The gelada is large and robust. It is covered with buff to dark brown, coarse hair and has a dark face with pale eyelids. Its arms and feet are nearly black. Its short tail ends in a tuft of hair. Adult males have a long, heavy cape of hair on their backs. The gelada has a hairless face with a short muzzle that looks more similar to a chimpanzee's than a baboon's. It can also be physically distinguished from a baboon by the bright patch of skin on its chest. This patch is hourglass-shaped. On males, it is bright red and surrounded by white hair; on females, it is far less pronounced. However, when in estrus, the female's patch will brighten, and a "necklace" of fluid-filled blisters forms on the patch. This is thought to be analogous to the swollen buttocks common to most baboons experiencing estrus. In addition, females have knobs of skin around their patches. Geladas also have well developed ischial callosities. There is sexual dimorphism in this species: males average 18. 5 kg (40. 8 lb) while females are smaller, averaging 11 kg (24. 3 lb). The head and body length of this species is 50–75 cm (19. 7–29. 5 in) for both sexes. Tail length is 30–50 cm (11. 8–19. 7 in).