Editing Tuatara (section)

==Description==
[[File:Tuatara scale.png|thumb|left|upright|Size comparison of male ''S.&nbsp;punctatus'' and human]]
[[File:Sphenodon punctatus LH288.jpg|thumb|Skeleton of the tuatara]]

Tuatara are the largest reptiles in New Zealand.<ref>{{Cite web |title=Tuatara |url=https://www.doc.govt.nz/nature/native-animals/reptiles-and-frogs/tuatara/ |access-date=2022-12-12 |website=[[Department of Conservation (New Zealand)|Department of Conservation]] |language=en-nz}}</ref> Adult ''S.&nbsp;punctatus'' males measure {{convert|61|cm|in|abbr=on}} in length and females {{convert|45|cm|in|abbr=on}}.<ref name="encyclo" /> Tuatara are [[sexual dimorphism|sexually dimorphic]], males being larger.<ref name="encyclo" /> The [[San Diego Zoo]] even cites a length of up to {{convert|80|cm|in|abbr=on}}.<ref>{{cite web |publisher=[[San Diego Zoo]] |series=Animal Bytes |title=Tuatara |url=http://www.sandiegozoo.org/animalbytes/t-tuatara.html |archive-url=https://web.archive.org/web/20121130133444/http://www.sandiegozoo.org/animalbytes/t-tuatara.html |archive-date=30 November 2012 |access-date=19 April 2008}}</ref> Males weigh up to {{convert|1|kg|lb|abbr=on}}, and females up to {{convert|0.5|kg|lb|abbr=on}}.<ref name="encyclo" /> Brothers Island tuatara are slightly smaller, weighing up to 660&nbsp;g (1.3&nbsp;lb).<ref name="NZRG" />

Their lungs have a single chamber with no [[bronchi]].<ref>{{cite book |author=Jacobson, E.R. |date=2007-04-11 |title=Infectious Diseases and Pathology of Reptiles |publisher=CRC Press |isbn=978-1-4200-0403-8 |url=https://books.google.com/books?id=hhO4WAZcVLEC&pg=PA13}}</ref>

The tuatara's greenish brown colour matches its environment, and can change over its lifetime. Tuatara shed their skin at least once per year as adults,<ref name="lutz16" /> and three or four times a year as juveniles. Tuatara sexes differ in more than size. The spiny crest on a tuatara's back, made of triangular, soft folds of skin, is larger in males, and can be stiffened for display. The male abdomen is narrower than the female's.<ref>{{cite web |title=Tuataras |website=Animal Corner |url=http://www.animalcorner.co.uk/reptiles/rep_tuatara.html |archive-url=https://web.archive.org/web/20150317073012/http://animalcorner.co.uk/reptiles/rep_tuatara.html |archive-date=17 March 2015 |access-date=31 December 2007}}</ref>

===Skull===
[[File:Tuatara skull diagram.svg|thumb|Skull diagram in top down and side-on views]]
Unlike the vast majority of lizards, the tuatara has a complete lower temporal bar closing the lower [[temporal fenestra]] (an opening of the skull behind the eye socket), caused by the fusion of the [[Quadrate bone|quadrate]]/[[Quadratojugal bone|quadratojugal]] (which are fused into a single element in adult tuatara) and the [[jugal bone]]s of the skull. This is similar to the condition found in primitive [[diapsid]] reptiles. However, because more primitive rhynchocephalians have an open lower temporal fenestra with an incomplete temporal bar, this is thought to be [[Derived (phylogenetics)|derived]] characteristic of the tuatara and other members of the clade [[Sphenodontinae]], rather than a primitive trait retained from early diapsids. The complete bar is thought to stabilise the skull during biting.<ref name=":02">{{Cite journal |last1=Simões |first1=Tiago R. |last2=Kinney-Broderick |first2=Grace |last3=Pierce |first3=Stephanie E. |date=2022-03-03 |title=An exceptionally preserved Sphenodon-like sphenodontian reveals deep time conservation of the tuatara skeleton and ontogeny |journal=Communications Biology |language=en |volume=5 |issue=1 |page=195 |doi=10.1038/s42003-022-03144-y |issn=2399-3642 |pmc=8894340 |pmid=35241764}}</ref>

The tip of the upper jaw is chisel- or beak-like and separated from the remainder of the jaw by a notch,<ref name="Günther1867" /> this structure is formed from fused [[premaxilla]]ry teeth, and is also found in many other advanced rhynchocephalians.<ref>{{Cite journal |last1=Herrera-Flores |first1=Jorge A. |last2=Stubbs |first2=Thomas L. |last3=Elsler |first3=Armin |last4=Benton |first4=Michael J. |date=July 2018 |title=Taxonomic reassessment of Clevosaurus latidens Fraser, 1993 (Lepidosauria, Rhynchocephalia) and rhynchocephalian phylogeny based on parsimony and Bayesian inference |journal=Journal of Paleontology |language=en |volume=92 |issue=4 |pages=734–742 |doi=10.1017/jpa.2017.136 |issn=0022-3360|doi-access=free |bibcode=2018JPal...92..734H |hdl=1983/59126b60-16d8-46d2-b657-954693a39d4e |hdl-access=free }}</ref> The teeth of the tuatara, and almost all other rhynchocephalians, are described as [[acrodont]], as they are attached to the apex of the jaw bone. This contrast with the [[pleurodont]] condition found in the vast majority of lizards, where the teeth are attached to the inward-facing surface of the jaw. The teeth of the tuatara are extensively fused to the jawbone, making the boundary between the tooth and jaw difficult to discern, and the teeth lack roots and are not replaced during the lifetime of the animal, unlike those of pleurodont lizards.<ref>{{Cite journal |last1=Jenkins |first1=Kelsey M. |last2=Jones |first2=Marc E. H. |last3=Zikmund |first3=Tomas |last4=Boyde |first4=Alan |last5=Daza |first5=Juan D. |date=September 2017 |title=A Review of Tooth Implantation Among Rhynchocephalians (Lepidosauria) |url=http://www.bioone.org/doi/10.1670/16-146 |journal=Journal of Herpetology |language=en |volume=51 |issue=3 |pages=300–306 |doi=10.1670/16-146 |issn=0022-1511 |s2cid=90519352}}</ref> It is a common misconception that tuatara lack teeth and instead have sharp projections on the jaw bone;<ref name="lutzp27">{{Harvnb|Lutz|2005|p=27}}</ref> histology shows that they have true teeth with enamel and dentine with pulp cavities.<ref name="Kieser2009">{{cite journal |vauthors=Kieser JA, Tkatchenko T, Dean MC, Jones ME, Duncan W, Nelson NJ |year=2009 |title=Microstructure of dental hard tissues and bone in the Tuatara dentary, ''Sphenodon punctatus'' (Diapsida: Lepidosauria: Rhynchocephalia) |url=https://www.karger.com/Article/Abstract/242396 |journal=Frontiers of Oral Biology |volume=13 |pages=80–85 |doi=10.1159/000242396 |isbn=978-3-8055-9229-1 |pmid=19828975}}</ref> As their teeth wear down, older tuatara have to switch to softer prey, such as [[earthworm]]s, [[larva]]e, and [[slug]]s, and eventually have to chew their food between smooth jaw bones.<ref>{{cite news |author=Mlot, C. |date=8 November 1997 |title=Return of the Tuatara: A relic from the age of dinosaurs gets a human assist |website=Science News |url=http://www.sciencenews.org/pages/pdfs/data/1997/152-19/15219-21.pdf |access-date=24 May 2007}}</ref>

The tuatara possesses palatal dentition (teeth growing from the bones of the roof of the mouth), which is ancestrally present in reptiles (and [[tetrapod]]s generally).<ref name=":13">{{cite journal |vauthors=Matsumoto R, Evans SE |date=January 2017 |title=The palatal dentition of tetrapods and its functional significance |journal=[[Journal of Anatomy]] |volume=230 |issue=1 |pages=47–65 |doi=10.1111/joa.12534 |pmc=5192890 |pmid=27542892}}</ref> While many of the original palatal teeth present in reptiles have been lost,<ref name=":13" /> as in all other known rhynchocephalians, the row of teeth growing from the [[palatine bone]]s in the tuatara have been enlarged, and as in other members of Sphenodontinae the palatine teeth are orientated parallel to the teeth in the [[maxilla]]; during biting the teeth of the lower jaw slot between the two upper tooth rows.<ref name="Jones2008">{{cite journal |author=Jones, M.E. |date=August 2008 |title=Skull shape and feeding strategy in Sphenodon and other Rhynchocephalia (Diapsida: Lepidosauria) |journal=Journal of Morphology |volume=269 |issue=8 |pages=945–66 |doi=10.1002/jmor.10634 |pmid=18512698 |s2cid=16357353 |doi-access=free}}</ref> The structure of the jaw joint allows the lower jaw to slide forwards after it has closed between the two upper rows of teeth.<ref name="Jones et al. 2012">{{cite journal |vauthors=Jones ME, O'higgins P, Fagan MJ, Evans SE, Curtis N |date=July 2012 |title=Shearing mechanics and the influence of a flexible symphysis during oral food processing in Sphenodon (Lepidosauria: Rhynchocephalia) |journal=The Anatomical Record |volume=295 |issue=7 |pages=1075–91 |doi=10.1002/ar.22487 |pmid=22644955 |s2cid=45065504|doi-access=free }}</ref> This mechanism allows the jaws to shear through [[chitin]] and bone.<ref name="encyclo" />

The brain of ''Sphenodon'' fills only half of the volume of its [[endocranium]].<ref name="larsson2001">{{cite book |vauthors=Larsson HC |year=2001 |chapter=Endocranial anatomy of ''Carcharodontosaurus saharicus'' (Theropoda: Allosauroidea) and its implications for theropod brain evolution |veditors=Tanke DH, Carpenter K, Skrepnick MW |title=Mesozoic Vertebrate Life |place=Bloomington & Indianapolis |publisher=Indiana University Press |isbn=0-253-33907-3 |pages=19–33}}</ref> This proportion has been used by paleontologists trying to estimate the volume of dinosaur brains based on fossils.<ref name="larsson2001" /> However, the proportion of the tuatara endocranium occupied by its brain may not be a very good guide to the same proportion in Mesozoic dinosaurs since modern birds are surviving dinosaurs but have brains which occupy a much greater relative volume in the endocranium.<ref name="larsson2001" />

{{gallery|Tuatara Skull Lateral (50669113641).jpg|Skull of the tuatara in oblique view|File:Sphenodon punctatus (AM LH288) 601767.jpg|Skull of the tuatara in oblique view, with [[sclerotic ring]]s in eye sockets|Sphenodon punctatus (AM LH288) 601763 (cropped).jpg|Skull of tuatara from above|File:Tuatara Skull Doral (50668366013).jpg|Skull of tuatara from above|Tuatara skull diagram.jpg|Tuatara skull in various views with palatine tooth row visible on underside of the skull|||||||width=200|height=180|lines=|align=center}}

===Sensory organs===
[[File:Tuatara (7714490358).jpg|thumb|left|Close-up of a tuatara's head]]

==== Eyes ====
The eyes can [[Accommodation (eye)|focus]] independently, and are specialised with three types of photoreceptive cells, all with fine structural characteristics of retinal [[cone cell]]s<ref>{{cite journal |vauthors=Meyer-Rochow VB, Wohlfahrt S, Ahnelt PK |year=2005 |title=Photoreceptor cell types in the retina of the tuatara (Sphenodon punctatus) have cone characteristics |url=https://www.sciencedirect.com/science/article/abs/pii/S0968432805000521 |journal=Micron |volume=36 |issue=5 |pages=423–428 |doi=10.1016/j.micron.2005.03.009 |pmid=15896966}}</ref> used for both day and night vision, and a ''[[tapetum lucidum]]'' which reflects onto the retina to enhance vision in the dark. There is also a third eyelid on each eye, the [[nictitating membrane]]. Five visual [[opsin]] genes are present, suggesting good [[colour vision]], possibly even at low light levels.<ref name="Gemmell2020">{{cite journal |vauthors=Gemmell NJ, Rutherford K, Prost S, Tollis M, Winter D, Macey JR, Adelson DL, Suh A, Bertozzi T, Grau JH, Organ C, Gardner PP, Muffato M, Patricio M, Billis K, Martin FJ, Flicek P, Petersen B, Kang L, Michalak P, Buckley TR, Wilson M, Cheng Y, Miller H, Schott RK, Jordan MD, Newcomb RD, Arroyo JI, Valenzuela N, Hore TA, Renart J, Peona V, Peart CR, Warmuth VM, Zeng L, Kortschak RD, Raison JM, Zapata VV, Wu Z, Santesmasses D, Mariotti M, Guigó R, Rupp SM, Twort VG, Dussex N, Taylor H, Abe H, Bond DM, Paterson JM, Mulcahy DG, Gonzalez VL, Barbieri CG, DeMeo DP, Pabinger S, Van Stijn T, Clarke S, Ryder O, Edwards SV, Salzberg SL, Anderson L, Nelson N, Stone C |date=August 2020 |title=The tuatara genome reveals ancient features of amniote evolution |journal=Nature |volume=584 |issue=7821 |pages=403–409 |doi=10.1038/s41586-020-2561-9 |pmc=7116210 |pmid=32760000 |doi-access=free}}</ref>

==== Parietal eye (third eye) ====
Like some other living vertebrates, including some lizards, the tuatara has a third eye on the top of its head called the [[parietal eye]] (also called a pineal or third eye) formed by the parapineal organ, with an accompanying opening in the skull roof called the pineal or parietal foramen, enclosed by the [[parietal bone]]s.<ref name=":1">{{Cite journal |last1=Smith |first1=Krister T. |last2=Bhullar |first2=Bhart-Anjan S. |last3=Köhler |first3=Gunther |last4=Habersetzer |first4=Jörg |date=April 2018 |title=The Only Known Jawed Vertebrate with Four Eyes and the Bauplan of the Pineal Complex |journal=Current Biology |volume=28 |issue=7 |pages=1101–1107.e2 |doi=10.1016/j.cub.2018.02.021 |issn=0960-9822|doi-access=free |pmid=29614279 |bibcode=2018CBio...28E1101S }}</ref> It has its own lens, a parietal plug which resembles a [[cornea]],<ref>{{cite journal |author1=Schwab, I.R. |author2=O'Connor, G.R. |date=March 2005 |title=The lonely eye |journal=The British Journal of Ophthalmology |volume=89 |issue=3 |pages=256 |doi=10.1136/bjo.2004.059105 |pmc=1772576 |pmid=15751188}}</ref> [[retina]] with rod-like structures, and degenerated nerve connection to the brain. The parietal eye is visible only in hatchlings, which have a translucent patch at the top centre of the skull. After four to six months, it becomes covered with opaque scales and pigment.<ref name="encyclo" /> While capable of detecting light, it is probably not capable of detecting movement or forming an image.<ref>{{Cite journal |last=Jones |first=Marc E.H. |last2=Cree |first2=Alison |date=December 2012 |title=Tuatara |url=https://linkinghub.elsevier.com/retrieve/pii/S0960982212013036 |journal=Current Biology |language=en |volume=22 |issue=23 |pages=R986–R987 |doi=10.1016/j.cub.2012.10.049}}</ref> It likely serves to regulate the [[circadian rhythm]] and possibly detect seasonal changes, and help with [[thermoregulation]].<ref name="encyclo" /><ref name=":1" />

Of all extant tetrapods, the parietal eye is most pronounced in the tuatara. It is part of the pineal complex, another part of which is the [[pineal gland]], which in tuatara secretes melatonin at night.<ref name="encyclo" /> Some [[salamander]]s have been shown to use their pineal bodies to perceive polarised light, and thus determine the position of the sun, even under cloud cover, aiding [[Animal navigation|navigation]].<ref>{{cite book |author=Halliday, T.R. |year=2002 |chapter=Salamanders and newts: Finding breeding ponds |editor1=Halliday, T. |editor2=Adler, K. |title=The New Encyclopedia of Reptiles and Amphibians |place=Oxford, UK |publisher=Oxford University Press |isbn=0-19-852507-9|page=52}}</ref>

==== Hearing ====
Together with [[turtle]]s, the tuatara has the most primitive hearing organs among the amniotes. There is no tympanum ([[eardrum]]) and no earhole,<ref name="lutzp27" /> and the [[middle ear]] cavity is filled with loose tissue, mostly [[adipose tissue|adipose (fatty) tissue]]. The [[stapes]] comes into contact with the [[Quadrate bone|quadrate]] (which is immovable), as well as the [[hyoid bone|hyoid]] and [[squamosal]]. The [[hair cell]]s are unspecialised, innervated by both [[Afferent nerve|afferent]] and [[efferent nerve]] fibres, and respond only to low frequencies. Though the hearing organs are poorly developed and primitive with no visible external ears, they can still show a frequency response from 100 to 800&nbsp;[[Hertz|Hz]], with peak sensitivity of 40&nbsp;[[Decibel|dB]] at 200&nbsp;Hz.<ref>{{cite web |author=Kaplan, Melissa |date=6 September 2003 |title=Reptile Hearing |website=Melissa Kaplan's herp care collection |url=http://www.anapsid.org/reptilehearing.html |access-date=24 July 2006}}</ref>

==== Odorant receptors ====
Animals that depend on the sense of smell to capture prey, escape from predators or simply interact with the environment they inhabit, usually have many odorant receptors. These receptors are expressed in the dendritic membranes of the neurons for the detection of odours. The tuatara has around 472 receptors, a number more similar to what birds have than to the large number of receptors that turtles and crocodiles may have.<ref name="Gemmell2020" />

===Spine and ribs===
The tuatara [[Vertebral column|spine]] is made up of hourglass-shaped [[Vertebral column#Classification|amphicoelous]] vertebrae, concave both before and behind.<ref name="lutzp27" /> This is the usual condition of fish vertebrae and some amphibians, but is unique to tuatara within the amniotes. The vertebral bodies have a tiny hole through which a constricted remnant of the notochord passes; this was typical in early fossil reptiles, but lost in most other amniotes.<ref>{{cite book |author1=Romer, A.S. |author2=Parsons, T.S. |year=1977 |title=The Vertebrate Body |edition=Fifth |location=Philadelphia, PA |publisher=W.B. Saunders |isbn=978-0-7216-7668-5 |page=624}}</ref>

The tuatara has [[gastralium|gastralia]], rib-like bones also called gastric or abdominal ribs,<ref>{{cite web |title=Tuatara |website=Berlin Zoo Aquarium |url=http://www.aquarium-berlin.de/en/experience/animal-highlights/tuatara.html |access-date=11 September 2007 |archive-url=https://web.archive.org/web/20070814075005/http://www.aquarium-berlin.de/en/experience/animal-highlights/tuatara.html <!--Added by H3llBot--> |archive-date=14 August 2007}}</ref> the presumed ancestral trait of diapsids. They are found in some [[lizard]]s, where they are mostly made of cartilage, as well as crocodiles and the tuatara, and are not attached to the spine or thoracic ribs. The true ribs are small projections, with small, hooked bones, called uncinate processes, found on the rear of each rib.<ref name="lutzp27" /> This feature is also present in birds. The tuatara is the only living [[tetrapod]] with well-developed gastralia and uncinate processes.

In the early tetrapods, the gastralia and ribs with uncinate processes, together with bony elements such as bony plates in the skin (osteoderms) and [[clavicle]]s (collar bone), would have formed a sort of exoskeleton around the body, protecting the belly and helping to hold in the guts and inner organs. These anatomical details most likely evolved from structures involved in locomotion even before the vertebrates ventured onto land. The gastralia may have been involved in the breathing process in early amphibians and reptiles. The pelvis and shoulder girdles are arranged differently from those of lizards, as is the case with other parts of the internal anatomy and its scales.<ref>{{cite web |author=Wattie, T. |website=www.kiwizone.org |title=Tuatara Reptile, New Zealand |url=http://nzphoto.tripod.com/animal/tuatara.htm |access-date=31 December 2007 |archive-url=https://web.archive.org/web/20071114212222/http://nzphoto.tripod.com/animal/tuatara.htm |archive-date=14 November 2007}}</ref>

===Tail and back===
The spiny plates on the back and tail of the tuatara resemble those of a crocodile more than a lizard, but the tuatara shares with lizards the ability to break off its tail when caught by a predator, and then regenerate it. The regrowth takes a long time and differs from that of lizards. Well illustrated reports on tail regeneration in tuatara have been published by Alibardi and Meyer-Rochow.<ref>{{cite journal |author1=Alibardi, L. |author2=Meyer-Rochow, V.B. |year=1990 |title=Ultrastructural survey of the spinal cord of young tuatara (''Sphenodon punctatus'') with emphasis on the glia |journal=New Zealand Journal of Zoology |volume=17 |pages=73–85 |doi=10.1080/03014223.1990.10422586}}</ref><ref>{{cite journal |author1=Alibardi, L. |author2=Meyer-Rochow, V.B. |year=1990 |title=Fine structure of regenerating caudal spinal cord in adult tuatara (''Sphenodon punctatus'') |journal=Journal für Hirnforschung |volume=31 |issue=5 |pages=613–21 |pmid=1707076}}</ref> The cloacal glands of tuatara have a unique [[organic compound]] named [[tuataric acid]].

=== Age determination ===
Currently, there are two means of determining the age of tuatara. Using microscopic inspection, hematoxylinophilic rings can be identified and counted in both the phalanges and the femur. Phalangeal hematoxylinophilic rings can be used for tuatara up to ages 12–14&nbsp;years, as they cease to form around this age. Femoral rings follow a similar trend, however they are useful for tuatara up to ages 25–35&nbsp;years. Around that age, femoral rings cease to form.<ref>{{cite journal |author1=Castanet, J. |author2=Newman, D.G. |author3=Girons, H.S. |date=1988 |title=Skeletochronological data on the growth, age, and population structure of the tuatara, ''Sphenodon punctatus'', on Stephens and Lady Alice Islands, New Zealand |journal=Herpetologica |volume=44 |issue=1 |pages=25–37 |jstor=3892195}}</ref> Further research on age determination methods for tuatara is required, as tuatara have lifespans much longer than 35&nbsp;years (ages up to 60<ref name="KCC" /> are common, and captive tuatara have lived to over 100&nbsp;years).<ref name="Disc-Mag-2009-01-26" /><ref name="NZHer-2009-01-26" /><ref name="BBCNews-2009-01-26" /> One possibility could be via examination of tooth wear, as tuatara have fused sets of teeth.

=== Physiology ===
[[File:TWC Wildlife Centre• Stewart Nimmo • MRD 8910.jpg|thumb|left|A tuatara basking at the West Coast Wildlife Centre, at [[Franz Josef / Waiau|Franz Josef]] on the [[West Coast, New Zealand|West Coast]]]]

Adult tuatara are [[Landform|terrestrial]] and [[nocturnal]] reptiles, though they will often bask in the sun to warm their bodies. Hatchlings hide under logs and stones, and are [[Diurnality|diurnal]], likely because adults are cannibalistic. Juveniles are typically active at night, but can be found active during the day. The juveniles' movement pattern is attributed to genetic hardwire of conspecifics for predator avoidance and thermal restrictions.<ref>{{Cite journal |last1=Terezow |first1=Marianna G. |last2=Nelson |first2=Nicola J. |last3=Markwell |first3=Timothy J. |date=January 2008 |title=Circadian emergence and movement of captive juvenile tuatara (''Sphenodon''spp.) |journal=New Zealand Journal of Zoology |volume=35 |issue=3 |pages=205–216 |doi=10.1080/03014220809510116 |issn=0301-4223 |s2cid=83781111|doi-access=free }}</ref> Tuatara thrive in temperatures much lower than those tolerated by most reptiles, and [[hibernation|hibernate]] during winter.<ref>{{cite web |date=18 January 2006 |title=Tuatara: Facts |url=http://www.southlandmuseum.com/tuatara_-_facts.htm |archive-url=https://web.archive.org/web/20070609034405/http://www.southlandmuseum.com/tuatara_-_facts.htm |archive-date=9 June 2007 |access-date=2 June 2007 |publisher=Southland Museum}}</ref> They remain active at temperatures as low as {{convert|5|°C|°F|0}},<ref>{{cite news |author=Schofield, E. |date=24 March 2009 |title=New arrivals thrill staff at sanctuary |newspaper=[[Otago Daily Times]] |place=Otago, NZ |url=http://www.odt.co.nz/your-town/dunedin/48665/new-arrivals-thrill-staff-sanctuary |access-date=23 March 2009}}</ref> while temperatures over {{convert|28|°C|°F|0}} are generally fatal. The optimal body temperature for the tuatara is from {{convert|16|to|21|C|F}}, the lowest of any reptile.<ref name="UofM">{{cite web |author=Musico, B. |year=1999 |title=''Sphenodon punctatus'' |url=http://animaldiversity.ummz.umich.edu/site/accounts/information/Sphenodon_punctatus.html |access-date=22 April 2006 |website=Animal Diversity Web |publisher=University of Michigan Museum of Zoology}}</ref> The body temperature of tuatara is lower than that of other reptiles, ranging from {{convert|5.2|-|11.2|C|F}} over a day, whereas most reptiles have body temperatures around {{convert|20|°C|°F|0}}.<ref>{{cite journal |author1=Thompson, M.B. |author2=Daugherty, C.H. |year=1998 |title=Metabolism of tuatara, ''Sphenodon punctatus'' |journal=Comparative Biochemistry and Physiology A |volume=119 |issue=2 |pages=519–522 |doi=10.1016/S1095-6433(97)00459-5}}</ref> The low body temperature results in a slower [[metabolism]].{{Clear}}