The first fossilized specimen of the species, though not recognized as such at the time, was a single fragment of humerus (arm bone) found in Pliocene strata in the Kanapoi region of West Lake Turkana by a Harvard University research team in 1965.
Fosil pertama spesies ini, meskipun tidak dikenali pada saat itu, adalah satu tulang lengan yang ditemukan di wilayah Kanapoi di Danau Turkana timur oleh tim penelitian Universitas Harvard tahun 1965.