PALEOECOLOGICAL SIGNIFICANCE OF A TURRITELLINE GASTROPOD-DOMINATED ASSEMBLAGE IN THE CRETACEOUS OF SOUTH-CAROLINA

Blocks of sandy limestone dredged from the bottom of a quarry in eastern Lee County, South Carolina, contain a turritelline gastropod-dominated macrofossil assemblage, including age-diagnostic Maastrichtian ammonites. Although turritelline-dominated assemblages are common in other areas and ages, this is the first report of such an assemblage of any age from South Carolina and the first Cretaceous turritelline-dominated assemblage from eastern North America. Whereas the matrix of the turritelline layer is calcareous, the carbonate is present only as cement and the fossil assemblage did not form in a typically carbonate-dominated environment. This fact agrees with the observed absence of ''turritella limestones'' in the Cretaceous. Such limestones are common in the Paleogene but absent in the Neogene. This pattern is consistent with the hypothesis that turritellines as a group have become less thermophilic since the Cretaceous.