1884, coined in Modern Latin in 1878 by U.S. paleontologist Othniel Charles Marsh (1831-1899) from Greek diploos "double" (see diploid) + dokos "a beam." So called for the peculiar structure of the tail bones.
A very large herbivorous dinosaur of the genus Diplodocus of the late Jurassic Period. Diplodocus had a long, slender neck and tail and a small head with peglike teeth, and could grow to nearly 27 m (90 ft) in length. Fossilized skin impressions show that it probably had dermal spines along its back. Diplodocus is one of the longest known sauropod dinosaurs.