Utilization of savanna-based resources by Plio-Pleistocene baboons

Abstract

13 C values of five cercopithecoid taxa from the Plio-Pleistocene deposits of Swart- krans Members 1 and 2 and Sterkfontein Member 4. These data were used to determine the relative proportions of C3 and C4 bio- mass consumed by extinct baboons and contemporary non-human primates. We compared these results with data on modern Papio hamadryas ursinus from different savanna areas in South Africa, as well as with published isotopic data and dietary interpretations based on molar morphology of these taxa. The data reveal little evidence for use of grasses or grass-based foods by modern South African baboons. The fossil papionins Papio hamadryas robinsoni, Papio (Dinopithecus) ingens, and Parapapio spp., however, utilized more savanna-based C4 resources than previously predicted (particularly in the case of P. (D.) ingens). Theropithecus oswaldi had 13 C values depicting, as expected, a largely grass-based diet, and we confirm earlier conclusions that this species incorporated a wider range of food items into its diet than do modern T. gelada, as reported in the literature. The colobine monkey, Cercopithecoides williamsi, made extensive use of savanna-.based C4 foods, confirm- ing some degree of terrestrial foraging by the species.