Diplodocus carnegiei. A model of the dinosaur Diplodocus carnegiei amongst trees. This huge reptile was abundant at the end of the Jurassic era, between 135 and 150 million years ago. It was a herbivore, with peg-shaped teeth at the front of the mouth probably used to graze the aquatic plants on which it fed. It could attain lengths of around 25 meters and weighed 10 or 11 tons. To support this weight the legs were thick and pillar-like. Most of the toenails of the front foot were hoof-like except for the inner toes which bore long claws, possibly for self-defense.