The Patas Monkey (Erythrocebus patas) is a ground-dwelling monkey distributed over West Africa, and into East Africa. It is the only species classified in the genus Erythrocebus. The Patas Monkey avoids dense woodlands and lives in more open savanna and semi-deserts. The Patas Monkey grows to 85 cm in length, excluding the tail, which measures 75 cm. Reaching speeds of 55 km/h, it is the fastest runner among the primates.