Camptosaurus dispar was a type of ornithopod ornithischian dinosaur which lived in western North America during the late Jurassic Period. It measured 20 feet long and possibly weighed a ton. Camptosaurus was the largest ornithopod found within the Morrison Formation. Other ornithopods include the 10-foot long Dryosaurus and the 5-foot long Othnielia.
Camptosaurus was discovered on September 4, 1879 by William Reed in Wyoming during the famous “Bone Wars”. Othniel Charles Marsh originally named the animal Camptonotus, but was forced to change it because another animal had already been given this name. In 1885, the dinosaur was re-named Camptosaurus.
For a long time, we thought we knew what Camptosaurus looked like, or at least what its head looked like. Publications as recent as the 1990s depicted Camptosaurus with a boxy rectangular-shaped skull. This is due to paleontologist Charles W. Gilmore. In 1909, Gilmore wrote a description of the genus Camptosaurus and its assorted species. A skull (YPM 1887), referred to in 1886 by Marsh as belonging to Camptosaurus amplus, was re-designated by Gilmore as belonging to Camptosaurus dispar. In 1980, Peter Galton and H. P. Powell stated that C. nanus, C. medius, and C. browni were not separate species, but were instead growth stages of C. dispar, making C. dispar the only valid species. They also used the skull catalogued as YPM 1887 as the skull of Camptosaurus dispar. For many years, this was taken as fact, and this skull was used in many illustrations of Camptosaurus. However in 2006, Kenneth Carpenter and K. Brill found that this skull actually belonged to a different dinosaur. The skull, and the animal associated with it was named Theiophytalia kerri.
Below is the traditional-but-incorrect depiction of what Camptosaurus‘ skull looked like. Image from The Dinosaur Data Book, by David Lambert. New York: Avon Books, 1990. Page 180. The original image has been modified so that the labels have been removed.
So what did Camptosaurus really look like? The skull was more triangular in shape, similar to that of Dryosaurus. However, it was not a close relative. According to current phylogenics, Camptosaurus was more advanced than Dryosaurus, but more primitive than Iguanodon and hadrosaurs.
The illustration which you see below is the current look of Camptosaurus. However, I should state that the old rectangular image is so prevalent that it will take quite some time before old-school paleo-buffs like me learn to disregard it. This drawing was made with regular No. 2 pencil (my favorite medium) on basic computer paper.
Keep your pencils sharp, everyone.