Final answer:
The Cercopithecinae subfamily includes Old World monkeys such as baboons, macaques, and guenons. These monkeys are characterized by omnivorous diets and cheek pouches for food storage, and they can be identified by their downward-facing nostrils and non-prehensile tails.
Step-by-step explanation:
The subfamily of the Old World monkeys that includes baboons, macaques, and guenons are known as Cercopithecinae. These primates are part of the Cercopithidae family and are classified under the superfamily Cercopithecoidea within the infraorder Catarrhini. This group is notable for their omnivorous diets and the presence of cheek pouches for storing food, which distinguishes them from other primate subfamilies like the Colobinae or leaf-eating monkeys.
Members of the Old World monkeys are found throughout Africa and Asia. They have a wide variety of habitats, from rainforests to savannas, and exhibit significant diversity in size and behavior. However, they all share the distinctive downward-facing nostrils, non-prehensile tails, and specialized molars, adapted for their versatile diets which differ from their New World counterparts.