Camptosaurus

Camptosaurus ( ) is an extinct genus of plant-eating, beaked ornithischian dinosaurs of the Late Jurassic period of western North America and possibly also Europe. The name means 'flexible lizard' (Greek ('''') meaning 'bent' and ('''') meaning 'lizard').

==History of discovery== thumb|left|Historical skeletal restoration by O.C. Marsh, with skull based on remains now referred to Theiophytalia On September 4, 1879 William Harlow Reed in Albany County, Wyoming found the remains of a small euornithopod. That same year Professor Othniel Charles Marsh described and named the find as Camptonotus, or "flexible back", from Greek κάμπτω, "to bend" and νῶτον, "back", in reference to the presumed flexibility of the sacral vertebrae. The holotype was YPM 1877, a partial skeleton. The genus was renamed Camptosaurus by him in 1885 because the original name was already in use for a cricket. In 1879, Marsh named C. dispar (type species of the genus) for material he received from his collectors at Quarry 13 near Como Bluff, Wyoming in the Morrison Formation and C. amplus based on the holotype YPM 1879, a foot found by Arthur Lakes at Quarry 1A. The foot was later shown to have belonged to Allosaurus. Throughout the 1880 and 1890s, he continued to receive specimens from Quarry 13 and in 1894 named two additional species: C. medius and C. nanus, based in part on size. Charles W. Gilmore named two additional species, C. browni and C. depressus in his 1909 redescription of the Marsh specimens. In the Morrison Formation, Camptosaurus fossils are present in stratigraphic zones 2–6. thumb|Outdated mount of a C. nanus skeleton at the AMNH, now thought to be a growth stage of C. dispar Then in 1980, Peter Galton and H.P. Powell in their redescription of C. prestwichi (see following), considered C. nanus, C. medius and C. browni to be different growth stages or different gender of the larger C. dispar, and therefore only C. dispar was a valid species. They also considered a skull, YPM 1887, in 1886 referred to C. amplus by Marsh, later confirmed by Gilmore, to belong to C. dispar as well. Gilmore had used this skull to describe the skull of Camptosaurus, but the specimen was recently shown by Brill and Carpenter not to belong to Camptosaurus. In 2007, they put it into its own genus and species, Theiophytalia kerri. thumb|left|Camptosaurus skeleton mounted in outdated quadrupedal posture, and with Theiophytalia skull, [[Natural History Museum of Milan]] Camptosaurus depressus was recovered from the Lakota Formation near the town of Hot Springs, South Dakota. It was described by Charles Gilmore in 1909 based on the holotype and only known specimen USNM 4753, a fragmentary postcranium, by the "narrowness or depressed nature of the ilia". Carpenter and Wilson (2008) referred this species to Planicoxa, as P. depressa, on the basis of similarities between its ilium and the holotype ilium of Planicoxa venenica. However, McDonald and colleagues (2010), and McDonald (2011) found that the horizontal postacetabular process of C. depressus is more likely a product of distortion. Therefore, McDonald put it into its own genus, Osmakasaurus. An additional species, Camptosaurus aphanoecetes, was named by Carpenter and Wilson in 2008 for specimens from Dinosaur National Monument. It differs from C. dispar in the lower jaw, shorter neck vertebrae, and straighter ischium ending in a small "foot" among other features. An analysis by Andrew McDonald and colleagues in 2010 suggested that like C. aphanoecetes is actually more closely related to more advanced iguanodonts (Styracosterna). It has been moved to the new genus Uteodon. thumb|Cast of a skull from Bone Cabin Quarry West, Wyoming While Marsh was describing Camptosaurus species in North America, numerous species from Europe were also referred to the genus in the late 19th and early 20th centuries: C. inkeyi, C. hoggii, C. leedsi, C. prestwichi, and C. valdensis. C. inkeyi (Nopcsa, 1900) consists of fragmentary material, a dentary and articular from Upper Cretaceous rocks of the Haţeg Basin in Romania. It is almost certainly a rhabdodontid and is no longer considered valid (nomen dubium). C. valdensis consists of the holotype and only known specimen NHMUK R167, a poorly preserved left femur lacking the distal end. It was earlier believed to be a dubious dryosaurid, but a more recent analysis contends that the diagnostic features of Dryosauridae do not overlap with its material, instead considering it an iguanodontian. C. leedsi is probably a valid dryosaurid that has been moved to the new genus Callovosaurus. C. hoggii was originally named Iguanodon hoggii by Richard Owen in 1874 and was moved to Camptosaurus by Norman and Barrett in 2002. It has since been transferred to the genus Owenodon.