English: Huayangosaurus is a stegosaurian dinosaur from the Middle Jurassic of China. It was one of the smallest known stegosaurians, at just 4 m in length and 500 kg in body mass. Like other stegosaurians, Huayangosaurus was a quadrupedal herbivore with a small skull and a spiked tail. It bore the distinctive double row of plates that characterize all the stegosaurians. In Huayangosaurus, the plates were spike-like. Unique to the Huayangosaurus were the broader skull and premaxillary teeth in the front of its mouth. All later stegosaurians lost these teeth.