with either eosimiids or crown simians (those simians that are part of the smallest clade that contains the living simians); the latter view is favored. Eosimiids were first described from findings in China in 1994 and are still best known there (two genera are now known, Eosimias and Phenacopithecus), but have also been recorded in Pakistan (Phileosimias) and Myanmar (Bahinia). All species had a small body size and a mix of primitive (ancestral) and derived traits. The largest eosimiid, Bahinia, is from the Pondaung Formation, the same stratum as Afrasia, and the morphology of its molars bridges the gap between the more primitive molars of Eosimias and the more derived molars of the later Eocene African simians. Afrasia, on the other hand, is more comparable in size to the eosimiids from China. The upper molars of Afrasia are nearly identical in morphology and size to those of Afrotarsius, an animal known from 38- to 39-million-year-old deposits in Libya (species Afrotarsius libycus) and about 30-million-year-old deposits in Egypt (A. chatrathi). Afrotarsius was originally described as a tarsier, but later suggested to be related to primitive simians. Because of their close similarities, Afrasia and Afrotarsius are together placed in the family Afrotarsiidae. A phylogenetic analysis placed Afrasia as a sister group to Afrotarsius, forming the family Afrotarsiidae. Afrotarsiidae was found to be most closely related to Eosimiidae, and unrelated to tarsiers. The clade formed by Afrotarsiidae and Eosimiidae was designated as the infraorder Eosimiiformes by Chaimanee et al. in 2012. Eosimiiformes are the sister group of crown simians. However, the classification of Afrotarsius as a stem simian is not accepted by all researchers, and the phylogenetic claims and their implications rest on only the four molars of Afrasia initially discovered. Biogeography Several hypotheses compete to explain the geographic origins of simians. Of the two most popular views, one hypothesis states that simians originated in Asia, while the other favors Africa as their place of origin. Both their ancient origins and the sparse fossil record in Africa and Asia complicate the debate. Convergent evolution also makes it difficult for researchers to determine the relationships between fossils. Also, the earliest fossils, which do not match up with molecular clock estimates for simian origins, have been found in both Afro-Arabia and Asia. At the time, both landmasses would have been separated by the Tethys Sea. The oldest undisputed simians from Africa also date to the