ABSTRACT
The earliest prosimians were prominent members of the new Eocene faunas. The middle Eocene genus Notharctus is derived from Pelycodus and differs from the latter genus in its larger size, possession of larger hypocones and mesostyles on the upper molars, greater reduction of the paraconid on the lower molars, and symphysial fusion. The early Eocene genera, Teilhardina and Anemorhysis, are the most primitive anaptomorphines and their teeth are among the most primitive known among primates. They probably lie near the base of the entire omomyid radiation. Tetonius, also from the early Eocene, is probably derived from a form like Teilhardina and in turn gave rise to Absarokius. Compared with living primates, Tetonius had relatively large olfactory bulbs and small frontal lobes, but the occipital and temporal lobes were expanded more than in contemporary insectivores, suggesting a visually, rather than olfactorily, oriented animal.
