Stegosaurus

*Stegosaurus armatus*

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***Stegosaurus*** (pronounced ˌstɛgəˈsɔrəs) is a genus of stegosaurid armoured dinosaur from the Late Jurassic period (late Kimmeridgian to Early Tithonian) in what is now western North America. In 2006, a specimen of *Stegosaurus* was announced from Portugal, showing that they were present in Europe as well. Due to its distinctive tail spikes and plates, *Stegosaurus* is one of the most recognizable dinosaurs, along with *Tyrannosaurus*, *Triceratops*, and *Apatosaurus*. The name *Stegosaurus* means "roof-lizard" and is derived from the Greek στέγος-, stegos- ("roof") and σαῦρος, -sauros ("lizard").
At least three species have been identified in the upper Morrison Formation and are known from the remains of about 80 individuals. They lived some 150 to 145 million years ago, in an environment and time dominated by the giant sauropods *Diplodocus*, *Camarasaurus*, and *Apatosaurus*.

A large, heavily built, herbivorous quadruped, *Stegosaurus* had a distinctive and unusual posture, with a heavily arched back, short forelimbs, head held low to the ground and a stiffened tail held high in the air. Its array of plates and spikes has been the subject of much speculation. The spikes were most likely used for defense, while the plates have also been proposed as a defensive mechanism, as well as having display and thermoregulatory (heat control) functions. *Stegosaurus* was the largest of all the stegosaurians (bigger than genera such as *Kentrosaurus* and *Huayangosaurus*) and, although roughly bus-sized, it nonetheless shared many anatomical features (including the tail spines and plates) with the other stegosaurian genera.

## Description

Averaging less than metres (29.5 ft) long and 4 metres (13 ft) 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. Although a large animal, it was dwarfed by its contemporaries the giant sauropods. Some form of armour appears to have been necessary, as it coexisted with large predatory theropod dinosaurs, such as the fearsome *Allosaurus* and *Ceratosaurus*.

The hind feet each had three short toes, while each forefoot had five toes; only the inner two toes had a blunt hoof. 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 tail appears to have been held well clear of the ground, while the head of *Stegosaurus* was positioned relatively low down, probably no higher than 1 metre (3.3 ft) above the ground.

The long and narrow skull was small in proportion to the body. It had a small antorbital fenestra, the hole between the nose and eye common to most archosaurs, including modern birds, though lost in extant crocodylians. The skull's low position suggests that *Stegosaurus* may have been a browser of low-growing vegetation. This interpretation is supported by the absence of front teeth and their replacement by a horny beak or rhamphotheca. Stegosaurian teeth were small, triangular and flat wear facets show that they did grind their food. The inset placement in the jaws suggests that *Stegosaurus* had cheeks to keep food in their mouths while they chewed.

Despite the animal's overall size, the braincase of *Stegosaurus* was small, being no larger than that of a dog. A well preserved *Stegosaurus* braincase allowed Othniel Charles Marsh to obtain in the 1880s a cast of the brain cavity or endocast of the animal, which gave an indication of the brain size. The endocast showed that the brain was indeed very small, maybe the smallest among the dinosaurs. The fact that an animal weighing over 4.5 tonnes (5 US short tons) could have a brain of no more than 80 grams (2.8 oz) contributed to the popular old idea that dinosaurs were unintelligent, an idea now largely rejected.

Most of the information known about *Stegosaurus* comes from the remains of mature animals; however more recently juvenile remains of *Stegosaurus* have been found. One sub-adult specimen, discovered in 1994 in Wyoming, is 4.6 metres (15 ft) long and 2 metres (7 ft) high, and is estimated to have weighed 2.3 tonnes (2.6 short tons) while alive. It is on display in the University of Wyoming Geological Museum. Even smaller skeletons, 210 centimetres (6.9 ft) long and 80 centimetres (2.6 ft) tall at the back, are on display at the Denver Museum of Nature & Science.

## Classification

*Stegosaurus* was the first-named genus of the family Stegosauridae. It is the type genus that gives its name to the family. Stegosauridae is one of two families within the infraorder Stegosauria, with the other being Huayangosauridae. Stegosauria lies within the Thyreophora, or armoured dinosaurs, a suborder which also includes the more diverse ankylosaurs. The stegosaurs were a clade of animals similar in appearance, posture and shape that mainly differed in their array of spikes and plates. Among the closest relatives to *Stegosaurus* are *Wuerhosaurus* from China and *Kentrosaurus* from east Africa.

### Origins

The origin of *Stegosaurus* is uncertain, as few remains of basal stegosaurs and their ancestors are known. Recently, stegosaurids have been shown to be present in the lower Morrison Formation, existing several million years before the occurrence of *Stegosaurus* itself, with the discovery of the related *Hesperosaurus* from the early Kimmeridgian. The earliest stegosaurid (the genus *Lexovisaurus*) is known from the Oxford Clay Formation of England and France, giving it an age of early to middle Callovian.

The earlier and more basal genus *Huayangosaurus* from the Middle Jurassic of China (some 165 million years ago) predates *Stegosaurus* by 20 million years and is the only genus in the family Huayangosauridae. Earlier still is *Scelidosaurus*, from Early Jurassic England, which lived approximately 190 million years ago. Interestingly, it possessed features of both stegosaurs and ankylosaurs. *Emausaurus* from Germany was another small quadruped, while *Scutellosaurus* from Arizona in the USA was an even earlier genus and was facultatively bipedal. These small, lightly-armoured dinosaurs were closely related to the direct ancestor of both stegosaurs and ankylosaurs. A trackway of a possible early armoured dinosaur, from around 195 million years ago, has been found in France.

## History

### Discovery and species

*Stegosaurus*, one of the many dinosaurs first collected and described in the Bone Wars, 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 belief that the plates lay flat over the animal's back, overlapping like the shingles (tiles) on a roof. A wealth of *Stegosaurus* material was recovered over the next few years and Marsh published several papers on the genus. Initially, several 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.

### Valid species

* Morrison Formation, Colorado, Wyoming, and Utah, U.S.A.

***S. stenops***
* Morrison Formation, Colorado, Wyoming, and Utah, U.S.A.

*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. Up to 9 metres (30 ft) long, it was the longest species within the genus *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. *Stegosaurus stenops* is known from at least 50 partial skeletons of adults and juveniles, one complete skull and four partial skulls. It was shorter than *S. armatus*, at 7 metres (23 ft).

### *Nomina dubia* (dubious names)

*Stegosaurus 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 armour plates. It might be a juvenile form of *S. armatus*, although the original material of *S. armatus* is yet to be fully described. The specimen discovered in Portugal and dating from the upper Kimmeridgian-lower Tithonian stage has been ascribed to this species.

*Stegosaurus sulcatus*, meaning "furrowed roof lizard" was described by Marsh in 1887 based on a partial skeleton. It is considered a synonym of *S. armatus*. *Stegosaurus duplex*, meaning "two plexus roof lizard" (in allusion to the greatly enlarged neural canal of the sacrum which Marsh characterized as a "posterior brain case"), is probably the same as *S. armatus*. Although named by Marsh in 1887 (including the holotype specimen), the disarticulated bones were actually collected in 1879 by Edward Ashley at Como Bluff, Wyoming.

*Stegosaurus seeleyanus*, originally named *Hypsirophus*, is probably the same as *S. armatus*. *Stegosaurus (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, although others note that the material is non-diagnostic and likely synonymous with *S. stenops*.

*Stegosaurus affinis*, described by Marsh in 1881, is only known from a pubis and is considered a *nomen dubium*. It is possibly synonymous with *S. armatus*.

### Reassigned species

*Stegosaurus 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 *Majungasaurus*, a hadrosaur or even a crocodylian.

Other remains originally attributed to *Stegosaurus* are now considered to belong to different genera. This is the case for *Stegosaurus marshi*, which was described by Lucas in 1901. It was renamed *Hoplitosaurus* in 1902. *Stegosaurus priscus*, described by Nopcsa in 1911, was reassigned to *Lexovisaurus*, and is now the type species of *Loricatosaurus*.

## Paleobiology

*Stegosaurus* was the largest stegosaur, reaching up to 10 meters (33 ft) in length and possibly weighing up to 5,000 kilograms (5.5 short tons). However, 7 to 9 metres 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 animal.
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 for higher foliage. This has been proposed by Bakker and opposed 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, giving a maximum speed of 6–7 kilometres per hour (4–5 mi/hr).

### "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. It has also been suggested that this "brain" might have given a *Stegosaurus* a temporary boost when it was under threat from predators. 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 which is postulated to facilitate the supply of glycogen to the animal's nervous system.

### Plates

The most recognizable 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 were not directly attached to the animal's skeleton, instead arising from the skin. In the past, some palaeontologists, notably Robert Bakker, have speculated the plates may have been mobile to some degree, although others disagree. Bakker suggested that the plates were the bony cores of pointed horn-covered plates that a *Stegosaurus* could flip from one side to another in order to present a predator with an array of spikes and blades that would impede it from closing sufficiently to attack the *Stegosaurus* effectively. The plates would naturally sag to the sides of the *Stegosaurus*, the length of the plates reflecting the width of the animal at that point along its spine. His reasoning for these plates to be covered in horn is that the surface fossilized plates have a resemblance to the bony cores of horns in other animals known or thought to bear horns, and his reasoning for the plates to be defensive in nature is that the plates had insufficient width for them to stand erect easily in such a manner as to be useful in display without continuous muscular effort. The largest plates were found over the animal's hips and measured 60 centimetres (2 ft) wide and 60 centimetres tall. The arrangement of the plates has long been a subject of debate but most palaeontologists 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 carnivorous *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. *Stegosaurus 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 lay flat along the back, like armour. This was Marsh's initial interpretation, which led to the name 'Roof Lizard'. As further and complete plates were found, their form showed that they stood on edge, rather than lying 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 1960s, 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 among other reptiles and it is difficult to understand how such a disparity could evolve.

### Thagomizer (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 that of other dinosaurs, as it lacked ossified tendons, thus lending credence to the idea of the tail as a weapon. However, as Carpenter has noted, the plates overlap so many tail vertebrae, that movement would be limited. Bakker also observed that *Stegosaurus* could have maneuvered 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. Additional support for this idea was a punctured tail vertebra of *Allosaurus* into which a tail spike fit perfectly.

*Stegosaurus stenops* had four dermal spikes, each about 60–90 centimetres (2–3 ft) long. Discoveries of articulated stegosaur armour 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* and related genera were herbivores. However, they adopted a feeding strategy different from that of the other herbivorous ornithischian dinosaurs. The other ornithischians possessed teeth capable of grinding plant material and a jaw structure capable of movements in planes other than simply orthal (i.e. they could chew plants). This contrasts with *Stegosaurus* (and all stegosaurians), which had small teeth having horizontal wear facets associated with tooth-food contact and a jaw probably capable of only orthal movements.

The stegosaurians must have been successful, as they became speciose and geographically widely distributed, in the late Jurassic. Palaeontologists believe it would have eaten plants such as mosses, ferns, horsetails, cycads and conifers or fruits and swallowed gastroliths to aid food processing (due to the lack of chewing ability), in the same manner used by modern birds and crocodiles. Low-level browsing on grasses, seen in modern mammalian herbivores, would not have been possible for *Stegosaurus*, as grasses did not evolve until late into the Cretaceous Period, long after *Stegosaurus* had become extinct.

One hypothesised feeding behaviour strategy considers them to be low-level browsers, eating low-growing fruit of various non-flowering plants, as well as foliage. This scenario has *Stegosaurus* foraging at most one 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, with adults being able to forage up to 6 metres (20 ft) above the ground.

### Behavior

Tracks discovered by Matthew Mossbrucker of the Morrison Natural History Museum from Colorado suggest that *Stegosaurus* lived in multi-age herds. One group of tracks is interpreted as showing four or five baby stegosaurs moving in the same direction, while another has a juvenile stegosaur track with an adult track overprinting it.

## Cultural Influence

***Stegosaurus*** is among the most recognizable of dinosaurs. It has been depicted in many ways; on film, in cartoons, comics, as children's toys, and as sculpture. It even was declared the State Dinosaur of Colorado in 1982. *Stegosaurus* is a subject for inclusion in dinosaur toy and scale model lines, such as the Carnegie Collection.

As late as the 1970s, *Stegosaurus*, along with other dinosaurs, was depicted in fiction as a slow-moving, dim-witted creature. The "dinosaur renaissance" changed the prevailing image of dinosaurs as sluggish and cold-blooded and this re-evaluation 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".

### Literature

A sketch of a *Stegosaurus* forms an important plot point in the opening chapters of *The Lost World* by Arthur Conan Doyle. Although it is out of print (used copies are available on the Web), Evelyn Sibley Lampman wrote a children's book about twins who find a talking Stegosaurus on their ranch; titled "The Shy *Stegosaurus* of Cricket Creek".

### Sculpture

Sculptor Jim Gary created several, almost-life-sized versions of *Stegosaurus*. One always was displayed among his traveling exhibition, *Jim Gary's Twentieth Century Dinosaurs*, and they are frequently used as an illustration of his work in books and articles about the artist because of their distinctive characteristics.

One displayed for months before the electrical engineering research facility at the University of North Carolina at Charlotte during a 2005 campus-wide display of the exhibition, which was hosted by Belk College, became a mascot of sorts to students studying in nearby buildings.

In the movie Howard the Duck, Howard walks under a Jim Gary *Stegosaurus* when a museum display of the sculptor's work is used as a set for the 1986 film, which was produced by George Lucas.

### Cinema

Over the years, *Stegosaurus* has seen its share of screen time, often pitted in battle against large carnivorous dinosaurs, in both theatres and television. It came up against *Ceratosaurus* in *Journey to the Beginning of Time* (1954), in *The Animal World* (1956), the documentary *When Dinosaurs Roamed America* (2001),and *Jurassic Fight Club* where it also faces *Allosaurus* (2008). It faced *Allosaurus* 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) (which was the first time use of the spike tail for defense was portrayed), and in the remake of the series *Land of the Lost* (1992–93). A baby *Stegosaurus* dubbed Spike is one of the lead characters in *The Land Before Time* (1988) and its direct-to-video sequels.

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. In the 2005 Peter Jackson remake *Stegosaurus* is nowhere to be seen, although in the extended edition the fictional *Triceratops*-like dinosaur "Ferructus" takes its place.

A *Stegosaurus* also has appeared in *The Lost World: Jurassic Park*, as one of the first dinosaurs to be seen. They also were 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 'Steg**a**saurus').

*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*. In the American version of King Kong vs. Godzilla this is remarked upon by a reporter, claiming Godzilla was half-Stegosaur, half-Tyrannosaur.

### Cartoons and comics

*Stegosaurus* has been featured in children's cartoons. The *Transformers* toyline and related television series features four characters which can transform into stegosaurids: Snarl, Slugfest, Saberback and Striker. In the 1980s cartoon *Dinosaucers*, the character Stego is an anthropomorphic *Stegosaurus* who while still only a trainee soldier accomplishes difficult tasks despite his inexperience. Also, Stegz was an anthropomorphic stegosaur featured in the series "Extreme Dinosaurs". Ironically, despite the tiny brain size of *Stegosaurus*, he is portrayed as the most intelligent of the characters in the show. One of the Dino Knights and Drago Clones in *Dinozaurs* were Dino Stego and his evil counterpart Drago Stegus.

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 ever had one, has, since the *Far Side* publication, been replaced by "thagomizer", which is used as a genuine anatomical term by many palaeontological authorities, including the Smithsonian Institution.

## JPInstitute.com Description

Easily one of the best known of all the dinosaurs, Stegosaurus is recognized the world over. The unique plates along its back, its small head and spiked tail make it a peculiar and unique dinosaur. This plant-eater evolved to find its food in the low-growing plants of the late Jurassic. The long fearsome spikes on its tail would have made a powerful weapon against predators.

Stegosaurus is often called the dumbest dinosaur because of its incredibly small brain. In fact, most scientists believe that its brain was too small to control such a large creature and that it used an auxiliary "brain" located above its rear legs to help control its movements. This was not actually a brain, but a bundle of nerves that helped relay information from its real brain.

Most fascinating to people are the plates along its back. There has been a great deal of debate about their use and arrangement. The plates were up to 2-feet tall and 2-feet wide (.6 m). The most prevalent theory is that they were used for cooling or heating the animal. A more recent theory, however, suggests that they could have been used as a display during courtship and that they may have been brightly colored. It is also possible that they could move up and down, perhaps to intimidate predators.

The spikes on its tail are also the subjects of some controversy. For years every model of Stegosaurus showed it with the spikes sticking up into the air. It is only since the 1990's that it has become accepted that these spikes stuck out horizontal to the ground, which would have been a potent defensive weapon when swung at a hunter.

Stegosaurus would have lived in family groups and possibly herds, moving slowly through forests while eating the low-growing plants. Its front legs were considerably shorter than its hind legs, making it adapted to nibbling the plants closest to the ground. Stegosaurus is the namesake for a large family of dinosaurs whose members were found all over the world.

## Dinosaur Field Guide Description

Stegosaurus ("roofed lizard") is the best-known "plated" dinosaur. It was a favorite food of Allosaurus and has been well studied by paleontologists for over 125 years. It has also been the subject of many false "dinosaur myths". among them that it had a brain no bigger than a walnut (it was, in fact, more than twice as big as a walnut), a second brain in its hips, and plates that could flap on command. Several questions about Stegosaurus have received a lot of study by scientists in the 1990s. It has been proposed at various times that Stegosaurus had
either one or two rows of plates along its back. A new specimen found by Ken Carpenter, Bryan Small, and a team at the Denver Museum of Natural History shows that Stegosaurus did have a double row of alternating plates down its back. This new specimen also shows that the tail spikes did not point upward--as in most museum exhibits--but instead pointed sideways.

### Fun Facts

Almost everything in popular books about Stegosaurus is based on the specimen at the Smithsonian in Washington, D.C.

### Trivia

Stegosaurus comes in two varieties: a large-plated species with four long tail spikes and a rarer, smallen-plated species with shorter tail spikes (possibly eight of them), based on a partial specimen. The second species may not be valid.

## Appearance in other media

### *Jurassic Park*

Stegosaurus is been known to have appeared in the Jurassic Park movies. (Except for the first movie).

## Links

http://web.archive.org/web/20040806054348fw\_/http://www.jpinstitute.com/dinopedia/dinocards/dc\_stego.html#

## References

1. ↑ 1.0 1.1 Escaso, F, Ortega, F., Dantas, P., Malafaia, E., Pimentel, N.L, Pereda-Suberbiola, X., Sanz, J.L., Kullberg, J.C., Kullberg, M.C., and Barriga, F. (2007). "New Evidence of Shared Dinosaur Across Upper Jurassic Proto-North Atlantic: *Stegosaurus* From Portugal." *Naturwissenschaften*,
2. ↑ Liddell & Scott, 1980; *Greek-*
English Lexicon, Abridged Edition*. Published by the Oxford University Press, in Oxford, UK. ISBN 0-19-910207-4*
3. ↑ *The Ultimate Dinosaur Book*; 1993, by Lambert, D. pages 110–129. Published by Dorling Kindersley, in New York. ISBN 1-56458-304-X
4. ↑ 4.0 4.1 4.2 Carpenter, K; 1998. Chapter: "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.
5. ↑ 5.0 5.1 5.2 5.3 5.4 *The Evolution and Extinction of the Dinosaurs (2nd Edition)*; 2005 Chapter: *Stegosauria: Hot Plates*. Fastovsky DE, Weishampel DB (editors) Fastovsky, DE, Weishampel, DB. pp. 107–130; Publisher: Cambridge University Press. ISBN 0-521-81172-4. Cite error: Invalid `<ref>` tag; name "FasWeis04" defined multiple times with different content
6. ↑ *The Dinosaur Heresies*; 1986. By Bakker, RT; publisher: William Morrow, in New York. Pages 365–374.
7. ↑ *Stegosaurus*. University of Wyoming Geological Museum. 2006. Retrieved October 6, 2006. University of Wyoming Geological Museum
8. ↑ *The Armored Dinosaurs*, 2001; Chapter: "New Primitive Stegosaur from the Morrison Formation, Wyoming". Carpenter, Kenneth(ed), Carpenter K, Miles CA, Cloward K (authors). Pages 55–75; published by Indiana University Press ISBN 0-253-33964-2 (.)
9. ↑ 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
10. ↑ 10.0 10.1 Marsh OC, 1877; *A new order of extinct Reptilia (Stegosauria) from the Jurassic of the Rocky Mountains*, from the American Journal of Science; vol. 3, issue 14, on pages 513–514.
11. ↑ 11.0 11.1 11.2 *The Armored Dinosaurs*; 2001; Chapter: "Othniel Charles Marsh and the Eight-Spiked *Stegosaurus*". Carpenter, Kenneth(ed); Carpenter K & Galton PM (authors); pages 76–102. Publisher: Indiana University Press. ISBN 0-253-33964-2 (.)
12. ↑ 12.0 12.1 Galton, Peter M.; Upchurch, Paul (2004). "Stegosauria (Table 16.1)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. Pp. 344-345. ISBN 0-520-24209-2.
13. ↑ 13.0 13.1 Marsh OC; 1887. "Principal characters of American Jurassic dinosaurs, part IX. The skull and dermal armour of *Stegosaurus*"; from the American Journal of Science, vol. 3, issue 34, pages 413–417.
14. ↑ Marsh OC; 1879, *Notice of new Jurassic reptiles*, from the American Journal of Science, vol. 3, issue 18, pages 501–505.
15. ↑ 15.0 15.1 15.2 15.3 15.4 15.5 15.6 15.7 *The Dinosauria (2nd Edition)*, 2004; Chapter: "Stegosauria". Weishampel DB, Dodson P, Osmólska H (editors) Galton PM, Upchurch P (authors) page 361. Published by the University of California Press, ISBN 0-520-24209-2 (.)
16. ↑ Marsh OC; 1881. *Principal characters of American Jurassic dinosaurs, part V*, from the American Journal of Science, vol. 3, issue 21, pages 417–423.
17. ↑ 17.0 17.1 17.2 *The Dinosaur Heresies*; 1986, by Bakker, RT. Published by William Morrow, in New York. ISBN 0-8217-2859-8 (.)
18. ↑ 18.0 18.1 18.2 Cite error: Invalid `<ref>` tag; no text was provided for refs named `gilmore14`
19. ↑ Galton PM (1981) "*Craterosaurus pottonensis* Seeley, a stegosaurian dinosaur from the Lower Cretaceous of England, and a review of Cretaceous stegosaurs". Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen 161(1):28–46
20. ↑ Maidment, Susannah C.R., and Norman, David B.; Barrett, Paul M.; and Upchurch, Paul; in press. *Systematics and phylogeny of Stegosauria (Dinosauria: Ornithischia)*, from the Journal of Systematic Palaeontology. DOI: 10.1017/S1477201908002459 (,) vol. 6, issue 4, pages 367–407.
21. ↑ 21.0 21.1 Marsh, O.C.; 1880. *Principal characters of American Jurassic dinosaurs, part III*, from the American Journal of Science, vol. 3, issue 19, pages 253–259.
22. ↑ 22.0 22.1 Marsh OC, 1891; "Restoration of *Stegosaurus*", from the American Journal of Science, vol. 3, issue 42, pages 179–181. Cite error: Invalid `<ref>` tag; name "Marsh1891" defined multiple times with different content
23. ↑ Bakker RT, 1978; *Dinosaur feeding behavior and the origin of flowering plants*, from the Journal of Nature, issue 274, pages 661–663, vol. 274. DOI: 10.1038/274661a0 (.)
24. ↑ Buchholz (née Giffin) EB, 1990; *Gross Spinal Anatomy and Limb Use in Living and Fossil Reptiles*, from the Journal of Paleobiology, vol. 16, pages 448–458.
25. ↑ 25.0 25.1 Buffrénil, 1986; "Growth and Function of *Stegosaurus* Plates", from the Journal of Paleobiology, vol. 12, pages 459–473.
26. ↑ Bakker, R, 1986; *The Dinosaur Heresies*, pages 229–234. Published by: Penguin Books.
27. ↑ 27.0 27.1 *The Theory of sexual selection*; 1961, by Davitashvili L. Page 538. Published by: Izdatel'stvo Akademia nauk SSSR.
28. ↑ Farlow JO, Thompson CV, Rosner DE, 1976; "Plates of the dinosaur *Stegosaurus*:Forced convection heat loss fins?", from the Journal of Science, issue 192, pages 1123-1125, vol. 192, DOI: 10.1126/science.192.4244.1123 (.) PMID 17748675 (.)
29. ↑ Main RP, Padian K, Horner J, 2000; "Comparative histology, growth and evolution of archosaurian osteoderms: why did *Stegosaurus* have such large dorsal plates?", issue 20 from the Journal of Vertebrate Paleontology 56A.
30. ↑ Mayell, H, "Stegosaur plates used for identification", from National Geographic News, (25th May, 2005.) [1]
31. ↑ *Dinosaurs: Their Discovery & Their World*, 1962; Colbert EH. Pages 82–99. Published by: Hutchinson Press, London. ISBN 1-111-21503-0 (.)
32. ↑ Dinosaurs Past & Present, Vol 2, 1987; "A Reevaluation of the Plate Arrangement on *Stegosaurus stenops*", Czerkas SJ, Olson EC (editors), Czerkas SA (author). Pages 82–99. Published by: the University of Washington Press, Seattle.
33. ↑ *The Armored Dinosaurs*; 2001, Chapter: "Posttraumatic Chronic Osteomyelitis in *Stegosaurus* dermal spikes". Carpenter, Kenneth (ed), McWhinney LA, Rothschild BM & Carpenter K (au). Pages 141–156; Publisher: the Indiana University Press. ISBN 0-253-33964-2 (.)
34. ↑ *The Carnivorous Dinosaurs*, 2005; Chapter: "Evidence for predator-prey relationships: Examples for *Allosaurus* and *Stegosaurus*". Carpenter, Kenneth(ed), Carpenter K, Sanders F., McWhinney L.& Wood L(au). Pages 325–350. Published by the Indiana University Press. ISBN 0-253-34539-1 (.)
35. ↑ *The Armored Dinosaurs*, 2001; Chapter: "Tooth wear and possible jaw action of *Scelidosaurus harrisoni* and a review of feeding mechanisms in other thyreophoran dinosaurs". Carpenter, Kenneth(ed), Barrett PM(au), pages 25–52. Published by: the Indiana University Press. ISBN 0-253-33964-2 (.)
36. ↑ *Stegosaurus ungulatus* Carnegie Museum of Natural History. Retrieved 26 October 2006.
37. ↑ Stegosaurs Jacobson, RJ. Dinosaur and Vertebrate Paleontology Information. Retrieved 26 October 2006.
38. ↑ Weishampel DB, 1984; *Interactions between Mesozoic Plants and Vertebrates:Fructifications and seed predation*, from the journal of N. Jb. Geol. Paläontol. Abhandl. Pages 224–250, vol. 167.
39. ↑ Rajewski,Genevieve, in May, 2008. *Where Dinosaurs Roamed*, from the Journal of Smithsonian, pages 20–24. [2].
40. ↑ Colorado Department of Personnel website - State emblems
41. ↑ Lucas, S.G. (2006). "The Three Faces of Dinosaurs". *Geotimes*.
42. ↑ *Feedback*, from the New Scientist Magazine. Published by: Elsevier, on 16th November, 2002.
43. ↑ *Light emitting diodes (LED) & optoelectronic device research at UNC Charlotte*, published by the: University of North Carolina at Charlotte. [3].
44. ↑ Crichton M, 1990; *Jurassic Park*. Published by: Alfred A. Knopf. ISBN 0-394-58816-9 (.)
45. ↑ "The word: Thagomizer," *New Scientist,* July 8, 2006. Retrieved October 26, 2006.
46. ↑ Stegosaurus Changes, Smithsonian National Museum of Natural History, Department of Paleobiology.