superfamily of reptiles (fossil)
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The Stegosaurs were a group of dinosaurs in the suborder Thyreophora. They have small heads, peg-like teeth and vertical bony plates and spines on their back and tail. They flourished from the Upper Jurassic to the Lower Cretaceous.

Temporal range: Middle JurassicLower Cretaceous, 176–100 mya
Stegosaurus 01.jpg
Fossil skeleton of a Stegosaurus,
National Museum of Natural History
Scientific classification
A fossil melée involving a stegosaurian (Tuojiangosaurus) and a mid-sized theropod (Monolophosaurus), Field Museum in Chicago


The Stegosauria was originally named as an order by O.C. Marsh in 1877.[1] Now it is treated as an infraorder or suborder (or simply a clade) within Thyreophora, the armoured dinosaurs. It includes the families Huayangosauridae and Stegosauridae.

The Huayangosauridae were an early family of stegosaurs which lived during the Middle Jurassic. They were smaller than later stegosaurs and had shorter and higher skulls. Currently, the only confirmed genus included is the type genus Huayangosaurus of China. The poorly-known remains of Regnosaurus from England, however, indicate it too could be a member. Its lower jaw is very similar to the former.

The vast majority of stegosaurs being to the Stegosauridae, found in the later part of the Jurassic and the early Cretaceous. It includes the well-known Stegosaurus. The family is widespread, with members across the Northern Hemisphere and Africa.

Suborder Thyreophora

Infraorder Stegosauria


  1. Marsh O.C. 1877. New order of extinct Reptilia (Stegosauria) from the Jurassic of the Rocky Mountains. American Journal of Science, 14(ser.3):513-514.
  2. Mateus, Octávio; Maidment, Susannah C.R.; Christiansen, Nicolai A. (2009). "A new long-necked 'sauropod-mimic' stegosaur and the evolution of the plated dinosaurs" (pdf). Proceedings of the Royal Society B: Biological Sciences. 276 (1663): 1815–21. doi:10.1098/rspb.2008.1909. PMC 2674496. PMID 19324778.
  3. Maidment, Susannah C. R.; Norman, David B.; Barrett, Paul M.; Upchurch, Paul (2008). "Systematics and phylogeny of Stegosauria (Dinosauria: Ornithischia)". Journal of Systematic Palaeontology. 6 (4): 367–407. doi:10.1017/S1477201908002459. S2CID 85673680.