Catarhine

Catarhine is a term sometimes used in older or less formal classifications to refer to a group of primates that includes Old World monkeys and apes. This grouping is contrasted with Platyrrhini, which encompasses New World monkeys. The distinction between Catarhini and Platyrrhini is based on several anatomical characteristics, most notably the shape of the nose. Catarhines typically have narrow nostrils that face downward or outward, whereas platyrrhines have wide nostrils that face outward.

Historically, the term catarhine was used by zoologists and naturalists to categorize primate diversity. While still understood by many, modern primatology often prefers to refer to the two distinct infraorders: Catarrhini (which includes cercopithecoids or Old World monkeys, and hominoids or apes) and Platyrrhini (New World monkeys). The infraorder Catarrhini is characterized by its lack of prehensile tails, and in most species, the presence of ischial callosities and dental formulas that are typically 2.1.2.3 over 2.1.2.3. This arrangement reflects a shared ancestry among these primate groups. The phylogenetic relationships within Catarrhini are well-studied, with apes and humans forming a monophyletic group within the superfamily Hominoidea, distinct from the cercopithecoids.