The frill-necked lizard (Chlamydosaurus kingii), also known as the frilled lizard or frilled dragon, is found mainly in northern Australia and southern New Guinea. This species is the only member of the genus Chlamydosaurus. Its name comes from the large frill around its neck, which usually stays folded against the lizard's body. It is largely arboreal, spending the majority of the time in the trees. The lizard's diet consists mainly of insects and small vertebrates. The frill-necked lizard is a relatively large lizard, averaging 85 cm in length.The frill-necked lizard is so called because of the large ruff of skin which usually lies folded back against its head and neck. The neck frill is supported by long spines of cartilage which are connected to the jaw bones. When the lizard is frightened, it produces a startling deimatic display: it gapes its mouth, exposing a bright pink or yellow lining; it spreads out its frill, displaying bright orange and red scales; raises its body; and sometimes holds its tail above its body. This reaction is used for territorial displays, to discourage predators, and during courtship.The lizard is a relatively large member of the agamid family, growing up to 85 cm (2.79 ft). It is capable of bipedal locomotion. The frill-necked lizard does not have a standard colour, but its body is darker than its frill.
From : http://en.wikipedia.org/wiki/Frill-necked_lizard