A SEM-based assessment of bioerosion in Late Holocene faunal bone assemblages from the southern Pampas of Argentina

Abstract

Over the last decades, research on microbial bioerosion affecting archaeological bone assemblages highlighted the fact that this is a significant factor determining the long-term survival of vertebrate hard tissues as well as the quality of the biological information retrievable from them (e.g. isotopic, genetic, histomorphological). In spite of this, information about bioerosion is still scarce or inexistent for most regions around the world. Among the likely causes of this situation are the perceived and factual technical difficulties that surround the implementation of a standard research on this subject. Taking this into account, the aim of this paper is twofold: on the one hand, to describe a protocol for the preparation of bone samples (thick sections) suitable for observation with BSE-SEM that fulfils the criteria of simplicity, low cost and effectiveness; on the other hand, to present and discuss the first results derived from the application of such protocol to artiodactyl bone samples recovered at different Late Holocene archaeological sites from the southern Pampas of Argentina. The obtained results indicate that the implemented technique was effective in terms of providing good quality information at a very low cost as measured from the resources (time and materials) invested. In addition, the results show that a significant part of the analysed specimens exhibit extensive and intensive histological alteration compatible with the action of bacteria, which is unexpected in light of the currently prevailing model about the origin and conditions of the bacterial attack on animal bones in archaeological deposits (i.e. the so-called “endogenous model”).