TAPHONOMY OF SCAPHOPOD ASSEMBLAGES FROM SHALLOW-WATER, CARBONATE ENVIRONMENTS OF SAN SALVADOR, BAHAMAS
A total of 20 bulk samples were collected along the northern coastline of San Salvador Island. Dead specimens dominated all samples and live specimens were observed only in those samples in which empty scaphopod shells were common. A total of 891 specimens representing four species from three genera and two orders were identified in the death assemblage. The dead specimens were dominated by two congeneric species: Antalis antillarum and Antalis ceratum. In addition, a few specimens and specimen fragments of Polyschides tetraschistus and Graptacme calamus were observed in some samples. Three of the four species were also found in sympatric live communities (n=57 specimens). The death assemblages were remarkably consistent in relative abundance patterns and high fidelity was observed when comparing death assemblages and live communities at locality levels. In terms of shell taphonomy, fragmentation and loss of color were widespread, whereas bioerosion, encrustation, abrasion were rare, a pattern likely reflecting the specific characteristics of the sampled depositional settings, and not intrinsic taphonomic characteristics of scaphopod shells themselves. In terms of shell ichnology, complete drillholes, most likely of predatory origin, were observed in some specimens of the two most commonly sampled species. Possible repair scars were also observed.
Despite extensive fragmentation, the sampled scaphopod death assemblages yielded numerous identifiable specimens, provided valuable ichnological data, and were highly congruent with concomitant life communities in terms of spatial distribution, taxonomic composition, and rank abundance patterns. These results suggest that the fossil record of scaphopods may be of comparable quality to those of bivalves and gastropods. However, additional case studies are critically needed to evaluate the general validity of patterns reported here.