Editing Giraffe (section)

===Neck===
The giraffe has an extremely elongated neck, which can be up to {{cvt|2.4|m|ft}} in length.<ref name="Taylor&Wedel2013">{{Cite journal |last1=Taylor |first1=M. P. |last2=Wedel |first2=M. J. |doi=10.7717/peerj.36 |title=Why sauropods had long necks; and why giraffes have short necks |journal=[[PeerJ]] |volume=1 |page=e36 |year=2013 |pmid=23638372 |pmc=3628838 |doi-access=free}}</ref> Along the neck is a mane made of short, erect hairs.<ref name="Dagg1971"/> The neck typically rests at an angle of 50–60 degrees, though juveniles are closer to 70 degrees.<ref name=Dagg2014/>{{rp|72–73}} The long neck results from a disproportionate lengthening of the [[cervical vertebrae]], not from the addition of more vertebrae. Each cervical vertebra is over {{cvt|28|cm}} long.<ref name=anatomy>{{cite book |author=Swaby, S. |year=2010 |contribution=Giraffe |editor=Harris, T.|title=Mammal Anatomy: An Illustrated Guide |publisher=[[Marshall Cavendish]] |pages=64–84 |isbn=978-0-7614-7882-9}}</ref>{{rp|71}} They comprise 52–54 per cent of the length of the giraffe's [[vertebral column]], compared with the 27–33 percent typical of similar large ungulates, including the giraffe's closest living relative, the [[okapi]].<ref name=bada>{{Cite journal |doi=10.1111/j.1096-3642.2008.00458.x |last1=Badlangana |first1=L. N. |last2=Adams |first2=J. W. |last3=Manger |first3=P. R. |title=The giraffe ''(Giraffa camelopardalis)'' cervical vertebral column: A heuristic example in understanding evolutionary processes? |journal=[[Zoological Journal of the Linnean Society]] |volume=155 |issue=3 |pages=736–757 |year=2009 |doi-access=free}}</ref> This elongation largely takes place after birth, perhaps because giraffe mothers would have a difficult time [[giving birth]] to young with the same neck proportions as adults.<ref name=van>{{Cite journal |doi=10.1002/jez.b.21353 |pmid=20700891 |last1=Van Sittert |first1=S. J. |last2=Skinner |first2=J. D. |last3=Mitchell |first3=G. |title=From fetus to adult – An allometric analysis of the giraffe vertebral column |journal=[[Journal of Experimental Zoology Part B: Molecular and Developmental Evolution]] |volume=314B |issue=6 |pages=469–479 |year=2010|bibcode=2010JEZB..314..469V }}</ref> The giraffe's head and neck are held up by large muscles and a [[nuchal ligament]], which are anchored by long [[thoracic vertebrae]] spines, giving them a hump.<ref name=Dagg1971/><ref name=Solounias1999/><ref name=MacDonald/>

[[File:Flickr - Rainbirder - High-rise living.jpg|thumb|left|upright|alt=Photograph of an adult male giraffe with its next fully extended feeding on an acacia|Adult male [[reticulated giraffe]] feeding high on an acacia, in Kenya]]
The giraffe's neck vertebrae have [[ball and socket joint]]s.<ref name=anatomy/>{{rp|71}} The point of articulation between the cervical and thoracic vertebrae of giraffes is shifted to lie between the first and second thoracic vertebrae (T1 and T2), unlike in most other ruminants, where the articulation is between the seventh cervical vertebra (C7) and T1.<ref name=bada/><ref name=van/> This allows C7 to contribute directly to increased neck length and has given rise to the suggestion that T1 is actually C8, and that giraffes have added an extra cervical vertebra.<ref name=Solounias1999>{{Cite journal|author=Solounias, N.|year=1999|title=The remarkable anatomy of the giraffe's neck |journal=[[Journal of Zoology]] |volume=247 |issue=2 |pages=257–268 |doi=10.1111/j.1469-7998.1999.tb00989.x |url=http://www.ikhebeenvraag.be/mediastorage/FSDocument/73/download.pdf |archive-url=https://web.archive.org/web/20090325215447/http://www.ikhebeenvraag.be/mediastorage/FSDocument/73/download.pdf |archive-date=25 March 2009 |url-status=live}}</ref> However, this proposition is not generally accepted, as T1 has other [[morphology (biology)|morphological]] features, such as an articulating [[rib]], deemed diagnostic of thoracic vertebrae, and because exceptions to the mammalian limit of seven cervical vertebrae are generally characterised by increased [[neurological disorder|neurological anomalies]] and maladies.<ref name=bada/>

There are several hypotheses regarding the evolutionary origin and maintenance of elongation in giraffe necks.<ref name=sim2010>{{Cite journal |doi=10.1111/j.1469-7998.2010.00711.x |last1=Simmons |first1= R. E. |last2=Altwegg |first2=R. | title=Necks-for-sex or competing browsers? A critique of ideas on the evolution of giraffe |journal=Journal of Zoology |volume=282 |issue=1 |pages=6–12 |year=2010}}</ref> [[Charles Darwin]] originally suggested the "competing [[browsing (predation)|browsers]] hypothesis", which has been challenged only recently. It suggests that competitive pressure from smaller browsers, like [[kudu]], [[steenbok]] and [[impala]], encouraged the elongation of the neck, as it enabled giraffes to reach food that competitors could not. This advantage is real, as giraffes can and do feed up to {{cvt|4.5|m}} high, while even quite large competitors, such as kudu, can feed up to only about {{cvt|2|m}} high.<ref name=dt1990>{{Cite journal |doi=10.1111/j.1365-2028.1990.tb01136.x |last=du Toit | first=J. T. |title=Feeding-height stratification among African browsing ruminants |journal=[[African Journal of Ecology]] |volume=28 |issue=1 |pages=55–62 |year=1990 |bibcode=1990AfJEc..28...55D |url=http://courses.biology.utah.edu/goller/7406/Goller7406/duToitPdfs/Feedingheightstrat_1990.pdf |access-date=21 November 2011 |url-status=dead|archive-date=10 November 2011 |archive-url=https://web.archive.org/web/20111110224355/http://courses.biology.utah.edu/goller/7406/Goller7406/duToitPdfs/Feedingheightstrat_1990.pdf}}</ref> There is also research suggesting that browsing competition is intense at lower levels, and giraffes feed more efficiently (gaining more leaf biomass with each mouthful) high in the canopy.<ref>{{Cite journal |last1=Cameron |first1=E. Z.|author-link=Elissa Cameron |last2=du Toit|first2=J. T.|year=2007|title=Winning by a Neck: Tall Giraffes Avoid Competing with Shorter Browsers |url=http://ecite.utas.edu.au/67394 |journal=[[American Naturalist]] |volume=169 |issue=1 |pages=130–135 |doi=10.1086/509940|pmid=17206591|bibcode=2007ANat..169..130C |s2cid=52838493|access-date=5 December 2019|archive-date=2 June 2020 |archive-url=https://web.archive.org/web/20200602031844/http://ecite.utas.edu.au/67394|url-status=live}}</ref><ref>{{Cite journal |author1=Woolnough, A. P. |author2=du Toit, J. T.| title=Vertical zonation of browse quality in tree canopies exposed to a size-structured guild of African browsing ungulates |journal=[[Oecologia]]| volume=129| issue=1| pages=585–590 |year=2001 |doi=10.1007/s004420100771| pmid=24577699  |bibcode=2001Oecol.129..585W|s2cid=18821024 |url=http://courses.biology.utah.edu/goller/7406/Goller7406/duToitPdfs/Verticalzonation_2001.pdf| access-date=7 March 2012| archive-url=https://web.archive.org/web/20111110224921/http://courses.biology.utah.edu/goller/7406/Goller7406/duToitPdfs/Verticalzonation_2001.pdf| archive-date=10 November 2011 |url-status=dead}}</ref> However, scientists disagree about just how much time giraffes spend feeding at levels beyond the reach of other browsers,<ref name=sim1996/><ref name=sim2010/><ref name=dt1990/><ref name=sexdiff>{{Cite journal| author1=Young, T. P.| author2=Isbell, L. A.| title=Sex differences in giraffe feeding ecology: energetic and social constraints |journal=[[Ethology (journal)|Ethology]]| volume=87| issue=1–2| pages=79–89| year=1991 |doi=10.1111/j.1439-0310.1991.tb01190.x | bibcode=1991Ethol..87...79Y|url=http://tpyoung.ucdavis.edu/publications/1991GiraffesEthology.pdf| access-date=2 February 2012| archive-url=https://web.archive.org/web/20130516034426/http://tpyoung.ucdavis.edu/publications/1991GiraffesEthology.pdf| archive-date=16 May 2013| url-status=dead}}</ref> and a 2010 study found that adult giraffes with longer necks actually suffered higher mortality rates under drought conditions than their shorter-necked counterparts. This study suggests that maintaining a longer neck requires more nutrients, which puts longer-necked giraffes at risk during a food shortage.<ref name=demography>{{cite journal|author1=Mitchell, G. |author2=van Sittert, S. |author3=Skinner, J. D. |year=2010 |title=The demography of giraffe deaths in a drought|journal=Transactions of the Royal Society of South Africa |volume=65|issue=3|pages=165–168|doi=10.1080/0035919X.2010.509153|bibcode=2010TRSSA..65..165M |hdl=2263/18957 |s2cid=83652889 |hdl-access=free}}</ref>

Another theory, the [[sexual selection]] hypothesis, proposes that long necks evolved as a secondary [[sexual dimorphism|sexual characteristic]], giving males an advantage in "necking" contests (see below) to establish dominance and obtain access to sexually receptive females.<ref name=sim1996>{{Cite journal |author1=Simmons, R. E.|author2=Scheepers, L. |title=Winning by a Neck: Sexual Selection in the Evolution of Giraffe |journal=[[The American Naturalist]] |volume=148 |issue=5| pages=771–786 |year=1996 |url=http://bill.srnr.arizona.edu/classes/182/Giraffe/WinningByANeck.pdf |doi=10.1086/285955 |bibcode=1996ANat..148..771S |s2cid=84406669 |url-status=dead| archive-url=https://web.archive.org/web/20040823200801/http://bill.srnr.arizona.edu/classes/182/Giraffe/WinningByANeck.pdf| archive-date=23 August 2004}}</ref> In support of this theory, some studies have stated that necks are longer and heavier for males than females of the same age,<ref name=sim1996/><ref name=sim2010/> and that males do not employ other forms of combat.<ref name=sim1996/> However, a 2024 study found that, while males have thicker necks, females actually have proportionally longer ones, which is likely because of their greater need to find more food to sustain themselves and their dependent young.<ref name=Cavener2024>{{cite journal|last1=Cavener|first1=D. R.|last2=Bond|first2=M. L.|last3=Wu-Cavener|first3=L|last4=Lohay|first4=G. G.|last5=Cavener|first5=M. W.|last6=Hou|first6=X|last7=Pearce|first7=D. L.|last8=Lee|first8=D. E.|year=2024|title=Sexual dimorphisms in body proportions of Masai giraffes and the evolution of the giraffe's neck|journal=Mammalian Biology|volume=104 |issue=5 |pages=513–527 |doi=10.1007/s42991-024-00424-4|doi-access=free}}</ref> It has also been proposed that the neck serves to give the animal greater vigilance.<ref>{{cite journal|author=Brownlee, A. |year=1963|title=Evolution of the Giraffe|journal=[[Nature (journal)|Nature]] |volume=200 |issue=4910 |page=1022 |doi=10.1038/2001022a0 |bibcode=1963Natur.200.1022B|s2cid=4145785|doi-access=free}}</ref><ref>{{cite journal |last1=Williams|first1=E. M.|title=Giraffe Stature and Neck Elongation: Vigilance as an Evolutionary Mechanism |journal=Biology |volume=5 |issue=3 |page=35 |doi=10.3390/biology5030035 |year=2016 |pmc=5037354 |pmid=27626454 |doi-access=free}}</ref>