#cercopithecidae

Dusky Leaf Monkey aka Spectacled Langur (Trachypithecus obscurus), family Cercopithecidae, Malaysia

A dusky leaf monkey (Trachypithecus obscurus) and its infant in Malaysia. Infants of this species are born orange/blonde, which fades as they age

Diana Guenon Monkey Cercopithecus diana

An Old World monkey found in the high canopy forests in Sierra Leone, Liberia, and western Côte d'Ivoire, named for its white brow which is said to resemble the bow of the Roman goddess Diana.

Diana monkeys retreat to the upper levels of the trees at night, though they do not make nests, preferring to sleep on branches. They feed mainly on fruit, blossoms and leaves, as well as occasional insects and invertebrates.

Someone who identified themself only as Pendrew asked for a "ruminant-like Old World Monkey":

After much of East Africa rifted off into a separate continent, shifting climate turned the alpine grasslands of what was once the Ethiopian Highlands into into warmer subtropical forests – and the highly terrestrial grass-eating geladas that inhabited the region adapted to new sources of food.

Yedenigelada pendrewsii is a large quadrupedal herbivorous monkey, about 1.5m tall at the shoulder (~5'). It has a specialized pseudoruminant digestive system with a three-chambered stomach, similar to that of camelids, and it occupies an ecological niche convergent with the ancient chalicotheres, selectively browsing on trees and shrubs while sitting upright and using its long clawed forelimbs to pull branches within reach. 

Unlike its highly social ancestors this species is mostly solitary, although during the breeding season groups of males come together in leks to compete for female attention. Displays consist of inflating large colorful throat pouches to make loud resonating calls, and flipping upper lips to bare teeth and gums.

become ungovernable

De Brazza's monkey (Cercophithecus neglectus), family Cercopithecidae (Old World monkeys)