MORPHOMETRIC COMPARISON OF PREHISTORIC AND MODERN CERION AT PIGEON CREEK SITE, SAN SALVADOR, BAHAMAS

Cerion glans, the land snail, is found in abundance on San Salvador Island, Bahamas. At Pigeon Creek (SS1) site, a large number of C. glans shells have been found buried in the coastal dunes. C. glans shells have been recovered from archaeological excavations conducted over the past 35 years. The Pigeon Creek site was a settlement of the Lucayans, the indigenous people of the Bahamas. Although currently, no living C. glans have been found on the surface of the dunes, their empty shells litter the ground. A contemporary population of Cerion lives at the intersection of Fortune Hill Road and Queen’s Highway, north of the Pigeon Creek site. Part of this paper is a comparative study of the morphometric characteristics of the C. glans shells found between Dune 1 and Dune 2 of the Pigeon Creek site, and the living C. glans population found at Fortune Hill Road and Queen’s Highway. This paper also seeks to discover whether Lucayan activity, as an anthropogenic agent of natural selection on the dunes, disrupted the C. glans’s population and successional history, as found in the sedimentological record.

Previous studies have demonstrated that population differences can be ascertained by size, so I conducted a morphometric study of 664 C. glans shells. I recorded seven measurements on each shell using a digital caliper. These measurements were shell height, shell width, aperature height, aperature width, fourth whorl height, fourth whorl width and total number of whorls. I used Principal Component Analysis to compare and contrast C. glans by location from the archaeological excavation units at the Pigeon Creek site (Dunes 1 and 2), Fortune Hill/Queen’s Highway (living population), and a modern collection on the surface of the dunes at the Pigeon Creek site (modern population). To analyze the possible Lucayan influence as a natural selection agent on C.glans, I divided the sedimentological record into sterile dune, cultural (i.e. archaeological), surface and living. My results indicated that between locations, the C. glans differed only slightly and that varying microclimatological conditions on the eastern side of the island may be the cause. Within the sedimentological record, the results of my PCA analysis indicate that there have been no species or population changes through time.