Editing Prosimian (section)

==Characteristics==
[[Image:GarnettsGalago CincinnatiZoo.jpg|thumb|The [[tapetum lucidum]] of a [[galago]], typical of prosimians, reflects the light of the photographer's flash.]]
Being an [[evolutionary grade]] rather than a [[clade]], the prosimians are united by being primates with traits otherwise found in non-primate mammals. Their diets typically are less dominated by fruit than those of the simians, and many are active arboreal predators, hunting for insects and other small animals in the trees.<ref name="WhittenBrockman2001"/> All prosimians outside Madagascar are [[nocturnal]], meaning that no prosimian competes directly with simian primates (the only nocturnal simians are [[New World monkey]]s of genus ''[[Aotus (monkey)|Aotus]]''<ref name=Lang>Cawthon Lang KA. 2005 July 18. [http://pin.primate.wisc.edu/factsheets/entry/owl_monkey/taxon Primate Factsheets: Owl monkey (''Aotus'') Taxonomy, Morphology, & Ecology]. Accessed 2012 July 25.</ref>).

Related to their frequently nocturnal lifestyle, prosimians lack the colour vision of higher primates. Like most [[Placentalia|placental mammals]], they are in effect [[Color blindness#Red–green color blindness|red–green colour blind]]. This allows for more [[rod cell]]s in the [[retina]], which may enhance vision under low-light conditions.<ref name=Ali&Klyne1985>{{Cite book|last1=Ali|first1=Mohamed Ather|last2=Klyne|first2=M.A.|title=Vision in Vertebrates|place=New York|publisher=Plenum Press|year=1985|pages=174–175|isbn=978-0-306-42065-8}}</ref> Except in tarsiers, the nocturnal vision is further augmented by a reflective [[tapetum lucidum]] behind the retina, similar to that found in other nocturnal mammals. This layer reflects the light that passes through the retina, increasing the [[Photoreceptor cell|photoreceptors]] exposure to the light. It is however not well developed in diurnal forms like many lemurs.<ref>{{cite journal|last=Pariente|first=GF|title=[Different aspects of the limit of the tapetum lucidum in prosimians]|journal=Vision Research|date=1976|volume=16|issue=4|pages=387–91|pmid=821249|doi=10.1016/0042-6989(76)90201-7|s2cid=53156761}}</ref>

All prosimians possess two laterally flattened [[toilet claw]]s, used for grooming. These are found on the second toe in [[lemurs]] and [[lorises]], and the second and third in [[tarsiers]]. [[Aye-aye]]s have functional [[claw]]s on all other digits except the hallux, including a toilet claw on the second toe. Clawlike nails are however also found in the small-bodied [[callitrichids]], a group of New World monkeys, though none of them have a toilet claw.<ref name=evolution>{{cite journal |author=Soligo, C. |author2=Müller, A.E. |year=1999 |title=Nails and claws in primate evolution |journal=Journal of Human Evolution |volume=36 |pages=97–114 |doi=10.1006/jhev.1998.0263 |pmid=9924135 |issue=1}}</ref>

Male strepsirrhine prosimians have relatively large [[Baculum|bacula]].<ref>{{Cite book |last=Ankel-Simons |first=Friderun |url=https://www.google.com/books/edition/Primate_Anatomy/Mwl3M6c5KzoC?hl=en&gbpv=1&pg=PA521&printsec=frontcover&dq=baculum |title=Primate Anatomy: An Introduction |date=2010-07-27 |publisher=Elsevier |isbn=978-0-08-046911-9 |language=en}}</ref> Male tarsiers do not have [[baculum|bacula]].<ref name="Ankel-Simons2010">{{cite book|author=Friderun Ankel-Simons|title=Primate Anatomy: An Introduction|url=https://books.google.com/books?id=Mwl3M6c5KzoC|date=27 July 2010|publisher=Academic Press|isbn=978-0-08-046911-9|pages=442, 521 }}</ref> The prosimians have retained the primitive mammalian condition of a [[bicornuate uterus]], with two separate uterus chambers. In the simians, the uterus chambers have fused, an otherwise rare condition among mammals. Prosimians usually have litters rather than single offspring, which is the norm in higher primates.<ref>{{cite book |last=Nowak |first=Ronald M. |title=Walker's primates of the world |year=1999 |publisher=Johns Hopkins University Press |location=Baltimore |isbn=978-0801862519 |page=[https://archive.org/details/walkersprimateso0000nowa/page/25 25] |url=https://archive.org/details/walkersprimateso0000nowa|url-access=registration |quote=prosimians uterus placenta. }}</ref>

While primates are often thought of as fairly intelligent animals, the prosimians are not very large-brained compared to other placental mammals. Their brain-cases are markedly smaller than those of simians of comparable sizes. In the large-eyed tarsiers, the weight of the brain is about the same as that of a single eye.<ref>{{cite journal|last=Rosenberger|first=Alfred L.|title=The Skull of Tarsius: Functional Morphology, Eyeballs, and the Nonpursuit Predatory Lifestyle|journal=International Journal of Primatology|date=16 October 2010|volume=31|issue=6|pages=1032–1054|doi=10.1007/s10764-010-9447-x|s2cid=3905636}}</ref> Prosimians generally show lower cognitive ability and live in simpler social settings than the simians. The prosimians with the most complex social systems are the diurnal lemurs, which may live in social groups of 20 individuals. The nocturnal prosimians are mainly solitary.<ref name="Reader">{{Cite journal | last = Reader | first = S. M. | author2 = Hager, Y. | author3 = Laland, K. N. | title = The evolution of primate general and cultural intelligence | journal = [[Philosophical Transactions of the Royal Society B: Biological Sciences]] | volume = 366 | issue = 1567 | pages = 1017–1027 | date = 2011-04-12 | url = http://lalandlab.st-andrews.ac.uk/pdf/Publication163.pdf | doi = 10.1098/rstb.2010.0342 | pmid = 21357224 | access-date = 2011-07-04 | url-status = dead | archive-url = https://web.archive.org/web/20111003152030/http://lalandlab.st-andrews.ac.uk/pdf/Publication163.pdf | archive-date = 2011-10-03 | pmc = 3049098 }}</ref>