A new species of great ape from the late Miocene epoch in Ethiopia

Suwa, Gen
Kono, Reiko T.
Katoh, Shigehiro
Asfaw, Berhane
Beyene, Yonas

¹The University Museum, the University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. ²Department of Anthropology, National Museum of Nature and Science, Hyakunincho, Shinjuku-ku, Tokyo 169-0073, Japan. ³Division of Natural History, Hyogo Museum of Nature and Human Activities, Sanda, Hyogo 669-1546, Japan. ⁴Rift Valley Research Service, P.O. Box 5717, Addis Ababa, Ethiopia. ⁵Department of Archaeology and Paleontology, Authority for Research and Conservation of Cultural Heritage, Ministry of Culture and Tourism, P.O. Box 13247, Addis Ababa, Ethiopia.

doi:10.1038/nature06113

Received 18 June; accepted 25 July 2007.

Supplementary Information is linked to the online version of the paper at www.nature.com/nature.

Author Information Reprints and permissions information is available at www.nature.com/reprints. The authors declare no competing financial interests. Correspondence and requests for materials should be addressed to G.S. ([email protected]).

Nature 448(7156):p 921-924, August 23, 2007. | DOI: 10.1038/nature06113

With the discovery ofArdipithecus, OrrorinandSahelanthropus, our knowledge of hominid evolution before the emergence of Pliocene species ofAustralopithecushas significantly increased, extending the hominid fossil record back to at least 6 million years (Myr) ago. However, because of the dearth of fossil hominoid remains in sub-Saharan Africa spanning the period 12-7 Myr ago, nothing is known of the actual timing and mode of divergence of the African ape and hominid lineages. Most genomic-based studies suggest a late divergence date-5-6 Myr ago and 6-8 Myr ago for the human-chimp and human-gorilla splits, respectively-and some palaeontological and molecular analyses hypothesize a Eurasian origin of the African ape and hominid clade. We report here the discovery and recognition of a new species of great ape,Chororapithecus abyssinicus,fromthe 10-10.5-Myr-old deposits of the Chorora Formation at the southern margin of the Afar rift. To the best of our knowledge, these are the first fossils of a large-bodied Miocene ape from the African continent north of Kenya. They exhibit a gorilla-sized dentition that combines distinct shearing crests with thick enamel on its 'functional' side cusps. Visualization of the enamel-dentine junction by micro-computed tomography reveals shearing crest features that partly resemble the modern gorilla condition. These features represent genetically based structural modifications probably associated with an initial adaptation to a comparatively fibrous diet. The relatively flat cuspal enamel-dentine junction and thick enamel, however, suggest a concurrent adaptation to hard and/or abrasive food items. The combined evidence suggests thatChororapithecusmay be a basal member of the gorilla clade, and that the latter exhibited some amount of adaptive and phyletic diversity at around 10-11 Myr ago.