CONICET | Buscador de Institutos y Recursos Humanos

Lipids are depleted in 13C stable isotope, in relation to proteins such as collagen and carbohydrates (Post et al. 2007, Logan et al. 2008). In the use of carbon stable isotopes there are two scenarios in which this difference can lead to paleo-dietary misinterpretations or inaccurate food chain reconstructions. The first one is in relation to the variability of lipid content depending on several variables such as tissues location, species and environment (ie. terrestrial vs. marine) (Post et al. 2007). The second problem arises in the context of archaeological or paleocological research involving samples with varying degrees of diagenesis that generate a differential preservation of lipids (Liden et al. 1995), particularly when these are compared with modern samples. Our study assess how lipid content affects the d13C values on terrestrial mammalian herbivores bone collagen, having as a final goal to determine the magnitude of the bias that this biochemical compound can introduce into paleo-dietary interpretations. For this reason we compare the isotopic signal (d13C) of 36 modern bone collagen samples, with varying degrees of preservation, against the same samples after being subject to lipid removal treatment. We have not found a strong correlation between this difference and the percentage of lipids. A third of the record showed differences within the technique uncertainty, and the rest exhibited variations in d13C up to 5.9. Considering a fractionation factor of 1 to 2 for the d13C between diet and consumer tissue, differences found between lipid treated and non treated collagen of grazing herbivores are relevant. Obtained data in this work will allow future discussions on the applicability of the discussed models and correction factors to the species and environments in question.

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