Origin of anthropoidea: dental evidence and recognition of early anthropoids in the fossil record, with comments on the Asian anthropoid radiation.

Abstract

Among the earliest fossil anthropoid primates known are Catopithecus browni, Serapia eocaena, Arsinoea kallimos, and Proteopithecus sylviae, from the late Eocene quarry L-41, Fayum Depression, Egypt. Two of these taxa, C. browni and S. eocaena, may be the oldest known members of the Propliopithecidae and Parapithecidae, respectively, while A. kallimos and P. sylviae are archaic anthropoids of less certain familial affiliation. Dental features of C. browni, S. eocaena, A. kallimos, and P. sylviae are compared with those of younger propliopithecids and parapithecids from the Fayum in order to determine the morphocline polarities of dental features among these early anthropoids. From this, a basal African anthropoid dental morphotype is constructed. Among the features of this morphotype are: dental formula of 2.1.3.3; incisors subvertically implanted and somewhat spatulate; p2 as large as p3, both lacking paraconids; p4 weakly obliquely oriented but not exodaenodont; all lower molars with small paraconids present; upper anterior premolars lacking protocone; upper molars with small, cingular hypocones, all cheek teeth nonbunodont; and canines projecting but not necessarily sexually dimorphic. Comparisons are made between this African anthropoid morphotype and two of the best-represented proposed basal anthropoids, Eosimias and Djebelemur, with the result that neither appears to be a good candidate to have been ancestral to the African anthropoids. Other possible basal simians such as Algeripithecus, Tabelia, and Biretia also are evaluated but are too poorly known for adequate analysis. The larger-bodied Asian primates Pondaungia, Amphipithecus, and Siamopithecus also are not likely ancestors for African anthropoids, but like Eosimias they may share a common ancestry. Despite many recent claims of an Asian origin for anthropoids, the evidence remains far from compelling. The true origins of Anthropoidea remain obscure.