'roof-lizard') is a genus of herbivorous, four-legged, armored dinosaur from the Late Jurassic, characterized by the distinctive kite-shaped upright plates along their backs and spikes on their tails.

[9] Arthur Lakes made another discovery later in 1879 at Como Bluff in Albany County, Wyoming, the site also dating to the Upper Jurassic of the Morrison Formation, when he found several large Stegosaurus fossils in August of that year.

[6] The majority of the fossils came from Quarry 13, including the type specimen of Stegosaurus ungulatus (YPM 1853), which was collected by Lakes and William Harlow Reed the same year and named by Marsh.

[14] Though considered one of the most distinctive types of dinosaur, Stegosaurus displays were missing from a majority of museums during the first half of the 20th century, due largely to the disarticulated nature of most fossil specimens.

Four possible plate arrangements have been proposed over the years: After the end of the Bone Wars, many major institutions in the eastern United States were inspired by the depictions and finds by Marsh and Cope to assemble their own dinosaur fossil collections.

[22] The American Museum of Natural History was the first to launch an expedition in 1897, finding several assorted, but incomplete, Stegosaurus specimens at Bone Cabin Quarry in Como Bluff.

The fossils included only a couple postcranial remains, though in the 1900s-1920s Carnegie crews at Dinosaur National Monument discovered dozens of Stegosaurus specimens in one of the greatest single sites for the taxon.

Sophie was first discovered by Bob Simon in 2003 at a quarry on the Red Canyon Ranch near Shell, Wyoming, and was excavated by crews from the Swiss Sauriermuseum in 2004 and later prepared by museum staff, who gave it the nickname Sarah after the landowner's daughter.

[31] The quadrupedal Stegosaurus is one of the most easily identifiable dinosaur genera, due to the distinctive double row of kite-shaped plates rising vertically along the rounded back and the two pairs of long spikes extending horizontally near the end of the tail.

The lower jaw had flat downward and upward extensions that would have completely hidden the teeth when viewed from the side, and these probably supported a turtle-like beak in life.

However, the type specimen of S. ungulatus preserves two flattened spine-like plates from the tail that are nearly identical in shape and size, but are mirror images of each other, suggesting that at least these were arranged in pairs.

[53] Ankylosauria Tuojiangosaurus Paranthodon Chungkingosaurus Gigantspinosaurus Isaberrysaura Huayangosaurus Jiangjunosaurus Dacentrurus Stegosaurus stenops Hesperosaurus Wuerhosaurus Loricatosaurus Alcovasaurus Kentrosaurus Adratiklit Miragaia In 2017, Raven and Maidment published a phylogenetic analysis including almost every known stegosaurian genus.

In their 2024 description of stegosaur fossil material from China's Hekou Group, Li et al. used a modified version of the dataset of Raven and Maidment to analyze the phylogenetic relations of the Stegosauria:[1] Bashanosaurus Chungkingosaurus Huayangosaurus Isaberrysaura Gigantspinosaurus Alcovasaurus Jiangjunosaurus Tuojiangosaurus Paranthodon Kentrosaurus Adratiklit Dacentrurus Hesperosaurus Miragaia Loricatosaurus Stegosaurus homheni (=Wuerhosaurus) Hekou Group Stegosaurus sp.

Thus, their conception of Stegosaurus would include three valid species (S. armatus, S. homheni, and S. mjosi) and would range from the Late Jurassic of North America and Europe to the Early Cretaceous of Asia.

[27] In 2024, Li and colleagues described specimen GSAU 201201, a partial skeleton of a stegosaur from the upper Hekou Group of Gansu Province, China (discovered in c. 2000-04), which dates to the Aptian–Albian ages of the Early Cretaceous.

Marsh suggested that they functioned as some form of armor,[69] though Davitashvili (1961) disputed this, claiming that they were too fragile and ill-placed for defensive purposes, leaving the animal's sides unprotected.

[77] Another possible function of the plates is they may have helped to control the body temperature of the animal,[77] in a similar way to the sails of the pelycosaurs Dimetrodon and Edaphosaurus (and modern elephant and rabbit ears).

Since a cooling trend occurred towards the end of the Jurassic, a large ectothermic reptile might have used the increased surface area afforded by the plates to absorb radiation from the sun.

[79][82] The vascular system of the plates have been theorized to have played a role in threat displaying as Stegosaurus could have pumped blood into them, causing them to "blush" and give a colorful, red warning.

[47] The plates' large size suggests that they may have served to increase the apparent height of the animal, either to intimidate enemies[8] or to impress other members of the same species in some form of sexual display.

[26] Bakker also observed that Stegosaurus could have maneuvered its rear easily, by keeping its large hind limbs stationary and pushing off with its very powerfully muscled but short forelimbs, allowing it to swivel deftly to deal with attack.

[88]A 2013 study concluded, based on the rapid deposition of highly vascularised fibrolamellar bone, that Kentrosaurus had a quicker growth rate than Stegosaurus, contradicting the general rule that larger dinosaurs grew faster than smaller ones.

[89] A 2022 study by Wiemann and colleagues of various dinosaur genera including Stegosaurus suggests that it had an ectothermic (cold blooded) or gigantothermic metabolism, on par with that of modern reptiles.

Stegosaurus, therefore, probably browsed primarily among smaller twigs and foliage, and would have been unable to handle larger plant parts unless the animal was capable of biting much more efficiently than predicted in this study.

Soon after describing Stegosaurus, Marsh noted a large canal in the hip region of the spinal cord, which could have accommodated a structure up to 20 times larger than the famously small brain.

The earliest popular image of Stegosaurus was an engraving produced by the French science illustrator Auguste-Michel Jobin,[102][103] which appeared in the November 1884 issue of Scientific American and elsewhere, and which depicted the dinosaur amid a speculative Morrison age Jurassic landscape.

This covering of spikes might have been based on a misinterpretation of the teeth, which Marsh had noted were oddly shaped, cylindrical, and found scattered, such that he thought they might turn out to be small dermal spines.

[105] Stegosaurus made its major public debut as a paper mache model commissioned by the U.S. National Museum of Natural History for the 1904 Louisiana Purchase Exposition.

The sculptor Louis Paul Jonas constructed nine life-size dinosaurs out of painted fiberglass, working with paleontologists Edwin H. Colbert and John Ostrom to reflect the scientific ideas of the early 1960s (including inaccurate upright, tail-dragging postures for Tyrannosaurus and "Trachodon" [Edmontosaurus] and a wrong head for Brontosaurus).

The poorly known armored dinosaur Stegosaurides Bohlin 1953 (meaning "Stegosaurus-like") from China was named for a supposed resemblance to Stegosaurus, but the fossil material is very incomplete, consisting only of two vertebrae and a spine.