| Iguanids Temporal range: | |
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Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Order: | Squamata |
| Suborder: | Iguania |
| Clade: | Pleurodonta |
| Family: | Iguanidae Oppel, 1811 |
| Genera | |
Amblyrhynchus Contents
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The Iguanidae is a family of lizards composed of the iguanas, chuckwallas, and their prehistoric relatives, [1] including the widespread green iguana.
Iguanidae is thought to be the sister group to the collared lizards (family Crotaphytidae); the two groups likely diverged during the Late Cretaceous, as that is when Pristiguana and Pariguana , the two earliest fossil genera, are known from. The subfamily Iguaninae, which contains all modern genera, likely originated in the earliest Paleocene, at about 62 million years ago. The most basal extant genus, Dipsosaurus, diverged from the rest of Iguaninae during the late Eocene, about 38 million years ago, with Brachylophus following a few million years later at about 35 million years ago, presumably after its dispersal event to the Pacific. All other modern iguana genera formed in the Neogene period. [2]
A phylogenetic tree of Iguaninae is shown here: [2]
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 are arboreal, living in trees, but some species tend to be more terrestrial, which means they prefer the ground. Iguanas are typically herbivores and their diets vary based on what plant life is available within their habitat. Iguanas across many species remain oviparious, and exhibit little to no parental care when their eggs hatch. They do, however, display nest-guarding behavior. Like all extant non-avian reptiles, they are poikilothermic, and also rely on regular periods of basking under the sun to thermoregulate. [3]
All but one of modern iguana genera are native to the Americas, ranging from the deserts of the Southwestern United States through Mexico, Central America, and the Caribbean, to throughout South America down to northernmost Argentina. Some iguanas like I. 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. [4] 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. [3] The only non-American iguana species are the members of the genus Brachylophus and the extinct Lapitiguana , which are found on Fiji and formerly Tonga; their distribution is thought to be the result of the longest overwater dispersal event ever recorded for a vertebrate species, with them rafting over 8000 km across the Pacific from the Americas to the Fiji and Tonga. [5]
| Image | Genus | Species |
|---|---|---|
 | Amblyrhynchus Bell, 1825 – marine iguana |
|
 | Brachylophus Cuvier, 1829 – Fijian/Tongan iguanas |
|
 | Cachryx Cope, 1866 – spinytail iguanas |
|
 | Conolophus Fitzinger, 1843 – Galápagos land iguanas |
|
 | Ctenosaura Wiegmann, 1828 – spiny-tailed iguanas |
|
 | Cyclura Harlan, 1825 – West Indian rock iguanas |
|
 | Dipsosaurus Hallowell, 1854 – desert iguanas |
|
 | Iguana Laurenti, 1768 – green and Lesser Antillean iguanas |
|
 | Sauromalus Dumeril, 1856 – chuckwallas |
|
| Image | Genus | Species |
|---|---|---|
 | Armandisaurus Norell & de Queiroz, 1991 |
|
 | Lapitiguana Pregill & Worthy, 2003 |
|
 | Pumilia Norell 1989 |
|
Cretaceous Pristiguana brasiliensis and Pariguana lancensis are later excluded from the family. [6] [7]
Several classification schemes have been used to define the structure of this family. The "historical" classification recognized all New World iguanians, plus Brachylophus and the Madagascar oplurines, as informal groups and not as formal subfamilies. [8]
Frost and Etheridge (1989) formally recognized these informal groupings as families. [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) as subfamilies 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 comprehensive phylogenies published to date, recognized most groups at family level, resulting in a narrower definition of Iguanidae. [13] [14] [15]
Family Iguanidae
Family Corytophanidae
Family Crotaphytidae
Family Hoplocercidae
Family Iguanidae
Family Opluridae
Family Phrynosomatidae
Family Polychridae
Family Tropiduridae
Family Iguanidae
Here families and subfamilies are proposed as clade names, but may be recognized under the traditional Linnean nomenclature.
Iguanidae
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 very fast-moving animals, with long limbs and tails; some species are capable of achieving bipedal running at top speed. This species is carnivorous, feeding mainly on insects and smaller lizards. The two genera contain 12 species.
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 two genera are described.
The Opluridae, or Madagascan iguanas, are a family of moderately-sized lizards native to Madagascar and Grande Comore. There are eight species across two genera, with most of them being under Oplurus. The other genus, Chalarodon, is easily distinguishable from Oplurus as it contains species with a dorsal crest, particularly distinct in males, and has a smoother tail covered in similarly sized scales. Genus Oplurus has large segmented spiny scales, and no dorsal crest along the spine.
Leiosauridae is a family of iguanian lizards containing six genera and 34 species. The family is endemic to Central America and South America.
The genus Brachylophus consists of four extant iguanid species native to the islands of Fiji and a giant extinct species from Tonga in the South West Pacific. One of the extant species, B. fasciatus, is also present on Tonga, where it has apparently been introduced by humans.
The Galápagos land iguanas comprise the genus Conolophus of the Galápagos Islands (Ecuador). The number of species of this variable genus has always been disputed; the most current taxonomic surveys suggest that three species exist:
Ctenosaura is a lizard genus commonly known as spinytail iguanas or ctenosaurs. The genus is part of the large lizard family Iguanidae and is native to Mexico and Central America. The name is derived from two Greek words: κτενός, meaning "comb", and σαύρα, meaning "lizard".
Liolaemus is a genus of iguanian lizards, containing many species, all of which are endemic to South America.
Iguania is an infraorder of squamate reptiles that includes iguanas, chameleons, agamids, and New World 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 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 iguanians are arboreal but there are several terrestrial groups. They usually have primitive fleshy, non-prehensile tongues, although the tongue is highly modified in chameleons. Today they are scattered occurring in Madagascar, the Fiji and Friendly Islands and Western Hemisphere.
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 by Austrian naturalist J.N. Laurenti in 1768. Two species are placed in the genus: The green iguana, which is widespread throughout its range and a popular pet; and the Lesser Antillean iguana, which is native to the Lesser Antilles. Genetic analysis indicates that the green iguana may comprise a complex of multiple species, some of which have been recently described, but the Reptile Database considers all of these as subspecies of the green iguana.
Polychrus gutturosus, also known as Berthold's bush anole or monkey tailed anole, is a species of lizard found in tropical Central and South America. It is sometimes referred to as a "forest iguana". It lives in forests and jungles from Honduras to Ecuador. It can reach up to 70 cm (2.3 ft) in total length, including its very long tail, and males are considerably smaller than females. This insectivorous lizard is a climbing species that can often be seen holding onto branches. It can even hold on with its hind legs, though it moves slowly that way.
Lapitiguana impensa is an extinct giant iguanid from Fiji. It probably became extinct following the human colonization of Fiji 3000 years ago.
Scleroglossa is a group of lizards that includes geckos, autarchoglossans, and amphisbaenians. Scleroglossa is supported by phylogenetic analyses that use morphological features. According to most morphological analyses, Scleroglossa is the sister group of the clade Iguania,[a] which includes iguanas, chameleons, agamids, and New World lizards. Together, Scleroglossa and Iguania make up the crown group Squamata, the smallest evolutionary grouping to include all living lizards and snakes.
Brachylophus gibbonsi is an extinct species of large iguanid lizard from Tonga in the South Pacific Ocean. Its remains have been found associated with cultural sites on Lifuka, four other islands in the Haʻapai group, and Tongatapu. It was consumed by the early Tongans and probably became extinct within a century of human colonization of the archipelago 2800 years ago.
The Polychrotidae family of iguanian lizards contains the living genus Polychrus and the extinct genus Afairiguana. The family Polychrotidae was once thought to encompass all anoles, including those in the genus Anolis. Studies of the evolutionary relationships of anoles based on molecular information has shown that Polychrus is not closely related to Anolis, but instead closer to Hoplocercidae. It is therefore not part of Dactyloidae and instead is treated as the family, Polychrotidae.
Chamaeleontiformes is a hypothesized clade of iguanian lizards defined as all taxa sharing a more recent common ancestor with Chamaeleo chamaeleon than with Hoplocercus spinosus, Polychrus marmoratus, or Iguana iguana. It was named by paleontologist Jack Conrad in 2008 to describe a clade recovered in his phylogenetic analysis that included the extinct genus Isodontosaurus, the extinct family Priscagamidae, and the living clade Acrodonta, which includes agamids and chameleons. It is a stem-based taxon and one of two major clades within Iguania, the other being Pleurodonta. Below is a cladogram from Daza et al. (2012) showing this phylogeny:
Acrodonta are a subclade of iguanian squamates consisting almost entirely of Old World taxa. Extant representation include the families Chamaeleonidae (chameleons) and Agamidae, with at least over 500 species described. A fossil genus, Gueragama, was found in Brazil, making it the only known American representative of the group.
Enyalius boulengeri, also known commonly as the Brazilian fathead anole, is a species of lizard in the family Leiosauridae. The species is endemic to Brazil.
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