A mandible ofBranisella boliviana (Platyrrhini,Primates) from the oligocene of South America

A mandibular specimen from the Bolivian Early Oligocene is provisionally assigned toBranisella boliviana. The crown anatomy of the single preserved tooth, an M₂, indicates platyrrhine affinities and several details of the broken jaw are suggestive of symphyseal fusion. Like the African Oligocene parapithecids,Branisella contrasts with extant anthropoids in the relative shallowness of its mandible.Branisella is the most ancient, and seemingly the most primitive, fossil platyrrhine monkey, lacking any of the derived features of the two major clades of modern ceboids. Taxonomically, it is best regarded as family incertae sedis.