How are Old World monkeys and apes categorized scientifically?

Old World monkeys and apes are categorized within the scientific classification of primates as Catarrhines. This group is distinguished by certain anatomical features, such as having narrow nostrils that face downward, which is a key characteristic differentiating them from New World monkeys (Platyrrhines) that have wider, side-facing nostrils. Additionally, Catarrhines include not only Old World monkeys but also apes and humans, placing them within a more specific evolutionary context.

Understanding the broader classification, Catarrhines are part of the infraorder Haplorhini, which includes higher primates. This classification helps anthropologists study evolutionary relationships, behavioral traits, and adaptations among various primate species. The other classifications mentioned, such as Tarsiiformes (which includes tarsiers) and Platyrrhines (New World monkeys), represent different evolutionary branches of primates that do not encompass the full range of Old World monkeys and apes. Anteaters, on the other hand, belong to a completely different order (Xenarthra) and are not primates, making them unrelated to the question. Thus, the categorization of Old World monkeys and apes as Catarrhines reflects their unique biological and evolutionary