Editing Tarsier (section)

==Anatomy and physiology==
[[File:Tarsius Syrichta-GG.jpg|thumb|right|Tarsiers tree-climbing]]

Tarsiers are small animals with enormous eyes; each eyeball is approximately {{convert|16|mm}} in diameter and is as large as, or in some cases larger than, its entire brain.<ref>{{cite book |last= Soluri |first= K. Elizabeth |author2= Sabrina C. Agarwal |title=The Laboratory Manual and Workbook for Biological Anthropology |publisher= W.W. Norton |year=2016 |isbn= 978-0-393-91291-3}}</ref><ref>{{cite book |last= Shumaker |first= Robert W. |author2=Benjamin B. Beck |title= Primates in Question |url= https://archive.org/details/primatesinquesti00shum |url-access= registration |publisher= Smithsonian Books |year= 2003 |isbn= 978-1-58834-151-8 }}</ref> The unique cranial anatomy of the tarsier results from the need to balance their large eyes and heavy head so they are able to wait silently for nutritious prey.<ref name="ShekelleMyronGursky2010">{{cite journal | last1 = Shekelle | first1 = Myron | last2 = Gursky | year = 2010 | title = Why tarsiers? Why now? An introduction to the special edition on tarsiers | journal = International Journal of Primatology | volume = 31 | issue = 6| pages = 937–940 | doi=10.1007/s10764-010-9459-6| s2cid = 326565 }}</ref> Tarsiers have a strong auditory sense, and their auditory cortex is distinct.<ref name="ShekelleMyronGursky2010" /> Tarsiers also have long hind limbs, owing mostly to the elongated [[tarsus (skeleton)|tarsus]] bones of the feet, from which the animals get their name. The combination of their elongated tarsi and fused tibiofibulae makes them morphologically specialized for vertical clinging and leaping.<ref>{{cite journal | last1 = Rasmussen | first1 = D. T. | last2 = Conroy | first2 = G. C. | last3 = Simons | first3 = E. L. | year = 1998 | title = Tarsier-like locomotor specializations in the Oligocene primate Afrotarsius | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 95 | issue = 25| pages = 14848–14850 | doi=10.1073/pnas.95.25.14848| pmid = 9843978 | pmc = 24538 | bibcode = 1998PNAS...9514848T | doi-access = free }}</ref> The head and body range from 10 to 15&nbsp;cm in length, but the hind limbs are about twice this long (including the feet), and they also have a slender tail from 20 to 25&nbsp;cm long. Their fingers are also elongated, with the third finger being about the same length as the upper arm. Most of the digits have nails, but the second and third toes of the hind feet bear claws instead, which are used for grooming. Tarsiers have soft, velvety fur, which is generally buff, beige, or ochre in color.<ref name=EoM>{{cite book|editor= Macdonald, D.|author= Niemitz, Carsten|author-link= Carsten Niemitz|year= 1984|title= The Encyclopedia of Mammals|publisher= Facts on File|location= New York|pages= [https://archive.org/details/encyclopediaofma00mals_0/page/338 338–339]|isbn= 978-0-87196-871-5|url-access= registration|url= https://archive.org/details/encyclopediaofma00mals_0/page/338}}</ref>

Tarsier morphology allows for them to move their heads 180 degrees in either direction, allowing for them to see 360 degrees around them.<ref name="RefA">Gron KJ. 2010 December 1. Primate Factsheets: Tarsier (Tarsius) Taxonomy, Morphology, & Ecology . http://pin.primate.wisc.edu/factsheets/entry/tarsier . Retrieved 12 November 2019.</ref> Their [[Dentition#Dental formula|dental formula]] is also unique: {{DentalFormula|upper=2.1.3.3|lower=1.1.3.3}}<ref>{{Cite book |last1=Simons |first1=Elwyn L. |url=https://books.google.com/books?id=9g_TwVzDOI0C |title=Tarsiers: Past, Present, and Future |last2=Wright |first2=Patricia C. |last3=Gursky |first3=Sharon |date=2003 |isbn=0-8135-3236-1 |pages=65 |publisher=Rutgers University Press |author-link=Elwyn L. Simons |author-link2=Patricia Wright (primatologist)}}</ref> Unlike many nocturnal vertebrates, tarsiers lack a light-reflecting layer ([[tapetum lucidum]]) of the retina and have a [[Fovea centralis|fovea]].

The tarsier's brain is different from that of other primates in terms of the arrangement of the connections between the two eyes and the [[lateral geniculate nucleus]], which is the main region of the [[thalamus]] that receives visual information. The sequence of cellular layers receiving information from the ipsilateral (same side of the head) and contralateral (opposite side of the head) eyes in the lateral geniculate nucleus distinguishes tarsiers from [[lemur]]s, [[lorises]], and [[monkey]]s, which are all similar in this respect.<ref name="Rosa1996">{{cite journal |last=Rosa |first=M. G. |author2=Pettigrew J. D. |author3=Cooper H. M. |year=1996 |title=Unusual pattern of retinogeniculate projections in the controversial primate ''Tarsius'' |journal=Brain, Behavior and Evolution |volume=48 |issue=3 |pages=121–129 |doi=10.1159/000113191 |pmid=8872317}}</ref> Some neuroscientists suggested that "this apparent difference distinguishes tarsiers from all other primates, reinforcing the view that they arose in an early, independent line of primate evolution."<ref name="Collins2005">{{cite journal |last=Collins |first=C. E. |author2=Hendrickson, A. |author3=Kaas, J. H. |year=2005 |title=Overview of the visual system of ''tarsius'' |journal=The Anatomical Record Part A: Discoveries in Molecular, Cellular, and Evolutionary Biology|volume=287 |issue=1 |pages=1013–1025 |doi=10.1002/ar.a.20263 |pmid=16200648 |doi-access= |s2cid=21448186 }}</ref>

[[Philippine tarsier]]s are capable of hearing frequencies as high as 91&nbsp;kHz. They are also capable of vocalizations with a dominant frequency of 70&nbsp;kHz.<ref name="Ramsier2012">{{cite journal |last=Ramsier |first=Marissa A. |author2=Cunningham A.J. |author3=Moritz G.L. |author4=Finneran J.J. |author5=Williams C.V. |author6=Ong P.S. |author7=Gursky-Doyen S.L. |author8= Dominy N.J. |year=2012 |title=Primate communication in the pure ultrasound |journal=Biology Letters |doi=10.1098/rsbl.2011.1149 |pmid=22319094 |volume=8 |issue=4 |pages=508–11 |pmc=3391437}}</ref>

Unlike most primates, 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>