Neck frill, the relatively extensive margin seen on the back of the heads of some reptiles
The Frill-necked Monarch measures around 14 cm (5.5 in) in length, and the neck feathers can become erect into a small frill; the male is predominantly black and white, and can be distinguished from the similar and more common Pied Monarch by its all-white breast-the latter species having a broad black breast band.
Similar to the portrayal of the dinosaur Dilophosaurus in Steven Spielberg's Jurassic Park, the frill-necked lizard can puff out these neck frills either side of its head when threatened.