Nacholapithecus kerioi was an ape that lived 14-15 million years ago[1] during the Middle Miocene. Fossils have been found in the Nachola formation in northern Kenya. The only member of the genus Nacholapithecus, it is thought to be a key genus in early hominid evolution. Similar in body plan to Proconsul, it had a long vertebral column with six lumbar vertebrae, no tail, a narrow torso, large upper limbs with mobile shoulder joints, and long feet.[2]
Together with other Kenyapithecinae such as Equatorius, Kenyapithecus, and Griphopithecus, Nacholapithecus displayed synapomorphies with Anoiapithecus.[3]
Nacholapithecus was initially classified as belonging in Kenyapithecus,[4] then attributed[5] to Equatorius (with Equatorius perhaps grouped into a sub-family Equatorinae, instead of both species in Afropithecini),[6][7] finally recognised by Ishida et al. (1999) as a separate genus.[8][9][10] Classified perhaps as a member of the family Proconsulidae.[11]
Nacholapithecus kerioi is known from the lowest part of the Aka Aiteputh Formation, one of five formations in the Neogene System in Nachola, Samburu District, northern Kenya.[12][13] The formation is largely part of the north-western rift flank overlying the Nachola Formation.[14]