Final answer:
The categories Catarhini and Platyrhini refer to two infraorders within the order Primates. Platyrhini, or New World monkeys, are found in Central and South America, have rounded nostrils to the sides, and often have prehensile tails. Catarrhini, found in Africa and Asia, consist of Old World monkeys and apes, including humans, with downward-facing nostrils and no prehensile tails.
Step-by-step explanation:
The categories Catarhini and Platyrhini refer to two infraorders within the order Primates. The infraorder Platyrhini, also known as platyrrhines or New World monkeys, are primates found exclusively in Central and South America. They are characterized by their distinctive rounded external nostrils that are oriented to the sides and often have prehensile tails, which they use as an additional limb for climbing and grasping in their arboreal habitats.
On the other hand, the infraorder Catarhini, also known as catarrhines, consists of primates that are native to Africa and Asia. Catarrhines have downward-facing, narrow nostrils and include both superfamilies, the Cercopithecoidea (Old World monkeys) and the Hominoidea (apes and humans). The Old World monkeys can be divided further into cheek pouch monkeys (Cercopithecinae) and leaf-eating monkeys (Colobinae), while the hominoids are notable for being tailless and, in many cases, terrestrial. Examples of Hominoidea include gibbons, chimpanzees, gorillas, orangutans, and humans.
The Haplorrhini primate clade encompasses both the infraorders Simiiformes—which divides into Platyrhini and Catarrhini—and Tarsiiformes. This categorization is based on various physical and evolutionary traits, including overall morphology, dental structures, and habitats, contributing significantly to our understanding of primate evolution.