Quantifying shell weight loss in archaeological deposits

Abstract

While a range of physical and chemical taphonomic processes are known to affect archaeological shell assemblages, it has been difficult to directly quantify the effects of these degradational processes on the shell itself. Here the measurements of Anadara granosa shell features are used to derive morphometric equations for estimating expected shell weights. A cubic regression model is developed to this end, based on measurements of all shell elements of complete A. granosa valves, resulting in high predictive power. The morphometric method proposed here therefore allows for the comparison of observed and expected shell weights to determine the extent of weight loss as an indication of these processes. A case study is presented by applying these morphometric equations to a midden assemblage from northeast Arnhem Land to investigate potential bias in shell preservation. This study demonstrates the efficacy of the proposed method, and the need to assess the interaction of different taphonomic processes on a site and species‐specific basis.

Loco or no Loco? Holocene Climatic Fluctuations, Human Demography, and Community Based Management of Coastal Resources in Northern Chile

“…both weights and MNIs has attracted criticism with discussion mostly focused on the validity of such approaches in providing unambiguous measures for the representation of taxa within a given assemblage (see Waselkov, 1987;Erlandson, 1994;Mason et al, 1998;Álvarez et al, 2011;Faulkner, 2011;Habu et al, 2011;Rick and Waselkov, 2015). Glassow, however, stated that "neither MNI nor weight proportions, is a universal unit of analysis for addressing the various questions about human predation on shellfish that archeologists frequently ask" (Glassow, 2000, p. 412).…”

Estudio experimental de alteración térmica sobre exoesqueletos de moluscos marinos (nacella magellanica) y sus implicancias para la interpretación de conjuntos arqueomalacológicos de concheros en patagonia argentina

“…En los exoesqueletos expuestos al calor se genera la alteración de la estructura cristalográfica y la textura. Los restos termoalterados se fracturan más fácilmente y se produce la pérdida de peso debido al daño de la estructura y la pérdida de humedad (Gaffey et al, 1991;Claassen, 1998;Maritan et al, 2007;Faulkner, 2011). Se ha postulado que los cambios microestructurales de las conchas comienzan a observarse aproximadamente a partir de los 200°C.…”

Making the most of fragments: a method for estimating shell length from fragmentary mussels (Mytilus californianus and Mytilus trossulus) on the Pacific Coast of North America

“…However, the occurrence of whole shellfish is rare in most depositional settings (Faulkner, 2011;Muckle, 1985;Wolverton et al, 2010) and this is particularly the case for Mytilus (Ford, 1992;Glassow, 2000). Mytilus survivorship may be further influenced by excavation and post-excavation sample processing (e.g., wet/dry screening, sorting, and curation).…”