>Reconstruction of a Late Triassic ornithischian.
The ornithischia, or 'bird-hipped' dinosaurs, are a group of dinosaurs having bird-like pelvic girdles, with four prongs to each side. All were herbivores. Four-legged types includes the stegosaurs, with triangular bony plates along the back, and the armadillo-like ankylosaurs. The two-legged duck-billed dinosaurs were well equipped for swimming. There is some evidence that birds are the living descendants of ornithiscians. See also saurischian.