Haplorhini
| Haplorhines Temporal range: Paleocene-Holocene, 63–0 Ma |
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| Common squirrel monkey (Saimiri sciureus) | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Primates |
| Suborder: |
Haplorhini Pocock, 1918 |
| Infraorders | |
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Haplorhini (the haplorhines or the "dry-nosed" primates, the Greek name means "simple-nosed") is a clade containing the tarsiers and the simians (or anthropoids). The name is also spelt Haplorrhini. The simians include catarrhines (Old World monkeys and apes including humans), and the platyrrhines (New World monkeys).
The extinct omomyids, which are considered to be the most basal haplorhines, are believed to be more closely related to the tarsiers than to other haplorhines.
Haplorhines share a number of derived features that distinguish them from the strepsirrhine "wet-nosed" primates (whose Greek name means "curved nose"), the other suborder of primates from which they diverged some 63 million years ago. The haplorhines, including tarsiers, have all lost the function of the terminal enzyme that manufactures vitamin C, while the strepsirrhines, like most other orders of mammals, have retained this enzyme and the ability to manufacture vitamin C. The haplorhine upper lip, which has replaced the ancestral rhinarium found in strepsirrhines, is not directly connected to their nose or gum, allowing a large range of facial expressions. Their brain to body ratio is significantly greater than the strepsirrhines, and their primary sense is vision. Haplorhines have a postorbital plate, unlike the postorbital bar found in strepsirrhines. Most species are diurnal (the exceptions being the tarsiers and the night monkeys).
All anthropoids have a single-chambered uterus; tarsiers have a bicornate uterus like the strepsirrhines. Most species typically have single births, although twins and triplets are common for marmosets and tamarins. Despite similar gestation periods, haplorhine newborns are relatively much larger than strepsirrhine newborns, but have a longer dependence period on their mother. This difference in size and dependence is credited to the increased complexity of their behavior and natural history.
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