Iguania is an

infraorder Order ( la, ordo) is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and ...

squamate Squamata (, Latin ''squamatus'', 'scaly, having scales') is the largest order of reptiles, comprising lizards, snakes, and amphisbaenians (worm lizards), which are collectively known as squamates or scaled reptiles. With over 10,900 species, it ...

reptiles that includes

iguanas ''Iguana'' (, ) is a genus of herbivorous lizards that are native to tropical areas of Mexico, Central America, South America, and the Caribbean. The genus was first described in 1768 by Austrian naturalist Josephus Nicolaus Laurenti in his ...

, chameleons,

agamid Agamidae is a family of over 300 species of iguanian lizards indigenous to Africa, Asia, Australia, and a few in Southern Europe. Many species are commonly called dragons or dragon lizards. Overview Phylogenetically, they may be sister to the ...

s, and

New World The term ''New World'' is often used to mean the majority of Earth's Western Hemisphere, specifically the Americas."America." ''The Oxford Companion to the English Language'' (). McArthur, Tom, ed., 1992. New York: Oxford University Press, p. ...

lizards like anoles and phrynosomatids. Using morphological features as a guide to evolutionary relationships, the Iguania are believed to form the sister group to the remainder of the Squamata, which comprise nearly 11,000 named species, roughly 2000 of which are iguanians. However, molecular information has placed Iguania well within the Squamata as sister taxa to the

Anguimorpha The Anguimorpha is a suborder of squamates. The group was named by Fürbringer in 1900 to include all autarchoglossans closer to '' Varanus'' and ''Anguis'' than ''Scincus''. These lizards, along with iguanians and snakes, constitute the propos ...

and closely related to snakes. The order has been under debate and revisions after being classified by Charles Lewis Camp in 1923 due to difficulties finding adequate synapomorphic morphological characteristics. Most Iguanias are

arboreal Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally, but others are exclusively arboreal. The habitats pose nu ...

but there are several terrestrial groups. They usually have primitive fleshy, non-prehensile tongues, although the tongue is highly modified in chameleons. The group has a fossil record that extends back to the

Early Jurassic The Early Jurassic Epoch (geology), Epoch (in chronostratigraphy corresponding to the Lower Jurassic series (stratigraphy), Series) is the earliest of three epochs of the Jurassic Period. The Early Jurassic starts immediately after the Triassic-J ...

(the oldest known member is '' Bharatagama'', which lived about 190 million years ago in what is now India). Today they are scattered occurring in Madagascar, the Fiji and Friendly Islands and Western Hemisphere.

Classification

The Iguania currently include these extant families: *Clade Acrodonta **Family Agamidae – agamid lizards, Old World arboreal lizards **Family Chamaeleonidae – chameleons *Clade

Pleurodonta Pleurodonta (from Greek '' lateral teeth'', in reference to the position of the teeth on the jaw) is one of the two subdivisions of Iguania, the other being Acrodonta ('' teeth on the top f the jaw'). Pleurodonta includes all families previously ...

– American arboreal lizards, chuckwallas, iguanas ** Family

Leiocephalidae Leiocephalidae, also known as the curlytail lizards or curly-tailed lizards, is a family of iguanian lizards restricted to the West Indies. One of the defining features of these lizards is that their tail often curls over. They were previously ...

***Genus '' Leiocephalus'': curly-tailed lizards ** Family

Corytophanidae Corytophanidae is a family of iguanian lizards, also called casquehead lizards or helmeted lizards, endemic to the New World. Nine species of casquehead lizards from three genera are recognized. Geographic range Corytophanids are found from Me ...

– helmet lizards ** Family

Crotaphytidae The Crotaphytidae, or collared lizards, are a family of desert-dwelling reptiles native to the Southwestern United States and northern Mexico. Alternatively they are recognized as a subfamily, Crotaphytinae, within the clade Pleurodonta. They are ...

– collared lizards, leopard lizards ** Family

Hoplocercidae Hoplocercidae are a family of lizards native to the tropical forests, woodlands and savanna-like habitats of Central and South America. Alternatively they are recognized as a subfamily, Hoplocercinae. 20 species in three genera are described. Sp ...

– dwarf and spinytail iguanas ** Family

Iguanidae The Iguanidae is a family of lizards composed of the iguanas, chuckwallas, and their prehistoric relatives, including the widespread green iguana. Taxonomy Iguanidae is thought to be the sister group to the collared lizards (family Crotaph ...

– marine, Fijian, Galapagos land, spinytail, rock, desert, green, and chuckwalla iguanas ** Family

Tropiduridae The Tropiduridae are a family of iguanid lizards."Tropiduridae". The Reptile Database. www.reptile-database.org. The family is sometimes considered a subfamily, Tropidurinae. The subfamily is native to South America, including the islands of Tri ...

– tropidurine lizards ***subclade of Tropiduridae Tropidurini – neotropical ground lizards ** Family

Dactyloidae Dactyloidae are a family of lizards commonly known as anoles () and native to warmer parts of the Americas, ranging from southeastern United States to Paraguay. Instead of treating it as a family, some authorities prefer to treat it as a subfam ...

– anoles ** Family

Polychrotidae The Polychrotidae family (sometimes classified as the Polychrotinae subfamily instead) of iguanian lizards contains the living genus '' Polychrus'' (commonly called bush anoles) and the extinct genus '' Afairiguana''. The family Polychrotidae was ...

***subclade of Polychrotidae ''

Polychrus ''Polychrus'' is the only extant genus of polychrotid lizards in the world. Commonly called bush anoles, they are found in Central and South America, as well as nearby Trinidad and Tobago. ''Polychrus'' means "many colored". True anoles in o ...

'' ** Family

Phrynosomatidae The Phrynosomatidae are a diverse family of lizards, sometimes classified as a subfamily (Phrynosomatinae), found from Panama to the extreme south of Canada. Many members of the group are adapted to life in hot, sandy deserts, although the spiny ...

– North American spiny lizards ** Family

Liolaemidae Liolaemidae are a family of iguanian lizards. They are traditionally included in the Iguanidae as subfamily Liolaeminae, which some more recent authors prefer to delimit in a more restricted way. A common name for this group is liolaemids. Liolae ...

– South American swifts ** Family Opluridae – Malagasy iguanas ** Family

Leiosauridae Leiosauridae is a family of iguanian lizards containing six genera and 34 species. The family is endemic to Central America and South America. Taxonomy A 2022 phylogenetic study found the Leiosauridae to be the sister taxa to the Opluridae, ...

– leiosaurs ***subclade of Leiosaurini Leiosaurae ***subclade of Leiosaurini Anisolepae

Phylogeny

Below is a

cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to ...

from the

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

analysis of Daza ''et al.'' (2012) (a morphological analysis), showing the interrelationships of extinct and living iguanians:

Conservation Status

As of 2020 The

IUCN Red List The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biol ...

of endangered species lists 63.3% of the species as

Least concern A least-concern species is a species that has been categorized by the International Union for Conservation of Nature (IUCN) as evaluated as not being a focus of species conservation because the specific species is still plentiful in the wild. T ...

, 6.7%

Near Threatened A near-threatened species is a species which has been categorized as "Near Threatened" (NT) by the International Union for Conservation of Nature as that may be vulnerable to endangerment in the near future, but it does not currently qualify f ...

, 8.2 vulnerable, 9.1%

endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and in ...

, 3.1% critically endangered, 0.3 extinct and 9.2% data deficient. The major threats include agriculture, residential and commercial development.https://www.iucnredlist.org/

Classification

Phylogeny

Conservation Status

References

Further reading