Diplodocus

Latin: "double-beam") is a type of dinosaur of subgroup Sauropoda. Diplodocus lived during the Jurassic period.

The first Diplodocus skeleton was found at Como Bluff, Wyoming in 1878 and was named Diplodocus longus ("long double-beam") by paleontologist Othniel Marsh. Other species include D. carnegiei (named after Andrew Carnegie) and D. hayi.

Diplodocus remains have been found in the Western United States of Colorado, Utah, and Wyoming. Fossils of this animal are common, except for the skull, which is often missing from otherwise complete skeletons. The skull was very small compared to the huge size of the animal, which could reach up to 27 m. Instead of the way Diplodocidae were formerly portrayed, with their necks high up in the air, it is now widely believed that the animal could only keep its head very low to the ground (for grazing), and that the very long tail served as a counterbalance for the long neck.