Final answer:
Old World and New World monkeys are part of the suborder Haplorrhini, with New World monkeys classified under the Platyrrhini infraorder and Old World monkeys under the Catarrhini infraorder.
Step-by-step explanation:
Old World and New World monkeys belong to the suborder Haplorrhini. This suborder is further divided into the infraorders Simiiformes and Tarsiiformes. The Simiiformes are further divided into Platyrrhini and Catarrhini. The Platyrrhini infraorder includes all New World monkeys found in the Americas, characterized by broad noses and most species having prehensile tails. The Catarrhini infraorder includes all Old World monkeys found in Africa and Asia, characterized by narrow downward-pointing noses.
The Catarrhini also encompasses the superfamilies Cercopithecoidea and Hominoidea; the former includes groupings such as cheek pouch monkeys and leaf-eating monkeys, while the latter includes the great apes and humans.