Diplodocus means double beam. This is a good name because its neck and legs are like beams. Diplodocus lived in the late Jurassic period. Diplodocus' fossils were found in Colorado, Montana, Utah and Wyoming. Diplodocus almost looks like three or four elephants piled on top of each other. Diplodocus had a fat body and a long neck. He had short legs. His head and teeth were very, very small. Diplodocus stood and walked on four legs. It didn't have claws. Its eyes were small, too. They probably built their nests on big rocks. The rocks were probably surrounded by water. Diplodocus was 90 feet long and stood 39 feet tall. Diplodocus had a 45 foot long tail. Its neck was 26 feet long. It weighed 25 tons. Diplodocus is a herbivore. That means it is a plant-eating dinosaur. At one time scientists thought it lived on the bottom of lakes. Its nose was on the top of its head. But it was a swamp-dweller. It used its tail for a weapon and most of the time it stayed in the water. Diplodocus guarded her eggs instead of sitting on them because if she did she would break the eggs. She guarded the eggs because other dinosaurs would eat them. It's the longest skeleton ever found. It had elephant-like legs. It had Y shaped spines on its tail vertebrae. Diplodocus' very long tail and very long neck balanced its barrel-like body. The bones in its neck weren't very heavy but were very, very strong. It made it a lot easier to lean down to plants. Scientists are trying to figure out how Diplodocus' blood got pumped all the way to its heart.