increased the importance of active defence by the thagomizer, which could ward off even large predators because the tail was in a higher position, pointing horizontally to the rear from the broad pelvis. Stegosaurs had complex arrays of spikes and plates running along their backs, hips and tails.

Stegosauria includes two families, the Huayangosauridae and the more diverse Stegosauridae. All species were quadrupedal herbivores with characteristic dorsal dermal plates. These large, thin,