View source for Lizard

{{Taxobox
| fossil_range = [[Upper Triassic]] {{ndash}} [[Holocene|present]] 202{{ndash}}0 mya
| image = Tokay.jpg  
| image_width = 250px
| image_caption = The tokay [[gecko]], From [[East Timor]]
| regnum = [[Animal]]ia
| phylum = [[Chordate|Chordata]]
| superclassis = [[Tetrapod]]
| classis = [[Reptile|Sauropsida]]
| ordo = [[Squamata]]
| subordo = '''Lacertilia'''
| subordo_authority = [[Albert C.L.G. Günther|Günther]], 1867
| subdivision_ranks = [[Family (biology)|Families]]
| subdivision = }}
[[File:Haeckel Lacertilia.jpg|thumb|right|250px|"Lacertilia", from [[Ernst Haeckel]]'s ''Kunstformen der Natur'', 1904]]

'''Lizards''' are a group of [[reptiles]]. Together with [[snake]]s, they make up most of the [[Order (biology)|order]] [[Squamata]].

There are about 6,000 [[species]],<ref>[http://www.reptile-database.org Reptile Database]. Retrieved on 2012-04-22</ref> which live all over the world, except in cold [[climate]]s. They range across all continents except [[Antarctica]], as well as most oceanic [[island]] chains.<ref>Capula, Massimo; Behler 1989. ''Simon & Schuster's guide to reptiles and amphibians of the world''. New York: Simon & Schuster. {{ISBN|0-671-69098-1}}.</ref>  One type, the [[marine iguana]], lives in the [[sea]]. Size varies greatly, from [[Gecko]]<nowiki/>s of a few inches or cm to the [[Komodo dragon]] of 3 meters (9 feet) and 70 kg (150 pounds).

Some kinds of lizards are: 
* [[Basilisk]]
* [[Gecko]]
* ''[[Iguana]]''
* [[Monitor lizard]]
* [[Frill-necked Lizard]]
* ''[[Draco (genus)|Draco]]'', flying lizard
* [[Slow-worm]]: a lizard without legs.
== Simplified classification ==
In the traditional taxonomy the Order Squamata is divided as follows:
*Order [[Squamata]] (the [[Scale (zoology)|scaled]] reptiles)
** Suborder Serpentes ([[snake]]s)
** Suborder Lacertilia / Sauria (lizards)

A modern view is that the snakes and lizards are all infraorders of the Squamata:<ref name="Benton">Benton, Michael 1997. ''Vertebrate palaeontology''. Chapman & Hall, London.</ref><sup>p238</sup>

*<big>Order [[Squamata]]</big>
** Infraorder [[Snake|Serpentes]]
** Infraorder [[Iguana|Iguania]]: [[Iguana]]s, [[chameleon]]s, [[Agamidae|agamas]] and relatives.
** Infraorder [[Gecko|Gekkota]]: [[Gecko]]s, legless lizards, blind lizards.
** Infraorder [[Skink|Scincomorpha]]: [[Skink]]s, wall lizards and relatives.
** Infraorder [[Anguimorpha]] (Platynota, Varanoidea): [[Monitor lizard]]s, [[Gila monster]]s, [[Anguis|Slow-worms]] and relatives.
** Infraorder [[Amphisbaenia]]: legless burrowing worm lizards.
There are other versions, and the taxonomy will probably not settle until more molecular evidence is collected.
== Natural history ==

== Anatomy ==
The skull structure of both snakes and lizards is distinctive. They can move their upper jaw relative to the braincase. They bear horny scales, and many use [[Toxin|venom]] for attack and defense.
== Evolution ==
The Squamates are definitely a [[monophyletic]] group; they are a sister group to the [[Tuatara]]. Judged by their fossil record, the Squamates were present in the [[Mesozoic]], but occupied a minor place in the land ecology. Three of the six lines are recorded first in the Upper [[Jurassic]], the others in the [[Cretaceous]].<ref name="Benton"/> The [[Mosasaur]]s of the [[Upper Cretaceous]] were by far the most successful of all the lizards, becoming the top predator in their [[ecosystem]]. 

It is now known that lizards originated in the [[Upper Triassic]], 237{{ndash}}201 million years ago.<ref>Fossil shows lizards millions of years older than thought. [https://www.bbc.co.uk/news/uk-england-bristol-63832928]</ref>

Although snakes and lizards look so different, neither are proper [[clades]]. Snakes did descend from early lizards, so both groups together do form a [[monophyletic]] clade, the Squamata. Within that clade there is another monophyletic clade, the [[Toxicofera]]. This includes all [[venom]]ous reptile species, as well as many related non-venomous species. The evidence for this is in recent [[sequence analysis|molecular analyses]].<ref>Vidal, Nicolas, and S. Blair Hedges. 2009. The molecular evolutionary tree of lizards, snakes, and amphisbaenians. ''Comptes rendus biologies'' '''332''', (2) 129-139. [http://webh01.ua.ac.be/funmorph/raoul/fylsyst/Vidal2009.pdf] {{Webarchive|url=https://web.archive.org/web/20131030065408/http://webh01.ua.ac.be/funmorph/raoul/fylsyst/Vidal2009.pdf|date=2013-10-30}}</ref><ref>Pyron R.A; Burbrink F.T. and Wiens J.J. 2013. A phylogeny and revised classification of Squamata, including 4161 species of lizards and snakes. ''BMC evolutionary biology'' '''13''', (1) 93.</ref><ref>Wiens, John J. ''et al'' 2012. Resolving the phylogeny of lizards and snakes (Squamata) with extensive sampling of genes and species. ''Biology letters'' '''8''', (6) 1043-1046.</ref>
== Physiology ==
[[Image:Jackson's Chameleon 2 edit1.jpg|thumb|left|Feral [[Jackson's Chameleon]] from a population introduced to Hawaii in the 1970s]]

Lizards use [[anti-predator defence]]s, including [[venom]], [[camouflage]], and reflex bleeding. They can also sacrifice and regrow their tails.

Sight is very important for most lizards, both for finding prey and for communication. Many lizards have highly acute color vision. Most rely heavily on body language, using specific postures, gestures and movements to define territory, resolve disputes, and entice mates. 

Most lizards use bright colors, but not all the time. These are usually kept out of sight, otherwise the animal would be seen by predators. The bright patches are usually hidden on the underside or between scales: they are only shown when necessary. For example, the ''dewlap'' is a brightly colored patch of skin on the throat, usually hidden between scales. When a display is needed, the lizards erect the hyoid bone of their throat. This shows a large vertical flap of brightly colored skin under its head which can be then used for communication.
== Images ==
<gallery>
Image:Coachella Valley Fringe-toed Lizard.JPG|Coachella Valley Fringe-toed Lizard, ''Uma inornata''
Image:plumed.basilisk.750pix.jpg|Plumed Basilisk, ''Basiliscus plumifrons''
Image:gila.monster.arp.jpg|[[Gila monster]], ''Heloderma s. suspectum''
Image:green.tree.monitor.lizard.arp.jpg|Green tree monitor lizard, ''Varanus prasinus''
</gallery>

== Lizard Media ==
<gallery widths='160px' heights='100%' mode='traditional' caption=''>
File:Mediterranean house gecko1.jpg|Mediterranean house gecko1

File:Red Tegu Skull.jpg|Red tegu (''[[Tupinambis rufescens]]'') skull, showing teeth of differing types

File:Gecko foot on glass.JPG|Adhesive pads enable [[gecko]]s to climb vertically.

File:Nile Monitor (Varanus niloticus) (16545024096).jpg|Nile monitor using its tongue for smell

File:Bearded Dragon Skeleton.jpg|Skeleton of bearded dragon ([[pogona]] sp.) on display at the [[Museum of Osteology]].

File:AZ Gila Monster 02.jpg|Some lizards including the [[Gila monster]] are [[venom]]ous.

File:EasternFenceLizard Egg.png|Two pictures of an [[eastern fence lizard]] egg layered onto one image.

File:Fighting Sand lizards (Lacerta agilis) 4295304.jpg|Fighting male [[sand lizards]]

File:Green anole.jpg|A green anole (''[[Anolis carolinensis]]'') [[signalling theory|signalling]] with its extended [[dewlap]]

File:Severed skink tail.webm|A skink tail continuing to move after [[autotomy]]
</gallery>
== References ==
{{Reflist}}

[[Category:Lizards|*]]
[[Category:Reptiles]]