Haplorhini

Haplorhines Temporal range: Late Paleocene – Holocene
Common squirrel monkey (Saimiri sciureus)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Synapsida
Class:	Mammalia
Order:	Primates
Suborder:	Haplorhini Pocock, 1918
Infraorders
Simiiformes (monkeys & apes) Tarsiiformes (tarsiers)

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 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.

Etymology

The taxonomic name Haplorhini derives from the Ancient Greek haploûs (ἁπλούς, "onefold, single, simple") and rhinos (ῥινός, "nose"). It refers to the lack of a rhinarium or "wet nose", which is found in many mammals, including strepsirrhine primates.

Classification and evolution

Haplorhini and its sister clade, Strepsirrhini, diverged about 65 million years ago (mya). Approximately 5 million years later (60 mya), only a short time afterward from an evolutionary perspective, the infraorder Tarsiiformes, whose only remaining family is that of the tarsier (Tarsiidae), branched off from the other haplorhines. The fossil Archicebus may be similar to the most recent common ancestor at this time.

The other major clade within Haplorhini, the simians (or anthropoids), is divided into two parvorders: Platyrrhini (the New World monkeys) and Catarrhini (the Old World monkeys and apes). The New World monkeys split from catarrhines about 40 mya, while the apes (Hominoidea) diverged from Old World monkeys (Cercopithecoidea) about 25 mya. The available fossil evidence indicates that both the hominoid and cercopithecoid clades originated in Africa.

The following is the listing of the living haplorhine families, and their placement in the Order Primates:

• ORDER PRIMATES
  • Suborder Strepsirrhini: lemurs, lorises, etc.
  • Suborder Haplorhini: tarsiers, monkeys, apes
    • Infraorder Tarsiiformes
      • Family Tarsiidae: tarsiers
    • Infraorder Simiiformes: monkeys, apes
      • Parvorder Platyrrhini: New World monkeys
        • Family Callitrichidae: marmosets, tamarins
        • Family Cebidae: capuchins, squirrel monkeys
        • Family Aotidae: night or owl monkeys (douroucoulis)
        • Family Pitheciidae: titis, sakis, uakaris
        • Family Atelidae: howler, spider, and woolly monkeys
      • Parvorder Catarrhini Old World anthropoids
        • Superfamily Cercopithecoidea: Old World monkeys
          • Family Cercopithecidae
        • Superfamily Hominoidea: apes
          • Family Hylobatidae: lesser apes (gibbons)
          • Family Hominidae: great apes and humans

References

Literature cited

• Primate Taxonomy (Smithsonian Institution Press, 2001), Colin Groves (ISBN 1-56098-872-X)
• Primates in Question (Smithsonian Institution Press, 2003), Robert W. Shumaker & Benjamin B. Beck (ISBN 1-58834-176-3)
• Neotropical Primates 10(3)