Abstract The species Proconsul (Xenopithecus) hamiltoni was based on two weathered molars in a maxillary fragment from the Erageleit beds, Lothidok, Turkana District, Kenya. New fossils from Lothidok show a unique suite of features indicating generic distinction of this taxon from other known large early catarrhines. A new generic diagnosis is given. The new genus, although still poorly known, may be the first Oligocene hominoid from East Africa. It retains many primitive features, but the few derived ones hint that it may be related to the Afropithecus group.