Belongs within: Genasauria.
The Stegosauria are a group of quadrupedal herbivorous dinosaurs known from the Middle Jurassic to the Lower Cretaceous, members of which bore a characteristic armature of dorsal vertical plates (Galton & Upchurch 2004). The largest and best known stegosaur is Stegosaurus from the Late Jurassic of North America, some examples of which were over seven metres in length.
Characters (from Galton & Upchurch 2004): Parietals with flattened dorsal surface; quadrate with transversely compressed proximal head; neural canals of cranial dorsal vertebrae with diameter greater than half that of centra; dorsal neural arches at least 1.5 times as high as dorsal centra; mid-dorsal transverse processes oriented at 50° to horizontal or more steeply; proximal caudals with dorsal portions of neural spines transversely widened and axially compressed; length:width ratio of distal caudal central 1.2 or lower; proximal scapular plate with larger surface area than coracoid; humerus with prominent triceps tubercle and descending ridge located caudolateral to deltopectoral crest; dorsoventral thickness of carpal elements exceeding 10% of humeral length; ulnare and intermedium fused in adults; proximal carpals block-shaped in cranial view; distal carpals absent or failing to ossify; ilium with preacetabular process directed outward at 35° to sagittal plane; pubis with acetabular portion cup-shaped, facing laterally; prepubis:pubic shaft length ratio higher than 0.4; pubic shaft length:acetabular diameter ratio at least 2.0; pedal digit I absent; pedal digit III with no more than three phalanges; pedial digit IV with no more than three phalanges; parasagittal rows of plates or spines present; ossified epaxial tendons absent.
<==Stegosauria | i. s.: Regnosaurus northamptoni Mantell 1848 (n. d.)B01 |--HuayangosauridaeB93 | |--Huayangosaurus Dong, Tang & Zhou 1982GU04 | | `--H. taibaii Dong, Tang & Zhou 1982GU04 | `--Tatisaurus Simmons 1965B93, NWW04b | `--T. oehleri Simmons 1965 [=Scelidosaurus oehleri]NWW04b `--StegosauridaeGU04 | i. s.: Craterosaurus Seeley 1874GU04 | `--C. pottonensis Seeley 1874GU04 | Dravidosaurus Yadagiri & Ayyasami 1979GU04 | `--D. blanfordi Yadagiri & Ayyasami 1979GU04 | Monkonosaurus Zhou in Dong 1990GU04 | `--M. lawulacus Zhou in Dong 1990GU04 | Paranthodon Nopcsa 1929GU04 | `--P. africanus (Broom 1912) (see below for synonymy)GU04 | Yingshanosaurus Zhou 1984D07 | `--Y. jichuanensisD07 | Jiangjunosaurus junggarensisP10 | Gigantspinosaurus sichuanensisP10 | Miragaia longicollumP10 |--Dacentrurus Lucas 1902 [incl. Omosaurus Owen 1875 non Leidy 1856; Dacentruridae]GU04 | |--D. armatus (Owen 1875)GU04 (see below for synonymy) | |--D. phillipsi (Seeley 1893) (n. d.)D07, GU04 [=Omosaurus phillipsiGU04] | `--‘Omosaurus’ vetustus Huene 1910 (n. d.)GU04 `--Stegosaurinae [Kentrosauridae]GU04 |--Chungkingosaurus Dong, Zhou & Zhang 1983GU04 | `--C. jiangbeiensis Dong, Zhou & Zhang 1983GU04 `--+--Wuerhosaurus Dong 1973GU04 | |--W. homheni Dong 1973GU04 | `--W. ordosensis Dong 1993GU04 `--+--Hesperosaurus Carpenter, Miles & Cloward 2001GU04 | `--*H. mjosi Carpenter, Miles & Cloward 2001CMC01 [=Stegosaurus mjosiP10] |--Lexovisaurus Hoffstetter 1957GU04 | |--L. durobrivensis (Hulke 1887) (see below for synonymy)GU04 | `--L. vetustusD07 `--+--Stegosaurus Marsh 1877 [incl. Diracodon Marsh 1881, Hypsirhophus Cope 1879]GU04 | |--*S. armatus Marsh 1877M96, GU04 (see below for synonymy) | |--S. affinis Marsh 1881 (n. d.)GU04 | |--S. longispinus Gilmore 1914GU04 | |--S. madagascariensis Piveteau 1926 (n. d.)NWW04a | `--S. stenops Marsh 1887 [incl. Diracodon laticeps Marsh 1881 (n. d.)]GU04 `--+--Kentrosaurus Hennig 1915 [incl. Doryphorosaurus Nopcsa 1916, Kentrurosaurus Hennig 1916]GU04 | |--K. aethiopicus Hennig 1915GU04 | `--K. longispinusD07 `--+--Tuojiangosaurus Dong, Li et al. 1977GU04 | `--T. multispinus Dong, Li et al. 1977GU04 `--Chialingosaurus Young 1959GU04 |--C. guangyuanensisD07 `--C. kuani Young 1959GU04
Dacentrurus armatus (Owen 1875)GU04 [=Omosaurus armatusGU04; incl. O. hastiger Owen 1877GU04, O. lennieri Nopcsa 1911GU04, Dacentrurus lennieriAPS03, Astrodon pusillus Lapparent & Zbyszewski 1957GU04]
Lexovisaurus durobrivensis (Hulke 1887) [=Omosaurus durobrivensis; incl. O. leedsi Seeley 1901, Stegosaurus priscus Nopcsa 1911]GU04
Paranthodon africanus (Broom 1912) [=Palaeoscincus africanus; incl. Par. owenii Nopcsa 1929, Anthodon serrarius Owen 1876]GU04
*Stegosaurus armatus Marsh 1877M96, GU04 [incl. S. duplex Marsh 1887GU04, Hypsirhophus seeleyanus Cope 1879GU04, S. sulcatus Marsh 1887GU04, S. ungulatus Marsh 1879GU04]
*Type species of generic name indicated
References
[APS03] Allain, R., & X. Pereda Suberbiola. 2003. Dinosaurs of France. Comptes Rendus Palevol 2 (1): 27–44.
[B93] Benton, M. J. 1993. Reptilia. In: Benton, M. J. (ed.) The Fossil Record 2 pp. 681–715. Chapman & Hall: London.
[B01] Blows, W. T. 2001. Possible stegosaur dermal armor from the Lower Cretaceous of southern England. In: Carpenter, K. (ed.) 2001. The Armored Dinosaurs pp. 130–140. Indiana University Press.
[CMC01] Carpenter, K., C. A. Miles & K. Cloward. 2001. New primitive stegosaur from the Morrison Formation, Wyoming. In: Carpenter, K. (ed.) 2001. The Armored Dinosaurs pp. 55–75. Indiana University Press.
[D07] Dixon, D. 2007. The Complete Illustrated Encyclopedia of Dinosaurs & Prehistoric Creatures. Hermes House: London.
[GU04] Galton, P. M., & P. Upchurch. 2004. Stegosauria. In: Weishampel, D. B., P. Dodson & H. Osmólska (eds) The Dinosauria 2nd ed. pp. 343–362. University of California Press: Berkeley.
[M96] Marsh, O. C. 1896. The Dinosaurs of North America: Washington.
[NWW04a] Norman, D. B., L. M. Witmer & D. B. Weishampel. 2004a. Basal Ornithischia. In: Weishampel, D. B., P. Dodson & H. Osmólska (eds) The Dinosauria 2nd ed. pp. 325–334. University of California Press: Berkeley.
[NWW04b] Norman, D. B., L. M. Witmer & D. B. Weishampel. 2004b. Basal Thyreophora. In: Weishampel, D. B., P. Dodson & H. Osmólska (eds) The Dinosauria 2nd ed. pp. 335–342. University of California Press: Berkeley.
[P10] Paul, G. S. 2010. Dinosaurs: A Field Guide. A & C Black.