n.
genus of sauropod dinosaur found as fossils in Late Jurassic rocks of North America and related to Apatosaurus .
Diplodocus and its relatives (diplodocids) were some of the longest land animals that ever lived, some approaching 100 ft (30 m). It had a long neck and extremely small brain and skull. Most diplodocids weighed about 30 tons, and some as much as 80 tons. It was formerly thought that Diplodocus may have spent a good deal of time in water, but fossil evidence indicates it moved freely on land, where it apparently fed on soft vegetation. It may be the most commonly displayed dinosaur.