Frilled lizards (Chlamydosaurus kingii), also called frill-necked lizards, are reptiles native to northern Australia and southern New Guinea. They are named for the large, scaly flap of skin around the neck, which can be about as wide as the lizard is long. Most of the time the frill lies folded over the shoulders like a cape.
When threatened, a frilled lizard opens its mouth and raises the frill out from its body, making its head look several times larger to scare off predators. It can also run upright on its hind legs with its forelegs and tail held up. According to Britannica, adults average about 85 cm (33 inches) long and spend most of their time in trees, feeding on insects and small mammals.
Source: Encyclopaedia Britannica: Frilled lizard
Image: Frilled lizard (Kragenechse), by Holger Krisp, CC BY 3.0, via Wikimedia Commons.