Dietary ecology and niche separation among three closely related species (Parapapio jonesi, Pp. whitei and Pp. broomi) of South African Plio-Pleistocene Cercopithecoidea from Makapansgat Limeworks site

Word processed copy.Includes bibliographical references (leaves 136-157).Three sympatric, contemporaneous fossil cercopithecoid genera (Cercopithecoides, Parapapio and Theropithecus) are represented in assemblages from the Makapansgat Limeworks hominin locality in South Africa. The presence of such a variety of primate taxa in a single ecosystem at the same time suggests a certain degree of ecological and/or dietary differentiation between taxa. This research explores the possibility of dietary niche separation within this sample. Stable isotope (13C/12C, 180/160 ) and trace-element (Sr, Ba, Ca) techniques for palaeodietary analysis are employed to investigate papionin dietary ecology, and especially to search for evidence of subtle niche separation between the more closely related, morphologically similar taxa of the genus Parapapio. Previous studies of fossil cercopithecoid dietary ecology report disjunctions between dietary and taxonomic groupings, possibly as a result of the use of fragmentary specimens or isolated teeth and ensuing taxonomic uncertainty, or perhaps because of problems in the taxonomy itself. Because such taxonomic uncertainties impede the interpretation of dietary data, craniometric analyses were also performed to ground the dietary interpretations in a morphological context. Only complete or partially complete cranial specimens from which morphological craniometric measurements could also be taken were sampled. Dietary analyses indicated two widely differing dietary ecologies within the Cercopithecoides williamsi sample, consistent with published results for this taxon from Swartkrans and Sterkfontein. Results for Theropithecus darti indicated a predominantly C4 diet. Two overlapping dietary ecologies, loosely correlated to taxonomic groupings, were found within the genus Parapapio; specimens attributed to Pp. broomi tended to have C3-dominated diets with a larger rootstock component than Pp. whitei and Pp. jonesi, which included more C4 grasses in their diet. The morphological analyses found no clear taxonomic signal in the craniometric data for Parapapio, suggesting that the current taxonomic assignments of Parapapio specimens are problematic. Additionally, for all of the analysed anatomical regions, the Parapapio sample was no more variable than the single geographically circumscribed extant chacma baboon sample. To sum, while biogeochemical dietary indicators indicate distinct dietary ecologies within and between genera, disjunctions exist between the dietary categories and the taxonomic assignment of specimens. Given these results, and in light of the taxonomic concerns highlighted by the craniometric investigation, reinvestigation of papionin taxonomy at Makapansgat may be warranted