What feature of old world monkeys is typically not found in their anatomy?

Old World monkeys, which belong to the family Cercopithecoidea, are characterized by several distinct anatomical features that differentiate them from their New World counterparts. One noteworthy aspect is their tail structure. Old World monkeys possess non-prehensile tails, meaning their tails do not have the ability to grasp or hold onto objects. This adaptation reflects their evolutionary history and habitat; these monkeys are typically found in the terrestrial environments of Africa and Asia, where a prehensile tail would be less advantageous.

In contrast, many New World monkeys have prehensile tails which allow them to grip branches, aiding in their arboreal lifestyle. The absence of prehensile tails in Old World monkeys is a clear marker of their anatomical traits, aligning with their adaptations suited to their environments.

Regarding body size, while Old World monkeys can range greatly in size, some species can be quite large. The hooked noses observed in many Old World monkeys, particularly in the characteristically flat and broad nasal structures, are distinct traits that further define this group. However, the prehensile tail does not feature in the anatomical characteristics of Old World monkeys, underpinning why this option is the distinguishing answer.