These monkeys are sexually dimorphic in size and pelage characters. Head and body length is reportedly between 508 and 1.143 mm, with the tail adding an additional 456 to 711 mm to the total length. Males weigh from 26 to 31 kg and females around 15 kg. Animals found in the Kalahari desert are reported to be somewhat smaller than average. The average brain weight in adults of this species is 214.4 g.
Males have large canine teeth, whereas the teeth of the females are much smaller. These animals have 32 teeth. The first lower premolar is modified and serves as a hone for the upper canine tooth. The skull of these baboons is large, and the face has a characteristic downward flex. The upper face is narrow and deeply constricted. The skin of the face is a dark, purple-black. The tail is bent.
Pelage of typical chacma baboons is dark brown to black dorsally, with the underparts and sides of the muzzle lighter. The fur on the hands and feet is black. The overall hair color is produced by individual hairs which are black with a single yellow-brown band. Light hairs typically have a black tip. Although males are not maned, as they are in anubis , hamadryas, and guinea baboons, they do have longish tufts of hair at the nape. The facial skin and the skin surrounding the ischial callosities is purplish-black. The natal pelage is black, and is replaced by adult-like fur around 6 months of age.
It should be noted that there is geographic variation in pelage coloration. Gray-footed baboons, an identifiable subgroup within the species, are found in the northeastern part of the species range. These baboons are slightly smaller than typical chacmas. They are distinguished from typical chacmas by the coloration of the fur, which is gray-buff. The fur on their hands and feet is the same grayish color as their arms, rather than the black seen in typical chacmas. Hairs show a different banding pattern than typical chacma baboons, with black tips and black rings. The post-orbital constriction is reduced in this variety of baboon. As in typical chacma baboons, the natal pelage is black, and this fur is replaced by the adult color around 6 months of age.
Transvaal baboons, another subgroup within P. ursinus, are known from a limited number of specimens collected near the region where gray-footed and typical chacma baboon ranges meet. It is not known whether this variety represents a stable baboon phenotype (and therefore a distinct population), or simply a few animals produced from hybridization of typical-chacma and gray-footed chacma baboons. Transvaal baboons are somewhat intermediate between the typical chacma and the gray-footed variety, supporting the hypothesis that they may represent hybrids of the other forms of chacma baboons. In fur color and hair-banding pattern they resemble gray-footed baboons. However, they possess black feet, like typical chacmas. In size and cranial shape, these baboons resemble typical chacmas. Nothing is known about the natal pelage of these baboons.
Range mass: 15 to 31 kg.
Range length: 508 to 1,143 mm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger; ornamentation