In 1968, French palaeontologists Camille Arambourg and Yves Coppens described ""Paraustralopithecus aethiopicus"" based on a toothless mandible from the Shungura Formation, Ethiopia (Omo 18). In 1976, American anthropologist Francis Clark Howell and Breton anthropologist Yves Coppens reclassified it as "A. africanus". In 1986, after the discovery of the skull KNM WT 17000 by English anthropologist Alan Walker and Richard Leakey classified it into "Paranthropus" as "P. aethiopicus". There is debate whether this is synonymous with "P. boisei", the main argument for separation being the skull seems less adapted for chewing tough vegetation.