DIAGENETIC EVOLUTION OF MAMMAL BONES IN 2 FRENCH NEOLITHIC SITES

The diagenetic evolution of bones of different mammal species from two French Neolithic sites (around 4,000 BC), Louviers (Eure) and Bercy ( Paris), has been studied using different approaches. Global carbon and nitrogen content of bone powders were a good proxy for collagen conte nt; delta(13)C values of whole bone carbon have been used to detect th e presence of humic contaminants; thin sections were investigated to d etermine the stare of preservation of histological structures and to d etect staining and microbial alterations. Collagen has been extracted and its yield and C/N ratio have been measured. Both sites are located on the edge of palaeochannels, and bones were recovered from differen t burial environments. Comparison of the diagenetic alteration in thes e different depositional environments demonstrates that different mech anisms are involved and lead to very different states of preservation of the histological structures and of the collagen. The results of thi s study suggest that such sites may be a useful model to understand th e early diagenetic alteration stages of much older palaeontological bo nes deposited in fluvial environments.