Stegosaurus stenops “gigas” (*) (S/F) / (S/F-S)

Stegosaurus is a genus of very large thyreophoran dinosaur in the family Stegosauridae, which is named after this animal. Its name means “roofed reptile” in reference to its dorsal plates; paleontologists originally assumed that these laid flat on its back, forming a kind of armored roof. The specific epithet of this particular species, S. stenops, means “narrow face.” This animal originally lived in the late Jurassic period, between 155 and 145 million years ago, and inhabited what is now western North America. Because InGen specimens bred for the company’s de-extinction theme parks have shown an ability to grow noticeably larger than their fossil counterparts, Jurassic-Pedia differentiates them from their ancestors using a subspecific epithet, gigas, meaning “giant.”

Fossilized remains of Stegosaurus were first discovered north of Morrison, Colorado in 1877 and were described by Othniel C. Marsh. He assigned them to a species he named Stegosaurus armatus, which he believed was a large turtle-like reptile; what are now known to have been upright dorsal plates were then thought to be armor resembling a shingled roof. An abundance of Stegosaurus remains were uncovered over the next few years, and Marsh named a second species S. ungulatus in 1879. Over the years, Marsh described a large number of Stegosaurus discoveries, and in 1886 he named three new species, including the subject of this article S. stenops as well as S. duplex and S. sulcatus. The species described in this article was found at Garden Park by Marshall P. Felch and named the following year. By 1891, Marsh realized that the armor of this creature did not lie flat, but was upright; he positioned them in a single row, but found this arrangement impossible since this would cause the plates to overlap.

Concept art of an adult Stegosaurus stenops

The known species were joined in 1901 by a new addition, Stegosaurus marshi, which was described by Frederick Lucas. In the early 1900s, Lucas also revisited older stegosaur discoveries and found that their anatomy was different from Marsh’s assumptions. Lucas’s research set the groundwork for our modern understanding of Stegosaurus, including reconstructions commissioned to legendary paleoartist Charles R. Knight.

Hind foot print of an InGen Stegosaurus. Note that it possesses one additional toe, whereas its ancestor had only three.

Today, there are three species of Stegosaurus known to science. The best-known, the type species since 2013, is S. stenops; a great many fossils of this animal have been found and it is one of the most abundant of the stegosaurs. It can be distinguished by its broad and proportionally large dorsal plates, while the plates of the tail are smaller and rounded. This species is smaller than other known stegosaurs, at 23 feet (7 meters) in length. The largest species is S. ungulatus at 29.5 feet (9 meters), and can be told apart by its smaller, pointier plates; it also has flat spine-shaped plates just before its thagomizer, as well as longer legs. The third species, S. sulcatus, is distinguishable based on its unique huge furrowed spikes; based on their large bases, these may have been attached at the shoulders or hips rather than being part of the thagomizer.

Stegosaurus stenops, easily identified by its plate shape, was cloned by International Genetic Technologies, Inc. at the Site B facilities on Isla Sorna using ancient DNA recovered from Jurassic amber inclusions sometime in the 1980s or early 1990s. As of June 11, 1993, InGen had engineered up to Version 2.035 of Stegosaurus. This species persists today after decades of captive breeding.

Largest known Stegosaurus specimen with humans to scale. The plates of this fifty-five-foot individual are around six feet tall.

While fossil animals reach only 23 feet in length, genetic tampering at InGen has yielded far larger animals. InGen Stegosaurus routinely grow to lengths of 30 to 40 feet (9.1 to 12.2 meters) and measure 19 feet (5.8 meters) to the tip of the tallest plate, and exceptional specimens can grow to an enormous 55 feet (16.8 meters) long. Its weight as an adult ranges from 1.7 to 7.7 tons (1,587 to 6,985 kilograms), a very wide range. Fossil animals were heavier with respect to size than InGen’s specimens, which weight about five tons at thirty feet long. But, since InGen stegosaurs grow much larger anyway, they are still heavier.

The head of Stegosaurus is famously small, making up only a tiny amount of its body size. Its skull is long and narrow, with a keratinous and toothless beak; these features demonstrate evolution in favor of browsing among low-growing vegetation. Some InGen stegosaurs bred for Jurassic World featured improperly formed beaks due to poor nutrition. Stegosaurus has teeth behind its beak; fossils show small, flat triangular teeth, though in InGen’s stegosaurs, these teeth are larger and rectangular rather than triangular, making them similar to mammalian molars. In both prehistoric and modern Stegosaurus, though, the teeth are built for grinding. Today’s Stegosaurus have fleshy cheeks similar to those found in many ornithischian dinosaurs, but there is debate as to whether the beak of the prehistoric Stegosaurus left any room for cheeks. Fossils show that, in prehistory, this animal would have had pebbly ossicles on the underside of its head, which InGen’s specimens lack; the neck is also shorter in these cloned versions. The nostrils and eyes are both small, with the eyes possessing round, birdlike pupils and dark orange sclerae. Tapeta lucida make the eyes reflective in the dark, aiding with vision in low light. Its tongue is short, pink, flat, and not especially muscular.

Stegosaurus has a famously small brain, similar in size to that of a domestic cat and shaped like a rounded cylinder. This is exceptionally small for a dinosaur; a five-ton adult Stegosaurus has a brain weighing only 2.8 ounces (80 grams). This makes Stegosaurus less intelligent than many other dinosaur species. However, its nervous system is sophisticated enough, with features such as the glycogen body near the hips used to maneuver the tail. The size and shape of this neurological feature led to it once being mistaken for an auxiliary brain, a misconception popularized in the media due to the potential for jokes about the animal having a second brain in its rear. In reality, Stegosaurus, like all known vertebrate animals, has only one brain, located in the head. Glycogen bodies are known in most other dinosaurs, including birds.

Stegosaurus is not a fast animal, though it can run for short bursts.

The neck is not terribly long, but the shoulder blade is robust, and the overall body is shaped a bit like a teardrop with a high back and low-hanging head. Like all but the most primitive stegosaurs, it is a quadruped, capable of only briefly rearing onto its hind legs. Its front limbs are shorter and thinner than its hind limbs, and the toes end in rounded claws. There are five toes on each front foot, with the inner two being blunt and hoof-like in the fossil record but not particularly notable in InGen specimens. While fossils show three-toed hind feet, InGen Stegosaurus have one extra toe for a total of four on each foot. To support the feet, Stegosaurus has pads behind its toes. Its anatomy means it is not speedy; it reaches its maximum speed at about 4.3 miles per hour (7 kilometers per hour), as running much faster than this would cause its hind legs to overstep its front legs. Because of this handicap it cannot keep a high speed for very long.

Of course, the most obvious and recognizable feature of this animal is its dorsal armor. This comes in the form of two rows of bony plates in staggered formation, increasing in size toward the hips and decreasing in size toward the head and tail. The largest plates in thirty-foot adults are three feet (91.4 centimeters) tall and about as wide. There are between seventeen and twenty-two plates, with twenty-two appearing to be the most common number, and evenly paired plates being much more common than asymmetrical numbers. In Stegosaurus stenops, these plates are close to pentagonal in shape, with the larger ones pointing slightly backward. These plates are highly modified osteoderms, similar to the tough scaly armor of crocodiles, and are covered with a vascularized keratin sheath. This feature allows the plates to be used for thermoregulation, as cool air passing over them decreases the blood temperature within. Plates on Stegosaurus are chiral; that is, the left and right plates are not exact mirror images of one another, similar to the left and right hands of a human. Also like a human’s hands, a Stegosaurus can show dominance in one set of plates versus the other, with either the left or right row leading. There is currently no research to determine whether the side of the leading plate row influences which way the Stegosaurus looks when aiming its tail. In the wild, no two plates on this animal look quite the same, but in the laboratory a greater degree of regularity can be achieved.

The rapid speed at which it swings its thagomizer means that Stegosaurus can puncture muscle and organs, and even bone.

After the dorsal plates, the most famous feature of Stegosaurus is its tail, which is long and flexible, ending with a structure called a thagomizer. This consists of four conical spikes, which protrude horizontally at slight upward angles from the tail and possess limited mobility. Unlike the staggered pattern of the plates, the spikes of the thagomizer are positioned precisely opposite one another in two pairs. Each spike is about as long as the animal’s tallest dorsal plate. The tail is highly innervated, though contrary to popular misconception it does not possess any kind of “secondary brain.” A stegosaur’s thagomizer is its main weapon against predators, and thanks to the tail’s strong muscles and flexibility, it can be swung at 30 to 131.2 feet (9.1 to 40 meters) per second. The tail is normally held well off the ground, but is flexible. Paleoveterinarians believe this to be a health defect, occurring due to improper nutrition causing low muscle tone. The Department of Prehistoric Wildlife concurs with this conclusion.

Stegosaurus modified with cnidarian genes to exhibit bioluminescence

This animal’s coloration is simple but variable, with dull forest or olive greens being the most dominant color. Some animals demonstrate a more vivid shade, while dusty yellow-greens and stony gray-greens are also known. The plates tend to be darker than the body, with some animals showing brown or reddish tints, and some having light-and-dark horizontal banding. Patterning may be as simple as the color fading from green to yellow across the body, or may include dark splotches or vertical stripes. At least one variant was genetically engineered for Jurassic World to display violet-blue bioluminescence, which manifested over most of the body including the plates. Unlike the lux variant of Parasaurolophus walkeri, which demonstrates bioluminescence through the expression of genes taken from freshwater algae, Stegosaurus gains this ability through genes taken from Aurelia (moon jellies).

Ontogeny of Stegosaurus is clearly demonstrated by this adult and juvenile side-by-side, Isla Sorna (7/19/2001)

Juvenile Stegosaurus can be easily told apart from adults by more than just size. The size and shape of its body armor changes as the animal ages. When it first hatches, the plates and spikes are small rounded nubs, along with other typical features of baby animals such as a disproportionately large head and shorter tail. They may also have duller colors, which aids the more vulnerable juveniles in blending in with forest undergrowth and thus staying hidden from predators until they grow large enough to begin defending themselves. Upon reaching adolescence, the onset of adult colors appears to be fairly rapid.

Juvenile Stegosaurus with mostly-developed plates

As the animal approaches adolescence, its plates begin to assume their full proportions and attain a backswept pentagonal shape. The thagomizer grows at a similar rate, reaching its full size just a little later in life. Growth rates differ slightly between InGen’s original stock and the later versions bred for Jurassic World; in the latter, plates grow noticeably faster. In older versions, even older adolescents and subadults can be seen to have more rounded plates than mature adults, suggesting that the finalization of plate growth is a means of displaying maturity. In newer versions, the speed of plate development has most likely been deliberately increased, in order to attain more visually impressive specimens at an earlier age.

There is a common misconception that it regularly sheds its plates off and grows new ones during its juvenile and adolescent stages, similar to a deer shedding its antlers. In reality, the plates of a Stegosaurus have bony cores and are part of its skeleton. The misconception comes from the other part of the plates: they are covered in a sheath of keratin, the same substance that makes up beaks, claws, and the horns of certain animals. Many dinosaurs with horns or armor structures have sheaths of keratin overtop the bony cores of these structures, and stegosaurs are among them. Ceratopsians such as Triceratops also have keratinized sheaths over their horns, and as they grow, they rub their horns against trees to help shed the sheaths. The plates of Stegosaurus are similarly rubbed against trees and other objects to hasten the shedding of keratin, not dissimilar to a human’s fingernails breaking and growing back, or hair falling out to make way for new growth. Large enough pieces of keratin may give the incorrect impression that a Stegosaurus has shed an entire plate, but in reality, just the protective outer layer is shed so that new keratin can grow in over the newly-enlarged plate. The bony core remains intact, and a whole plate can only be broken off by traumatic injury, after which it will not grow back. Spines of the thagomizer, too, remain fully attached with just the keratinous outer layer shedding as the spines grow; a whole spine breaking off is a grievous wound that leaves the stegosaur with a weaker defense.

Sexual Dimorphism

While some paleontologists have suggested that the dorsal plates of Stegosaurus and its relatives may have been sexually dimorphic, this is not yet confirmed by scientific research. These theories suggest that the males’ plates are broader while the females’ are taller. However, InGen stegosaurs do not appear to demonstrate this kind of dimorphism. While males and females of the original breed have been positively identified, there are few easily noticeable differences that can be used to sex the animals. Newer breeds of Stegosaurus have not been explored thoroughly either, making it impossible to sex them based on casual observation alone. Like certain modern birds, it may be that Stegosaurus males and females tell each other apart through behavioral cues.

Preferred Habitat
Note the fleshy lips of this specimen, caused by the lack of a beak. Low levels of keratin production as a result of improper nutrition can cause this health condition.

This animal prefers forested environments, since this is where its food sources are most plentiful, and denser vegetation offers it shelter from the elements as well as larger predators. Its bulk allows it to push through undergrowth efficiently, toppling smaller trees that get in its way and crushing shrubs and low growth. Stegosaurus has been seen in both coniferous and angiosperm forests. It feeds mainly on the ferns found in dense woodland. However, it can also survive in more open areas, and has been sighted on grasslands and in brush, as well as at least one animal having been sighted in an arid mountainous region. It seems to avoid marine coasts, as it is a poor swimmer, and prefers warm environments as opposed to cold ones. It is also tolerant, to some degree, of arid environments such as those found in the American Southwest, and may be tolerant of chillier climates as well. Its efficient thermoregulation allows it to flourish better in warm environments, so this is where it is commonly seen.

Fossil evidence suggests that the best habitat for this animal would be a semi-arid flatland with wet and dry seasons. In the Jurassic period, it inhabited prairies and floodplains with gallery forests along the riverbanks, where it would probably go to feed, drink, and find shelter. Plant life known to exist in its ancient habitat includes tree ferns and cycads, Araucaria conifers, and ginkgoes. Today, it is found in woodlands, with clear indicators of its territory including heavily-grazed clearings among larger trees.

Muertes Archipelago

This dinosaur was originally bred in the Embryonics facility on Isla Sorna, where InGen performed its research and development in the 1980s and 1990s. The date at which the first Stegosaurus was cloned is not known, but it was sometime between 1986 and mid-1993. For undisclosed reasons, this animal was not considered ready for exhibition at Jurassic Park by 1993, and so was left on Isla Sorna. When the island was struck by Hurricane Clarissa in 1995, the facilities were abandoned and the animals were turned out into the wild. As of 1993, there were eleven Stegosaurus confirmed living on Isla Sorna. None have been reported on other islands of the Muertes Archipelago.

Stegosaurus has been spotted in both eastern and western Isla Sorna, though this may represent migratory patterns rather than separate populations. In May 1997, breeding was recorded in the island’s northwestern regions in a coniferous forest south of the game trail. A family unit consisting of a mated pair, a subadult, and a juvenile female was sighted on May 28, with a similar group with one additional adult being sighted not far away (this was possibly the same group, though the young juvenile was only sighted on one of those occasions). Nesting grounds were reported by Dr. Sarah Harding in the preceding week, suggesting that the stegosaurs had recently bred, but that the infant mortality rate was fairly high.

One adult male and one juvenile, possibly members of this herd, were captured by the InGen Harvester expedition led by Peter Ludlow. They were released by animal rights activist Nick Van Owen during the night, from which point they most likely returned from the Harvester camp to their home.

A herd of nine animals including two young juveniles was sighted on May 30, 1997 around midday in the north-central part of the island, some miles inland from the beach. This herd, again, may have included the members of the herd seen a few days prior, though these locations are fairly far apart. There could have been between fourteen and nineteen Stegosaurus on Isla Sorna at that time.

In the summer of 2001, stegosaurs were sighted in the island’s western region, with at least two being reported by Eric Kirby near the safe house in June or July. A herd of fifteen animals was sighted in the western grassland near the airstrip on July 18, including two younger juveniles and three subadults, while a smaller herd on the central peninsula the following day included four adults and one older juvenile. These numbers imply a population of at least fifteen to twenty-two Stegosaurus. If the animals seen in the west were not the same as those seen in the east four years prior, there could have been as many as forty-one stegosaurs on Isla Sorna by 2001, a large increase from the original eleven animals in 1993.

Known (red) and suspected (purple) range of S. stenops on Isla Sorna between 1997 and 2001

As could be expected, the population increase had drastic effects on Isla Sorna, and by 2004 the populations of most of its dinosaurs were in decline. Competition for food grew fierce, and some animals began to die off. The well-protected Stegosaurus may have fared well during these trying times, but by late 2004 or early 2005, surviving animals were captured by InGen Security under the direction of Masrani Global Corporation and shipped to Isla Nublar. Supposedly, there are no dinosaurs remaining on Isla Sorna today, though some evidence of continued activity has been documented.

Jurassic Park: San Diego

Artwork of InGen’s original Jurassic Park locale in San Diego, California suggests that Stegosaurus was a planned attraction there. Since the park was not completed and instead was abandoned in favor of the Costa Rican location, much information about the intended exhibits is unknown. However, an adult and juvenile Stegosaurus were both captured during the attempted 1997 revival of the park, though neither of them were successfully brought off of Isla Sorna.

Isla Nublar

Stegosaurus was one of fifteen species originally intended to be exhibited at Jurassic Park on Isla Nublar. By the summer of 1993, Version 2.035 Stegosaurus embryos were in storage at the park facility, but no live animals had been introduced. They were intended to be housed in a paddock in the central part of the island, visible from the main tour road which bordered it on the south and east, separated from it by a concrete moat. It was also separated using a concrete moat from a service road to the north. This paddock bordered the Jungle River to the west and southwest, and the Jurassic Park Aviary to the northwest. Aside from the Aviary, the Stegosaurus habitat did not directly border any other animal paddocks.

Planned (orange) range for S. stenops on Isla Nublar prior to June 11, 1993

Due to the failure of Jurassic Park in mid-1993, Stegosaurus did not reach Isla Nublar until late 2004 or early 2005. During that time, surviving animals from Isla Sorna were imported to stock the upcoming theme park, Jurassic World. This species was not yet present on the island by September 2004 and was not among the eight species on display when the park opened on May 30, 2005, but fairly quickly became a staple at the new park. It was introduced to Gyrosphere Valley, and was able to venture as far as the Jungle River, meaning its range spanned Sectors 4 and 6. There were also stegosaurs in Sector 5, with some being members of Herd M.

Like the other dinosaurs, this species was actively bred in Jurassic World, with new animals hatching regularly from the Hammond Creation Lab. Once they reached the juvenile stage, they would be introduced to the Gentle Giants Petting Zoo until they were deemed ready for introduction to the paddocks. As of December 22, 2015, there was one Stegosaurus in the petting zoo, with fully-developed plates and larger body size indicating that it was nearly adolescent.

By late 2015, the stegosaur population was healthy and sustainable. Along with the juvenile in the petting zoo, there were at least eighteen adults and one young juvenile in Gyrosphere Valley, as well as two adults and one subadult living near the Jungle River. Fourteen adults were also sighted near Camp Cretaceous on December 19 of that year, members of Herd M; these included at least four striped, three spotted, and three plain animals. They would have grazed during the day, and inhabited nighttime paddocks when not outside. Also living in Sector 5 were the genetically-engineered bioluminescent stegosaurs; only two females were created by December 2015, with the second one having hatched shortly before the 22nd. Unlike the bioluminescent Parasaurolophus, these were not integrated into a park attraction. Six adult Stegosaurus were kept in a Sector 4 veterinary station for undisclosed medical conditions as of December 22.

Jurassic World experienced a severe safety incident on December 22, 2015 which caused its permanent closure, leaving the Stegosaurus and other dinosaurs to fend for themselves. Those in the veterinary station were abandoned, though all but one were fortunately released on December 24 by Camp Cretaceous attendees who became stranded on the island. Two of the stegosaurs moved north and probably joined Herd M; the others probably moved into the valley. While conditions were too hazardous to release the last animal at the time, it is likely that the campers later returned to free the final dinosaur. Much of the population appears to have originally converged on Gyrosphere Valley, where the bulk of the animals already lived. The two bioluminescent stegosaurs survived into March 2016, but no more appear to have hatched. They lived in the southern parts of the island east of Sector 3.

As time went on, the population diverged, with some favoring the forests near Camp Cretaceous and Mount Sibo while others migrated to the farthest south of Isla Nublar, near the Ferry Landing docks. By late March 2016, at least two were even living in the harbor building, having utilized the maintenance tunnels to reach it. Both populations still sometimes traveled throughout the island’s middle ranges, being sighted near the Kon penthouse pier, field genetics lab, and Sudden Drop. It is unknown what became of the adolescent from the petting zoo. By June 23, 2018, there were at least nine and possibly as many as fifteen adult Stegosaurus living near Mount Sibo’s eastern foothills, while the carcass of a fifty-five-foot-long animal was found to the volcano’s south. It appeared to be recently deceased. None of the animals sighted here were those from Herd M, nor were they the bioluminescent stegosaurs, which may have died out as they could not efficiently hide from predators. Other than this, the stegosaur population appears to have suffered less than some of the other dinosaurs on the island. Assuming that the southern herd was around the size of the northern one, there could have been around thirty stegosaurs living on Isla Nublar by the summer of 2018, only a small decrease from the nearly forty confirmed there in 2015.

On June 23 that year, Mount Sibo violently erupted after months of buildup, driving the stegosaur herd along with the other dinosaurs away from the volcano. Most were killed in the eruption, either due to suffocation, injury from volcanic debris, or drowning in the ocean. Any that survived would have eventually died as their food sources were eliminated. Six adults were captured by mercenaries led by Ken Wheatley, with at least one being taken from the northern population, and removed from Isla Nublar via the S.S. Arcadia. The northern stegosaur was measured at 5,950 kilograms (6.6 U.S. short tons) at the time of loading, making it a reasonable weight for a mid-sized InGen specimen. It was cosigned by Adam Tate and logged into the ship’s manifest at 13:50, held in Container #33-1021-2042 (Cargo #72362).

Due to the eruption of Mount Sibo, it is most likely that Stegosaurus is extinct on Isla Nublar.

Mantah Corp Island

At some point between 1997 and 2015, longtime InGen rival Mantah Corp obtained either a live Stegosaurus specimen or a genetic sample through illicit means. At least one animal was in their possession held at the testing facility on Mantah Corp Island. As of June 2016, it was in the medical bay for treatment; its normal habitat is so far undisclosed, but the forested biome would suit it.

Biosyn Genetics Sanctuary

Stegosaurus is among the animals which is housed in the Biosyn Genetics Sanctuary, run by Biosyn Genetics. In the early 2020s, specimens were collected from the wild by the company with explicit approval and encouragement by multiple national governments. Herds of Stegosaurus inhabited the fern-covered areas of the valley, among lush forests and fresh waterways where their needs were easily met.

In late 2022, a wildfire destroyed much of their habitat, and they were temporarily herded into the emergency containment areas underneath Biosyn’s headquarters. After the fire died out, the animals were reintroduced to what remained of their habitat and settled in again as the plants started to recover. The incident led to Biosyn’s exclusive ownership of the valley being revoked by the United Nations, which now administers much of the facility.

Black market

Poaching may have taken Stegosaurus away from InGen facilities between 1997 and 2018, with a few adults entering the black market in June 2018. They were captured from Isla Nublar by mercenary hunter Ken Wheatley at the behest of Eli Mills, who sought to fund Henry Wu‘s research by selling the animals. One adult Stegosaurus was successfully sold to an unknown buyer, and samples of DNA were sold to a Russian buyer (probably the mobster Anton Orlov). The sold assets were transported from the Lockwood estate in Orick, California where the illegal auction was held, but their final destinations remain undisclosed. Other stegosaurs were released into the wild that night after the auction was disrupted.

Since the events of 2018, de-extinct animals and their genetic material have circulated around the global black market. A major hub of trade is the Amber Clave, located in Valletta, Malta.

Wild populations

This dinosaur evolved during the late Jurassic period, about 155 million years ago. Its original habitat was the prairies and floodplains of western Laurasia, which at that point was in the process of separating off into North America. Its remains are most common in the western parts of North America, since fossilization is more common there; however it may have ventured east as well and simply not fossilized. Stegosaurus appears to have been reasonably common. This was among the last of the stegosaurs; it became extinct somewhere in the vicinity of 145 million years ago. By that time, the Jurassic period was drawing to a close, and few stegosaur species survived into the Cretaceous. Many millions of years after it died out, its DNA was recovered by paleontologists, which allowed geneticists to reconstruct its genome. Through genetic engineering and cloning, they were able to resurrect it in a new modified form.

The first confirmed case of a Stegosaurus on the mainland was the 2018 incident at the Lockwood Estate in Orick, California. During these events, six adult stegosaurs from Isla Nublar were illegally transported to the manor to be sold on the black market by Eli Mills, working at the behest of Henry Wu. One of these animals was sold to an unknown buyer, and its location has not yet been determined. The other five were held overnight on June 24, but were released by Maisie Lockwood in order to save them from a hydrogen cyanide gas leak.

Stegosaurus sighted on North Cascades Highway (3/10/2019)

Since their escape into the forests of the Pacific Northwest, some of these stegosaurs have been spotted in the wild. One was filmed by park rangers at an undisclosed location probably in California sometime during June or July of 2018. A Stegosaurus was also sighted in Diablo, Washington on May 10, 2019, suggesting the animals were making their way north from Orick. As of 2021, the CIA’s dinosaur tracking division had reported a population in the Coast Mountains in southern British Columbia, with others having spread eastward into the central Rocky Mountains in Colorado. The most northern population, probably brought there by human activity, lies in Greenland, where this dinosaur is reported east of Maniitsoq. This population appears to be very small and is likely unhealthy compared to those in warmer environments with better food availability.

Sightings of this dinosaur were still most common in the state of California as of early 2022. However, some sightings from farther away began to occur by then, likely due to illegal breeding and trafficking as well as other human activity. One animal was unexpectedly seen in the woods near Carrabasset Valley, Maine between Sugarloaf Mountain and Bigelow Preserve. Another was reported to the Department of Prehistoric Wildlife in Sanford, Florida. The DPW suspects that Florida presents an ideal habitat for these animals, since another was sighted later that spring near Disney World in Orlando. In the summer, an adult was spotted crossing the street in a remote area of South Hazelton, British Columbia, Canada.

The game Jurassic World Evolution 2 depicts more Stegosaurus living in the American Southwest, including a herd in the Sonoran Desert in Arizona. Four Stegosaurus are reported near Las Vegas, Nevada in the course of the game (they are said to have caused two injuries to local citizens). They can be captured by the U.S. Fish and Wildlife Service and transported to the Dinosaur Welfare Facility in Arizona. Another herd is depicted in the North Cascades of Washington State, near an abandoned dinosaur poacher camp.

Maps provided from the CIA’s tracking operation demonstrate Stegosaurus to be among the less common dinosaurs outside North America, but it has managed to survive in the wild in a few areas. Its only Eurasian populations as of 2021 were in central France near the Saône River and at Lake Onega in Russia. A single African population is known, located in the Atlas Mountains of northwestern Algeria.

Behavior and Ecology
Activity Patterns

Stegosaurus is diurnal, meaning it is active during daylight hours. It feeds during the morning and evening, and generally rests around the heat of midday. Activity has been reported during the night, but this is uncommon and usually the result of human interference. Even after a year of living on the North American mainland, wild Stegosaurus do not appear to have adjusted their lifestyle, though it is possible that they will change their behavior patterns with more time.

Diet and Feeding Behavior

This animal is a herbivore and spends the bulk of its free time eating. The head of Stegosaurus is built low to the ground, and its beaked jaws are capable of only up-and-down motion. Its teeth differ from those of its ancestors, being molariform rather than peg-shaped, but are still designed for grinding food. It is possible that the modification of its teeth may have been intentional on the part of InGen’s geneticists as a way to ensure Stegosaurus could get all the food it needs to survive, since the fossil record provides surprisingly few clues as to how this animal sustained itself in its own time.

Stegosaurus oral cavity. Note the molariform teeth, different from those in the fossil record, and the lack of teeth in the beak, which is consistent with fossils.

Its anatomy means that it normally can only feed on low-growing plants, with ferns being perhaps the most notable staple in its diet. It can reach plants growing around three feet off the ground, though if it is able to rear up, it can feed from trees. Stegosaurus is believed to also feed on mosses, conifer cones and other fruits, and cycads. According to Jurassic World: Evolution, its preferred food is paw paws, but it also enjoys mosses and cycads, while it cannot digest horsetails, palms, or rotten wood. However, it is able to consume live woody plants. It is probably not adapted to chew grass on its own, but its genetic modifications may have enabled it to eat this common food source in its new, modern habitat. Stegosaurus is known to feed on the bracken fern, which can cause bracken poisoning if consumed in excess. The sequel game portrays it feeding on a mixture of fallen fruits and fibrous ground cover.

In prehistory, this dinosaur lived in and near forests with ginkgoes and Auracaria trees; today, it has been known to make its home among redwoods. Coniferous trees probably provide it with food. In 1997, it was confirmed to frequently feed on lysine-rich plants such as soy and agama beans to compensate for its genetically-engineered lysine deficiency. Stegosaurus may also strip the bark off of trees, according to Darius Bowman, though he has not been given the chance to describe whether they eat the bark itself or the wood beneath.

There is currently no fossil evidence of Stegosaurus using gastroliths, despite its inability to chew; it is unknown if it makes use of gastroliths in the modern day in S/F canon, though it is confirmed to do so in C/N canon.

Social Behavior
Demonstration of individualism in Stegosaurus

This stegosaurid is a social herd animal, though some solitary individuals have been seen. They chiefly form family units with members of their own kind, and herds in the wild will often consist of mated pairs and their offspring. Young may remain with their parents into the subadult or even adult stage, with the older adults taking the lead. These older adults are more likely to be familiar with the reliable food sources and predictable threats of their local area, as well as being familiar with migratory routes.

Although it forms herds, Stegosaurus is unintelligent and has fairly few ways to socialize. These mostly consist of keeping in close physical proximity to their friends and family. When they travel, the subadults and juveniles will stick close to the adults, either their parents or whichever adults they have imprinted on. The distinctive plates of Stegosaurus probably help it recognize its own kind; this is supported by paleontological evidence, since different species of Stegosaurus have differently-shaped plates. Taking this a step further, members of the same species have subtle differences in the shapes and arrangements of their own plates, which suggests that Stegosaurus can recognize individual members of its herd. This animal also has a number of vocalizations that it uses while traveling or feeding, which ensure that different members of the herd know where their fellows are. In the game Jurassic World: Evolution 2, two Stegosaurus in the same herd may mutually push up against each other as they walk as a way of affirming their bond.

Stegosaurus bred for Jurassic World. Note that the tail droops lower than it should; this is possibly a health defect, though it is seen in most Jurassic World stegosaurs.

Despite its low intelligence, social bonds among Stegosaurus are reasonably strong, and they will work together to fend off threats to their young. If a predator is spotted, the stegosaurs will coordinate their movements to surround the predator, cutting off its movements. While a lone stegosaur is quite capable of defending itself, working with their herd members makes them an impenetrable force; not even the largest theropods will attempt to attack a whole herd if it stands together. If they manage to drive away or kill a threat, the herd will also retreat from the area as one, not leaving any of their fellows behind. Herds will fan out when they are relaxed, but travel in single file when wary; when actively fleeing a threat, the adults will flank the juveniles to keep them safe.

Competition for dominance in herds is mostly non-violent, with rough shoving being as far as they will go. When two animals compete for control of a territory, they will make shows of strength by swinging their tails at one another, never actually striking. To demonstrate their strength, they may swat rocks and other objects through the air, with a farther throw or a heavier object clearly showing which competitor is the more powerful.

The most distinct feature of this dinosaur is its set of dorsal plates, which are probably used for display.

The large dorsal plates of Stegosaurus are probably used in courtship, since they are its most obvious physical features. The strong, flexible tail with its four bony spikes may also be used to court mates, as a more powerful tail is a desirable survival trait. Stegosaurus has never been observed mating, leaving much speculation as to how it mates with such ornamentation on its body. Most dinosaurs have a cloaca which houses the reproductive organs, and Stegosaurus is probably no exception. Mated pairs may remain together for years and breed multiple times throughout their lives. It appears to be monogamous.

This dinosaur appears to breed during the winter months, since mid-sized juveniles appearing a few months old have been encountered in late winter to midsummer. In Costa Rica, the rainy season lasts from May to November, with November to May being the dry season. If Stegosaurus juveniles in the wild have grown to around eight feet in length before summer fully hits, then it stands to reason that the eggs hatch some months earlier than this, during the late rainy season. Eggs of dinosaurs this size normally incubate for six months to a year, though the duration for Stegosaurus eggs in particular is not known.

Even though it is not an intelligent dinosaur, Stegosaurus is known to be quite a good parent. This was discovered in 1997 by Dr. Sarah Harding, who studied the behavior and family dynamics of a Stegosaurus herd on Isla Sorna. She found that the nesting site showed signs of having been heavily used by both adults and juveniles, despite the eggs having hatched some time ago, suggesting that the parents remain in the nesting site for long periods of time. At least two juveniles, and at most four, were observed on the island on three separate occasions during the span of the next three days, always with adults present. The relatively small number of juveniles suggests a high infant mortality rate, making it even more important for the parents to care for their offspring.

Juvenile Stegosaurus. Note the rounded plates and small, nub-shaped thagomizer spikes.

Dr. Harding observed a multigenerational herd on Isla Sorna during this time, including a pair-bond and offspring from at least two breeding seasons. Offspring appear to remain with their parents for many years, and can sometimes still be seen living alongside them as subadults or adults. At this age, they can help care for their younger siblings, assisting their parents in driving off predators. This behavior is common in some modern birds.

Like most InGen dinosaurs, these Stegosaurus are often treated with growth-boosting hormone supplements to accelerate their maturation. Their natural growth rate is not known, but fossil evidence suggests that it would be slower than some other stegosaurs. Some of the stegosaurs bred before 1993 were adults by 1997, and some subadults which were bred probably around 1993 were also observed. This implies that some Stegosaurus reach adult size in four or five years. As they grow, their plates and spikes are delayed in development compared to the rest of the skeleton. Younger stegosaurs have small plates and spikes, which begin to take on their adult shapes during adolescence. In some of InGen’s original stegosaurs, subadults were still developing their plates, while in more recent animals the plates are fully-formed during adolescence. Fossil evidence suggests that the plates begin to grow more rapidly once skeletal maturity is reached. Sexual maturity probably follows this, with the fully-developed plates advertising that the animal is ready to breed.


Befitting a less intelligent dinosaur, this creature’s communication methods are fairly simple. It largely vocalizes with grunts and hoots. These are often heard while groups of Stegosaurus travel together, and appear to be a way to ensure that the herd stays together similar to the flight calls of modern birds. If one has wandered away, the vocalizations of its kin will summon it back. They are also heard making similar noises while eating, which can similarly keep the herd as a cohesive unit while foraging for food. Though these sounds are not complex, they can help to reaffirm social bonds.

Herd of Stegosaurus including two juveniles, Isla Sorna (5/30/1997)

Juveniles are small and generally quieter than the adults, which makes sense, since they are more vulnerable to predators. However, they can be quite loud when they are frightened, emitting yowls and groans which alert the adults. When a juvenile emits these sounds, all the adults nearby will immediately respond with an aggressive display toward any potential threat they see, and will not stop until they believe it to be neutralized. An angered adult Stegosaurus can produce a bull-like bellow to intimidate enemies, which is often heard when the animal is charging. A similar sound is produced by angered Triceratops and Parasaurolophus, suggesting that it is a convergent behavior.

Along with vocalizations, this animal probably uses visual cues to communicate. Its high dorsal plates are its most noticeable feature, making it appear larger when viewed from the side and easily helping Stegosaurus identify one another. When fleeing a threat, adults will flank the juveniles to protect them; when in this position, the tall bodies and plates of the adults create a kind of living corridor that the juveniles know to remain inside. This helps them recognize the adults as a source of safety. It is likely that body language involving plate display and tail movement are used in a variety of situations by Stegosaurus.

Ecological Interactions

This is one of the biggest armored herbivores, with its tall dorsal plates making it stand out among other species. It will tolerate other herbivorous neighbors, but mostly those which do not compete with it for food; this dinosaur’s aggression levels vary from low to moderate, and it can be somewhat territorial and cantankerous in the wild. Those in captivity tend to be calmer and friendlier, but this behavior quickly changes once they are no longer actively cared for. It may tolerate other stegosaurs (the game Jurassic Park: Operation Genesis describes Kentrosaurus as its favored companion, and they are known to use compatible vocalizations as per Jurassic World: Camp Cretaceous).

A charging Stegosaurus is a difficult force to stop.

On Isla Sorna, when this animal was first observed in the wild, it was known to inhabit coniferous forests including coast redwood trees. These trees are too large for an average Stegosaurus to damage, but they probably fed on the cones. Stegosaurus can push over smaller trees, and the large size of its body means that it will crush and topple plant life as it moves through woodland. It mainly feeds on plant that grow low to the ground, such as ferns and cycads. In 1997, these dinosaurs were observed living in areas near herds of Parasaurolophus, Pachycephalosaurus, Gallimimus, and Mamenchisaurus. However, these species tended to live on the game trail, rather than in the wooded areas nearby. This, and the differing food sources preferred by these dinosaurs, meant that they did not compete with Stegosaurus for food, and they interacted fairly little. Its relationship to the ceratopsian Triceratops is less understood. However, since these two herbivores (along with Parasaurolophus) share an aggression cry, it is possible they interact with each other. Trikes can be territorial, especially toward the young of other species, making them a potential competitor and threat. The use of a similar cry to denote aggression would make it impossible for one animal to mistake the other’s intent if they came into conflict.

Carnivores may attempt to prey on Stegosaurus, as on Isla Sorna it shared overlapping territory with the island’s apex predator Tyrannosaurus rex. This large theropod is likely the only animal which would have threatened an adult Stegosaurus at the time, with powerful crushing jaws that could overcome the stegosaur’s bony armor. To defend itself, Stegosaurus brings its spiked tail into play, swinging it at high speeds and using the thagomizer to puncture skin, muscle, and even bone. A wound from these three-foot spikes can be devastating, and Stegosaurus strikes with reasonable accuracy and can pivot around on its front limbs while looking over its shoulder to aim. It does not necessarily try to kill its foes, rather intending to drive them back before fleeing. Living in herds is another defense against predators; not even a Tyrannosaurus would dare attack a whole herd of Stegosaurus on alert.

An adult seen in 1997 showed scarring on its flank consistent with Velociraptor attack, suggesting that these smaller carnivores may also come into conflict with Stegosaurus. It is more likely that they try to prey on the juveniles, and the adults fight them off. When fighting a smaller predator, Stegosaurus can still use its tail, but may opt to simply crush the offending animal under its multi-ton weight. It also shares territory with Pteranodon, which could be a threat to juveniles as it is known to prey on young dinosaurs. The fragile and lightweight body of Pteranodon compared to the might of an adult Stegosaurus means that this pterosaur would have to rely on its agility in the air to avoid being trampled or struck by a thagomizer.

Smaller dinosaurs may use the mass of Stegosaurus for protection. Some have been seen with bird droppings among their plates, suggesting that birds may sometimes roost there. This would be beneficial to both parties, since the birds are protected from predators, and may eat parasites such as ticks off of the stegosaur. Other small dinosaurs such as Compsognathus are known from stegosaur territories, but their relationship to the stegosaurs is largely not researched. The stegosaurs at least produce copious amounts of dung that the compies can eat, allowing them to obtain nutrients that they could not find in their own carnivorous diet. Compies also eat flies, including mosquitoes, which at least bit stegosaurs during prehistory; this is how InGen was able to obtain its DNA. It is not known whether modern mosquitoes can feed on stegosaur blood.

By 2001, the dinosaur population of Isla Sorna grew, and new species appeared. Stegosaurus came into more regular contact with other species, forcing this reclusive animal to interact with its neighbors more often. Along with the familiar Triceratops and Parasaurolophus, it was observed living alongside Corythosaurus, Brachiosaurus, and Ankylosaurus. New predators in its territories included Ceratosaurus and the huge semi-aquatic Spinosaurus, though neither of them have been confirmed attempting to prey on Stegosaurus.

DPG illustration featuring Stegosaurus as a part of an artificial ecosystem with other species of the Jurassic period. Also featured are Apatosaurus, Allosaurus, and Compsognathus.

The situation on Isla Nublar was similarly crowded, with Stegosaurus being integrated into habitats containing many familiar species. It also encountered at least three herbivores it is not known to have lived alongside on Isla Sorna: Edmontosaurus, Microceratus, and Apatosaurus. Eventually, this number grew to include upcoming new species such as Sinoceratops. For the most part, Jurassic World’s park rangers kept the peace between these varying dinosaur species, but Stegosaurus does not seem to have gotten particularly attached to its neighbors. For example, on December 21, 2015, a stegosaur in Herd M panicked during a thunderstorm and struck an Ankylosaurus with its thagomizer by accident, showing no signs of recognizing its mistake. The ankylosaur was uninjured thanks to its heavy armor, but this incident nonetheless increased tension in Herd M that eventually led to a stampede.

Once released into the wild, they also encountered Ouranosaurus, Stygimoloch, and Peloroplites. Their relationships with these other herbivores are not well understood. New carnivores, such as Allosaurus, Baryonyx, Carnotaurus, and Teratophoneus, also became a part of their ecosystem; those living near the Jungle River would have encountered more Baryonyx as well as the Suchomimus and Metriacanthosaurus. In the eastern and western regions, Stegosaurus was less common, but those venturing here would have encountered small populations of Monolophosaurus.

Stegosaurus near the Jungle River

Most of these carnivores do not seem to have bothered the herd-dwelling and impressively defensive Stegosaurus. Unlike many dinosaurs, whose populations decreased dramatically following the closure of Jurassic World, the Stegosaurus herds remained mostly consistent in size. However, no juveniles were seen any later than March 2016, suggesting that while the adults could defend themselves, they were failing to breed. No evidence for predation on adults has been confirmed; however, the carcass of a huge individual showed signs of scavenging from the many carnivores on Isla Nublar at the time.

Though it is mightily defended, Stegosaurus is susceptible to disease, which can be spread by small pests such as mosquitoes and ticks as discussed above. However, according to Jurassic World: Evolution, this animal is at least unaffected by the common cold.

Cultural Significance

This is easily one of the most famous and recognizable dinosaurs, making it highly marketable, and it appears in numerous museums, films, video games, and comics. Toys of Stegosaurus are quite common. The first-recorded paleoart of this dinosaur was an engraving by A. Tobin for the November 1884 Scientific American, but due to the fragmentary nature of early Stegosaurus discoveries, it was many years before informed reconstructions could really be made. The name of the stegosaur’s weaponized tail, the “thagomizer,” was coined in one of Gary Larson’s Far Side cartoons and has become popularized in the scientific community as well as among laypeople. It has not been accepted for professional use and so is technically only an informal term, but its meaning is almost universally recognized. Along with its visually stunning dorsal plates, the thagomizer makes Stegosaurus an exciting creature as it has a unique and powerful means of defending itself. It is frequently depicted fending off predators with this weapon.

Popular culture often depicts Stegosaurus as a sluggish and dimwitted creature, owing to both the small size of its brain and the historical assumption that dinosaurs were slow-moving ectothermic reptiles. In the modern day, dinosaurs are now known to be endothermic, more like their modern representatives the birds than their cousins the crocodiles. While it is understood as a more active and dynamic animal, Stegosaurus does indeed lack intellect and is not very speedy. Films and books will frequently describe it as the least intelligent dinosaur; while this superlative is up for debate, the reality is that one does not need to be smart if one can impale all of one’s problems with a swish of the tail.

Stegosaurus stenops has not been designated a state dinosaur or fossil of any U.S. state, but its close relative Stegosaurus armatus is the state fossil and dinosaur of Colorado.

This most dinosaurian of dinosaurs was used by the Dinosaur Protection Group to form their logo, with the letters “DPG” printed on the logo’s plates. Using Stegosaurus was meant to convey the idea of dinosaurs living peacefully, thanks to the popular depiction of this dinosaur as a friendly and placid creature. While this is a common misconception (it is only somewhat docile when in captivity), it served its symbolic purpose to the DPG.

According to Universal Studios, the Stegosaurus is the official dinosaur of the Gemini astrological sign (May 21 – June 20).

In Captivity

Although Stegosaurus was successfully bred by InGen by 1993 and was planned to appear in Jurassic Park, none were shipped by Isla Nublar before a series of incidents prevented the park from opening. Had it been a success, Stegosaurus would have been visible from both the main tour and the Jungle River Cruise. Already, this dinosaur was featured on merchandise for the park, which capitalized on the immense popularity of Stegosaurus. Some InGen documentation misspelled its name as “Stegasaurus.”

Due to its popularity, InGen selected it as one of several herbivorous dinosaur species meant to feature in the resurrected Jurassic Park: San Diego in 1997, which would have housed one adult male and one juvenile female. These plans were intentionally sabotaged, meaning that once again Stegosaurus failed to reach its intended park destination. It was finally put on display for the public in Jurassic World, with the Isla Sorna population being shipped to Isla Nublar as originally intended.

Tourists in Gyrosphere Valley encounter a juvenile Stegosaurus

While in the park, this dinosaur was housed in three locations: two were accessible to the public, the Gyrosphere attraction and the Cretaceous Cruise. A third group of Stegosaurus was kept in Sector 5’s Herd M, a research subject that benefited the overall park. Juveniles, bred in the Hammond Creation Lab, were kept in the Gentle Giants Petting Zoo until they were deemed old enough to live in the paddock areas. Genetic engineering yielded new versions of this animal, and they flourished on the island. By 2015, a new breed had been engineered by Dr. Henry Wu to exhibit bioluminescence by incorporating DNA from moon jellies. The CEO of Masrani Global Corporation, Simon Masrani, had drafted up plans to put bioluminescent dinosaurs on parade down Main Street during the night. These plans were ultimately scrapped due to the impracticality of organizing and cleaning up after this event, so the bioluminescent stegosaurs were housed in Sector 5 on their own and were never shown to the public.

This dinosaur is territorial and cantankerous, and when stressed can easily become a threat to humans. It is large enough to be dangerous when aggressive, but not so large that it can safely ignore human-sized animals; if it feels that its space is being invaded, or that its offspring are possibly under threat, it will attack to trample or impale the offending human. As with many territorial dinosaurs, it interprets a high-pitched whistle as a challenge and will also attack if whistled at. On the other hand, it differs from some dinosaurs (such as Brachiosaurus) in that it will ignore attempts by humans to mimic its own vocalizations. Whether this is because humans cannot sufficiently mimic its sounds, or because it is not intelligent enough to realize that the human is attempting to communicate, is not known. During Jurassic World’s ten years of operation, no major incidents with Stegosaurus were reported, suggesting that this simple-minded creature was one of the park’s more unproblematic inhabitants. This is likely due to the comforts of captivity; with their needs met and their offspring never threatened by predators, captive stegosaurs have lower stress levels and so are less likely to attack. This can lead to people believing the dinosaurs are friendly, but realistically, only professionals should handle such a large and powerful creature.

While they remained a popular attraction featured in numerous Jurassic World advertisements and merchandise, they did not quite reach the levels of stardom that Tyrannosaurus and Triceratops enjoyed. Still, they are the favorite dinosaur of many people, including the Hammond Foundation‘s Cabot Finch.


Paleontologists had not discovered extensive stegosaur remains before Stegosaurus; when fossils were first found, they were so fragmentary that its identity was unknown for some time. It was initially reconstructed as a long-necked bipedal animal bristling with spines, and the plates were thought to be shell-like armor. Later fossils demonstrated that it was a quadruped, and that the plates stood upright while there were only four spikes located on the end of the tail.

Excellent remains have made Stegosaurus one of the best dinosaurs for study. Its environment, physiology, ontogeny, and evolution are all thoroughly researched, though new information about lesser-known topics (such as, surprisingly, its dietary needs) is still being uncovered. At the moment there are three species confirmed to exist, each of which has distinct anatomical traits setting it apart from the others. This has led to fascinating hypotheses about how dinosaurs visually identified each other, and what other behaviors such species recognition features could have enabled.

In the Genetic Age, this was among the earlier de-extinct dinosaurs created by InGen during the 1980s and 1990s. While it was not yet ready for Jurassic Park at the time the Park was cancelled, it was repeatedly selected for attempts at continuing the project until Jurassic World opened in 2005. It has been used more for genetic research than paleontological study, though: in order to bring it back to life, InGen scientists needed to splice genes into sections of its genome that had decayed with time to create viable specimens for cloning. This means that InGen Stegosaurus are noticeably different than their ancient ancestors. Some of these features may have been selected on purpose for either tourism appeal or management purposes, such as its greatly enhanced size and molariform teeth. Some of the stegosaurs were modified to exhibit blue-violet bioluminescence, which was a cosmetic alteration meant to enhance them for planned nighttime shows. This dinosaur has been researched by InGen in the years since it was first cloned, and in more recent years has been used as a research subject by former Mantah Corp biologist Dr. Mae Turner. She used it as a starting point to study the behavior and neurology of other stegosaurs, such as her personal project Kentrosaurus.

Genetic modification with such precision required that InGen had sequenced at least most of this asset’s genome. Having all of its genetic data available has also enabled Stegosaurus to partake in one of Dr. Henry Wu‘s most advanced and controversial fields of study, the science of artificial hybridogenesis. In the wild, different species may sometimes hybridize and give rise to new forms of life, though they more often produce weaker offspring. Using highly advanced genetic engineering techniques, Dr. Wu was able to intentionally accelerate this process by combining select compatible genes from differing sources. Stegosaurus in particular became the template for the hybrid genus Stegoceratops. Today, it continues to yield new scientific information in the form of biopharmaceuticals to researchers in Biosyn Genetics Sanctuary.


Jurassic World closed its doors in late 2015 due to a highly-publicized security incident. These animals came under threat from volcanic activity during 2017 and 2018, with a cataclysmic eruption on June 23 causing the localized extinction of most of Isla Nublar’s wildlife (both modern and de-extinct). Throughout the preceding months, the Dinosaur Protection Group lobbied to have the dinosaurs including Stegosaurus rescued, and frequently used images of this animal to further the cause. This species’s easily recognizable profile and popularity with children was surely one of the reasons it so often appeared in their material.

Stegosaurus infographic used by the Dinosaur Protection Group

While both government and corporate entities rejected the proposed rescue mission to Isla Nublar, the operation was financed and carried out illegally by the Lockwood Foundation. Several adult stegosaurs were removed from the island after being captured by head mercenary hunter Ken Wheatley, who was employed by the Foundation’s manager Eli Mills. Wheatley notably took a tooth from one of the last stegosaurs as a trophy, though he viewed his quarry with a kind of malicious glee and delighted in causing it to suffer. The whole operation was in fact corrupt, and the animals were taken to the Lockwood estate to be sold on the black market. One Stegosaurus was sold at around the halfway point, selling to bidder #187 for US $17,000,000. During the night, the others were threatened by a hydrogen cyanide gas leak and were released into the wild by Maisie Lockwood to save their lives. The location and status of the sold individual is unknown.

Since their release into the wild, Stegosaurus have been involved in a few incidents with human interaction. In the days following the incident at the Lockwood estate, park rangers in a nearby area followed a Stegosaurus which eventually turned to chase them away. On May 10, 2019, people were watching a Stegosaurus wandering along the North Cascades Highway when a 2015 Subaru Forester WRX emerged from a tunnel at high speed. The stegosaur, already stressed from being crowded by the humans and separated from its own kind, swung its tail as the vehicle swerved to avoid it, causing the vehicle to fall over the edge of a cliff. An escaped stegosaur in Maine woodlands in 2022 was involved with a more minor incident in which a mountain biker unexpectedly came across it and veered off-trail, though the biker did not sustain any major injuries.


Even before it was brought back from extinction, Stegosaurus has always had the power to draw crowds from the first time it was reconstructed. Museums have mounted fossils and built models of this dinosaur to educate and entertain visitors for over a hundred years, and the de-extinction of Stegosaurus meant that live versions of the animal going on display was an inevitability. While efforts to house them in Jurassic Park never came to fruition, the Park’s successor Jurassic World had success with exhibiting them to the world. People traveled the world to see these creatures, which seem to have taken well to captivity. They were among the park’s greater successes, even if they were outclassed by yet more famous dinosaurs.

Being genetically far-removed from living archosaurs, Stegosaurus has biochemistry and physiology that endow it with unique biopharmaceutical properties. Its genetic modifications may have generated wholly novel properties that the original animal did not possess. Substantial research into its immune system and other traits were performed by Biosyn Genetics between 2018 and 2022, though research slowed due to the company incurring severe legal penalties and political setbacks in 2022 (none of these crimes directly concerned or involved Stegosaurus).

Considered a valuable creature, Stegosaurus is often the target of people with far less ethical aims. The animal was being tested by Mantah Corp under the direction of Kash Langford; the facility at which it was held would eventually have been converted into an entertainment venue for the extremely wealthy and highly discerning to watch dinosaurs fight to the death. Several Stegosaurus were captured in June 2018 for sale on the black market by hunter Ken Wheatley, who was working under orders of the Lockwood Foundation’s Eli Mills. The sales were meant to fund Henry Wu’s continued research. He had already used Stegosaurus for other genetics research projects, chiefly involving gene splicing. This time, the Stegosaurus were going to serve him only as a source of money. One Stegosaurus sold to currently-unknown buyers for seventeen million dollars; its buyers’ motives are as unknown as their identity. A case of DNA samples including one from Stegosaurus was sold to a Russian buyer, most likely notorious gangster Anton Orlov. Along with its use as a status symbol or a source of exotic animal byproducts, some criminals may primarily value Stegosaurus for its combat abilities, as it is a durable and well-defended creature that can exact heavy damage with its thagomizer. The tail is powerful and can strike with extreme accuracy and precision, making it a lethal implement.


Stegosaurus were popularized in Jurassic World as friendly and docile herbivores, giving the false impression that they are safe to be around. Once they are out in the wild, their survival instincts kick in almost immediately and they will become territorial, liable to lash out if they feel threatened. Some herbivorous dinosaurs are non-aggressive toward humans because they are so large that we cannot pose a threat to them. Stegosaurus is not one of these dinosaurs. It may be attacked by medium-sized carnivores not much bigger than a human, so when it sees you, it sees a potential hazard.

To avoid being impaled and dying an immensely painful death, keep a safe distance from any Stegosaurus you encounter. At a minimum, you should be farther away than its tail can reach, but ideally you should be as far away from it as you can get. While most people can run faster than a Stegosaurus, you may find yourself in an unexpected scenario where escape is difficult, especially in densely forested areas where this dinosaur likes to live. Be especially wary if there are herds, and do not approach juveniles no matter how much you feel compelled to pet them. The adults are extremely defensive of all their herd’s offspring and will react immediately if any juveniles become distressed. Should an adult charge you, dive out of its way and flatten yourself on the ground: if it does not trample you it will bring its spiked tail into play, swishing it horizontally at your body height. Dodging the charge and initial tail swipe does not guarantee you survival either. If you duck beneath its tail, it may twist it to the side to try and strike you from above; the spikes are more maneuverable than they appear. Never look away from the tail, and try to predict where it is going to strike from. Roll away, conceal yourself, and do not emerge from hiding until the dinosaurs lose interest and leave. They will stop the attack if they believe you are no longer a threat.

You can practice safety to keep such dangerous encounters from happening in the first place. Wild Stegosaurus are much more easily agitated than their captive counterparts, but even “tame” Stegosaurus will go feral quickly. Assume none are safe, no matter how acclimated to human contact they may seem. Their behavior can change at a moment’s notice. Among the most common mistakes people make around these dinosaurs include sudden movements or noises that can startle the animals. Keep in mind that they are not very bright, and anything even slightly unexpected might be construed as a threat. Stay out of sight if you hear one coming, but if you cannot stay hidden, ensure it knows you are there before it gets too close. Whistling seems to be a very consistent agitator; nearly all Stegosaurus will become aggressive if they are whistled at. However, a loud and shrill sound such as a whistle, air horn, or car horn can also surprise a charging stegosaur and give it pause; some may even withdraw. If you have accidentally aggravated a stegosaur with noise, you may be able to resolve the situation the same way, essentially proclaiming that you are not intimidated and that the animal should consider backing down. In most cases you certainly will be intimidated, but Stegosaurus is not very smart and does not know this.

The simplest but most effective safety measure is simply to give them space. Observe them from a distance, preferably in a vehicle (with the engine idling, ready to move at a moment’s notice). Do not crowd them, especially if you see one alone. Being separated from its own kind may be stressing it out already, and if you contribute to that problem you can make a bad situation worse. Instead, report lone wandering stegosaurs to the Department of Prehistoric Wildlife or your governmental experts, so that they may be relocated to the nearest herd and away from inhabited areas.

Behind the Scenes

Originally, Stegosaurus was planned to appear in the film Jurassic Park like its novel counterpart, but this role was eventually given to Triceratops instead. After numerous fan requests, Steven Spielberg agreed to include Stegosaurus in the sequel, The Lost World: Jurassic Park, where it played a notable role. This is in contrast to the novel, which features only a single Stegosaurus for a brief scene. A regular favorite, Stegosaurus has gone on to appear in virtually all Jurassic media since 1997.

The animal was redesigned for Jurassic World, which upset fans as the new design was given a drooping tail which is able to touch the ground when it swings low. This was in contrast to the upright posture of the original design. The precise reason for this was not given by filmmakers, but is often presumed to be out of nostalgia for earlier dinosaur reconstructions. In Jurassic World: Fallen Kingdom, the stegosaurs were designed without beaks, which was more likely a production oversight than a deliberate choice. However, their tails were modified from the 2015 models.

Notable Individuals

Claire – female seen as a juvenile in 1997

Disambiguation Links

Stegosaurus stenops “gigas” (S/F-Ride)

Stegosaurus stenops (JN)

Stegosaurus stenops (C/N)

Stegosaurus stenops (T/C)

Stegosaurus stenops (L/M)

Stegosaurus stenops(?) (CB-Topps)