Final answer:
Old World monkeys are part of the Catarrhini, a group of primates with nostrils close together and directed downward, and include species such as baboons and macaques. They differ from New World monkeys in their non-prehensile tails and both arboreal and ground-dwelling species.
Step-by-step explanation:
The term for primates that includes Old World monkeys, gibbons, great apes, and humans is the Catarrhini. These primates are characterized by nostrils that are close together and directed downward. Unlike their New World counterparts who have broad noses and prehensile tails, Old World monkeys include both arboreal and ground-dwelling species, and their tails are never prehensile. The social relationships within these species often exhibit sexual dimorphism, where males are typically larger than females. Examples of Catarrhini include baboons, mandrills, langurs, and macaques, as well as all modern apes and humans.