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 ...
of
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, ...
reptile
Reptiles, as most commonly defined are the animals in the class Reptilia ( ), a paraphyletic grouping comprising all sauropsids except birds. Living reptiles comprise turtles, crocodilians, squamates (lizards and snakes) and rhynchocephalians ( ...
s 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 ...
,
chameleon
Chameleons or chamaeleons (family Chamaeleonidae) are a distinctive and highly specialized clade of Old World lizards with 202 species described as of June 2015. The members of this family are best known for their distinct range of colors, bein ...
s,
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 I ...
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. 3 ...
lizards like
anoles and
phrynosomatids. Using
morphological features as a guide to evolutionary relationships, the Iguania are believed to form the
sister group
In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree.
Definition
The expression is most easily illustrated by a cladogram:
Taxon A and t ...
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
''Scincus'' is a genus of skinks, lizards in the family Scincidae. Th ...
and closely related to
snakes
Snakes are elongated, limbless, carnivorous reptiles of the suborder Serpentes . Like all other squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales. Many species of snakes have skulls with several more joi ...
.
The order has been under debate and revisions after being classified by
Charles Lewis Camp
Charles Lewis Camp (March 12, 1893 Jamestown, North Dakota – August 14, 1975 San Jose, California) was a palaeontologist and zoologist, working from the University of California, Berkeley. He took part in excavations at the 'Placerias Quarry', in ...
in 1923 due to difficulties finding adequate
synapomorphic morphological characteristics.
Most Iguanias are
arboreal
Arboreal locomotion is the Animal locomotion, 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. Th ...
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
Agamidae is a family (biology), 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
phylogenetics, Phylogenetic ...
– 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 o ...
***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
The Opluridae, or Madagascan iguanas, are a family of moderately sized lizards native to Madagascar and Grande Comore. There are eight species in two genera, with most of the species being in ''Oplurus''. The Opluridae, along with ''Brachylophus'' ...
– 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, a ...
– 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 d ...
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 fo ...
, 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 inva ...
, 3.1% critically endangered, 0.3 extinct
Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...
and 9.2% data deficient
A data deficient (DD) species is one which has been categorized by the International Union for Conservation of Nature (IUCN) as offering insufficient information for a proper assessment of conservation status to be made. This does not necessaril ...
. The major threats include agriculture, residential and commercial development.[https://www.iucnredlist.org/]
References
Further reading
*
*
{{Taxonbar, from=Q661136
Early Jurassic first appearances