One of the best known of all dinosaurs, Diplodocus was one of the gigantic sauropods, the dominant herbivores of the Jurassic Period. Many specimens have been collected from the Upper Jurassic Morrison Formation of western North America. Diplodocus had the typical sauropod build, with a large barrellike body, postlike legs, a long neck and tail, and a very small head. The name (meaning "double beam") alludes to the peculiar construction of certain tailbones, which had projections fore and aft and which protected blood vessels from friction with the ground. Although less robust (estimated live weight — 11 to 15 tons) than Apatosaurus, it grew to a greater length — 23 m (90 ft) or more. Usually thought to+N2833 have been a semiaquatic animal that fed on soft water plants, it has also been pictured as a terrestrial treetop browser.

Bibliography: Colbert, E. H., Dinosaurs (1986); Desmond, Adrian J., The Hot-Blooded Dinosaurs (1976) N2822