Diets of fossil primates from the Fayum Depression of Egypt: a quantitative analysis of molar shearing

Over the last 90 years, Eocene and Oligocene aged sediments in the Fayum De pression of Egypt have yielded at least 17 genera of fossil primates. Howev er, of this diverse sample the diets of only four early Oligocene anthropoi d genera have been previously studied using quantitative methods. Here we p resent dietary assessments for 11 additional Fayum primate genera based on the analysis of body mass and molar shearing crest development. These studi es reveal that all late Eocene Fayum anthropoids were probably frugivorous despite marked subfamilial differences in dental morphology. By contrast, l ate Eocene Fayum prosimians demonstrated remarkable dietary diversity, incl uding specialized insectivory (Anchomomys), generalized frugivory (Plesiopi thecus), frugivory+insectivory (Wadilemur), and strict folivory (Aframonius ). This evidence that sympatric prosimians and early anthropoids jointly oc cupied frugivorous niches during the late Eocene reinforces the hypothesis that changes in diet did not form the primary ecological impetus for the or igin of the Anthropoidea. Early Oligocene Fayum localities differ from late Eocene Fayum localities in lacking large-bodied frugivorous and folivorous prosimians, and may document the first appearance of primate communities w ith trophic structures like those of extant primate communities in continen tal Africa. A similar change in primate community structure during the Eoce ne-Oligocene transition is not evident in the Asian fossil record. Putative large anthropoids from the Eocene of Asia, such as Amphipithecus mogaungen sis, Pondaungia cotteri, and Siamopithecus eocaenus, share with early Oligo cene Fayum anthropoids derived features of molar anatomy related to an emph asis on crushing and grinding during mastication. However, these dental spe cializations are not seen in late Eocene Fayum anthropoids that are broadly ancestral to the later-occurring anthropoids of the Fayum's upper sequence . This lack of resemblance to undisputed Eocene African anthropoids suggest s that the "progressive" anthropoid-like dental features of some large-bodi ed Eocene Asian primates may be the result of dietary convergence rather th an close phyletic affinity with the Anthropoidea. (C) 2001 Academic Press.