Paranthropus aethiopicus is an extinct species of robust australopithecine from the Late Pliocene to Early Pleistocene of East Africa about 2.7–2.3 million years ago. However, it is much debated whether or not Paranthropus is an invalid grouping and is synonymous with Australopithecus, so the species is also often classified as Australopithecus aethiopicus. Whatever the case, it is considered to have been the ancestor of the much more robust P. boisei. It is debated if P. aethiopicus should be subsumed under P. boisei, and the terms P. boisei sensu lato ("in the broad sense") and P. boisei sensu stricto ("in the strict sense") can be used to respectively include and exclude P. aethiopicus from P. boisei. Like other Paranthropus, P. aethiopicus had a tall face, thick palate, and especially enlarged cheek teeth. However, likely due to its archaicness, it also diverges from other Paranthropus, with some aspects resembling the much earlier A. afarensis. P. aethiopicus is known primarily by the skull KNM WT 17000 from Koobi Fora, Lake Turkana, Kenya, as well as some jawbones from Koobi Fora; the Shungura Formation, Ethiopia; and Laetoli, Kenya. These locations featured bushland to open woodland landscapes with edaphic (water-logged) grasslands. Taxonomy Research history In 1968, French palaeontologist Camille Arambourg and Breton anthropologist Yves Coppens described "Paraustralopithecus aethiopicus" based on a toothless mandible (Omo 18) from the Shungura Formation, Ethiopia. The name aethiopicus refers to Ethiopia. In 1976, American anthropologist Francis Clark Howell and Coppens reclassified it as A. africanus. In 1985, the skull KNM WT 17000 dating to 2.5 million years ago was reported from Koobi Fora, Lake Turkana, Kenya, by anthropologists Alan Walker and Richard Leakey. A partial jawbone from a different individual, KNM-WT 16005, was also discovered. They clearly belonged to a robust australopithecine. By this point in time, much younger robust australopithecines had been reported from South Africa (robustus) and East Africa (boisei), and been variously assigned to either Australopithecus or a unique genus Paranthropus. Walker and Leakey assigned KNM WT 17000 to the boisei clade. They noted several anatomical differences, but were unsure if this stemmed from the specimens' archaicness or represented the normal range of variation for the species. If the former, they recommended classifying them and similar specimens into a different species, aethiopicus (and recommended that Paraustralopithecus be invalid). The discovery of these archaic specimens overturned previous postulations that P. robustus was the ancestor of the much more