Haplorhini was proposed byPocock in 1918 when he realized the tarsiers were actually sister to the monkeys rather than the lemurs, also following findings ofHugh Cuming 80 years earlier andLinnaeus 160 years earlier.[1][3] For Linnaeus, this ensemble of primates constituted a genus "Simia". For religious reasons,Homo constituted its own genus (which has remained).[citation needed]
The extinctomomyids, which are considered to be the mostbasal haplorhines, are believed to be more closely related to thetarsiers than to other haplorhines. The exact relationship is not yet fully established – Williams, Kay and Kirk (2010) prefer the view that tarsiers and simians share acommon ancestor, and that common ancestor shares a common ancestor with the omomyids, citing evidence from analysis by Bajpal et al. in 2008; but they also note two other possibilities – that tarsiers are directly descended from omomyids, with simians being a separate line, or that both simians and tarsiers are descended from omomyids.[4]
Haplorhines share a number of derived features that distinguish them from thestrepsirrhine "wet-nosed" primates (whose Greek name means "curved nose"), the other suborder of primates from which theydiverged some 63 million years ago[citation needed]. The haplorhines, including tarsiers, have all lost the function of the terminalenzyme that manufacturesVitamin C, while the strepsirrhines, like most other orders of mammals, have retained this enzyme.[5] Genetically, fiveshort interspersed nuclear elements (SINEs) are common to all haplorhines whilst absent in strepsirrhines.[4] The haplorhineupper lip, which has replaced the ancestralrhinarium found in strepsirrhines, is not directly connected to their nose or gum, allowing a large range offacial expressions.[6] Theirbrain-to-body mass ratio is significantly greater than the strepsirrhines, and their primary sense is vision. Haplorhines have apostorbital plate, unlike thepostorbital bar found in strepsirrhines. Most species arediurnal (the exceptions being the tarsiers and thenight monkeys).
All anthropoids have a single-chambereduterus; tarsiers have abicornate uterus like the strepsirrhines. Most species typically have single births, although twins and triplets are common formarmosets andtamarins. Despite similargestation 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.[7]
Thetaxonomic name Haplorhini derives from theAncient Greekhaploûs (ἁπλούς, 'onefold', 'single', 'simple') andrhinos (ῥις (genitive ῥινός), 'nose'). It refers to the lack of arhinarium or "wet nose", which is found in many mammals, includingstrepsirrhine primates.[8]
Molecular estimates based on mitochondrial genomes suggest Haplorhini and its sister clade,Strepsirrhini, diverged 74 million years ago (mya), but no crown primate fossils are known prior to the beginning of theEocene, 56 mya.[9] The same molecular analysis suggests the infraorderTarsiiformes, whose only remaining family is that of the tarsier (Tarsiidae), branched off from the other haplorhines 70 mya.[9] The fossilArchicebus may be similar to the most recent common ancestor at this time.
The other major clade within Haplorhini, thesimians (or anthropoids), is divided into two parvorders: Platyrrhini (theNew World monkeys) andCatarrhini (theOld World monkeys andapes). The New World monkeys split from catarrhines about 35 - 40 mya[10] and have African origin,[11] while the apes (Hominoidea) diverged from Old World monkeys (Cercopithecoidea) about 25 mya.[12] The available fossil evidence indicates that both the hominoid and cercopithecoid clades originated in Africa.[11]
The following is the listing of the living haplorhine families, and their placement in the Order Primates:[13][14]
The exact placement of early haplorhine families is uncertain owing to limited evidence. The following sets out a possible order put together by Williams, Kay and Kirk in 2010, based on cladograms put together by Seiffert et al. (2005), Marivaux (2006) and Bajpai et al. (2008), and should not be seen as definitive. They do not includePropliopithecoidea as they classify them as early catarrhines.[4] Also included are Archicebidae, the discovery of which was announced by Ni et al. in 2013.[15] (but see notes below regarding placement).
Sigé et al. (1990) describeAltiatlasius as an Omomyiform, but also state that it could be an early anthropoid, with the latter view being supported by Godinot (1994) and Bajpai et al. (2008).[4]
Kay et al. (2004) point out that a case can be made for Amphipithecidae being placed either asadapiformes (i.e. early strepsirrhines) or as early anthropoids, noting in particular that they had a long evolution separate from other groups, and that key parts of their anatomy are missing from the fossil record. They conclude that either possibility is equally plausible.[16]
Kay and Williams (2013, edited by Feagle and Kay), look at possible hypotheses about how oligopiths, parapiths and propliopiths relate to each other and catarrhines and platyrrhines: - that parapiths and propliopiths are closely related, with their common ancestor being related to oligopiths, and the common ancestor of all three being related to the platyrrhines with extant catarrhines (i.e.cercopithecoidea andhominoidea) being descended from the propliopiths; - or that parapiths and propliopiths are closely related but their common ancestor is closely related to the platyrrhines and the common ancestor of all three is related to the oligopiths, with extant catarrhines again being descended from the propliopiths; - or that propliopiths and oligopiths are closely related, and parapiths are related to the common ancestor of both and the common ancestor of all three is related to the platyrrhines, with cercopithecoidea being descended from the parapiths and hominoidea being descended from propliopiths. - finally, they also consider the hypothesis that oligopiths are adapiformes (i.e. early strepsirrhines rather than early haplorhines)[17]
Ni et al., in announcingArchicebus achilles in 2013 as what they describe as the earliest known primate with such detailed remains, place it somewhat differently to the above as they place Omomyids within Tarsiiformes, with Omomyids and Tarsiidae sharing a common ancestor, and that common ancestor sharing a common Tarsiiform ancestor with the Archicebidae.[15]
^Pollock, J. I; Mullin, R. J (1987). "Vitamin C biosynthesis in prosimians: Evidence for the anthropoid affinity ofTarsius".American Journal of Physical Anthropology.73 (1):65–70.doi:10.1002/ajpa.1330730106.PMID3113259.
^Rylands AB, Mittermeier RA (2009). "The Diversity of the New World Primates (Platyrrhini)". In Garber PA, Estrada A, Bicca-Marques JC, Heymann EW,Strier KB (eds.).South American Primates: Comparative Perspectives in the Study of Behavior, Ecology, and Conservation. Springer.ISBN978-0-387-78704-6.
^Callum F Ross, Richard F. KayAnthropoid Origins: New Visions, Springer, 2004,ISBN978-1-4419-8873-7 p. 114
^Richard F. Kay, Blythe A WilliamsAnthropoid Origins: New Visions (Developments in Primatology: Progress and Prospects), Springer, 2013,ISBN978-1461347002 p. 365
