Gelada baboon - Theropithecus gelada
“The face of the gelada baboon does not have the doglike shape of other baboons. The nostrils are lateral instead of terminal, as in some of the smaller monkeys. There is no bright color in the face, but on the chest are naked areas of red.”
The gelada, or bleeding-heart monkey, is the only herbivorous baboon, despite their impressive teeth.
More specifically, they’re gramnivorous, meaning that they eat primarily (90%+) grass blades. They’re ground-dwelling creatures, and only live along the cliffs of high-mountain meadows of Ethiopia, whereas almost all other old-world monkeys live in the savanna or forest. Their impressive canines belie their well-developed molars, which can grind grass, tubers, and flowers almost as well as an ungulate (about 90% the efficiency of zebra).
Album of Abyssinian Birds and Mammals. Louis Agassiz Fuertes, 1928.