Chlamydosaurus

The frilled lizard (''Chlamydosaurus kingii''), also known as the 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 from head to tail and can weigh . Males are larger and more robust than females.

The frilled lizard is largely arboreal, spending most of its time in the trees. Its diet consists mainly of insects and other invertebrates. It is more active during the wet season, which is when it breeds and spends more time near or on the ground. It is less observed during the dry season, during which it seeks shade in the branches of the upper canopy. The lizard uses its frill to scare off predators and display to other individuals. The species' distinctive appearance has been used in films and TV.

Taxonomy

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 northwestern Australia, while part of an expedition conducted by Captain Phillip Parker King from . The generic name, ''Chlamydosaurus'', is derived from the Ancient Greek ''chlamydo'' (χλαμύς), meaning "cloaked" or "mantled", and Latin ''saurus'' (''sauros''), meaning "lizard". The specific name, ''kingii'', is a Latinised form of King's last name. It is the only species classified in its genus.

The frilled lizard split from its closest living relatives around 10 million years ago. A 2017 mitochondrial DNA analysis of the species across its range using revealed three lineages of recent divergence demarkated 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 was 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."

The following cladogram is based on Pyron and colleges (2013).

Description

The frilled lizard grows to around , for the head-body length, and may weigh around . It has a particularly large and thick head; as well as a long neck to accommodate the frill; long legs and a tail that makes most of its total length. The species is sexually dimorphic, with males being larger than females and having proportionally bigger frills, heads and jaws. The corners of its eyes are pointed, while the rounded nostrils face away from each other and angle downwards. Most of the lizard's scales are keeled, having a ridge down the center. From the backbone to the sides, the scales alternate between small and large.

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 animal's torso in diameter. Otherwise it wraps around the body. The frill is laterally symmetrical; the right and left sides are attached at the bottom in a V-shape, while cartilage-like tissue connects the top ends to each side of the head near the ear openings. The frill is supported by rod-like hyoid bones, and is spread out by movements of these bones, the lower jaw and the Grey’s cartilages. This structure mainly functions as a threat display to predators and for communication between individuals. It can also act as camouflage when folded, but this is unlikely to have been a consequence of selection pressure. 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. There is no evidence for other suggested functions, such as food storage, gliding or temperature regulation.

Frilled lizards vary between gray, brown, orangish-brown and black dorsally with the underside being paler white or yellow. Males may have black belly but a lighter chest. The underside and lateral sides are sprinkled with dark brown markings that may merge to create bands on the tail. The frill displays a variation of colours from west to east; lizards west of the Ord River have red-coloured frills, those living between the river and the Carpentarian Gap have orange frills, while those east of the gap have yellow to white frills. New Guinean frilled lizards are yellow-frilled. The more colourful frills have white patches which may add to the display. Colouration is mainly created by carotenoids and pteridine pigments; lizards with red and orange frills have more carotenoids than yellow and white frills, the latter two also lacking pteridines. Yellow colouration has been linked to greater steroid hormones. Among western lizards, the amount of red or orange colouring correlates with success in display competitions between males of similar size.

Distribution and habitat

The frilled lizard inhabits northern Australia and southern New Guinea. Its Australian range stretches from the Kimberley region of Western Australia east though the "top end" of Northern Territory to Queensland's Cape York Peninsula and nearby islands of Muralug, Badu, and Moa, and south to Brisbane. In New Guinea, it lives in the Trans-Fly ecosystem on both the Papua New Guinean and Indonesian sides of the island. The species mainly inhabits savannahs and sclerophyll woodlands. It prefers highly elevated areas with good soil draining and a greater variety of tree species, mostly ''Eucalyptus'' species, and avoids lower plains with mostly '' Melaleuca'' and '' Pandanus'' trees. 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 it may be declining in some local areas.

Behaviour and ecology

The frilled lizard is a diurnal and arboreal species, spending over 90% of its days 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 may move around more, per day versus for females. In Kakadu National Park, male lizards were found to have an average home range of during the dry season and during the wet season while females used and for the wet and dry seasons respectively. Male lizards may assert their boundaries with frill displays. Frilled lizards are capable of moving bipedally and do so while feeding or to escape from predators. To keep balance, they lean their heads far back enough, so it lines up behind the tail base.

These lizards are more active during the wet season, when they select smaller trees and are more commonly seen near the ground, while during the dry season, they use larger trees and are found at greater heights. 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. Body temperatures can approach . The species will bask verticially on the main tree trunk in the morning and near the end of the day, though in the dry season they cease basking at a lower body temperature to better maintain energy and water. When it gets hotter during day, they climb higher in the canopy for shade.

Frilled lizards primarily feed on insects and other invertebrates, and very rarely take vertebrates. Prominent prey include termites, ants and centipedes; termites are particularly important food during the dry season, while moth larvae become important during the wet season. This species is a sit-and-wait predator: it watches for potential prey from a tree and upon finding 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.
Several species of nematode infest the gastrointestinal tract. There is at least one record of an individual dying of Cryptosporidiosis. Frilled lizards face threats from birds of prey and larger lizards and snakes. 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.

Frilled lizards can breed during the late dry and early wet seasons. Competing males display with gapping mouths and spread frills. Fights can ensue, in which the lizards pounce and bite each other's heads. The female digs a shallow cavity to leave her eggs. They can lay multiple clutches per season, and the number of eggs in a clutch can vary from four to over 20. The incubation period can last two to four months, with milder temperatures producing more males and more extreme temperatures producing more females. Hatchlings have proportionally smaller frills than adults. Lizards grow during the wet season when food is more abundant, and males grow faster than females. Juvenile males also disperse further from their hatching area. The species reaches sexual maturity within two years; males live up to six years compared to four years for females.

Relationship with humans

The frilled lizard is considered to be among the most iconic Australian animals along with the kangaroo and koala. Archeological evidence indicates that frilled lizards were eaten by some indigenous cultures. In the Jawoyn language of the Katherine area, it is known as ''leliyn''. 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.

Because of its unique appearance and behavior, the creature has often been used in film and television. A frilled lizard named "Frank" appeared in the 1990 Disney animated film ''The Rescuers Down Under''. In Steven Spielberg's 1993 film '' Jurassic Park'', the dinosaur ''Dilophosaurus'' was portrayed with a similar looking neck frill that raised when attacking, and generated an increase in demand for frilled lizards as pets. Its image has also been used in the 1994 LGBT-themed film ''The Adventures of Priscilla, Queen of the Desert''.

The frilled lizard was featured on the reverse of the Australian 2-cent coin until 1991. A frilled lizard named "Lizzie" was the mascot for the 2000 Summer Paralympic Games. The lizard features on the emblem of the Northern Australian regiment NORFORCE. In the 1980s it gained notoriety in Japan after featuring prominently in a commercial for the Mitsubishi Mirage.

References

External links

Australia Advances - Frilled Neck Lizard
by CSIRO

Frilled-neck lizard babies are out!
by ABC Science

Frilled Lizard (''Chlamydosaurus kingii'' )
by Zoo and Aquarium Association

{{Taxonbar, from1=Q501566, from2=Q14425550

Agamidae
Reptiles of Western Australia
Agamid lizards of New Guinea
Taxa named by John Edward Gray
Reptiles of Queensland
Agamid lizards of Australia
Reptiles described in 1825