| Camptosaurus | |
|---|---|
 | |
| Reconstructed skeleton in Japan | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Dinosauria |
| Clade: | †Ornithischia |
| Clade: | †Ornithopoda |
| Clade: | †Dryomorpha |
| Clade: | †Ankylopollexia |
| Superfamily: | †Camptosauroidea Marsh, 1885 |
| Family: | †Camptosauridae Marsh, 1885 |
| Genus: | †Camptosaurus Marsh,1885 |
| Type species | |
| Camptonotus dispar Marsh, 1879 | |
| Otherspecies | |
| Synonyms | |
| |
Camptosaurus (/ˌkæmptəˈsɔːrəs/KAMP-tə-SOR-əs) is agenus of plant-eating, beakedornithischiandinosaurs of theLate Jurassicperiod of westernNorth America and possibly alsoEurope.[1] The name means 'flexible lizard' (Greekκαμπτος (kamptos) meaning 'bent' andσαυρος (sauros) meaning 'lizard').
On September 4, 1879William Harlow Reed inAlbany County, Wyoming found the remains of a smalleuornithopod. That same year ProfessorOthniel Charles Marsh described and named the find asCamptonotus, or "flexible back", from Greek κάμπτω, "to bend" and νῶτον, "back", in reference to the presumed flexibility of thesacral vertebrae. Theholotype was YPM 1877, a partial skeleton.[2] The genus was renamedCamptosaurus by him in 1885 because the original name was already in use for acricket.[3] In 1879, Marsh namedC. dispar (type species of the genus) for material he received from his collectors atQuarry 13 nearComo Bluff,Wyoming in theMorrison Formation andC. amplus based on the holotype YPM 1879, a foot found byArthur Lakes atQuarry 1A. The foot was later shown to have belonged toAllosaurus.[4][5] Throughout the 1880 and 1890s, he continued to receive specimens from Quarry 13 and in 1894 named two additional species:C. medius andC. nanus, based in part on size.[6]Charles W. Gilmore named two additional species,C. browni andC. depressus in his 1909[7] redescription of the Marsh specimens. In the Morrison Formation,Camptosaurus fossils are present in stratigraphic zones 2–6.[8]
Then in 1980,Peter Galton and H.P. Powell in their redescription ofC. prestwichi (see following), consideredC. nanus,C. medius andC. browni to be different growth stages or different gender of the largerC. dispar, and therefore onlyC. dispar was a valid species.[4] They also considered a skull, YPM 1887, in 1886 referred toC. amplus by Marsh, later confirmed by Gilmore, to belong toC. dispar as well. Gilmore had used this skull to describe the skull ofCamptosaurus, but the specimen was recently shown by Brill and Carpenter not to belong toCamptosaurus. In 2007, they put it into its own genus and species,Theiophytalia kerri.[9]
Camptosaurus depressus was recovered from theLakota Formation near the town ofHot Springs, South Dakota. It was described byCharles 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".[7] Carpenter and Wilson (2008) referred this species toPlanicoxa, asP. depressa, on the basis of similarities between its ilium and the holotype ilium ofPlanicoxa venenica.[10] However, McDonald and colleagues (2010), and McDonald (2011) found that the horizontal postacetabular process ofC. depressus is more likely a product of distortion.[11] Therefore, McDonald put it into its own genus,Osmakasaurus.[12] An additional species,Camptosaurus aphanoecetes, was named by Carpenter and Wilson in 2008 for specimens fromDinosaur National Monument.[10] It differs fromC. dispar in the lower jaw, shorter neck vertebrae, and straighterischium ending in a small "foot" among other features. An analysis by Andrew McDonald and colleagues in 2010 suggested that likeC. aphanoecetes is actually more closely related to more advanced iguanodonts (Styracosterna).[11] It has been moved to the new genusUteodon.[12]
While Marsh was describingCamptosaurus 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, andC. valdensis.C. inkeyi (Nopcsa, 1900) consists of fragmentary material, a dentary and articular from Upper Cretaceous rocks of theHaţeg Basin inRomania. It is almost certainly a rhabdodontid and is no longer considered valid (nomen dubium).[13]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 adubious dryosaurid,[14][12] but a more recent analysis contends that the diagnostic features of Dryosauridae do not overlap with its material, instead considering it an iguanodontian.[15]C. leedsi is probably a valid dryosaurid that has been moved to the new genusCallovosaurus.[16]C. hoggii was originally namedIguanodon hoggii byRichard Owen in 1874 and was moved toCamptosaurus by Norman and Barrett in 2002.[17] It has since been transferred to the genusOwenodon.[14]
The remaining European speciesCamptosaurus prestwichii was recovered from Chawley Brick Pits,Cumnor Hurst inOxfordshire in England. The fossil was found when atramway was driven into the side of a hill. It was described by Hulke in 1880 asIguanodon prestwichii, and then placed in its own genusCumnoria by Seeley in 1888, but was soon sunk intoCamptosaurus by Lydekker in 1889.[18] However, Naish & Martill (2008), McDonald and colleagues (2010), and McDonald (2011) found that Seeley's original generic distinction was valid.Cumnoria has been recovered as astyracosternan, more closely related to advanced iguanodonts than toCamptosaurus dispar, similar to the case ofUteodon.[11][12]
In 2022, the first confirmed European remains belonging to aff.Camptosaurus .sp were described by Sánchez-Fenollosaet al..[1] A single specimen was found in the Fuentecillas member of theVillar del Arzobispo Formation inSpain, consisting of an anterior cervical centrum; an anterior dorsal centrum; a dorsosacral centrum; four sacral centra; a caudosacral centrum; two anterior caudal centra; three medial caudal centra; and a distal fragment from the left humerus. The Fuentecillas specimen is seen to be closer toCamptosaurus than toDraconyx from the Jurassic of Portugal,[19] hence its tentative placement within theCamptosaurus genus.[1]
Camptosaurus is a relatively heavily built form, with robust hindlimbs and broad feet, still having four toes.[4] Due to the separate status ofUteodon it has become problematic which material from theMorrison Formation belongs toCamptosaurus. The specimens with certainty belonging toCamptosaurus dispar, from Quarry 13, have been recovered from very deep layers, probably dating to theCallovian-Oxfordian.[10] The largest fragments from later strata indicate adult individuals around 6.79 metres (22.3 ft) long.[20] The Quarry 13 individuals are smaller though. It is estimated thatCamptosaurus typically reached 5–6 metres (16–20 ft) long and weighed 500–1,000 kilograms (1,100–2,200 lb).[21][22][10]
Earlier reconstructions, such as those by Marsh and Gilmore, were based on the skull ofTheiophytalia and display an incorrect, more rectangular profile. The skull was in fact triangular with a pointed snout, equipped with a beak. Its teeth were more tightly packed in the jaw compared to other Morrison euornithopods.[21] Museum curator John Foster describes them as having "thick median ridges on their lateral sides and denticles along their edges," these features were similar to, but "more fully developed" than those inDryosaurus.[21]Camptosaurus teeth frequently exhibit extensive wear, which indicates that individuals in the genus had a diet of relatively tough vegetation.[21]
Marsh in 1885 assignedCamptosaurus to a family of its own: the Camptosauridae. Alternatively some authors considered it an early member of theIguanodontidae.
Modernphylogenetics has madeCamptosaurus by definition part of thecladeAnkylopollexia, of which group it would then be a basal member. This would mean that the genus is closely related to the ancestor of lateriguanodontid andhadrosaurid dinosaurs and was morederived than contemporaries such asDryosaurus andNanosaurus.[21]
In the 2010 and 2011cladistic analyses of McDonald and colleagues,Camptosaurus was placed as follows:[12][23]
Based on studies of other iguanodonts (cladeIguanodontia), scientists believe they may have been able to achieve running speeds of 25 km per hour (15 mph).[21] A tiny 9 inch fossilized embryo, referred toCamptosaurus, was retrieved from Morrison Formation strata at Dinosaur National Monument in Utah.[21]
Media related toCamptosaurus at Wikimedia Commons
