The oldest known anthropoid postcranial fossils and the early evolution ofhigher primates

The middle Eocene primate family Eosimiidae, which is known from sites in c entral and eastern China(1,2) and Myanmar(3), is central to efforts to reco nstruct the origin and early evolution of anthropoid or 'higher' primates ( monkeys, apes and humans)(1-6). Previous knowledge of eosimiid anatomy has been restricted to the dentition(3-3,7) and an isolated petrosal bone(5), a nd this limited anatomical information has led to conflicting interpretatio ns of early anthropoid phylogeny(1-6,8,9). Here we describe foot bones of E osimias from the same middle Eocene sites in China that yield abundant dent al remains of this primate. Tarsals of Eosimias show derived anatomical tra its that are otherwise restricted to living and fossil anthropoids. These n ew fossils substantiate the anthropoid status of Eosimias and clarify the p hylogenetic position of anthropoids with respect to other major primate cla des. Early anthropoids possessed a mosaic of primitive and derived traits i n their postcranial skeletons, reflecting their derivation from haplorhine ancestors that retained marry prosimian-like features.