Plateosaurus, meaning “Broadway lizard,” is a genus of plateosaurid dinosaur from the Late Triassic Period (216 to 199 million years ago), which lived in what is now Central and Northern Europe. It is a primitive sauropodomorph dinosaur. There are two recognized species: the type species P. engelhardti from the late Norian and Rhaetian stages, and the slightly earlier P. gracilis from the lower Norian.

Plateosaurus was discovered in 1834 by Johann Friedrich Engelhardt and described three years later by Hermann von Meyer. Plateosaurus is the fifth ever named dinosaur genus that it still considered valid today. It was not one of the three genera originally used to define Dinosauria in 1842, because it was a poorly known genus. Today, however, it is among the dinosaurs best known to science with more than 100 skeletons found, some of them nearly complete.

Material assigned to Plateosaurus has been found at over 50 sites in Germany (mainly along the Neckar and Pegnitz river valleys), Switzerland and France.

The type species, P. engelhardti, reached an adult length of 16 to 33 feet, with an average mass of 1,300 to 8,800 pounds. The older species, P. gracilis, was somewhat smaller, with a total length of 13 to 16 feet.

Plateosaurus was a bipedal herbivore with a small skull on a long, mobile neck, sharp plant-crushing teeth, powerful hind limbs, short muscular arms and grasping hands with large claws on three fingers, used mainly for defense and feeding.

The skull of Plateosaurus is small and narrow, rectangular in side view, and nearly three times as long as it is high. There is an almost rectangular lateral temporal foramen at the back, and a large, round eye socket. The nostrils are egg-shaped. The snout carried many small, leaf-shaped, socketed teeth in both the upper and lower jaw. The teeth had bluntly serrated, thick, leaf-shaped crowns suitable for crushing plant material. The low position of the jaw joint gave the chewing muscles great leverage, so that Plateosaurus could deliver a powerful bite. These features suggest that it fed mostly on plants. Its eyes were positioned to the sides, providing all-around vision to watch for predators.