ECOLOGICAL AND EVOLUTIONARY PATTERNS FROM PALEOGENE MOLLUSCA OF THE CAROLINAS

The Paleogene molluscan faunas of the carbonate provinces of the Carolinas have several distinctive features, reflecting the regional paleoecology. Several families have a much higher diversity than in coeval Gulf Coast faunas, whereas others appear poorly represented. The high abundance of cypraeids, pleurotomariids, fissurellids, and endolithic bivalves reflects the widespread presence of suitable hardground habitats. High diversity in the Volutidae and Tonnoidea probably reflects the high diversity of prey. The numerous Tethyan elements suggest relatively warm water, although deeper and cooler than in Florida, and amphi-Atlantic circulation. The typically large size of conspecific specimens, in comparison to Gulf Coast material, also reflects environmental differences. Other differences may be taphonomic. As a rule, smaller specimens are harder to obtain and identify from moldic faunas than are larger ones. Additionally, diverse families with many similar species and genera are more difficult to identify from partial molds than are relatively distinctive forms. Nevertheless, some representatives of such taxa are known from the Carolinas. Despite these differences, there are also several similarities with the Gulf Coast fauna, as expected for adjacent faunal regions. Comparison of evolutionary patterns for the two regions reveals both disparate and uniform patterns. Occasionally, regional biases are large enough to produce opposite patterns.