Evidence from the comparative anatomy and biochemistry of living primates indicates that tarsiers are more closely related to anthropoids than are tooth-combed prosimians, suggesting an omomyid ancestry for anthropoids. On the other hand, paleontological evidence indicates that adapids are more suitable as anthropoid ancestors than are omomyids. These conclusions and the data from which they were derived have been viewed as mutually incompatible. However, these data sets are incompatible only in light of certain assumptions. The neontological argument in favor of an omomyid ancestry depends on the assumption that tooth-combed prosimians are descenced from or are the sister group of adapids. This phylogenetic link has never been established by either the identification of shared derived characteristics or by the discovery of fossils intermediate in morphology. Instead, it is possible that adapids form a clade with omomyids, tarsiers and anthropoids, and that this clade shares a common ancestor with tooth-combed prosimians (Gingerich and Schoeninger, 1977). Consideration of this hypothesis leads to the conclusions that the comparative study of soft anatomy and biochemistry cannot be used to refute an adapid ancestry of anthropoids, that the haplorhine-strepsirhine dichotomy is of extremely limited value when applied to fossil taxa, and that tooth-combed prosimians, rather than tarsiers, may provide the best behavioural and ecological model of an anthropoid ancestor despite their cladistic relationships.
