LACK OF EVIDENCE FOR MOLLUSCAN GENUS-LEVEL DIVERSITY DECLINE ACROSS THE REPUTED MULTI-PHASED PLIO-PLEISTOCENE MASS EXTINCTION IN SOUTHEASTERN NORTH CAROLINA?
When rarefied to 1440 specimens, expected genus-level richness for bivalves from the 2010 lower Waccamaw sites is high (Neils Eddy = 48, Holloman = 51.9). The 95% confidence intervals (CI) overlap with that of our most diverse sample, the Duplin on the Lumber River (Lumberton, NC; 56.7 genera). Bivalves at Acme are less rich (44.2 genera), but when rarefactions are run excluding the dominant genus the Acme sample becomes statistically equivalent to the Lumber River Duplin. Rarefied richness of the Duplin at Robeson Farm (40.5) is significantly less than the Lumber River Duplin (though greater than the Natural Well Duplin) but 95% CI overlap with those for Acme. In contrast, Robeson Farm gastropod richness (rarefied to 100 specimens) is not significantly different from that of previously studied Duplin sites (22-24 genera); however, the lower Waccamaw at Acme (with and without dominants) and Holloman also overlap in 95% CI with the Duplin samples. The data fail to support a significant decline in richness between the Duplin and lower Waccamaw in southeast North Carolina, though previously studied upper Waccamaw bivalves and gastropods from Shallotte, NC, are significantly less rich (~37 and 8 rarefied genera respectively) than the lower Waccamaw.