Iguanidae is thought to be the sister group to thecollared lizards (familyCrotaphytidae). This family likely first appeared inCenozoic, previously identified twoCretaceous genera (Pristiguana andPariguana) are unlikely to belong to this family.[2] The subfamilyIguaninae, which contains all modern genera, likely originated in the earliestPaleocene, about 62 million years ago. The mostbasal extant genus,Dipsosaurus, diverged from the rest of Iguaninae during the lateEocene, about 38 million years ago, withBrachylophus following a few million years later at about 35 million years ago, presumably after its dispersal event to thePacific. All other modern iguana genera formed in theNeogene period.[3]
Iguanas and iguana-type species are diverse in terms of size, appearance, and habitat. They typically flourish in tropical, warm climates, such as regions of South America and islands in the Caribbean and in the Pacific. Iguanas typically possess dorsal spines across their back, a dewlap on the neck, sharp claws, a long whip-like tail, and a stocky, squat build. Most iguanas arearboreal, living in trees, but some species tend to be moreterrestrial, which means they prefer the ground. Iguanas are typicallyherbivores and their diets vary based on what plant life is available within their habitat. Iguanas across many species remainoviparious, and exhibit little to noparental care when their eggs hatch. They do, however, display nest-guarding behavior. Like all extant non-avian reptiles, they arepoikilothermic, and also rely on regular periods of basking under the sun tothermoregulate.[4]
All but one of the modern iguana genera are native to the Americas, ranging from thedeserts of theSouthwestern United States throughMexico,Central America, and theCaribbean, to throughoutSouth America down to northernmostArgentina. Some iguanas likeI. iguana have spread from their native regions of Central and South America into many Pacific Islands, and even to Fiji, Japan, and Hawai'i, due to the exotic pet trade and illegal introductions into the ecosystems.[5] Other iguanas, like the Galapagos pink iguana (C. marthae) are endemic only to specific regions on the Galapagos islands. The Grand Cayman blue iguana,C. lewisi, is endemic only to the Grand Cayman island, limited to a small wildlife reserve.[4] The only non-American iguana species are the members of the genusBrachylophus and the extinctLapitiguana, which are found onFiji and formerlyTonga; their distribution is thought to be the result of the longest overwaterdispersal event ever recorded for a vertebrate species, with them rafting over 8000 km across thePacific from theAmericas to the Fiji and Tonga.[6]
Several classification schemes have been used to define the structure of this family. The "historical" classification recognized all New World iguanians, plusBrachylophus and the Madagascaroplurines, as informal groups and not as formal subfamilies.[8]
Frost and Etheridge (1989) formally recognized these informal groupings asfamilies.[9][10]
Macey et al. (1997), in their analysis of molecular data for iguanian lizards recovered a monophyletic Iguanidae and formally recognized the eight families proposed by Frost and Etheridge (1989) assubfamilies of Iguanidae.[11]
Schulte et al. (2003) reanalyzed the morphological data of Frost and Etheridge in combination with molecular data for all major groups of Iguanidae and recovered a monophyletic Iguanidae, but the subfamilies Polychrotinae and Tropidurinae were not monophyletic.[12]
Townsend et al. (2011), Wiens et al. (2012) and Pyron et al. (2013), in the most comprehensivephylogenies published to date, recognized most groups at family level, resulting in a narrower definition of Iguanidae.[13][14][15]
^Bauer, Aaron M. (1998). Cogger, H.G.; Zweifel, R.G. (eds.).Encyclopedia of Reptiles and Amphibians. San Diego: Academic Press. pp. 140–142.ISBN0-12-178560-2.
^Etheridge, Richard; de Queiroz, Kevin (1988). Estes, R.; Pregill, G. (eds.).Phylogenetic Relationships of the Lizard Families, Essays Commemorating Charles L. Camp. Stanford, California: Stanford University Press. pp. 283–368.ISBN0-8047-1435-5.
^D.R. Frost & R. Etheridge (1989) «A phylogenetic analysis and taxonomy of iguanian lizards (Reptilia: Squamata)»Univ. Kansas Mus. Nat. Hist. Misc. Publ. 81
^Macey J.R., Larson A., Ananjeva N.B., Papenfuss T.J. (1997). "[Evolutionary shifts in three major structural features of the mitochondrial genome among iguanian lizards.]".Journal of Molecular Evolution.44 (6):660–674.Bibcode:1997JMolE..44..660M.doi:10.1007/pl00006190.PMID9169559.S2CID30106562.{{cite journal}}: CS1 maint: multiple names: authors list (link)
^Schulte II J.A., Valladares J.P., Larson A. (2003). "[Phylogenetic relationships within Iguanidae inferred using molecular and morphological data and a phylogenetic taxonomy of iguanian lizards.]".Herpetologica.59 (3):399–419.doi:10.1655/02-48.S2CID56054202.{{cite journal}}: CS1 maint: multiple names: authors list (link)
^Townsend; Mulcahy; Noonan; Sites Jr; Kuczynski; Wiens; Reeder (2011). "Phylogeny of iguanian lizards inferred from 29 nuclear loci, and a comparison of concatenated and species-tree approaches for an ancient, rapid radiation".Molecular Phylogenetics and Evolution.61 (2):363–380.Bibcode:2011MolPE..61..363T.doi:10.1016/j.ympev.2011.07.008.PMID21787873.
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