"Here are two male Dusky Leaf Monkeys, found primarily on the Malay Peninsula, including southern Burma and parts of Thailand. They also inhabit the islands of Langkawi, Penang, and Perhentian Besar. (According to Lekagul and McNeely in 1977 and Medway, 1969. We doubt strongly if they are still there.....)"
The dusky leaf-monkey is a folivorous species or leaf eater, that also consumes fruit and flowers. Young leaves constitute a high proportion of the diet. This species has a sacculated stomach to assist in the breakdown of cellulose found in plant cell walls and has enlarged salivary glands to assist it in breaking down food. (Source)
