Editing Lizard (section)

===Venom===
[[File:AZ Gila Monster 02.jpg|thumb|left|Some lizards including the [[Gila monster]] are [[venom]]ous.]]
{{further|Evolution of snake venom}}
Until 2006 it was thought that the [[Gila monster]] and the [[Mexican beaded lizard]] were the only venomous lizards. However, several species of monitor lizards, including the [[Komodo dragon]], produce powerful venom in their oral [[gland]]s. [[Varanus varius|Lace monitor]] venom, for instance, causes swift loss of consciousness and extensive bleeding through its pharmacological effects, both lowering [[blood pressure]] and preventing [[blood clotting]]. Nine classes of [[toxin]] known from snakes are produced by lizards. The range of actions provides the potential for new [[medicinal drug]]s based on lizard venom [[protein]]s.<ref name=Fry2005>{{cite journal |last1=Fry |first1=Bryan G.|display-authors=etal|title=Early evolution of the venom system in lizards and snakes |journal=Nature |date=16 November 2005 |volume=439 |issue=7076 |pages=584–588 |doi=10.1038/nature04328|pmid=16292255 |bibcode=2006Natur.439..584F |s2cid=4386245}}</ref><ref name=Casey2013>{{cite magazine |last1=Casey |first1=Constance |title=Don't Call It a Monster |url=http://www.slate.com/articles/health_and_science/science/2013/04/gila_monster_revolting_creature_the_large_venomous_lizard_of_the_u_s_southwest.html |magazine=Slate |date=26 April 2013 |access-date=5 July 2017 |archive-date=10 October 2018 |archive-url=https://web.archive.org/web/20181010001503/http://www.slate.com/articles/health_and_science/science/2013/04/gila_monster_revolting_creature_the_large_venomous_lizard_of_the_u_s_southwest.html |url-status=live }}</ref>

Genes associated with venom toxins have been found in the salivary glands of a wide range of lizards, including species traditionally thought of as non-venomous, such as iguanas and bearded dragons. This suggests that [[Evolution of snake venom|these genes evolved in the common ancestor]] of lizards and [[snake]]s, some 200 million years ago (forming a single [[clade]], the [[Toxicofera]]<!--seems a reasonable overlink-->).<ref name=Fry2005/> However, most of these putative venom genes were "housekeeping genes" found in all cells and tissues, including skin and cloacal scent glands. The genes in question may thus be evolutionary precursors of venom genes.<ref>{{cite journal |last1=Hargreaves |first1=Adam D. |display-authors=etal |title=Testing the Toxicofera: Comparative transcriptomics casts doubt on the single, early evolution of the reptile venom system |journal=Toxicon |date=2014 |volume=92 |pages=140–156 |doi=10.1016/j.toxicon.2014.10.004 |pmid=25449103 |bibcode=2014Txcn...92..140H |url=https://research.bangor.ac.uk/portal/en/researchoutputs/testing-the-toxicofera-comparative-reptile-transcriptomics-casts-doubt-on-the-single-early-evolution-of-the-reptile-venom-system(5e889426-c4ec-4324-81e8-6df67558bd3b).html |hdl=2160/26793 |hdl-access=free |access-date=2019-08-19 |archive-date=2020-11-06 |archive-url=https://web.archive.org/web/20201106092216/https://research.bangor.ac.uk/portal/en/researchoutputs/testing-the-toxicofera-comparative-reptile-transcriptomics-casts-doubt-on-the-single-early-evolution-of-the-reptile-venom-system(5e889426-c4ec-4324-81e8-6df67558bd3b).html |url-status=live }}</ref>