Early bioerosion in skeletal tissues: persistence through deep time

Abstract

Microbial bioerosion is an important factor in the long-terms survival of vertebrate skeletal remains and in the quality of any preserved biological information contained within them – e.g. genetic, isotopic or trace element evidence. Over the past two decades there has been a dramatic improvement in our understanding of the diagenetic changes experienced by ancient bones and the impact of those changes on preserved information, although the identity of the organisms responsible for microbial degradation remains something of a mystery. Because of the long timescales involved, the damages seen in bones excavated from archaeological and fossil sites have proved difficult to replicate in the laboratory. Field experiments in a tropical location (Taiwan) have successfully replicated the early stages of many of the features seen in genuinely ancient bones and these changes can be linked to specific burial environments. These key diagenetic signatures are shown to persist in fossil bones over millions of years and can be identified in electron microscope images of histological sections. Thus, investigation the histology of fossil bones using backscatter electron microscopy (BSEM) is a useful addition to other techniques, e.g. rare earth element analyses, in understanding the diagenetic histories of fossil assemblages.