Middle Pliocene hominin species diversity has been a subject of debate over the past two decades, particularly after the naming of Australopithecus bahrelghazali and Kenyanthropus platyops in addition to the well-known species Australopithecus afarensis. Further analyses continue to support the proposal that several hominin species co-existed during this time period. Here we recognize a new hominin species (Australopithecus deyiremeda sp. nov.) from 3.3–3.5-million-year-old deposits in the Woranso–Mille study area, central Afar, Ethiopia. The new species from Woranso–Mille shows that there were at least two contemporaneous hominin species living in the Afar region of Ethiopia between 3.3 and 3.5 million years ago, and further confirms early hominin taxonomic diversity in eastern Africa during the Middle Pliocene epoch. The morphology of Au. deyiremeda also reinforces concerns related to dentognathic (that is, jaws and teeth) homoplasy in Plio–Pleistocene hominins, and shows that some dentognathic features traditionally associated with Paranthropus and Homo appeared in the fossil record earlier than previously thought.
We thank the Authority for Research and Conservation of Cultural Heritage and the Afar Regional State of Ethiopia for permission to conduct field and laboratory research, the Afar people of the Woranso–Mille area for their hospitality, and the project’s fieldwork crew members for their incredible contributions in our fieldwork endeavours. We would also like to thank S. W. Simpson and W. H. Kimbel for their constructive comments and discussions throughout the preparation of this manuscript; G. Suwa, T. White and B. Asfaw for access to the original Ardipithecus ramidus material; W. H. Kimbel for access to the original Australopithecus afarensis material; F. Spoor for discussion of Kenyanthropus platyops morphology and Lomekwi mandibular metrics; D. F. Su for comments and assistance with the figures. This research was financially supported by grants from the LSB Leakey Foundation, the National Geographic Society, the Cleveland Museum of Natural History, and the National Science Foundation (BCS-0234320, BCS-0321893, BCS-0542037, BCS-1124705, BCS-1124713, BCS-1124716, BCS-1125157 and BCS-1125345).
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This file contains Supplementary Notes 1-8 and Supplementary References.