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Stegosaurus Temporal range: Late Jurassic
Model Stegosaurus, Bałtów Jurassic Park, Poland.
Conservation status
Fossil
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Sauropsida
Superorder:	Dinosauria
Order:	Ornithischia
Suborder:	Thyreophora
Infraorder:	Stegosauria
Family:	Stegosauridae
Genus:	Stegosaurus Marsh, 1877
Species
S. armatus Marsh, 1877 (type) S. stenops Marsh, 1887 S. longispinus Gilmore, 1914

Stegosaurus (IPA pronunciation /ˈsteg.əˌsɔː.rəs/) meaning 'roof-lizard' (Greek stego-/στεγο- meaning 'roof' and sauros/σαυρος meaning 'lizard') is a genus of stegosaurid armored dinosaur from the Late Jurassic Period (Kimmeridgian to Early Tithonian) of what is now western North America. Because of its distinctive tail spikes and plates, Stegosaurus is one of the most recognisable dinosaurs after Tyrannosaurus and Diplodocus.

A large heavily-built herbivorous quadrupedal animal, Stegosaurus had a distinctive and unusual posture, with a heavily arched back, head and short forelimbs held very low to the ground while the stiffed tail was held high in the air. Its array of plates and spikes have been the subject of much speculation; the spikes was most probably used for defence while the plates have been proposed as defence, display and heating devices. Larger than other stegosaurids like Kentrosaurus and Huayangosaurus, the roughly bus-sized Stegosaurus nevertheless shared many of the same anatomical features, including the tail spines and plates, which were seen in most other stegosaur genera.

At least three species were found in the Upper Morrison Formation and are known from numerous remains. It thrived some 155 to 145 million years ago, in an environment and time dominated by the giant sauropods Diplodocus, Camarasaurus and Apatosaurus.

Description

Averaging around nine metres (30 feet) long and four metres (14 feet) tall, the quadrupedal Stegosaurus is one of the most easily identifiable dinosaurs, due to the distinctive double row of kite-shaped plates rising vertically along its arched back and the two pairs of long spikes extending horizontally near the end of its tail. It was a moderate-sized dinosaur, dwarfed by its contemporaries, the giant sauropods. Some form of defence appears to have been necessary, as it co-existed with such predators as the fearsome Allosaurus and Ceratosaurus.

The hind feet each had three short toes, while each forefoot had five toes. All four limbs were supported by pads behind the toes. The forelimbs were much shorter than the stocky hindlimbs, which resulted in an unusual posture; the small and narrow skull of Stegosaurus was positioned relatively low to the ground, while the tail appears to have been held well clear of the ground.

Juvenile Stegosaurus have also been found. One subadult specimen, discovered in 1994, is 4.6 metres (15 feet) long and 2 metres (7 feet) high. It is estimated to have weighed 2.6 tons while alive.

Classification

As the first legitimately named member, Stegosaurus was the type genus of, and gives its name to, the family Stegosauridae and the infraorder Stegosauria, which lie within the Thyreophora, or armoured dinosaurs, a suborder which also includes the more diverse ankylosaurs.

The stegosaurs appear to be a closely knit group, similar in appearance, posture and shape, mainly differing in their array of spikes and plates. Among the closest relatives to Stegosaurus are Wuerhosaurus from China, and Kentrosaurus from Eastern Africa.

Origins

The origin and lineage of Stegosaurus is uncertain, as few remains of primitive stegosaurs and their ancestors are known. Recently, stegosaurs have been shown to be present in the Morrison formation several million years before the occurrence of Stegosaurus itself, with the discovery of the related Hesperosaurus from the early Kimmeridgian.

The more primitive Huayangosaurus from Middle Jurassic China 165 million years ago predates Stegosaurus by 20 million years, yet has some features of its own which suggests it was evolved from a common ancestor rather than is a direct ancestor itself. Earlier still, Scelidosaurus from Early Jurassic England around 190 million years ago has features of both stegosaurs and ankylosaurs. Scelidosaurus, Emausaurus from Germany, and Scutellosaurus from Arizona in the USA, were small quadrupedal dinosaurs that were closely related to the direct ancestors of armoured dinosaurs. A trackway of a possible early armoured dinosaur from around 195 million years ago has been found in France.

Discovery and species

Stegosaurus was originally named by Othniel Charles Marsh in 1877, from remains recovered north of Morrison, Colorado. These first bones became the holotype of Stegosaurus armatus. The basis for its scientific name, 'roof(ed) lizard' has been thought to have been Marsh's initial idea that the plates laid flat over the animal's back, overlapping like the shingles (tiles) on a roof.

Initially several Stegosaurus species were described; however, many of these have since been considered to be invalid or synonymous with existing species, leaving two well known and one poorly known species.

Stegosaurus armatus, meaning "armoured roof lizard", was the first species to be found, and is known from two partial skeletons, two partial skulls and at least thirty fragmentary individuals. This species had four horizontal tail spikes and relatively small plates. At 9 meters (30 ft), it was the longest species of Stegosaurus.

Stegosaurus stenops, meaning "narrow-faced roof lizard", was named by Marsh in 1887, with the holotype having been collected by Marshal Felch at Garden Park, north of Cañon City, Colorado, in 1886. This is the best known species of Stegosaurus, mainly because its remains include at least one complete articulated skeleton. It had large, broad plates and four tail spikes. S. stenops is known from at least 50 partial skeletons of both adults and juveniles, one complete skull and four partial skulls. It was shorter than S. armatus, at 7 m (23 ft).

Stegosaurus longispinus, meaning "long-spined roof lizard", was named by Gilmore and known from one partial skeleton, from the Morrison Formation in Wyoming, S. longispinus is notable for its set of four unusually long tail spines. Some consider it a species of Kentrosaurus. Like S. stenops, it grew to 7 m (23 ft) in length.

Dubious species

S. ungulatus, meaning "hoofed roof lizard", was named by Marsh in 1879 from remains recovered at Como Bluff, Wyoming, it is known from a few vertebrae and armor plates. It might be a juvenile form of S. armatus, though the original material of S. armatus is yet to be fully described.

S. sulcatus, meaning "furrowed roof lizard", and described by Marsh in 1887, is a partial skeleton, probably the same as S. armatus. S. duplex, meaning "two-level roof lizard", is probably the same as S. armatus. This animal was also named by Marsh in 1887, with the holotype, which consists of some disarticulated bones, having been collected in 1879 by Edward Ashley at Como Bluff, Wyoming.

S. seeleyanus, originally named Hypsirophus, is probably the same as S. armatus. S. (Diracodon) laticeps was described by Marsh in 1881 from some jawbone fragments. Just as some consider S. stenops a species of Diracodon, others consider Diracodon itself to be a species of Stegosaurus. Bakker had resurrected D. laticeps in 1986, though others note the material is nondiagnostic and likely synonymous with S. stenops.

S. affinis, described by Marsh in 1881, is only known from a pubis and is considered a nomen dubium possibly synonymous with S. armatus. S. madagascariensis from Madagascar is known solely from teeth and was described by Piveteau in 1926. The teeth were variously attributed to a stegosaur, the theropod Majungatholus, a hadrosaur or even a crocodylian. Other remains originally attributed to Stegosaurus are now considered to be synonyms of different genera. This is the case for S. marshi, which was described by Lucas in 1901; it is a synonym of either Hoplitosaurus or Polacanthus. Another synonym is S. priscus, described by Nopcsa in 1911, synonym of Lexovisaurus.

Paleobiology

Stegosaurus was the largest stegosaur, reaching up to 12 m (39.4 ft) in length and possibly weighing up to 5,000 kg (5.5 short tons). However, 7 to 9 m was a more usual length. Soon after its discovery, Marsh considered Stegosaurus to have been bipedal, due to its short forelimbs. He had changed his mind, however, by 1891, after considering the heavy build of the creature. Although Stegosaurus is undoubtedly now considered to have been quadrupedal, there has been some discussion over whether it could have reared up on its hind legs, using its tail to form a tripod with its hind limbs and browsing from higher foliage. This has been proposed by Bakker and argued against by Carpenter.

Stegosaurus did have very short forelimbs, in relation to its hind legs. Furthermore, within the hindlimbs, the lower section comprising the tibia and fibula was short compared with the femur. This suggests that it couldn't walk very fast, as the stride of the back legs at speed would have overtaken the front legs, and a maximum speed of 6-7km/hr.

Skull

The skull of Stegosaurus was long and narrow and, due to its short forelimbs, its head was carried close to the ground, probably no higher than 1 m (3.3 ft). It has been thought that it was a browser of low-growing vegetation, because of this. The front teeth had disappeared, being replaced by a horn-covered beak or rhamphotheca. Stegosaurian chewing teeth were small and triangular and apparently did little grinding, as they lacked wear surfaces. However, their placement in the skull suggests that Stegosaurus had cheeks. They appeared to have adopted a different strategy to many other herbivorous dinosaurs which were well-equipped with teeth to grind and chew plant material, and must have been successful as they were successful in the late Jurassic. One scenario has it as a low browser eating low growing fruit of various non-flowering plants, as well as foliage - foraging about a metre above the ground.

On the other hand, if Stegosaurus could have raised itself on two legs as suggested by Bakker, then it could have browsed on vegetation and fruits quite high up, up to 6 metres above the ground.

Despite its size, the braincase of Stegosaurus was small, being no larger than that of a dog. Unlike most dinosaurs, it did not have an antorbital fenestra, the hole between the nose and eye.

"Second brain"

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 brain. This has led to the famous idea that dinosaurs like Stegosaurus had a 'second brain' in the tail, which may have been responsible for controlling reflexes in the rear portion of the body.

More recently, it has been argued that this space (also found in sauropods) may have been the location of a glycogen body, a structure in living birds whose function is not definitely known but postulated to facilitate the supply of glycogen to the animal's nervous system.

Plates

The most obvious features of Stegosaurus are its dermal plates, which consisted of 17 separate flat plates. These were highly modified osteoderms (bony-cored scales), similar to those seen in crocodiles and many lizards today. They are not directly attached to the animal's skeleton, instead arising from the skin. In the past, some paleontologists, notably Robert Bakker, have speculated the plates may have been mobile to some degree, though others disagree. The largest plates were found over the animal's hips and measured 60 centimeters (2 ft) wide and 60 cm tall. The arrangement of the plates has long been a subject of debate but most paleontologists now agree that they formed a pair of alternating rows, one running down each side of the midline of the animal's back.

The function of the plates has been much debated. Initially thought of as some form of armour, they appear to have been too fragile and ill-placed for defensive purposes, leaving the animal's sides unprotected.

More recently, researchers have proposed that they may have helped to control the body temperature of the animal, in a similar way to the sails of the large meat-eating Spinosaurus or of the pelycosaur Dimetrodon (and the ears of modern elephants and jackrabbits). The plates had blood vessels running through grooves and air flowing around the plates would have cooled the blood. This theory has been seriously questioned, since the closest relative to the common plate-wielding species, Stegosaurus stenops, had low surface area spikes instead of plates, implying that cooling was not important enough to require specialized structural formations such as plates.

Their large size suggests that the plates may have served to increase the apparent height of the animal, in order either to intimidate enemies or to impress other members of the same species, in some form of sexual display, although both male and female specimens seemed to have had them. A study published in 2005 supports the idea of their use in identification. Researchers believe this may be the function of other unique anatomical features, found in various dinosaur species. S. Stenops also had disk-shaped plates on its hips.

One of the major subjects of books and articles about Stegosaurus is the plate arrangement. The argument has been a major one in the history of dinosaur reconstruction. Four possible plate arrangements have been mooted over the years:

1. The plates laid flat along the back, like armor. This was the initial thought by Marsh and why he gave the animal the name 'Roof Lizard'. As further and complete plates were found, their form showed that they stood on edge, rather than laying flat.
2. By 1891, Marsh published a more familiar view of Stegosaurus, with a single row of plates. This was dropped fairly early on (apparently because it was poorly understood how the plates were embedded in the skin and it was thought that they would overlap too much in this arrangement). It was revived, in somewhat modified form, in the 1980s, by an artist (Stephen Czerkas), based on the arrangement of iguana dorsal spines.
3. The plates paired in a double row along the back. This is probably the most common arrangement in pictures, especially earlier ones (until the 'Dinosaur Renaissance' in the '70s). (The Stegosaurus in the 1933 film, King Kong has this arrangement.) However, no two plates of identical size and shape have ever been found within the same animal.
4. Two rows of alternating plates. By the early '60s, this had become (and remains) the prevalent idea, mainly because the one Stegosaurus fossil with the plates still articulated indicates this arrangement. An objection to it is that this phenomenon is unknown amongst other reptiles and it is difficult to understand how such a disparity could evolve.

Tail spikes

There has been debate about whether the tail spikes were used for display only, as posited by Gilmore in 1914 or used as a weapon. Robert Bakker noted the tail was likely to have been much more flexible than other dinosaurs as it lacked ossified tendons, thus lending credence to the idea of the tail as a weapon. He also observed that Stegosaurus could have manoeuvred its rear easily by keeping its large hindlimbs stationary and pushing off with its very powerfully muscled but short forelimbs, allowing it to swivel deftly to deal with attack.

More recently, a study of tail spikes, by McWhinney et al., which showed a high incidence of trauma-related damage, confirms the spikes were indeed used in combat.

Stegosaurus stenops had four dermal spikes, each about 2 to 3 feet long. Discoveries of articulated stegosaur armor show that, at least in some species, these spikes protruded horizontally from the tail, not vertically as is often depicted. Initially, Marsh described S. armatus as having eight spikes in its tail, unlike S. stenops. However, recent research re-examined this and concluded this species also had four.

Diet

Stegosaurus was a herbivore; paleontologists believe it would have eaten plants such as mosses, ferns, horsetails, cycads, and conifers. Grasses did not evolve until late into the Cretaceous Period, well after Stegosaurus became extinct. Stegosaurus had small, weak teeth unsuitable for grinding or chewing their food; it has been proposed that Stegosaurus swallowed gastroliths, which were used to aid digestion in the same manner used by modern birds and crocodiles.

Popular culture

As one of the most recognizable dinosaurs, Stegosaurus has been widely depicted on film, in cartoons, comics, as children's toys, and has even been declared the State Dinosaur of Colorado in 1982. Stegosaurus is a popular subject for inclusion in dinosaur toy and scale model lines, such as the Carnegie collection. Stegosaurus toys, both plastic and plush, are popular among children. As late as the 1970s, Stegosaurus along other dinosaurs were depicted in fiction as slow-moving, dim-witted creatures. The "dinosaur renaissance" changed the prevailing image of dinosaurs as sluggish and cold-blooded, and this reevaluation has been reflected in popular media.

Science

In September 2002, a hoax poster was presented at the Society of Vertebrate Paleontology, entitled "The case for Stegosaurus as an agile, cursorial biped", ostensibly by T.R. Karbek (an anagram of R.T. Bakker) from the non-existent "Steveville Academy of Palaeontological Studies". This was reported in New Scientist magazine, where it was remarked that Stegosaurus was generally believed to be "about as cursorial as a fridge-freezer".

Cinema

Over the years, Stegosaurus has seen its share of screen time, often pitted in battle with large carnivorous dinosaurs, on both the big and small screen. It came up against Ceratosaurus in "Journey to the Beginning of Time" (1954), in "The Animal World" (1956) and in the documentary "When Dinosaurs Roamed America" (2001). It faced Allosaurus in "Dinosaur Valley Girls" (1996), and in episode two of "Walking With Dinosaurs" (1999), as well as in the special "The Ballad of Big Al" (2000). It was even seen pitted against Tyrannosaurus, in "Planet of Dinosaurs" (1978), Walt Disney's "Fantasia" (1940), and in the remake of the series "Land of the Lost" (1992-93).

In the classic monster film, King Kong (1933), the first creature that the band of rescuers meet, as they chase the abducted Fay Wray deep into Skull Island, is a roaring Stegosaurus, which charges. It eventually succumbs to a bomb, thrown by Carl Denham.

Stegosaurus has also appeared in The Lost World: Jurassic Park as one of the first dinosaurs to be seen. They were also seen briefly in Jurassic Park III. (An ailing Stegosaurus is encountered by the characters in the novel Jurassic Park, but was replaced by a Triceratops in the film version.) Although it makes no actual appearance in the film, the name is used; it is on one of the embryo vials stolen (misspelled as 'StegAsaurus').

Stegosaurus is one of the three dinosaur species whose physical characteristics were combined by the designers at Toho, to create the Japanese monster Godzilla; the other two dinosaurs were Tyrannosaurus and Iguanodon.

Cartoons and comics

Dinosaurs are popular amongst children, and Stegosaurus is no exception. It is one of the more frequently depicted dinosaurs in cartoons. The Transformers television series features four characters which can transform into Stegosaurids: Snarl, Slugfest, Saberback and Striker. In The Land Before Time and its sequels, the character Spike is a young Stegosaurus. In the 1980s cartoon Dinosaucers, the character Stego is an anthromorphic Stegosaurus.

Gary Larson's The Far Side comic strip often used stegosaurs when he showed dinosaurs. The term "Thagomizer" originated as a joke from a Far Side comic strip, in which a group of cavemen in a lecture hall are taught by their caveman professor that the spikes were named in honor of "the late Thag Simmons". The implication is that the Thagomizer was responsible for Thag's death. Whatever the original word for the spiked tail of Stegosaurus was, if it indeed ever had one, since the Far Side publication the term "thagomizer" has been adopted as a genuine anatomical term and is used by multiple palaeontological authorities, including the Smithsonian Institution.

Stegosaurus also appears in The Phantom comic strip as part of the animals living on the island surrounded by piranhas.

Footnotes

1. Liddell & Scott (1980). Greek-English Lexicon, Abridged Edition. Oxford University Press, Oxford, UK. ISBN 0-19-910207-4.
2. Lambert D (1993). The Ultimate Dinosaur Book. Dorling Kindersley, New York. pp. 110–129. ISBN 1-56458-304-X.
3. ^ Carpenter K (1998). "Armor of Stegosaurus stenops, and the taphonomic history of a new specimen from Garden Park Colorado". The Upper Jurassic Morrison Formation: An Interdisciplinary Study. Part 1. Modern Geol. Vol. 22. pp. 127–144. Cite error: The named reference "Carpenter98" was defined multiple times with different content (see the help page).
4. Stegosaurus. University of Wyoming Geological Museum. 2006. Retrieved October 6, 2006. University of Wyoming Geological Museum
5. Carpenter K, Miles CA, Cloward K (2001). "New Primitive Stegosaur from the Morrison Formation, Wyoming". In Carpenter, Kenneth(ed) (ed.). The Armored Dinosaurs. Indiana University Press. pp. 55–75. ISBN 0-253-33964-2. {{cite book}}: |editor= has generic name (help)CS1 maint: multiple names: authors list (link)
6. Le Loeuff J, Lockley M, Meyer C, Petit J-P(1999) Discovery of a thyreophoran trackway in the Hettangian of central France. C. R. Acad. Sci. Paris 2 328, 215-219
7. Marsh OC (1877). "A new order of extinct Reptilia (Stegosauria) from the Jurassic of the Rocky Mountains". American Journal of Science. 3 (14): 513–514.
8. ^ Carpenter K & Galton PM (2001). "Othniel Charles Marsh and the Eight-Spiked Stegosaurus". In Carpenter, Kenneth(ed) (ed.). The Armored Dinosaurs. Indiana University Press. pp. 76–102. ISBN 0-253-33964-2. {{cite book}}: |editor= has generic name (help)
9. Marsh OC (1887). "Principal characters of American Jurassic dinosaurs, part IX. The skull and dermal armour of Stegosaurus". American Journal of Science. 3 (34): 413–417.
10. ^ Gilmore CW (1914). "Osteology of the armored Dinosauria in the United States National Museum, with special reference to the genus Stegosaurus". Series: Smithsonian Institution. United States National Museum. Bulletin 89 (89). Government Printing Office, Washington.
11. Marsh OC (1879). "Notice of new Jurassic reptiles". American Journal of Science. 3 (18): 501–505.
12. Marsh OC (1887). "Principal characters of American Jurassic dinosaurs, part IX. The skull and dermal armour of Stegosaurus". American Journal of Science. 3 (34): 413–417.
13. Marsh OC (1881). "Principal characters of American Jurassic dinosaurs, part V". American Journal of Science. 3 (21): 417–423.
14. ^ Bakker RT (1986). The Dinosaur Heresies. William Morrow, New York. Cite error: The named reference "bakker86" was defined multiple times with different content (see the help page).
15. ^ Marsh OC (1880). "Principal characters of American Jurassic dinosaurs, part III". American Journal of Science. 3 (19): 253–259.
16. Marsh OC (1891). "Restoration of Stegosaurus". American Journal of Science. 3 (42): 179–181.
17. ^ Galton PM, Upchurch P (2004). "Stegosauria". In Weishampel DB, Osmólska H, Dodson P (ed.). The Dinosauria (2nd Edition). University of California Press. p. 361. ISBN 0-520-24209-2.{{cite book}}: CS1 maint: multiple names: editors list (link)
18. Bakker RT (1978). "Dinosaur feeding behavior and the origin of flowering plants". Nature (274): 661–663.
19. ^ Fastovsky DE, Weishampel DB (2005). "Stegosauria:Hot Plates". In Fastovsky DE, Weishampel DB (ed.). The Evolution and Extinction of the Dinosaurs (2nd Edition). Cambridge University Press. pp. 107–130. ISBN 0-521-81172-4.
20. Weishampel DB (1984). "Interactions between Mesozoic Plants and Vertebrates:Fructifications and seed predation". N. Jb. Geol. Paläontol. Abhandl.: 224–250. {{cite journal}}: Unknown parameter |vol= ignored (|volume= suggested) (help)
21. Lambert D (1993). The Ultimate Dinosaur Book. Dorling Kindersley, New York. pp. 110–129. ISBN 1-56458-304-X.
22. Buchholz (née Giffin) EB (1990). "Gross Spinal Anatomy and Limb Use in Living and Fossil Reptiles". Paleobiology. 16: 448–458.
23. ^ Buffrénil (1986). "Growth and Function of Stegosaurus Plates". Paleobiology. 12: 459–473.
24. ^ Davitashvili L (1961). The Theory of sexual selection. Izdatel'stvo Akademia nauk SSSR. p. 538.
25. Farlow JO, Thompson CV, Rosner DE (1976). "Plates of the dinosaur Stegosaurus:Forced convection heat loss fins?". Science (192): 1123–1125.{{cite journal}}: CS1 maint: multiple names: authors list (link)
26. Main RP, Padian K, Horner J (2000). "Comparative histology, growth and evolution of archosaurian osteoderms: why did Stegosaurus have such large dorsal plates?". Journal of Vertebrate Paleontology 56A (20).{{cite journal}}: CS1 maint: multiple names: authors list (link)
27. "Stegosaur plates used for identification". National Geographic News. 25 May 2005. Retrieved 26 October 2006.
28. Colbert EH (1962). Dinosaurs: Their Discovery & Their World. Hutchinson Press, London. pp. 82–99. ISBN 1111215030.
29. Marsh OC (1891). "Restoration of Stegosaurus". American Journal of Science. 3 (42): 179–181.
30. Czerkas SA (1987). "A Reevaluation of the Plate Arrangement on Stegosaurus stenops". In Czerkas SJ, Olson EC (ed.). Dinosaurs Past & Present, Vol 2. University of Washington Press, Seattle. pp. 82–99. ISBN.
31. McWhinney LA, Rothschild BM & Carpenter K (2001). "Posttraumatic Chronic Osteomyelitis in Stegosaurus dermal spikes". In Carpenter, Kenneth(ed) (ed.). The Armored Dinosaurs. Indiana University Press. pp. 141–156. ISBN 0-253-33964-2. {{cite book}}: |editor= has generic name (help)
32. Stegosaurus ungulatus Carnegie Museum of Natural History. Retrieved 26 October, 2006.
33. [http://www.dinoruss.com/de_4/5c52ddb.htm Stegosaurs. Jacobson, RJ. Dinosaur and Vertebrate Paleontology Information. Retrieved 26 October, 2006.
34. Colorado Department of Personnel website - State emblems
35. Lucas, S.G. (2006). "The Three Faces of Dinosaurs". Geotimes. Retrieved October 7, 2006.
36. "Feedback". New Scientist Magazine. Elsevier. 16 Nov 2002.
37. Crichton M (1990). Jurassic Park. Alfred A. Knopf. ISBN 0-394-58816-9.
38. "The word: Thagomizer," New Scientist, 08 July 2006. Retrieved October 26, 2006.
39. "Stegosaurus Changes". Smithsonian National Museum of Natural History, Department of Paleobiology. Retrieved 2006-03-07.

External links

• Walking With Dinosaurs - Stegosaurus
• Stegosaurus "roofed lizard", by T. Mike Keesey at The Dinosauricon.
• Stegosaurus From the Smithsonian National Museum of Natural History.

• Jurassic dinosaurs
• Jurassic Park species
• North American dinosaurs
• Stegosaurs