Reduncini are water-dependent, grazing, small to large antelopes with high crowned teeth. The two living genera are Kobus (kobs, lechwes, and waterbuck) and the smaller genus Redunca (reedbucks). Only the male Reduncini have horns in modern examples. This cranium of Kobus sigmoidalis has two almost complete horncores but is missing the tip of the left one. This specimen also has associated dention but the skull was broken so it is not complete.
Kobus sigmoidalis shares many features with the extant waterbuck Kobus ellipsiprymnus found in east Africa today, and is of a similar size and presumably occupied a similar habitat. It was prevalent in the Upper Burgi Member of the Koobi Fora Formation, dated at about 2 million years. It is the most common of the Reduncini living at that time.
