Colobine primates are well adapted for eating leaves. what leaf-eating traits have evolved in these monkeys?

They are very arboreal, have high and pointed molars which are good for shearing leaves and a three or four chambered stomach similar to that of a cow. Colobine are leaf-eating specialists with high-cusped molars and multi-chambered stomachs housing mutualistic microbes that digest cellulose and detoxify plant defensive compounds. Leaves are a major component of many species diets up to 90% in a population of Ugandan red colobus.