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The term quadrupedalism refers both to a locomotor mode involving the use of all four limbs to move on horizontal substrates and to a locomotor repertoire dominated by the locomotor mode of quadrupedalism. Among extant primates there are numerous types of quadrupedal repertoires and modes, only some of which have been well characterized in terms of their functional morphology. Most Miocene catarrhines are only known from fragmentary postcranial specimens, and do not closely resemble particular anthropoid taxa. Thus, their possible quadrupedalism can only be characterized in a fairly general way. Much of the postcranial skeleton is known for the hominoid Proconsul . Limb proportions and the detailed morphology of the trunk and limbs indicate a locomotor repertoire dominated by quadrupedalism. Proconsul's quadrupedal mode involved palmigrade hand placement, and fairly eclectic movement at the limb joints. Variations on this type of quadrupedal mode are likely for the hominoids Kenyapithecus, Dryopithecus, and Sivapithecus, although other components of the locomotor repertoire are likely to have been more strongly expressed in these genera. The primitive catarrhine Pliopithecus differs from Proconsul in having more gracile limbs and relatively longer forelimbs. These atelid-like features suggest a stronger representation of suspension and climbing in the locomotor repertoire. However, as in Proconsul, there are many features indicating the primacy of quadrupedalism. The primitive catarrhine Dendropithecus and its close relatives resemble Pliopithecus in many aspects of their locomotor morphology. The hominoid Oreopithecus differs from all the other Miocene taxa in having a Pongo -like locomotor repertoire dominated by climbing and suspension, but probably with a minor quadrupedal component. Oreopithecus apart, the known Miocene catarrhines are predominantly quadrupedal animals. This fact must be incorporated into any attempt to chart the emergence of the locomotor specializations of extant hominoids.