mandrill, large monkey, Mandrillus sphinx, of central W Africa, related to the baboons. Mandrills are found in forests, while baboons live in open country. The fur of the mandrill is mostly dark brown, but the bare areas—face and buttocks—are patterned in bright colors that are especially spectacular in the adult male, the most colorful of all mammals. The long, heavy doglike muzzle has bright red skin covering the chin, mouth, and nose and extending upward in a narrow strip to the striking, close-set, yellow-brown eyes. The cheeks are bright blue and are folded into an elaborate pattern of ridges. The fur around the eyes is black, and the beard and the edges of the mane are pale yellow. The buttock pads are bright blue, red, and purple. The tail is a short stump. Male mandrills, about 3 ft (90 cm) long, are considerably larger than females and have enormous canine teeth that they display in yawnlike threatening gestures. Mandrills travel on the ground in small family groups, feeding chiefly on insects and vegetation. Powerful animals, and formidable when provoked, they are retiring in habits and avoid contact with humans. They are extremely difficult to observe in the wild. The closely related drill, M. leucophaeus, is also a forest dweller. It is brown with a black face partially outlined in red; the buttock pads are pink. The mandrill and the drill are classified in the phylum Chordata, subphylum Vertebrata, class Mammalia, order Primates, family Cercopithecidae.

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