INFRARED AND ISOTOPIC EVIDENCE FOR DIAGENESIS OF BONE APATITE AT DOS-PILAS, GUATEMALA - PALAEODIETARY IMPLICATIONS

The use of stable carbon isotopic analysis of bone apatite to reconstr uct prehistoric diets is hindered by the possibility of diagenetic alt eration of carbonate during burial. We examine apatite preservation in Classic Period Maya skeletal remains from Dos Pilas, Guatemala, using Fourier transform infrared spectroscopy (FTIR). We use weight % CO2 e volved from apatite, FTIR carbonate/phosphate absorbance ratios, phosp hate peak splitting crystallinity indices, fluoride peaks, and stable oxygen isotopic ratios to identify diagenetic change in apatite chemis try. isotopically light carbon taken up from burial soil is adequately removed from most Dos Pilas bone by treatment with dilute acetic acid , but more severe alteration cannot be reversed by standard preparatio n methods. Infrared criteria identify recrystallized apatite in a subs et of Dos Pilas burials, that is accompanied by isotopic exchange, and that no longer preserves biogenic delta(13)C. These results illustrat e that comparatively recent bone may be diagenetically altered and dem onstrate a need for systematic evaluation of mineral integrity in all archaeological bone prior to interpreting paleodiets with apatite delt a(13)C. (C) 1996 Academic Press Limited