Final answer:
A monkey capable of hanging by its tail would be categorized as a primate with a prehensile tail, an adaptation found in certain arboreal species like spider monkeys.
Step-by-step explanation:
If a monkey can hang by its tail, it will be categorized as a primate with a prehensile tail. Spider monkeys are an example of such arboreal mammals that have evolved this adaptation, which allows them to grasp and hang from branches with their tails. In contrast, monkeys from the ceropithecoid group, like baboons and macaques, and hominoids, such as gibbons and orangutans, do not have prehensile tails and cannot hang by them. While the hominoids lack tails entirely, the ceropithecoids have non-grasping tails. Some primate species have developed other specializations; for instance, the proboscis monkey has webbed fingers to aid in swimming, and certain monkeys, like the rhesus macaque, have adapted to urban environments.
Understanding the difference between monkeys, apes, and other primates can often be guided by observing their tail. Monkeys usually have tails, but apes and humans do not. Additionally, their means of locomotion differs, with the adapted mode of brachiation being prominent among those with very long arms for swinging from tree to tree.