, and Galeommatoidea. This study has also found many temporal and geographic range extensions of species previously only known from Yorktown, Duplin, Jackson Bluff, Pinecrest, Caloosahatchee, and recent faunas. Most species found do not exceed 12 mm in maximum dimension. The fauna of the site reflects a warmer, more stable climate than the present. The recent fauna with which it shares the most species is South Carolina to North Florida, somewhat south of the site, with about 150 species overlapping. The fauna represents habitats ranging from still freshwater and riverine, to brackish, saltmarsh, beach, and inlet, to mid-shelf cementing bivalve reef and sandy shell hash.