{{Short description|Family of lizards}} {{automatic taxobox | name = Varanids | fossil_range = <br />Late Cretaceous – Holocene, {{fossilrange|80|0}} | image = Komodo dragons (Varanus komodoensis) fighting.jpg | image_caption = Male Komodo dragons (''Varanus komodoensis'') fighting, Indonesia | image2 = Saniwa FMNH.jpg | image2_caption = Fossil of ''Saniwa'', an extinct varanid known from the Eocene of North America | taxon = Varanidae | authority = Merrem, 1820 | subdivision_ranks = Genera | subdivision = *''Varanus'' *†''Aiolosaurus'' *†''Archaeovaranus'' *†''Ovoo'' *†''Paravaranus'' *†''Proplatynotia'' *†''Saniwa'' *†''Saniwides'' *†''Telmasaurus'' *†''Zhongyuanxi'' }}
The '''Varanidae''' are a family of lizards in the superfamily Varanoidea and order Anguimorpha. The family, a group of carnivorous and frugivorous lizards,<ref name="Welton2010">{{cite journal | vauthors = Welton LJ, Siler CD, Bennett D, Diesmos A, Duya MR, Dugay R, Rico EL, Van Weerd M, Brown RM | display-authors = 6 | title = A spectacular new Philippine monitor lizard reveals a hidden biogeographic boundary and a novel flagship species for conservation | journal = Biology Letters | volume = 6 | issue = 5 | pages = 654–658 | date = October 2010 | pmid = 20375042 | pmc = 2936141 | doi = 10.1098/rsbl.2010.0119 }}</ref> includes the living genus ''Varanus'' and a number of extinct genera more closely related to ''Varanus'' than to the earless monitor lizard (''Lanthanotus'').<ref name=":0">{{cite journal | vauthors = Dong L, Wang YQ, Zhao Q, Vasilyan D, Wang Y, Evans SE | title = A new stem-varanid lizard (Reptilia, Squamata) from the early Eocene of China | journal = Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences | volume = 377 | issue = 1847 | article-number = 20210041 | date = March 2022 | pmid = 35125002 | pmc = 8819366 | doi = 10.1098/rstb.2021.0041 }}</ref> ''Varanus'' includes the Komodo dragon (the largest living lizard), crocodile monitor, savannah monitor, the goannas of Australia and Southeast Asia, and various other species with a similarly distinctive appearance. Their closest living relatives are the earless monitor lizard and Chinese crocodile lizard.<ref name="Fry2006">{{cite journal | vauthors = Fry BG, Vidal N, Norman JA, Vonk FJ, Scheib H, Ramjan SF, Kuruppu S, Fung K, Hedges SB, Richardson MK, Hodgson WC, Ignjatovic V, Summerhayes R, Kochva E | display-authors = 6 | title = Early evolution of the venom system in lizards and snakes | journal = Nature | volume = 439 | issue = 7076 | pages = 584–588 | date = February 2006 | pmid = 16292255 | doi = 10.1038/nature04328 | first12 = V. | first13 = R. | s2cid = 4386245 | first14 = E. | bibcode = 2006Natur.439..584F | first111 = W.C. }}</ref> The oldest members of the family are known from the Late Cretaceous of Mongolia.<ref name=":0" />
==Taxonomy== The Varanidae were defined (using morphological characteristics) by Estes, de Queiroz and Gauthier (1988) as the clade containing the most recent common ancestor of ''Lanthanotus'' and ''Varanus'' and all of its descendants.<ref name="estes1998">{{cite book | veditors = Estes RJ, Pregill GK | vauthors = de Queiroz K, Gauthier J |date=1988 |title=Phylogenetic Relationships of the Lizard Families: Essays Commemorating Charles L. Camp |chapter=Phylogenetic Relationships within Squamata |publisher=Stanford University Press |isbn=978-0-8047-1435-8 |oclc=16646258 |page=166}}</ref> A similar definition was formulated by Conrad ''et al.'' (2008) (also using morphological data), who defined the Varanidae as the clade containing ''Varanus varius'', ''Lanthanotus borneensis'', and all descendants of their last common ancestor.<ref name=conrad2008>{{cite journal | vauthors = Conrad J |year=2008 |title=Phylogeny and systematics of Squamata (Reptilia) based on morphology |journal=Bulletin of the American Museum of Natural History |doi=10.1206/310.1 |hdl=2246/5915 |volume=310 |pages=1–182|s2cid=85271610 }}</ref> Using one of these definitions leads to the inclusion of the earless monitor lizard (''L. borneensis'') in the family Varanidae.
Lee (1997) created a different definition of the Varanidae, defining them as the clade containing ''Varanus'' and all taxa more closely related to ''Varanus'' than to ''Lanthanotus'';<ref name=LeeMSY>{{cite journal | pmid=20986455 | date=1946 | author1=WARNER R | title=Pectoral girdles vs. Hyobranchia in the snake genera Liotyphlops and Anomalepis | journal=Science | volume=103 | issue=2686 | pages=720–722 | doi=10.1126/science.103.2686.720 }}</ref><ref>{{cite journal | vauthors = Lee MS | title = Molecular evidence and marine snake origins | journal = Biology Letters | volume = 1 | issue = 2 | pages = 227–230 | date = June 2005 | pmid = 17148173 | pmc = 1626205 | doi = 10.1098/rsbl.2004.0282 }}</ref> this definition explicitly excludes the earless monitor lizard from the Varanidae. Whether ''L. borneensis'' is included in or excluded from the Varanidae depends on the author; for example, Vidal ''et al.'' (2012) classify the earless monitor lizard as a member of a separate family Lanthanotidae,<ref>{{cite journal | vauthors = Vidal N, Marin J, Sassi J, Battistuzzi FU, Donnellan S, Fitch AJ, Fry BG, Vonk FJ, Rodriguez de la Vega RC, Couloux A, Hedges SB | display-authors = 6 | title = Molecular evidence for an Asian origin of monitor lizards followed by Tertiary dispersals to Africa and Australasia | journal = Biology Letters | volume = 8 | issue = 5 | pages = 853–855 | date = October 2012 | pmid = 22809723 | pmc = 3441001 | doi = 10.1098/rsbl.2012.0460 }}</ref> while Gauthier ''et al.'' (2012) classify it as a member of Varanidae.<ref>{{cite journal | vauthors = Gauthier JA, Kearney M, Maisano JA, Rieppel O, Behlke AD |year=2012 |title=Assembling the Squamate Tree of Life: Perspectives from the Phenotype and the Fossil Record |journal=Bulletin of the Peabody Museum of Natural History |doi=10.3374/014.053.0101 |volume=53 |issue=1 |pages=3–308|s2cid=86355757 }}</ref>
===Genera=== :<small>Genera marked with {{extinct}} are extinct</small> Genera included in Varanidae according to Dong ''et al.'', 2022<ref name=":0" /> *{{extinct}}''Ovoo'' <small>Norell, Gao, & Conrad, 2008</small><ref name=PLOS12>{{cite journal | vauthors = Conrad JL, Balcarcel AM, Mehling CM | title = Earliest example of a giant monitor lizard (Varanus, Varanidae, Squamata) | journal = PLOS ONE | volume = 7 | issue = 8 | article-number = e41767 | year = 2012 | pmid = 22900001 | pmc = 3416840 | doi = 10.1371/journal.pone.0041767 | bibcode = 2012PLoSO...741767C | doi-access = free }}</ref> (Mongolia, Late Cretaceous) *{{extinct}}''Aiolosaurus'' <small>Gao and Norell, 2000</small><ref name=PLOS12/> (Mongolia, Late Cretaceous) *{{extinct}}''Cherminotus'' <small>Borsuk-Bialynicka, 1984</small> (Mongolia, Late Cretaceous) *{{extinct}}''Saniwides'' <small>Borsuk-Bialynicka, 1984</small> (Mongolia, Late Cretaceous) *{{extinct}}''Paravaranus'' <small>Borsuk-Bialynicka, 1984</small> (Mongolia, Late Cretaceous) *{{extinct}}''Proplatynotia'' <small>Borsuk-Bialynicka, 1984</small> (Mongolia, Late Cretaceous) *{{extinct}}''Telmasaurus'' <small>Gilmore, 1943</small><ref name=PLOS12/> (Mongolia, Late Cretaceous) *{{extinct}}''Zhongyuanxi'' <small>Xu, 2025</small> (China, Late Cretaceous)<ref>{{cite journal |last1=Xu |first1=L. |last2=Dong |first2=L. |last3=Gao |first3=D. |last4=Li |first4=Y. |last5=Wu |first5=Y. |last6=Chang |first6=F. |last7=Li |first7=J. |last8=Evans |first8=S. |title=A new anguimorph lizard from the Upper Cretaceous of Henan Province, China |journal=Journal of Systematic Palaeontology |year=2025 |volume=23 |issue=1 |at=2470790 |doi=10.1080/14772019.2025.2470790 |bibcode=2025JSPal..2370790X }}</ref> *{{extinct}}''Saniwa'' <small>Leidy, 1870</small> (Europe, North America, Eocene) *{{extinct}}''Archaeovaranus'' <small>Dong ''et al.'', 2022 (</small>China, Eocene) *''Varanus'' <small>Shaw, 1790</small>
===Phylogeny=== Below is a cladogram from Dong et al. 2022.<ref name=":0" />
{{Clade|{{Clade |1=†''Ovoo gurvel'' |2={{Clade |1={{Clade |1=†''Telmasaurus grangeri'' |2={{Clade |1=†''Aiolosaurus oriens'' |2=†''Saniwides mongoliensis'' }} }} |2={{Clade |1={{Clade |1=†''Paravaranus angustifrons'' |2=†''Proplatynotia longirostrata'' }} |2={{Clade |1=†''Saniwa ensidens'' |2={{Clade |1=†''Archaeovaranus lii'' |2=''Varanus'' }} }} }} }} }}|label1=Varanidae}}
==Biology== [[File:Grays Monitor WWP.jpg|thumb|Gray's monitor (''Varanus olivaceus'') is a tree-dwelling varanid from the Philippines that primarily feeds on fruit]] Monitor lizards are reputed to be among the most intelligent lizards. Most species forage widely and have large home ranges,<ref name="Perry_and_Garland_2002">{{cite journal | vauthors = Perry G, Garland Jr T |author-link2=Theodore Garland, Jr. |year=2002 |title=Lizard home ranges revisited: effects of sex, body size, diet, habitat, and phylogeny |journal=Ecology |volume=83 |pages=1870–1885 |url=http://www.biology.ucr.edu/people/faculty/Garland/PerryGarland2002.pdf |doi=10.1890/0012-9658(2002)083[1870:LHRREO]2.0.CO;2 |issue=7}}</ref> and many have high stamina.<ref name="Clemente_et_al_2009">{{cite journal | vauthors = Clemente CJ, Withers PC, Thompson GG |year=2009 |title=Metabolic rate and endurance capacity in Australian varanid lizards (Squamata; Varanidae; ''Varanus'') |journal=Biological Journal of the Linnean Society |doi=10.1111/j.1095-8312.2009.01207.x |volume=97 |issue=3 |pages=664–676|doi-access=free }}</ref> Although most species are carnivorous, three arboreal species in the Philippines (''Varanus olivaceus'', ''Varanus mabitang'', and ''Varanus bitatawa'') are primarily frugivores.<ref name=Welton2010/><ref name = "Greene">{{cite book | vauthors = Greene HW |date=1986 |title=Diet and Arboreality in the Emerald Monitor, Varanus prasinus, with Comments on the Study of Adaptation |publisher=Field Museum of Natural History |location=Chicago |oclc=14915452 |ol=7155983M}}</ref> Among species of living varanids, the limbs show positive allometry, being larger in larger-bodied species, although the feet become smaller as compared with the lengths of the other limb segments.<ref name="Christian_and_Garland_1996">{{cite journal | vauthors = Christian A, Garland Jr T |author-link2=Theodore Garland, Jr. |year=1996 |title=Scaling of limb proportions in monitor lizards (Squamata: Varanidae) |journal=Journal of Herpetology |doi=10.2307/1565513 |jstor=1565513 |volume=30 |issue=2 |pages=219–230 |url=http://www.biology.ucr.edu/people/faculty/Garland/ChriGa96.pdf}}</ref>
Varanids possess unidirectional pulmonary airflow, including air-sacs akin to those of birds.<ref>[http://svpow.com/2013/12/11/unidirectional-airflow-in-the-lungs-of-birds-crocs-and-now-monitor-lizards/ Unidirectional Airflow In The Lungs Of Birds, Crocs And Now Monitor Lizards]</ref>
== References == {{Reflist|30em}}
== External links == * [http://www.jcvi.org/reptiles/families/varanidae.php Varanidae] {{Webarchive|url=https://web.archive.org/web/20100327052142/http://www.jcvi.org/reptiles/families/varanidae.php |date=2010-03-27 }}
{{Squamata families}} {{varanoidea}}
{{Taxonbar|from=Q3082684}} {{Authority control}}
Category:Varanidae Category:Lizard families Category:Taxa named by Blasius Merrem Category:Extant Campanian first appearances