LAUSR

Abstract This paper presents the results of an isotopic study of δ 13 C and δ 15 N values for bone collagen from 209 modern faunas from central-western Argentina. The samples come from two ecologically distinct areas: the Monte and Patagonian Deserts. The results confirm high intra- and inter-taxonomic variation in both isotopes. Previous studies of camelids, rodents and ostrich eggshells in this region showed a clear relation between animal δ 13 C and δ 15 N values, altitude, and the percentage of C 3 and C 4 plants. This pattern was not fully met among the species considered in this paper. No statistical differences were seen between δ 13 C values from Monte and Patagonian Deserts, although differences in δ 15 N were found. When samples from saltmarsh contexts were considered separately, differences among δ 15 N isotopic values become more pronounced, pointing to a relation between δ 15 N isotopic signatures and soil salinity. Archaeological human diet reconstruction based on isotopic data needs to pay attention to this significant variation in resources isotopic patterns in order to be used as a reliable dietary indicator.