MOLECULAR SCALE PRESERVATION OF BONE DURING EARLY DIAGENESIS

Fossils are a tangible record of the history of life on Earth, but physical and chemical alterations that occur to organisms between death and discovery can complicate interpretations about biology and ancestry. Taphonomy, the study of how organisms decay and preserve, also seeks to understand what biological information can withstand decay. Weathering stages categorize the physical and chemical breakdown of bones at the morphological scale during early diagenesis (i.e., in the early postmortem surface environment, prior to burial). And as new technology is incorporated into taphonomic studies, we can begin to consider early molecular alterations that impact interpretations of biomolecules (e.g., proteins) that may survive to be present in fossils. Here, we examine the molecular taphonomy of a single individual – the focus of the longest taphonomic experiment of a vertebrate in a natural setting to date – using the 6 weathering stages of morphological degradation for context. One bone from a cow carcass was collected each year for 15 years from Amboseli National Park, Kenya. We applied bottom-up proteomics to correlate morphological and molecular scale preservation and to examine early protein changes and diagenetic modifications. We found that protein loss happens very quickly, but even the most degraded looking bone still preserves collagens. We also evaluated the presence of protein modifications that occur postmortem to consider correlations between age and morphological decay.