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The frilled lizard (Chlamydosaurus kingii), also known commonly as the frilled agama, the frillneck lizard, the frill-necked lizard, and the frilled dragon, is a species of lizard in the family Agamidae. The species is native to northern Australia and southern New Guinea and is the only member of the genus Chlamydosaurus. Its common names refer to the large frill around its neck, which usually stays folded against the lizard's body. The frilled lizard grows to Template:Cvt from head to tail tip and can weigh Template:Cvt. 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.
The frilled lizard is largely arboreal, spending most of its time in trees. Its diet consists mainly of insects and other invertebrates. It is more active during the wet season, when it spends more time near or on the ground, and is less observed during the dry season, during which it seeks shade in the branches of the upper canopy. It breeds in the late dry season and early wet season. The lizard uses its frill to scare off predators and display to other individuals. The species is considered to be of least concern by the International Union for Conservation of Nature.
TaxonomyEdit
British zoologist John Edward Gray described the frilled lizard in 1825 as Clamydosaurus kingii. He used a specimen collected by botanist Allan Cunningham at Careening Bay, off north-western Australia, while part of an expedition conducted by Captain Phillip Parker King in Template:HMS.<ref name="upside down">Template:Cite book</ref><ref name="Kent1897">Template:Cite book</ref> The generic name, Chlamydosaurus, is derived from the Ancient Greek chlamydo (χλαμύς), meaning "cloaked" or "mantled", and Latin saurus (sauros), meaning "lizard".<ref>Template:Cite book</ref> The specific name, kingii, is a Latinised form of King.<ref name=EDR>Template:Cite book</ref> It is the only species classified in its genus.<ref name=Cogger/>
The frilled lizard is classified in the family Agamidae and the subfamily Amphibolurinae. It split from its closest living relatives around 10 million years ago based on genetic evidence.<ref>Template:Cite journal</ref> A 2017 mitochondrial DNA analysis of the species across its range revealed three lineages demarcated by the Ord River and the southeast corner of the Gulf of Carpentaria (Carpentarian Gap). One lineage ranged across Queensland and southern New Guinea and is sister to one that ranged from western Queensland to the Ord River. The ancestor of these two split from a lineage that populates the Kimberley. Frilled lizards entered southern New Guinea possibly around 17,000 years ago during a glacial cycle, when sea levels were lower and a land bridge connected the island to Cape York. The study upholds C. kingii as one species with the different populations being "shallow allopatric clades".<ref name=pepper17>Template:Cite journal</ref>
The following cladogram is based on Pyron and colleagues (2013).<ref>Template:Cite journal</ref>
DescriptionEdit
The frilled lizard can reach a total length of around Template:Convert and a head-body length of Template:Cvt, and weighs at least Template:Cvt.<ref name=pepper17/><ref name=Shine1989/><ref>Template:Cite journal</ref> It has a particularly large and wide head; a long neck to accommodate the frill; long legs and a tail that makes most of its total length.<ref name=Cogger>Template:Cite book</ref><ref name=Shine1989/><ref name=Thompson2005>Template:Cite journal</ref> The species is sexually dimorphic, males being larger than females<ref name=pepper17/><ref name=Shine1989/> and having proportionally bigger frills, heads and jaws.<ref>Template:Cite journal</ref> The corners of the frilled lizard's eyes are pointed and the rounded nostrils face away from each other and angle downwards. Most of the lizard's scales are keeled, having a ridge down the centre. From the backbone to the sides, the scales alternate between small and large.<ref name=Cogger/>
The distinctive frill is a flap of skin that extends from the head and neck and contains several folded ridges. When fully extended, the frill is disc-shaped and can reach over four times the length of the animal's torso in diameter, or around Template:Convert across. When not extended, the frill wraps around the body,<ref name=Montandon/><ref name=Shine90/><ref name=pepper17/> like a cape over the neck and shoulders.<ref>Wilson, S.; Swan, G. (2023). A Complete Guide to Reptiles of Australia, Sixth Edition. Sydney: Reed New Holland. pp. 442–443. Template:ISBN.</ref> The frill is laterally symmetrical; the right and left sides are attached at the bottom in a V-shape, and cartilage-like connective tissue (Grey's cartilage) connects the top ends to each side of the head near the ear openings.<ref name=Thompson2005/><ref name=Montandon>Template:Cite journal</ref> The frill is supported by rod-like hyoid bones, and is spread out by movements of these bones, the lower jaw and Grey's cartilage.<ref name=Montandon/> This structure mainly functions as a threat display to predators and for communication between individuals.<ref name=Shine90/> It can also act as camouflage when folded, but this is unlikely to have been a consequence of selection pressure.<ref name=Shine90/> The frill may be capable of working like a directional microphone, allowing them to better hear sounds directly in front of them but not around them.<ref>Template:Cite journal</ref> There is no evidence for other suggested functions, such as food storage, gliding or temperature regulation.<ref name=Shine90>Template:Cite journal</ref>
Frilled lizards vary between grey, brown, orangish-brown, and black dorsally, the underside being paler white or yellow. Males have a dark belly but a lighter chest. The underside and lateral sides of the species are sprinkled with dark brown markings that merge to create bands on the tail.<ref name=Cogger/> The colours of the frills vary based on range; lizards west of the Ord River have red-coloured frills, those living between the river and the Carpentarian Gap have orange frills, and those east of the gap have yellow to white frills. New Guinean frilled lizards are yellow-frilled.<ref name=pepper17/> The more colourful frills have white patches which may add to the display.<ref name=antipredator/> Colouration is mainly created by carotenoids and pteridine pigments; lizards with red and orange frills have more carotenoids than those with yellow and white frills, the latter two are also lacking in pteridines.<ref name=pepper17/><ref name=McLean2019/> Yellow colouration has been linked to higher steroid hormones.<ref name=McLean2019>Template:Cite journal</ref>
Distribution and habitatEdit
The frilled lizard inhabits northern Australia and southern New Guinea. Its Australian range stretches from the Kimberley region of Western Australia east through the Top End of the Northern Territory to Queensland's Cape York Peninsula and nearby islands of Muralug, Badu, and Moa, and south to Brisbane.<ref name="iucn status 19 November 2021"/><ref name=Cogger/> In New Guinea, it lives in the Trans-Fly ecosystem on both the Papua New Guinean and Indonesian sides of the island.<ref name="iucn status 19 November 2021"/> The species mainly inhabits savannahs and sclerophyll woodlands.<ref name="Cogger" /><ref name="pepper17" /> It prefers highly elevated areas with good soil drainage and a greater variety of tree species, mostly Eucalyptus species, and avoids lower plains with mostly Melaleuca and Pandanus trees.<ref name=Shine1989>Template:Cite journal</ref> Frilled lizards also prefer areas with less vegetation on the ground, as they can then better spot prey from above.<ref name=fire/>
Behaviour and ecologyEdit
The frilled lizard is a diurnal (daytime) and arboreal species,<ref name=pepper17/> spending over 90% each day up in the trees. It spends as little time on the ground as possible, mostly to feed, interact socially, or to travel to a new tree. Males move around more, Template:Cvt per day on average versus Template:Cvt for females at Kakadu National Park.<ref name=Shine1989/> In the same area, male lizards were found to have an average home range of Template:Cvt during the dry season and Template:Cvt during the wet season; females used Template:Cvt and Template:Cvt for the wet and dry seasons, respectively.<ref name=Shine1989/><ref name=Griffiths1999>Template:Cite journal</ref> Male lizards assert their boundaries with frill displays.<ref name=Shine90/> Frilled lizards are capable of moving bipedally and do so while hunting or to escape from predators. To keep balanced, they lean their heads far back enough, so it lines up behind the tail base.<ref name=Shine1989/><ref name=Thompson2005/><ref name=antipredator>Template:Cite journal</ref>
These lizards are more active during the wet season, when they select smaller trees and are more commonly seen near the ground; during the dry season, they use larger trees and are found at greater heights.<ref name=Griffith1996>Template:Cite journal</ref> Frilled lizards do not enter torpidity during the dry season, but they can greatly reduce their energy usage and metabolic rate in response to less food and water.<ref>Template:Cite journal</ref> Body temperatures can approach Template:Cvt.<ref name=Shine1989/> The species will bask vertically on the main tree trunk in the morning and near the end of the day,<ref name=Shine1989/><ref name=Christian1995/> though in the dry season they cease basking at a lower body temperature to better maintain energy and water.<ref name=Christian1995>Template:Cite journal</ref><ref>Template:Cite journal</ref> When it gets hotter during day, they climb higher in the canopy for shade.<ref name=Shine1989/> Frilled lizards will use large trees and termite mounds as refuges during wildfires. After a forest is burnt, the lizards select trees with more continuous canopies.<ref name=fire>Template:Cite journal</ref>
Frilled lizards primarily feed on insects and other invertebrates, and very rarely take vertebrates. Prominent prey includes termites, ants and centipedes; termites are particularly important food during the dry season, and moth larvae become important during the wet season.<ref name=Griffith1996/> Consumption of ants drops after early dry season fires but rises following fires later in the season.<ref name=fire/> This species is a sit-and-wait predator: it watches for potential prey from a tree and, upon seeing it, climbs down and rushes towards it on two legs before descending on all four to grab and eat it. After feeding, it retreats back up a tree.<ref name=Shine1989/>
Frilled lizards face threats from birds of prey and larger lizards and snakes.<ref name=Shine1989/><ref name=antipredator/> When threatened, the species erects its frill to make itself look bigger. This display is accompanied by a gaping mouth, puffing, hissing, and tail lashes. The lizard may also flee and hide from its predators.<ref name=antipredator/> Several species of nematode infest the gastrointestinal tract.<ref>Template:Cite journal</ref> There is at least one record of an individual dying of cryptosporidiosis.<ref>Template:Cite journal</ref>
Frilled lizards can breed during the late dry and early wet seasons.<ref name=Shine1989/> Competing males display with gaping mouths and spread frills. Fights can ensue, in which the lizards pounce and bite each other's heads.<ref name=Shine90/> The female digs a shallow cavity to leave her eggs.<ref name=reproduction/><ref name=sex-determination>Template:Cite journal</ref> They can lay multiple clutches per season, and the number of eggs in a clutch can vary from four to over 20.<ref name=Shine1989/><ref name=reproduction>Template:Cite book</ref> The incubation period can last two to four months,<ref name=reproduction/><ref name=sex-determination/> with milder temperatures producing more males and more extreme temperatures producing more females.<ref name=sex-determination/> Hatchlings have proportionally smaller frills than adults.<ref name=Shine90/> Lizards grow during the wet season when food is more abundant,<ref name=Griffith1996/> and males grow faster than females.<ref>Template:Cite journal</ref> Juvenile males also disperse further from their hatching area.<ref>Template:Cite journal</ref> The species reaches sexual maturity within two years; males live up to six years compared to four years for females.<ref name=Griffiths1999/>
ConservationEdit
The International Union for Conservation of Nature lists the frilled lizard as of least concern, due to its abundance and wide range, but warns that its population may be locally declining in some areas. It is a popular species in the pet trade, which may threaten some wild populations. Most pet lizards appear to come from Indonesia, as export of them is banned in Australia and Papua New Guinea.<ref name="iucn status 19 November 2021"/> Nevertheless, the Indonesian government themselves have allocated the frilled lizard as a protected species under the Article 20 of the Environment and Forestry Ministerial Regulation On Types of Protected Plants and Animals.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Being difficult to breed in captivity, many presumed captive bred lizards are likely to have been taken from the wild. Frilled lizards may also be threatened by feral cats,<ref name="iucn status 19 November 2021"/> though they do not appear to be significantly affected by the invasive cane toad.<ref>Template:Cite journal</ref>
Relationship with humansEdit
The frilled lizard is considered to be among the most iconic Australian animals along with the kangaroo and koala.<ref name=Shine1989/> Archaeological evidence indicates that frilled lizards were eaten by some indigenous peoples in ancient times.<ref>Template:Cite book</ref> In the late 19th century, William Saville-Kent brought a live lizard to England where it was observed by fellow biologists. Another specimen was kept at a reptile display in Paris, as reptiles were becoming more popular in captivity.<ref name="upside down"/>
Because of its unique appearance and behaviour, the creature has often been used in media. In Steven Spielberg's 1993 film Jurassic Park, the dinosaur Dilophosaurus was portrayed with a similar neck frill that rose when attacking.<ref name="Montandon" /> Its image has been used in the 1994 LGBT-themed film The Adventures of Priscilla, Queen of the Desert.<ref>Template:Cite journal</ref> The species has been featured on some Australian coins.<ref name="Shine1989" />
ReferencesEdit
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