Agamidae Temporal range: | |
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Male Mwanza flat-headed rock agama (Agama mwanzae), in the Serengeti, Tanzania | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Reptilia |
Order: | Squamata |
Suborder: | Iguania |
Clade: | Acrodonta |
Family: | Agamidae Gray, 1827 [1] |
Subfamilies | |
6, see text |
Agamidae is a family of over 550 species of iguanian lizards indigenous to Africa, Asia, Australia, and a few in Southern Europe. Many species are commonly called dragons or dragon lizards.
Phylogenetically, they may be sister to the Iguanidae, and have a similar appearance. Agamids usually have well-developed, strong legs. Their tails cannot be shed and regenerated like those of geckos (and several other families such as skinks), though a certain amount of regeneration is observed in some. [2] [3] Many agamid species are capable of limited change of their colours to regulate their body temperature. [4] In some species, males are more brightly coloured than females, [5] and colours play a part in signaling and reproductive behaviours. [6] Although agamids generally inhabit warm environments, ranging from hot deserts to tropical rainforests, at least one species, the mountain dragon, is found in cooler regions. They are particularly diverse in Australia. [7] [8] [9]
This group of lizards includes some more popularly known, such as the domesticated bearded dragon, Chinese water dragon, and Uromastyx species.
One of the key distinguishing features of the agamids is their teeth, which are borne on the outer rim of their mouths (acrodonts), rather than on the inner side of their jaws (pleurodonts). This feature is shared with the chameleons and the tuatara, but is otherwise unusual among lizards. Agamid lizards are generally diurnal, with good vision, and include a number of arboreal species, in addition to ground- and rock-dwellers. Most need to bask in the sun to maintain elevated body temperatures, meaning they are heliothermic. They generally feed on insects and other arthropods (such as spiders), although for some larger species, their diet may include small reptiles or mammals, nestling birds, and flowers or other vegetable matter. [10]
The great majority of agamid species are oviparous. [11] The eggs are mostly found in damp soil or rotting logs to retain enough moisture during the incubation period. The clutch size varies from four to 10 eggs for most species, and incubation period lasts around 6–8 weeks. Specifically in the Leiolepidinae subfamily of agamids, all species use a burrowing system that reaches moist soil, where eggs are deposited in late spring/early summer or at the beginning of the dry season. The Leiolepidinae burrow system is also used for daily or seasonal retreats, as it allows them to regulate their body temperature or act as a refuge from predators.
Very few studies of the Agamidae have been conducted. The first comprehensive assessment was by Moody (1980) [12] followed by a more inclusive assessment by Frost and Etheridge (1989). [13] Subsequent studies were based on mitochondrial DNA loci by Macey et al. (2000) [14] and Honda et al. (2000) [15] and also by sampling across the Agamidae by Joger (1991). [16] Few other studies focused on clades within the family, and the Agamidae have not been as well investigated as the Iguanidae.
The agamids show a curious distribution. They are found over much of the Old World, including continental Africa, Australia, southern Asia, and sparsely in warmer regions of Europe. They are absent from Madagascar and the New World. The distribution is the opposite of that of the iguanids, which are found in just these areas, but absent in areas where agamids are found. A similar faunal divide is found in between the boas and pythons. [17]
Among the Agamidae, six subfamilies are generally recognized: [18] [19]
The oldest known unambiguous agamid is Protodraco from the mid-Cretaceous (early Cenomanian) aged Burmese amber of Myanmar, dating to around 99 million years ago. It is similar to primitive living Southeast Asian agamids. [20] Gueragama from the Late Cretaceous of Brazil may also be an agamid. [21] Jeddaherdan, a supposed agamid from the Late Cretaceous of Morocco, was later shown to be actually a young subfossil of the living genus Uromastyx. [22]
Body temperature helps determine the physiological state of agamids and affects their predator responses. A positive correlation is seen between a flight response (running speed) and body temperature of various agamid species. [23] At higher body temperatures, these lizards tend to flee quickly from predators, whereas at lower temperatures, they tend to have a reduced running speed and show an increased fight response, where they are more likely to be aggressive and attack predators.
Certain physical features of some lizards of these species, such as frilled-neck lizards, play a role in their defensive responses, as well. During the mating season, males tend to display more of their frill, and give fight responses more often. Both males and females display their frills when they are threatened by predators, and during social interactions. [24]
Lizard is the common name used for all squamate reptiles other than snakes, encompassing over 7,000 species, ranging across all continents except Antarctica, as well as most oceanic island chains. The grouping is paraphyletic as some lizards are more closely related to snakes than they are to other lizards. Lizards range in size from chameleons and geckos a few centimeters long to the 3-meter-long Komodo dragon.
Squamata is the largest order of reptiles, comprising lizards and snakes. With over 12162 Species, it is also the second-largest order of extant (living) vertebrates, after the perciform fish. Squamates are distinguished by their skins, which bear horny scales or shields, and must periodically engage in molting. They also possess movable quadrate bones, making possible movement of the upper jaw relative to the neurocranium. This is particularly visible in snakes, which are able to open their mouths very wide to accommodate comparatively large prey. Squamates are the most variably sized living reptiles, ranging from the 16 mm (0.63 in) dwarf gecko to the 6.5 m (21 ft) reticulated python. The now-extinct mosasaurs reached lengths over 14 m (46 ft).
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.
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.
Draco is a genus of agamid lizards that are also known as flying lizards, flying dragons or gliding lizards. These lizards are capable of gliding flight via membranes that may be extended to create wings (patagia), formed by an enlarged set of ribs. They are arboreal insectivores.
The frilled lizard, also known as the frillneck lizard, frill-necked lizard or frilled dragon, is a species of lizard in the family Agamidae. It is native to northern Australia and southern New Guinea. This species is the only member of the genus Chlamydosaurus. Its common names come from the large frill around its neck, which usually stays folded against the lizard's body. It reaches 90 cm (35 in) from head to tail and can weigh 600 g (1.3 lb). Males are larger and more robust than females. The lizard's body is generally grey, brown, orangish-brown, or black in colour. The frills have red, orange, yellow, or white colours.
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.
Draco dussumieri, also known commonly as the Indian flying lizard, the southern flying lizard, and the Western Ghats flying lizard, is a species of lizard in the family Agamidae. The species is capable of gliding from tree to tree. It is found principally in the Western Ghats and some other hill forests of Southern India. It is almost completely arboreal, found on trees in forests and adjoining palm plantations where it climbs trees to forage for insects and glides to adjoining trees by expanding the patagium, loose skin on the sides of the body which is supported by elongated ribs to act as wings. The skin on the sides of the neck is also extended to the sides using the hyoid bones of the tongue as support. During the breeding season males maintain small territories which they defend from other males while courting females. The male has a more colourful patagium than the female, and it prominently extends its yellow dewlap forward in display. Although living almost its entire life in trees, the female descends to the ground to lay eggs in soil. This is the species with the westernmost distribution within the genus Draco, the majority of species occurring in Southeast Asia.
Saara hardwickii, commonly known as Hardwicke's spiny-tailed lizard or the Indian spiny-tailed lizard is a species of lizard in the family Agamidae. The species is found in patches across the Thar desert, Kutch, and surrounding arid zones in India and Pakistan. It is mainly herbivorous and lives in numbers in some areas. Since it is found in loose clusters it often attracts predators such as raptors. It is also hunted by local peoples in the belief that the fat extracted from it is an aphrodisiac.
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 book Specimen Medicum, Exhibens Synopsin Reptilium Emendatam cum Experimentis circa Venena. 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.
Barbaturex is an extinct genus of giant herbivorous iguanian lizards from Pondaung Formation, the Eocene of Myanmar. It is represented by a single species, Barbaturex morrisoni, which is known from several partial dentaries and a fused pair of frontals, two bones that form part of the top of the skull. Based on the size of these bones, Barbaturex morrisoni is estimated to have been about 1 metre (3.3 ft) from snout to vent, and possibly up to 6 feet (1.8 m) including the tail. Barbaturex morrisoni was named after The Doors frontman Jim Morrison, a play on his epithet "The Lizard King". The genus's name is a portmanteau of the Latin words Barbatus and rex, meaning "bearded king", in reference to ridges along the mandible and the lizard's large size.
Scincogekkonomorpha is a proposed clade of lizards that includes scleroglossans and all lizards more closely related to scleroglossans than to iguanians. These "stem" scleroglossans include extinct lizards from the Late Jurassic and Early Cretaceous such as Bavarisaurus, Eichstaettisaurus, Liushusaurus, and Scandensia. Scincogekkonomorpha was named in 1961 and is now occasionally used as a stem-based taxon in contrast to the node-based taxon Scleroglossa. According to phylogenies based on morphological characteristics, Scincogekkonomorpha is the sister taxon of Iguania and together they make up crown group Squamata, the smallest clade including all living snakes and lizards. The grouping has not been recovered as monophyletic in recent molecular studies, with Iguania generally found deeply nested within Squamata.
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:
Saichangurvel is an extinct genus of iguanian lizards from the Late Cretaceous of Mongolia. It is a member of a clade called Gobiguania, an exclusively Late Cretaceous group of iguanian lizards that was likely endemic to the Gobi Desert. The type species, Saichangurvel davidsoni, was named by paleontologists Jack Conrad and Mark Norell of the American Museum of Natural History in 2007. It is known from a single nearly complete and fully articulated skeleton called IGM 3/858, which was found eroding from a block of sandstone during a thunderstorm at a fossil locality called Ukhaa Tolgod. IGM 3/858 comes from the Djadochta Formation, which is between 75 and 71 million years in age. Just as it is today, the Gobi was a desert during the Cretaceous. IGM 3/858 may have died in a collapsing sand dune, the rapid burial preserving its skeleton in pristine condition.
Gueragama is an extinct genus of iguanian lizard from the Cretaceous of Brazil. It belongs to a group of iguanians called Acrodonta, whose living members include chameleons and agamids and are currently restricted to the Old World. Gueragama is the only acrodont known from South America, providing evidence that the group once ranged across much of Gondwana and only became restricted to the Old World after the supercontinent broke apart. The type species, Gueragama sulamericana, was named in 2015 on the basis of an isolated lower jaw from Goio-Erê Formation in the Bauru Basin, which was deposited in a desert environment. Although description shows age of Formation at Turonian to Campanian, later study proposes age around Aptian to Albian instead. Unlike modern acrodontans, whose teeth implant on the margins of the jaws, Gueragama has teeth that implant along the inner surface of the lower jaw, a feature common in most non-acrodontan lizards and characteristic of the second major group of iguanians, Pleurodonta. The non-acrodont dentition of Gueragama is evidence of its basal position within Acrodonta, and is shared with the taxon of Late Cretaceous acrodontan relatives, the family Priscagamidae. In 2022, it is considered that is unlikely to be acrodontan, more likely to be scincoids or teiids instead.
Diploderma swinhonis, also known commonly as the Taiwan japalure, Swinhoe's japalure, Swinhoe's lizard, and Swinhoe's tree lizard, is a species of lizard in the family Agamidae. The species is native to Taiwan. It is considered an invasive alien species in Japan after likely being transported from Taiwan by humans. A foraging ambush predator, this lizard preys primarily on arthropods and thus remains at the bottom of forests perched on trees where sunlight is present. D. swinhonis is not a major threat to humans and is able to adapt to a variety of habitats, including urban environments. The male D. swinhonis is physically distinct from the female, with its body size being much larger and having a yellow stripe. This species sexually reproduces on a seasonal basis and hibernates during the winter time.
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.
Ctenophorus caudicinctus, commonly known as the ring-tailed dragon or ring-tailed bicycle-dragon is a native species of agamid lizard occurring in rocky ranges and outcrops of Australia. Ctenophorus caudicinctus is most commonly found in the Pilbara region and offshore islands of Western Australia. The ctenophorus has 28 known species in the northern, southern, and western parts of Australia. It is recognized to be the most speciose group of Australian agamids.
Ctenophorus mckenziei, more commonly known as the dwarf-bicycle dragon, is a species of endemic Australian lizard within the family Agamidae and genus Ctenophorus. Originally identified as the agamid Amphibolurus mckenziei, the lizard had been identified within the regions of Western Australia and South Australia in which it occupied the shrubbery and woodland areas as its habitat. It was subsequently transferred to the genus Ctenophorus along with other Agamid species in which it shared similar morphology and characteristics. The name mckenziei is in reference to Norman Leslie Mckenzie, who was a zoologist and discovered the existence of the lizard. Listed on the IUCN red list page, threats to its population numbers are evaluated as least concern; however, their numbers are threatened by habitat loss, climate change, and feral predators.
Ctenophorus parviceps, commonly known as the Gnaraloo heath dragon or northwestern heath dragon is a species of agamid lizard occurring in pale coastal sands and shell grit with open heaths and beach spinifex, between the North West Cape and Carnarvon, Western Australia and on Bernier Island. The Gnaraloo heath dragon is a lizard that can be found along the coast of Western Australia between Exmouth Gulf and Shark Bay, and is also known as the northwestern heath dragon. It is native to Australia and usually inhabits sandy coastal dunes. The species' longevity is 3–50 years and its population density is extremely low. The Gnaraloo heath dragon is a member of the Agamidae family, which contains 15 genera. The lizard is under the Ctenophorus genus which has up to 33 species. This genus shows the most morphological and ecological diversity out of the three large agamid genera. 83% of the lizards in this genus lack a crest, while 17% possess crests. They are smaller than most agamids but do have relatively large heads. The Gnaraloo heath dragon can be differentiated from related species by a series of spines on the tail's base, a pale-grey brown broad vertebral band along its back, and hour-glass bars extending upwards to meet the pale vertebral band. It is usually 45mm in terms of length, measuring from snout to vent.