The Haplorhini suborder contains the following parvorders: Tarsiiformes (tarsiers), Platyrrhini (New World Monkeys), and Catarrhini (Old World Monkeys and apes, including humans). Distinctive characteristics of haplorhines include: a "dry nose" (i.e. rhinarium), the inability to manufacture vitamin C, a larger brain to body ratio than is found in strepsirrhine primates, a particularly well-developed set of vision relative to strepsirrhine primates, and a primarily diurnal behavioral pattern (with the exceptions of the Owl Monkey and the tarsiers).
Today, primates are split into two major suborders: Strepsirrhini (lemurs, galagos, lorises, and pottos) and Haplorhini (tarsiers, New World Monkeys, Old World Monkeys, and apes). In the past, this division was contentious. Tarsiers proved particularly troublesome, as these animals exhibit a blend of anatomical features similar to both major groups. The now obsolete suborder Prosimii ("prosimians") grouped tarsiers with the species now classified as strepsirrhines while pooling the other primate species (New World Monkeys, Old World Monkeys, and apes) under the suborder Anthropoidea. However, this Prosimii-Anthropoidea split has since been disproved; genetic testing has conclusively shown that tarsiers are more closely related to the "anthropoid" species. Thus, Prosimii is a polyphyletic suborder and is therefore obsolete. The Anthropoidea clade, while paraphyletic, is still useful at times. Anthropoids include all haplorhine species except the tarsiers.