Measuring the post-depositional destruction of bone in archaeological assemblages

Post-depositional processes have affected most archaeozoological assemblages, often causing fragmentation or destruction of bone which can vary by assemblage and hamper interpretations of the original element representation (Klein & Cruz-Uribe, 1984, The Analysis of Animal Bones from Archaeological Sites. Chicago: University of Chicago Press.). Prior to performing interassemblage comparisons analysts must first assess the post-depositional destruction for each assemblage. Hammerstone breakage and hyaena ravaging experiments show that compact bones (carpals, tarsals, fibulae) are rarely fragmented, therefore fragmentation of these bones in archaeozoological assemblages should be the result of post-depositional destruction. A "Completeness Index" for compact bones provides a description of the magnitude of post-depositional destruction because the "Completeness Index" is independent of differential fragmentation and transport by bone collectors, and quantification variation between researchers. The efficacy of the "Completeness Index" for showing varing completeness of archaeological bone is demonstrated by comparing two Late Pleistocene archaeological sites in Kenya. When guided by experimental results the "Completeness Index" allows an evaluation of the impact of post-depositional destruction on the two Kenyan assemblages. Published archaeozoological reports must provide a measure of post-depositional destruction or else the usefulness of the data for comparative analysis is compromised.