New platyrrhine monkeys from the Solimões Formation (late Miocene, Acre State, Brazil).

We report here a new fossil primate from the late Miocene of Brazil. The material consists of a lower first molar and a maxilla with P3-4. The fossils were collected in the Solimões Formation at the locality of Patos, upper Acre River, Acre State, Brazil. The locality is assigned to the Huayquerian South American Land Mammal Age based on faunal content (late Miocene; dated to between 9 and 6 Ma). The new material is the oldest known occurrence of fossil primates in Brazil and is recognized as a new genus and species, Solimoea acrensis. Solimoea is the oldest known member of the ateline subfamily, which includes the living genera Ateles, Lagothrix, and Brachyteles. By analogy with the molar structures and diets of extant platyrrhines, Solimoea primarily had a diet of fruit, perhaps similar to that of the spider monkey, Ateles. Two other primate teeth described previously from the same formation in Bolivia document the occurrence of alouattines and cebines. One of those specimens is a late Miocene representative of the middle Miocene Colombian genus Stirtonia. The other represents one of the largest known platyrrhine primates, for which is erected a new primate genus, Acrecebus fraileyi.