Final answer:
Rough patches of skin on the buttocks and non-prehensile tails are characteristic traits of Old World monkeys, distinguishing them from New World monkeys, hominins, and lemurs.
Step-by-step explanation:
Rough patches of skin on the buttocks and non-prehensile tails are characteristic traits of Old World monkeys. These primates belong to the Catarrhini, which are found throughout Africa and Asia. Unlike their New World counterparts, Old World monkeys possess narrow, downward-facing nostrils and their tails are never prehensile. Some species also have ischial callosities which are thickened patches of skin on their buttocks that help them sit on rough surfaces without discomfort. This feature can be found in baboons, mandrills, langurs, and macaques among other Old World monkeys.