The hind limbs are very long and straight, the fore limbs relatively short, and the short high arched back and extremely deep and compressed body served to exaggerate the height and prominence of the great plates.

The surface of these plates, covered with a network of blood-vessels, shows that they bore a covering of thick horny skin during life, which probably projected as a ridge beyond their edges and still further increased their size.

The spines of the tail, also, were probably cased in horn.
This extraordinary animal was a contemporary of the Brontosaurus and Allosaurus, and its discovery was one of the great achievements of the late Professor Marsh.

The skeletons which he described are mounted in the Yale and National Museums.

Another skeleton was found in the famous Bone-Cabin Quarry, near Medicine Bow, Wyoming, by the American Museum Expedition of 1901.