Keratin C and N stable isotope ratios of fossil cattle horn from Kerma (Sudan): A record of dietary changes

Abstract

A set of 100 analyses was carried out on eight samples of fossil cattle keratin horn from the necropolis of Kerma (Sudan). They were analysed for their carbon and nitrogen stable isotope composition to check whether keratin horn can provide information on cattle diet and cattle feeding strategies besides those on local environmental conditions. The carbon stable isotope composition suggests that animals grazed a mixed C3/C4 pasture with a seasonal dominance of C3 or C4 plants. The weaning process is probably reflected by the gradual decrease of the nitrogen stable isotope values from the outer to the inner section of the horn keratin. The δ15N values suggest very arid environmental conditions during the Classic Kerma period (1750-1500 BC). The strongly δ15N enriched values obtained are the result of both an arid condition and of the higher trophic level of the animals during the beginning of keratin formation in comparison to adults. Different specimens exhibit different ranges of nitrogen and carbon isotope values, that probably indicate that the individuals were raised in different areas belonging to different herds.