Morphometric and taphonomic analysis of granular ark (Anadara granosa) dominated shell deposits of Blue Mud Bay, northern Australia

Abstract

Metrical analyses of complete mollusc shells have commonly been used to examine aspects of prehistoric mollusc demography, and by extension to investigate potential human exploitation of a variety of species. Recently it has been highlighted that several taphonomic processes, such as fragmentation, have the potential to introduce size bias into these archaeological samples, particularly towards smaller size classes, and thus the potential to significantly skew results of these metrical analyses. This is investigated here by deriving morphometric equations for the sand/mudflat bivalve Anadara granosa, a species prevalent in archaeological sites across northern Australia. A linear regression model based on a series of valve measurements, resulting in high coefficients of determination, demonstrates strong predictive power for size reconstruction. The effects of fragmentation on assemblages from two case study sites are then examined as a means of reviewing issues of differential size preservation, variation in mean valve size, and evaluating the strength of previous interpretations of intensive human exploitation in Blue Mud Bay. Based on these analyses it appears that A. granosa mean size is not significantly affected by fragmentation as other species described in the literature, and previous interpretations retain their validity. © 2010 Elsevier Ltd.