Jurassic and Cretaceous quadrupedal dinosaurs of herbivorous habit. They included Diplodocus, from the Upper Jurassic, one skeleton of which, measuring 26.6 m, at one time made Diplodocus the longest terrestrial animal known, but larger sauropods have since been discovered. Brachiosaurus, from the Late Jurassic of the USA and Tanzania, is estimated to have weighed 80 t, and Supersaurus is estimated to have been 15 m tall and possibly 30 m long. Apatosaurus (Brontosaurus) was also a sauropod, and although shorter than Diplodocus its skeleton was more massively built.