Tyrannosaurus rex (S/F) / (S/F-T/G) / (S/F-S)

Tyrannosaurus is a genus of very large theropod dinosaur that lived in the Late-Cretaceous Period about 68 to 65.5 million years ago. Tyrannosaurus rex represents perhaps the most well-known group of dinosaurs, the tyrannosaurids. There is only one recognized species; its scientific name means “tyrant reptile king.” This theropod was widespread across North America, with known fossil sites including the Hell Creek Formation (Montana, South Dakota, and North Dakota), the Livingston Formation, Ferris Formation, and Lance Formation (all in Wyoming), the Laramie Formation and Denver Formation (both in Colorado), the Javelina Formation (Texas), the McRae Formation (New Mexico), and North Horn Formation (Utah), all in the United States, as well as the Scolland Formation (Alberta) and Frenchman Formation (Saskatchewan), both in Canada. T. rex was the apex predator of its environment. It mainly hunted ceratopsians and hadrosaurs. Evidence of predation include part of the caudal vertebrae (tail bones) of an Edmontosaurus being bitten off and healed, as well as Triceratops horns being broken off and healed.

The earliest finds now attributed to Tyrannosaurus were isolated teeth found by geologist Arthur Lakes near Golden, Colorado in 1874. Paleontologist John Bell Hatcher discovered some postcranial remains during the 1890s, and in 1892, Edward Drinker Cope of Bone Wars fame found vertebrae belonging to it. However, he initially thought they belonged to a ceratopsid dinosaur, which he named Manospondylus gigas. Hatcher realized in 1907 that they actually were theropod remains.

The first partial skeleton confirmed to be T. rex was found in 1900 by Barnum Brown, the assistant curator of the American Museum of Natural History. Two years later, he found more remains (including thirty-seven bones) in Montana’s Hell Creek Formation. It was this second skeleton which was ultimately named Tyrannosaurus rex by the president of the AMNH, Henry Fairfield Osborn, in 1905. The first skeleton was named Dynamosaurus imperiosus, but a year later, Osborn corrected himself and determined that both skeletons belonged to Tyrannosaurus. At the time, no theropods of comparable size were known from the Cretaceous of North America.

Paleontological interest in Tyrannosaurus was high during the 1960s, leading to over forty skeletons being recovered from sites in western North America. Interest was sustained for decades; a large number of tyrannosaur remains were found during the 1990s, including the two most complete skeletons found so far. The most famous was discovered by amateur paleontologist Sue Hendrickson in 1990, and nicknamed “Sue” in honor of its discoverer. Naming particularly complete T. rex fossils has become something of a tradition since. An abundance of fossils have been found of this species, including good examples of juveniles and subadults.

In 1988, InGen first succeeded in cloning Tyrannosaurus rex. While at least seven were originally cloned and a few bred in the wild, most of the attention was devoted to the individual shipped to Isla Nublar for Jurassic Park in the 1990s. Ultimately, this specimen would end up having the longest confirmed lifespan of any of InGen’s animals. As of June 11, 1993, InGen had created only Version 1.0 of this animal.

Exploitation and poor management has led to this apex predator reaching the brink of extinction; after Jurassic World was closed down in December of 2015, only one living specimen was confirmed.

Description

The largest-known of the tyrannosaurs, Tyrannosaurus rex was also the third-largest theropod cloned by InGen (slightly smaller than Spinosaurus, and significantly smaller than the projected adult size for the artificially-created Indominus rex). This animal grows to 12.3 to 13 meters (40 to 42 feet) long, 3.5 meters (12.5 feet) tall at the hip, 5.2 meters (17 feet) tall at the head, and weighs between seven and twelve tons as an adult. A single exceptional female has been reported at up to 13.5 meters (44.3 feet) in length, exceeding known dimensions of fossil specimens.

Much of its bulk consists of its massive head, with gaping jaws that can open at an eighty-degree angle and clamp down with a bite force of up to 34,500 Newtons. The fifty-eight teeth are equally huge, reaching seven inches in length and featuring jagged serrations on the inner edge. The tooth tip is designed to puncture, not tear, and the serrations allow bacteria to flourish within its jaws. Lost teeth are replaced throughout its life. Its tongue is extremely muscular and, unlike what is known from the fossil record, highly dexterous. It is long and triangular, capable of extending outside of the mouth, which the tyrannosaur may use to try and extract prey from tight spaces. Above the eyes, it possesses bony protrusions; the male also has a bumpy keratinous growth on the snout.

Eye of a female T. rex reacting to light

The eyes are large, with yellow sclerae and round black pupils. Within each eye is a tapetum lucidum, most likely a retinal tapetum located within the retinal pigment epithelium similar to crocodiles. This layer of tissue reflects visible light back through the retina, giving the tyrannosaur superior night vision. The Tyrannosaurus has stereoscopic binocular vision, but is incapable of differentiating between stationary objects and a stationary background. This was in line with paleontological theory as of 1993 (though no such theories have ever existed in real life), but Dr. Laura Sorkin hypothesized that this disability was actually the result of DNA from frogs used to replace decayed segments of Tyrannosaurus genome by Dr. Henry Wu. Whatever the cause, the animal can still detect nearby animals using its excellent sense of smell; according to Drs. Sarah Harding and Robert Burke, the olfactory cavities of the Tyrannosaurus are surpassed in size only by those of the turkey vulture (Cathartes aura), and the tyrannosaur’s sense of smell covers an area with a radius of ten miles. It also has excellent hearing, demonstrated by a mated pair on Isla Sorna which were able to hear the sounds of their wailing infant from several miles away despite the sound of an approaching storm. It also has excellent hearing, according to the Jurassic World Facts mobile application; it is able to hear low-frequency sounds. However, it is most sensitive to smells and movement.

Typical footprint of a Tyrannosaurus rex. (Image from the Dinosaur Protection Group)

In addition to immensely powerful jaws, the limbs of Tyrannosaurus are very muscular. Its massive legs allow it to run at a maximum speed of 32 miles per hour, though only for short bursts; it typically runs at a slower speed, estimated at slightly under 25 miles per hour according to the InGen IntraNet website. The feet have four toes, three of which end in a large hooked talon each (the remaining toe is a dewclaw). These give it traction, enabling it to run efficiently on both soil and vegetation; its toes can also spread apart to prevent it from sinking in mud. The arms are very small, a compensation for its enormous head. Despite this, the overall massive size of the Tyrannosaurus means that its proportionally weak arms can still lift up to five hundred pounds. The hands have two fingers each, which terminate in sharp claws. As with all InGen’s theropods, the hands are pronated, which is a phenotypic error not present in fossil specimens.

The tail is lengthy, which helps counterbalance the head. It lacks any distinguishing features and is mostly used for balance while running. While it is somewhat more flexible than those of fossil specimens, it is not suitable for use in combat. It may knock aside smaller animals, but only by accident, as the tail cannot flex far enough for the tyrannosaur to see what it is doing with it.

Sample of T. rex urine in a laboratory flask. The light yellow color suggests good hydration.

 

Coloration consists of earthy tones, usually with some striping on the snout. The male and female have very different coloration, but both are suited for camouflage in a forest environment. It has thick, scaly skin, with even the infant lacking feathers. An adult described in the Jurassic Park Adventures junior novel Survivor appears gray in color with red splotches.

Unlike modern birds, the Tyrannosaurus secretes liquid urine which appears pale yellow in color.

Growth
Young male T. rex. Note the lighter green coloration in comparison to a fully mature adult, Isla Sorna (6/18/2001)

InGen records of hatchling Tyrannosaurus rex are sparse, but the mural in the Workers’ Village Operation Center depicts one hatching from an egg. It is depicted having a narrower snout, thinner body, and proportionally larger head than the later stages; its coloration is depicted as gray-green. In the opening logo sequence of Jurassic World: Evolution, a hatchling female T. rex is depicted as a brown color similar to the adult female.

The juvenile and young adult stages of the male have been observed, but only the adult and senescent stages of the female have been observed. Infants appear to grow much more quickly than fossil evidence would indicate, likely due to genetic manipulation; a supposedly months-old infant in 1997 was observed at a noticeably larger size than it would have been had it grown at a natural rate. This infant male could be seen to have a proportionally shorter snout, but already had the prominent brows and raised snout of the adult. Its coloration was a mixture of green and brown, ideal for camouflaging in a forest environment, with darker striping on its back.

According to the Jurassic World Facts application, juveniles have more narrow, pointed teeth than adults do; the application claims that adults have thicker and more rounded teeth.

Demonstration of senescence in a female T. rex. Upper image is a 5-year-old under the influence of growth-enhancing substances and a lifetime in captivity (6/12/1993); lower image is the same animal at age 27 after thirteen years in captivity (12/23/2015).

The subadult male seen in 2001 was proportionally much like the adult animal, but the coloration was noticeably a brighter shade of green. This shift from camouflaging green-and-brown to a vibrant green to the final coloration of dark green with yellow striping indicates that, despite their visual disabilities, InGen’s Tyrannosaurus do have excellent color vision and use bodily coloration as a form of signalling health and maturity.

In females, only the adult and senescent stages have been demonstrated. The senescent female is generally thinner than the mature adult, with tighter skin and paler coloration. In particular, the stripes of the female appear to fade with senescence. Otherwise, both of these growth stages appear rather similar. Many paleontologists believe the lifespan for a Tyrannosaurus rex in the wild to be between twenty and thirty years, but when in captivity and provided with medical care, they can live longer; their lifespan in captivity is currently unknown. An individual hatched in 1988 was still visibly healthy in 2018, thirty years later, and showed few signs of aging other than being thinner and paler.

Sexual Dimorphism
Female (left) and male (right) T. rex adults. In the lower center is a juvenile male.

The most straightforward way to tell the difference between a male and female Tyrannosaurus is by bodily coloration. Females appear an earthy brown color, though they may have brown or gray striping on the back as well as the snout. Males, on the other hand, are green in color; in the subadult stage, they are a more vibrant shade, but become darker with maturity. Like the female, the male has striping on the back and snout, but it appears dark green in the subadult and pale yellow in the mature adult.

In addition, the male can be told apart by its skull ornamentation. The male’s brows are more prominent than those of the female, and the snout is adorned with a rugged keratinous growth. On the neck, the male can be seen to have a throat wattle. In males, scarring on the face is common, as are broken and missing teeth; this indicates a greater degree of combative behavior in males, though it is not known whether this is interspecific (conflict with other species) or intraspecific (conflict with others of the same species). Production personnel of The Lost World have suggested that the scars did come from intraspecific combat, particularly clashes for mating rights, but this has not been confirmed within the film itself. Both the adult male seen in 1997 and the subadult male seen in 2001 could be seen to have scarring on the right side of the muzzle.

Males typically use deeper vocalizations than females, but females are not incapable of making these same sounds. Females appear able to attain a larger size.

Habitat
Preferred Habitat
Tyrannosaurus rex hunting two Gallimimus bullatus on Isla Nublar. Image from the Dinosaur Protection Group.

In nearly every case, Tyrannosaurus rex favors the edges of forests as its habitat. This permits it to hide its bulk among plant growth, where its coloration helps it camouflage. From here it hunts via ambush. Nesting and feeding both occur in forested areas; it will typically drag prey to a suitable area to eat. However, it is quite comfortable in the open; it is a very exploratory animal by nature, and often ventures into habitats that are not its typical hunting ground. However, it nearly always hunts from the cover of forested regions. Population estimates in 2021 calculated that two adult Tyrannosaurus could inhabit an area roughly the size of Washington, D.C. in their native Cretaceous period.

In the game Jurassic World: Evolution, the Tyrannosaurus requires 21,100 square meters of grassland and 5,200 square meters of forest in its habitat to be comfortable.

Isla Nublar

InGen constructed a paddock for Tyrannosaurus rex on Isla Nublar in a heavily-forested area. Despite being one of Jurassic Park‘s largest paddocks, it was intended to house one adult and one juvenile animal only; the second animal did not reach the island before the incident occurred. In 1989, a one-year-old female Tyrannosaurus was introduced to the paddock, where she would remain for the next four years of her life.

Paddock range (red) of T. rex on Isla Nublar (prior to June 11, 1993)

On June 11, 1993, Jurassic Park’s power grid was sabotaged by a disgruntled employee, permitting the island’s only Tyrannosaurus to breach containment. The animal established new territory first in a westward direction, then northward. The 1994 survey carried out by InGen personnel reported on October 5 that the tyrannosaur had claimed the entire island as territory.

Known (red) and hypothetical (purple) range of T. rex on Isla Nublar on and after June 11, 1993 and before April 19, 2002

Under Masrani Global Corporation, InGen reclaimed Isla Nublar in 2002. On April 19, Week 3 of the operation, the tyrannosaur was recaptured by Vic Hoskins and InGen Security personnel. As of September 2004, she was held in Paddock 9, located some miles northeast of Main Street due to concerns that tourist activity would be overstimulating. By 2014, Paddock 9 had been relocated to just west of Main Street, where she was exhibited in an attraction called T. rex Kingdom.

In addition, any surviving Tyrannosaurus from Isla Sorna were collected by InGen and transported to Isla Nublar between September 2004 and the park’s May 30, 2005 opening date. Like the other carnivores, it is likely that they would have been kept in the quarantine paddock, separate from each other, for a period of a few weeks each before being integrated into their habitat.

The exact location of this habitat is not known, but they were not held in Paddock 9 with the elder female from the old park. The Jurassic World website’s IMAX Theater page describes subadult male tyrannosaurs living in a nearby paddock, suggesting that at least two subadult males were present on the island in 2014 when the website went live. DNA belonging to Tyrannosaurus was in stock in the Hammond Creation Laboratory, where dinosaurs would be hatched; the Jurassic World website implies that Tyrannosaurus were actively being hatched during the park’s operational years. If any survived infancy, it is most likely that they would have been placed in the separate paddock located somewhere near the IMAX Theater. The non-canon animated short film Jurassic World: The Secret Exhibit and subsequent miniseries Legend of Isla Nublar depict multiple adult tyrannosaurs living in fenced paddocks near the Gondola Lift and Gyrosphere attractions as of summer 2012, but based on the depictions in the film canon proper, it is unlikely that such a paddock existed.

One tyrannosaur may have recently died as of December 20, 2015, since what appeared to be a fresh Tyrannosaurus eyeball was seen being studied in Dr. Henry Wu‘s field genetics laboratory on that date.

On December 22, 2015, Jurassic World technician Lowery Cruthers opened the Paddock 9 maintenance gates, permitting the park’s Senior Assets Manager Claire Dearing to lure the now-senescent female out of her paddock. After driving the escaped Indominus rex to its death in the Jurassic World Lagoon, the tyrannosaur made its way eastward to the forest. The island was abandoned by Masrani Global due to the incident, leaving the Tyrannosaurus to claim Sector 3 as territory. She built a nest within her old paddock, but hunted in the surrounding areas. As of June 2016, she was still inhabiting Sector 3, being sighted on Main Street. The remaining tyrannosaurs, having never been released, likely starved to death.

According to books released in promotion of Jurassic World: Fallen Kingdom, only the one female remained alive on the island in 2018. Despite competition for food and territory with numerous other large carnivores, the animal had survived up until the June 23 eruption of Mount Sibo; she was found to have migrated north, toward the volcano along with her food sources. During the eruption, she was driven toward Jurassic World’s East Dock, where she was captured by mercenaries employed by Eli Mills under the direction of Ken Wheatley. From here, she was removed from Isla Nublar by means of the S. S. Arcadia.

Isla Sorna
Dr. Robert Burke identifies fresh Tyrannosaurus rex tracks near a game trail

The first Tyrannosaurus rex was hatched on Isla Sorna in 1988 and shipped to Isla Nublar in 1989. As of InGen’s last population survey reported in 1993, there were six Tyrannosaurus rex living on Isla Sorna, meaning that a total of seven between both islands had survived up until that point. They were maintained together in a small paddock.

John Hammond continued to monitor populations on Isla Sorna for the next four years. Tyrannosaur populations appeared concentrated in the island interior, near the central channel, based on thermal readings in early 1997. That year, fresh Tyrannosaurus tracks were found at Isla Sorna’s northeastern game trail, confirming that tyrannosaurs were hunting there. A nest with a single infant male, estimated by Roland Tembo to be a few months old, was located in the forest several miles south of the game trail. Its mother and father hunted in the surrounding area.

Known (red) and hypothetical (purple) range of T. rex on Isla Sorna. Known range is prior to events in 1997; hypothetical range is extrapolated from 2001 and later.

The 1997 Isla Sorna incident altered the perceived territory of the tyrannosaur family involved, resulting in them no longer considering their nesting area safe. They first began defending the northeastern cliffs in a territorial manner after their infant was brought there, but then tracked the InGen “Hunter” team inland toward the Workers’ Village. Following the incident, the family remained a few miles north of this area, being sighted in the northern-central part of the island.

Known (red) and hypothetical (purple) range of T. rex on Isla Sorna as of 1997. Hypothetical range is extrapolated from 2001 and later.

While their film-canon status has been left ambiguous apart from Survivor, the Jurassic Park Adventures junior novels have described several additional tyrannosaurs on Isla Sorna. Eric Kirby encountered an adult with gray skin and red markings on May 23, 2001 on the western coast of the island; he later encountered a female in sickly condition at some point in June somewhere south of the tanker truck that he would eventually inhabit. This individual was possibly killed by a large Velociraptor pride. Finally, later in June, he witnessed one animal at a location south of the tanker truck; this is likely the same one that would be encountered the following month by the group attempting to rescue Eric.

A male tyrannosaur was encountered north of the airfield on Site B on July 18, 2001. It was subsequently killed during a territorial dispute with a Spinosaurus. There has been some speculation that this was the same male encountered in 1997 due to near-identical facial scarring, but this is highly unlikely due to this male’s vibrant coloration and slightly smaller size. It has also been speculated that this was the same animal as the juvenile encountered in 1997, but this has not been officially confirmed.

In further Jurassic Park Adventures junior novels (which, again, have ambiguous canon status), a green theropod is partially seen on the western island. As subadult Tyrannosaurus are the only large theropods confirmed to have this particular shade of body coloration, this presumably was a subadult tyrannosaur. Later, a Tyrannosaurus is encountered in that same area, possibly the same individual.

With these sources combined, all six Tyrannosaurus initially known on Isla Sorna are accounted for:

  • Adult male encountered in 1997
  • Adult female encountered in 1997
  • Gray, red-spotted individual encountered in 2001
  • Adult female encountered in 2001; possibly deceased in June
  • Young male encountered in 2001; deceased in July
  • Subadult male encountered in 2002

Additionally, a seventh adult female would have been transported away to Isla Nublar in 1989, and a male was hatched in early 1997. It is not known if any others were bred on the island following its abandonment. A model of Pteranodon longiceps hippocratesii made for Jurassic Park /// features the fresh carcass of a young male Tyrannosaurus in approximately the same growth stage as the young male encountered in 1997, but there is no evidence of any other breeding on Isla Sorna at that time other than this out-of-film model.

Known (red) and hypothetical (purple) range of T. rex on Isla Sorna following interference by InGen under Masrani Global Corporation during 1998-1999. Known range is as of June 18, 2001; hypothetical range is extrapolated from 1997 and dates following 2001.

In 2004, Isla Sorna suffered an ecological catastrophe as a result of its burgeoning population; this had been hastened by the interference of Masrani Global Corporation, which illegally bred animals on the island between 1998 and 1999. Any surviving Tyrannosaurus would have been collected and transported to Isla Nublar in 2004, where they remained.

Other

This was the first dinosaur to have its global population estimates calculated by scientists. In 2021, a team led by Charles Marshall estimated that there would be about 20,000 adult Tyrannosaurus alive at any one time, with computer estimates ranging between a minimum of 1,300 and a maximum of 328,000. Marshall’s team calculated that about 127,000 generations of Tyrannosaurus existed from the time it evolved until it went extinct, giving a grand total of 2.5 billion Tyrannosaurus rex having ever walked the Earth.

In 1997, an adult and juvenile male were transported to San Diego, California by InGen under the direction of Peter Ludlow. The juvenile was brought by airplane to the Jurassic Park: San Diego construction site, while the adult was transported to the InGen waterfront complex via the S. S. Venture 5888 after being airlifted out of central Isla Sorna just north of the Workers’ Village. The male was unintentionally overdosed on naltrexone after having already overdosed on carfentanyl, and broke free of confinement; he was then confined within the ship’s cargo hold until it collided with the dock at the waterfront. InGen personnel then unknowingly released him from the ship, allowing him to roam the city streets in a confused state. He was lured back to the ship by Drs. Ian Malcolm and Sarah Harding, using the infant’s distress calls to draw him into the cargo hold. From here, both males were transported back to Isla Sorna.

It is possible, but unconfirmed, that hatchling or juvenile Tyrannosaurus may have been poached from either the Muertes Archipelago or Isla Nublar between 1997 and 2015. However, the species which were affected by poaching are currently unknown.

T. rex would reach California again on June 24, 2018, this time at the behest of Eli Mills. The sole surviving Tyrannosaurus was transported via the S.S. Arcadia to Benjamin Lockwood‘s estate just outside of Orick, California. She was released that night by Maisie Lockwood and ventured away into the forest. She was last seen breaking into a zoo in the northern part of the state, engaging in a territorial display with a pride of lions. Despite authorities’ attempts to recapture her, she fled into the nearby pine forest.

Behavior and Ecology
Activity Patterns

While the Tyrannosaurus is primarily active during the daytime, it may become active at any time, meaning it is cathermal. During the 1993 incident, the tyrannosaur engaged in exploratory and playful behavior at dusk and shortly after sunset, and engaged in hunting behavior shortly after. It also engaged in hunting behavior throughout the following day: it had a meal late in the morning, but fed again around midday; a third time, it attempted to hunt in the evening. It was again spotted hunting at dusk that day. During the third day of the incident, it hunted at dawn.

During the 1997 incident, the tyrannosaurs’ behavior was drastically impacted by human interference and thus data may be unreliable. They were seen acting primarily at night, engaging in territorial behavior against the invading human presence. The infant, however, was seen feeding during the day. After being released back into the wild, the tyrannosaur family was observed to be active during the daytime, engaging in social behavior.

In 2001, observed tyrannosaur activity was mostly diurnal. The junior novels describe one tyrannosaur engaging in territorial patrolling activity during the day, with another eventually being observed hunting at dusk. Another, in a later book, appears hunting at dawn. During the 2001 incident, a subadult male was seen feeding and resting during the daytime.

Tyrannosaur behavior was also heavily modified by humans in Jurassic World, where T. rex Kingdom featured a feeding show every two hours. The earliest show was at 8:00 AM, when the park opened for the day; this would mean feeding occurred until 10:00 PM, when the park closed. In all, the Tyrannosaurus was fed seven times each day. This individual was apparently awake and alert late at night on December 22, 2015, and also early in the morning the following day; on both occasions, it was establishing territory. Further territorial and hunting behavior was observed in the early afternoon during the eruption of Mount Sibo on June 23, 2018; the animal was also active late that night due to human interference and then the following morning, where she exhibited exploratory and territorial behaviors. Later, after escaping confinement, she engaged in more territorial behavior in the morning.

Diet and Feeding Behavior
Artwork by DPG personnel of a Tyrannosaurus ambushing a herd of Parasaurolophus and Gallimimus. Several Compsognathus are present fleeing the resultant stampede.

The Tyrannosaurus is an opportunistic generalist carnivore: it is not a matter of what it will eat so much as what it can fit in its mouth. While wild on Isla Nublar, the individual there was known to primarily prey on Parasaurolophus and Gallimimus, also feeding on the goats that were left on the island. It was also seen to prey on Triceratops, Velociraptor, and at least one human. On Isla Sorna, there is further evidence of Parasaurolophus predation; in addition, Edmontosaurus remains can be seen in the tyrannosaur nest, as well as what appear to be Pachycephalosaurus remains. Edmontosaurus in particular is said to be its favored prey in Jurassic Park: Operation Genesis. The tyrannosaurs on Isla Sorna did also prey on humans, but this was mostly out of retaliation and defense of their territory. An adult male released into San Diego by accident preyed on a domestic dog and at least one human before using another human to teach his son how to hunt. The original script and junior novelization of Jurassic Park /// describe a tyrannosaur feeding from a small sauropod carcass, and the original storyboards explicitly label the carcass as tyrannosaur kill. This implies that Tyrannosaurus can take down small sauropods, though InGen reports from October 5, 1994 describe the tyrannosaur of Isla Nublar as failing to kill adult Brachiosaurus. The Jurassic Park Adventures junior novels describe Tyrannosaurus attempting to prey on Triceratops, exhibiting aggressive behavior toward a Brachiosaurus, and attempting to prey on Pteranodons.

Tyrannosaurus rex swallowing a goat by tilting its head upward, Isla Nublar (6/11/1993)

InGen’s Tyrannosaurus are unable to distinguish stationary objects from a stationary background, meaning they can only perceive objects that are moving. This may be due to genetic hybridization with amphibians, according to Dr. Laura Sorkin. However, the extraordinary sense of smell of this animal gives it an easy advantage when hunting; a prey animal may freeze as a defense mechanism, but it cannot stop exhibiting its natural scent when surprised. Thus, a tyrannosaur can still track prey very easily. Furthermore, some tyrannosaurs have developed another technique to spot prey; if unable to detect nearby animals by scent, for example if another more overpowering smell is nearby, the tyrannosaur can give a deafening roar to startle prey into movement.

Both Jurassic Park and Jurassic World fed their tyrannosaur a steady diet of live goats. In both cases, the goats were left tethered and unable to escape; this deprived the tyrannosaur of the stimulation provided by active hunting. This was criticized by Dr. Alan Grant during his 1993 visit to Isla Nublar. In Jurassic World, there would be seven feedings per day, alternating between one whole live goat and large pieces of prepared meat. Like the Mosasaurus, it is highly likely that the animal sometimes refused food if it had already eaten more than it needed. According to the Jurassic World website, a Tyrannosaurus consumes roughly 22 tons of meat per year; more recent sources state that it eats 308 pounds of meat daily, which is closer to 56 tons per year. This may explain the underfed appearance of the tyrannosaur in Jurassic World as of 2015.

According to InGen lead herbivore trainer Bertie (c. 2004), many dinosaurs have a preference for certain foods. The elder female tyrannosaur on Isla Nublar, for example, prefers goats over any other type of food. Periodically, instead of live food, the tyrannosaur would be fed prepared meat enhanced with amino acids and other nutrients to ensure it remained healthy.

Due to its immense dietary needs, the Tyrannosaurus must feed from a variety of food sources, and therefore must utilize multiple strategies to obtain food. When hunting, it primarily relies on ambush techniques. Despite its massive bulk, it is well-camouflaged against the forested environments where it normally conceals itself. When prey ventures close, it lunges out, typically engaging in a brief pursuit before delivering a crushing bite with its jaws. It can shatter bone when it clamps down, causing debilitating internal injuries and often killing its prey within seconds. The Jurassic World Facts application claims that juvenile Tyrannosaurus hunt by pursuit rather than simple ambush, as the adults have difficulty turning at high speed; it also states that there is evidence that Tyrannosaurus engage in cooperative hunting.

Game trails such as the one in Isla Sorna’s northeast are typical hunting grounds for this animal. From here, it can position itself in a prime spot to ambush prey, dashing out from the treeline before its victims can react. However, it may also take advantage of other environmental features to capture prey. When prey items are distracted, they are easier to kill; one Tyrannosaurus was witnessed using such a technique to kill a Velociraptor it had been stalking during the 1993 Isla Nublar incident. Tyrannosaurs are modestly intelligent and can adapt to the situation when hunting; this enables them to bring down more well-defended prey such as Triceratops. During combat, they are able to test their enemies for weak points, such as the necks of better-armored prey that simple biting techniques might not immediately best. Smaller prey items provide it with much less food, but are easier to kill; the tyrannosaur simply picks them up in its jaws and thrashes them back and forth. This causes severe internal injury to the prey, which the tyrannosaur then either drops to the ground or slams into any nearby object to finish the kill. During such attacks, it is common for body parts to fly off of the prey.

Even if a prey item escapes, the tyrannosaur’s teeth are designed to cause death by sepsis. The tips of the teeth puncture the prey’s flesh, and the serrations on the inner edges cause tearing wounds on the way out. Flesh caught in the wounds provides food for symbiotic bacteria in its mouth. These bacteria are then transmitted to prey via biting; a bitten prey item will quickly succumb to the septic bite, making it too weak to continue fleeing. The tyrannosaur can track the prey item and kill it in its weakened state.

In addition to both ambush and pursuit hunting, the Tyrannosaurus will scavenge carrion. This, in fact, is a better use of its energy; eating prey that is already dead is much less energetically expensive than chasing down and killing another animal. It also practices kleptoparasitism, or the stealing of other animals’ kills. According to the mobile game Jurassic World Alive, it particularly targets Carnotaurus, bullying the smaller animal away from kills it has made. It was also observed performing this behavior with Velociraptors which had killed a Parasaurolophus during the 1993 incident; in this case, not only did the tyrannosaur steal the kill, it also killed one raptor. This practice is called kleptopredation: feeding on an animal that has itself recently fed. The sheer size of the tyrannosaur permits it to dominate any carcasses it finds, and it will aggressively chase away any animals that approach it.

Tyrannosaurus tearing off a bite-sized chunk of meat from a Gallimimus, a common prey item, Isla Nublar (6/12/1993)

Once it has secured a food source, the tyrannosaur will usually pin the carcass down with a foot and tear off large chunks of meat using its jaws. It cannot chew, and simply swallows pieces of meat whole; it will consume muscle, organs, and bone alike. However, it cannot actually digest bone; Dr. Laura Sorkin noted in her journal that bone fragments can be found in tyrannosaur dung. Small enough prey items, such as goats, may simply be swallowed whole. The tyrannosaur will raise its head upward, allowing prey to slide into its throat easily; if there is not enough room for this, it may use its muscular tongue to draw prey into its throat instead.

The virtual-reality short film Jurassic World: Blue implies that Tyrannosaurus may eat eggs, as it depicts a Tyrannosaurus killing a parent Baryonyx at its nest and subsequently getting into a mild scuffle with a Velociraptor over the eggs. However, as the animal was frightened away from the nest before eating any, it is not known if it was targeting the eggs themselves or the adult dinosaur.

Social Behavior
A family group of Tyrannosaurus. The mother (right) shows affection toward her son (middle), while the father (left) stands lookout as a herd of Stegosaurus passes by (not pictured)

Because of their large food requirements and highly territorial nature, Tyrannosaurus are typically solitary animals. However, they will tolerate the presence of others under some circumstances. The most obvious case is a mated pair and offspring; family bonds between Tyrannosaurus are extremely strong, even leading to emotional behavior overriding logical behavior. Jurassic World also succeeded in keeping multiple Tyrannosaurus together; there were at least two subadult males, though the actual number of animals in the park is not known. According to the park website, no aggressive disputes had ever been observed between the captive animals. However, they were not exhibited in T. rex Kingdom alongside the eldest female, suggesting that she would not permit her territory to be shared. Additionally, the website acknowledges that fossil evidence suggests that this species often engaged in intraspecific combat; it is not known if the social behavior in Jurassic World’s younger tyrannosaurs was naturally-occurring or if their tolerance of one another was enforced by park staff.

Physical contact between even friendly tyrannosaurs is still fairly low. Parents will comfort and encourage their young by nudging with their snouts and making eye contact. Males and females also utilize different vocalizations to communicate, presenting the possibility of socially-established roles for male and female animals. However, these have not been detailed. In mated pairs, the male appears to be responsible for hunting and defense of the family, as males are usually seen with scarring and broken teeth. Females in familial groups are usually more responsible for providing emotional care for the offspring. Despite this, however, both the male and female will provide their offspring with care and protect them from danger, so these roles are not without exceptions. Hunting between mated pairs appears to be a joint effort, raising the possibility that mature animals from the same family groups could hunt cooperatively to bring down prey.

Jurassic World: Evolution portrays this animal as solitary, not tolerating any others of its own kind within its territory.

Reproduction
Cloaca of a female Tyrannosaurus rex. Note the position posterior to the hips.

Tyrannosaurus mating behaviors are unknown. Both the male and female have cloacae; in the male, this is located between the legs, while at least one female has been observed with a cloaca on the base of the tail as in some lizards. This is most likely to make mating more accessible for these multi-ton animals.

According to production crew of The Lost World, facial scarring on the male represents wounds received while engaging in combat with other males for mating rights. As nearly-identical scarring can be observed on a younger male encountered in 2001, it is quite likely that this physical combat for mating rights is commonplace among Tyrannosaurus males and occurs in the subadult as well as adult stages.

A mural in the Operation Center of the Isla Sorna Workers’ Village depicts a Tyrannosaurus rex nest containing seven white, ovoid eggs; one hatchling is shown emerging head-first. Three adults are present in the illustration, and the nest is depicted as consisting of leaves and other natural objects arranged to hold the eggs. It is unknown if this was speculation on the part of InGen’s artists or if it was based on actual research done on Isla Sorna. If the mural’s depiction of tyrannosaur nesting is based on InGen research, it may be that tyrannosaur infant mortality rates are fairly high, or even that siblicide may occur as it does in some bird species.

The opening logo sequence of Jurassic World: Evolution depicts a hatching Tyrannosaurus emerging from a round, ostrich-like egg (most likely a surrogate egg) by breaking the shell using one of its clawed hands rather than its snout. As this sequence is a reference to the opening scene of Jurassic World, which featured a hatching Indominus rex, it is doubtful that this game’s depiction is canon.

Biologists referenced by the Dinosaur Protection Group suggest that tyrannosaurs mate for life. Only one instance of reproduction has been reported, but the rearing behavior exhibited in that family is highly detailed. The adults had nested within a large depression in northeastern Isla Sorna, away from most of the central island’s predators. Only one infant survived as of 1997; it is not known how many eggs were laid, or how they were incubated. Roland Tembo estimated that the infant was only a few months old at the time; however, it was already several feet long. This suggests that the early-life growth rate of InGen Tyrannosaurus is exceptionally rapid, or that Tembo’s age estimate was incorrect. If he was correct, then the juvenile would have hatched early that year, during the dry season.

Depiction of a male and female Tyrannosaurus confronting a pack of V. a. nublarensis and several Compsognathus over a Parasaurolophus carcass. The tyrannosaurs’ offspring appears to have become surrounded by raptors.

Both adults participated in the rearing process. By the time of the 1997 incident, the juvenile was old enough to be left on its own for periods of time; however, Tembo noted that the nest was constructed in such a way that it was mainly approachable from downwind, so the adults would be able to scent the nest even while away from it. With an ability to scent for up to ten miles, they could easily detect any threat to their nest and make a quick return. They also stockpiled food within the nesting area for their offspring to feed on; carcasses in various states of decay could be seen around the nest perimeter, ensuring that the juvenile always had food readily available.

Even non-breeding female tyrannosaurs will build nests, suggesting that eggs are laid in preexisting structures rather than the adults constructing new homes for their offspring. Nests are built in sheltered areas, usually with only one entrance or exit to reduce the chances of home invasion. The tyrannosaur will build its nest out of objects it finds in its environment including sticks and logs, stones, artificial debris such as metal objects, and even the bones of other animals. These may seem messy and random, but the tyrannosaur is actually quite selective about what items it uses to construct its nest and will carefully arrange them in a way that seems comfortable and safe.

Any threat to their offspring would be dealt with swiftly and aggressively. The mother was the main source of comfort to the infant, and also typically the initiator in lethal attacks against threats. She could be seen comforting her infant through eye contact and by making cooing sounds. The father’s role was defense of the family; his scars and broken teeth suggest that he often engaged in combat with other dinosaurs, so he may also have been the family’s main hunter. Emotional bonds between parents and offspring are strong enough to override logic; when they scented their offspring’s blood, they responded by chasing it across the island despite knowing that their offspring was in the nest. A tyrannosaur’s sense of smell, of course, is more powerful than its vision; this is likely why they responded more strongly to the smell of their infant than the sight of it. The infant communicates fear or discomfort to its parents using a unique distress call, which both adults respond to vigorously.

Juvenile Tyrannosaurus makes its first kill while encouraged by its father.

The father gave his offspring an opportunity to hunt live prey during the San Diego incident, though this was done outside of their natural environment. He cornered a small prey item (in this case, InGen CEO Peter Ludlow), broke the prey’s leg to prevent escape, and knocked it down. He then encouraged his offspring to move in for the kill by nudging with his snout.

In the wild, once they were free of human interference, the mother was seen nuzzling her son using her snout while the father kept a watchful eye on a passing herd of Stegosaurus accompanied by a Pteranodon flock.

The natural growth rate of InGen’s Tyrannosaurus is not known. Under the influence of growth boosters, an individual hatched in 1988 reached adult size by 1993, or about five years. Other adults had reached sexual maturity by 1997; assuming they were also hatched in 1988, this would make them nine years old.

Communication

The vocalizations of the Tyrannosaurus are highly diverse. Perhaps the most famous is the iconic territorial bellow, a deafening and unmistakable ringing sound that can carry for quite a distance. When giving this roar, the animal usually assumes one of two poses: lowering the head to the ground, or raising the head skyward. Typically, the head-lowered pose is used when entering a new territory, while the head-raised pose is used after defeating a territorial rival. This suggests that the former is used for warning potential territorial rivals, whereas the latter is used to reinforce dominance.

Jurassic Park’s resident Tyrannosaurus breaches containment, giving a characteristic territorial bellow, Isla Nublar (6/11/1993)

A variety of other roars and growls are used to frighten and intimidate rivals during combat situations and in defense of resources or territory, but they are also used to scare victims into running during play activity. Tyrannosaurus are intelligent and require stimulation, but victims may freeze in self-defense; therefore, the tyrannosaur uses loud vocalizations to frighten its playthings into motion.

Other sounds it makes are involuntary; when angry or frustrated, such as when it sustains an injury or is unable to reach prey, it can be heard making moaning and groaning sounds, and occasionally screaming when particularly angry. When lunging for prey, it can sometimes be heard making an apparently involuntary trumpeting noise just before it bites.

Tyrannosaurus rex is, as per the Jurassic World Facts application, able to hear very low-frequency sounds. This suggests that it uses such sounds to communicate. There is some evidence that the Tyrannosaurus utilizes very low-frequency noises to establish territory, as low-pitched booming sounds and vibrations have been witnessed when these animals move into new areas. These are often assumed to be its footfalls, though even an adult Tyrannosaurus would not be heavy enough to create such strong vibrations at the distances observed. Instead, it has been suggested that these may not be impact tremors at all, but territorial infrasound calls.

Of particular note are the sex-specific noises which can be heard being made by male and female tyrannosaurs. The male makes a variety of lower-pitched calls and roars, while the female can be heard to make higher-pitched yowls and screeches. The female may also make softer cooing sounds when comforting its infant; the infant itself has a unique wailing distress cry that it makes to alert its parents when it is frightened or in pain. The sex-specific cries, however, appear not to be physiologically mandated, but rather socially taught. The female tyrannosaur from Jurassic Park has been observed making the male’s characteristic calls, despite having hatched long before the introduction of Hyperolius viridiflavus DNA that inadvertently caused the affected dinosaurs to become capable of protogyny. This rules out the possibility of the animal having changed sex. Instead, it appears that sex-specific vocalizations are ingrained into the tyrannosaurs by social conditioning. Since the Tyrannosaurus from Jurassic Park would not have had exposure to others of her kind from the time she was introduced to Isla Nublar in 1989 until the Isla Sorna animals were shipped to Isla Nublar in 2004 or 2005, she would not have socialized normally, and therefore could develop behaviors that are outside the norm for her species.

Ecological Interactions

As an apex predator, the Tyrannosaurus has a drastic impact on its environment. Its predatory activity regulates the populations of smaller animals, including but not limited to Triceratops, Gallimimus, Velociraptor, Parasaurolophus, Edmontosaurus, Pachycephalosaurus, and goats. Eating these animals actually reduces predatory pressure on their prey, most of which consists of local plant life; however, eating small carnivores such as Velociraptor can also reduce pressure on animals as well. The Tyrannosaurus also scavenges carrion, which can become a potent source of disease if left unchecked.

A typical “victory pose” after defeating a territorial rival; in this case, a Carnotaurus, Isla Nublar (6/23/2018)

On such a small island as Isla Nublar or Isla Sorna, however, Tyrannosaurus is also fiercely competitive with other carnivores for food. It has been shown engaging in territorial conflict on repeated occasions, and is usually the first to strike during these disputes. Velociraptors are often seen as prey items, but can also be competition for food. Baryonyx, Carnotaurus, and Allosaurus introduced to Isla Nublar following 2004 have been suggested by the Dinosaur Protection Group as potential competitors for food for the Tyrannosaurus, and the films have already established Spinosaurus as a fearsome territorial competitor. A Baryonyx was seen being killed by the Tyrannosaurus in the virtual-reality film Jurassic World: Blue, and two Carnotaurus have been seen being fought by the same Tyrannosaurus in June 2018. In one case, the attack was fatal for the Carnotaurus. The mobile game Jurassic World Alive states that it is common for Carnotaurus to have their kills stolen by Tyrannosaurus, implying that these two species are frequently at odds. Kleptoparasitism has already been documented in Tyrannosaurus in Jurassic Park: The Game, in which a Tyrannosaurus not only steals a Parasaurolophus carcass from a Velociraptor, but also kills the raptor itself. The Dinosaur Protection Group also has shown an artist’s rendition of a Tyrannosaurus approaching a sickly and wounded Suchomimus, presumably about to kill the weakened animal. Similarly to its carrion-scavenging behavior, this would cull a possible source of disease in the environment.

Dominance is established via prolonged eye contact.

However, not all ecological interactions between Tyrannosaurus rex and other species are predatory or competitive. During the 2015 incident which marked the end of Jurassic World, the park’s senescent female Tyrannosaurus had been released to drive back the escaped Indominus rex, with park staff hoping her territorial instincts would cause her to fight this rival. During combat, a genetically-modified Velociraptor named “Blue” joined in, attacking the Indominus in retaliation for her packmates being killed. The tyrannosaur tolerated the raptor’s presence, and after firmly establishing dominance via eye contact once the hybrid animal had been killed, both animals parted ways. In the following years, however, there is no sign of any friendly relationship; Jurassic World: Blue depicts a mild fight over food between these same two animals.

It lives in heavily-forested areas, with trees such as pines and redwoods commonly growing in places where it hunts. The activity of such a large animal would topple smaller trees and crush other plants, but the largest flora would remain mostly unharmed.

Symbiosis in Tyrannosaurus and various other animal species is firmly established. Groups of Compsognathus have been seen near Tyrannosaurus. These smaller carnivores opportunistically devour scraps of food that the tyrannosaur drops. The compies do recognize the threat posed by this much larger creature, though, and will scatter at the tyrannosaur’s approach. Compies also could be seen fleeing as a Tyrannosaurus engaged in a territorial dispute with a Spinosaurus.

The relationship between Compsognathus and Tyrannosaurus is parasitic, as the compies steal food from the larger animal. However, a commensal relationship exists between Tyrannosaurus and flies. Flies eat carrion and lay their eggs in rotting meat, a substance which the tyrannosaur leaves behind in abundance. When the tyrannosaur makes a large kill, it rarely eats the entire thing; any meat left behind attracts flies and other insects. Tyrannosaur nests in particular feature stockpiles of food for the infants, which are usually left partially-eaten. Vast swarms of flies gather around these nests. Flies may also gather near the jaws of tyrannosaurs, attracted by the smell of rotting meat caught in their teeth. In the event that a tyrannosaur does eat any flies or maggots, it is unlikely to be harmful, and would merely be some additional protein.

Other small invertebrates, such as female mosquitoes, are hematophagous and feed on the tyrannosaur’s blood. They most likely drink from the sensitive areas such as mucous membranes, as the skin is too tough for most insects or other invertebrates to pierce. This relationship existed as far back as the Cretaceous period, which is how InGen obtained tyrannosaur DNA from amber samples. It is not known what parasites feed on tyrannosaur blood in the modern day.

Mutual symbiosis exists between Tyrannosaurus and bacteria that live in its mouth. When the tyrannosaur feeds on meat, some gets caught in the serrations of its teeth. Bacteria feed on these, flourishing in the mouth. Then, when the animal bites a prey item, these bacteria are transmitted into the wound and cause sepsis. The prey dies due to this, allowing the tyrannosaur to feed and continue to support its oral flora.

Not all microorganisms in its mouth are beneficial. When a tyrannosaur breaks a tooth, microbes may invade the injury from inside the gum line. This causes a disease known as ragged tooth, which can lead to tissue breakdown in the jaw. Eventually, death by starvation may occur as the dinosaur’s ability to hunt is impaired. Jurassic World’s paleoveterinarians would regularly inspect the Tyrannosaurus for signs of common oral infections such as this one.

In Jurassic World: Evolution, the Tyrannosaurus (as with most theropods) is a host to Campylobacter, a bacterium that affects modern birds. This can lead to campylobacteriosis.

Cultural Significance
Symbolism

This is absolutely one of the most famous dinosaurs ever discovered, and everything from its astounding size and predatory adaptations to the fittingly intimidating name scientists assigned it propel this dinosaur to stardom. Even its discoverer, Barnum Brown, described it as such: “Quarry No. 1 contains the femur, pubes, humerus, three vertebrae and two undetermined bones of a large Carnivorous Dinosaur not described by Marsh…I have never seen anything like it from the Cretaceous.

It is a rare work of dinosaur-themed media that does not feature, or at the very least mention, Tyrannosaurus rex in some capacity. Whether in books, film, comics, video games, or works of art, this dinosaur’s presence is ubiquitous in popular culture more so than any other. The accuracy of the depictions is highly variable; aside from the “coolness” factor which determines cosmetic choices in creature design, new scientific discoveries are constantly providing new hints as to what the dinosaur would have looked like in life. With incoming information perpetually on the update, the image of Tyrannosaurus rex is always being honed. Paleoartists of all skill levels, from childhood to paid professional, must at some point try their hand at illustrating it; this is practically a rite of passage. A popular subject is to show it hunting down and attacking a Triceratops, which did really live in the same time and place. This showdown is not scientifically unfounded, either; there is fossil evidence of Tyrannosaurus preying on Triceratops and the latter defending itself.

Popular culture ascribes it an almost supernatural power, depicting it as an unstoppable force with an insatiable appetite. Even science-based documentaries can hardly help portraying it as the ultimate carnivore, endowed with devastating strength and keen senses. Its personality is near-universally assumed to be aggressive. The discovery that an asteroid or comet impact may have resulted in its extinction has only accentuated its legendary reputation; such a dramatic natural disaster is fitting enough an end for this most respected of hunters. The small arms are the only part of its anatomy it is ever teased for, but dinosaur enthusiasts are quick to point out that despite their small size the arms are actually well-muscled and have only become small as a tradeoff for its massive jaws. In actuality, InGen studies have found that the tyrannosaur (while indeed a powerful predator) prefers its privacy, is more likely to be playful than aggressive, and does indeed sometimes think about things other than food.

InGen has used this dinosaur as the face of de-extinction, referencing it in social media and Jurassic World tour information to appeal to visitors. A Tyrannosaurus skeleton was used as the Jurassic Park logo, and this motif was reused when the park was rebranded as Jurassic World.

According to Universal Studios, Tyrannosaurus rex is the dinosaur of the Leo astrological sign (July 22 – August 22).

In Captivity

No dinosaur commands immediate respect quite like Tyrannosaurus rex, and so it is understandable that InGen intended for this dinosaur to become a Jurassic Park centerpiece as soon as they knew they had its DNA. Such a creature would have drawn in crowds like no other. It was planned to have a paddock to itself, with the size of the paddock estimated to house an adult and a juvenile; however, only the adult was ever successfully transported from Isla Sorna and introduced. This animal, a female and the first of her kind, was placed in the paddock in 1989 when she was roughly a year old. She would have been visible from the main tour road, near where one of the rest stops was located; this would ensure that her visibility was maximized.

She was fed live but tethered goats, which deprived her of the chance to hunt prey. This led to understimulation and restlessness, and she was contained only by a massive electric fence. Her paddock was expansive and naturalistic, giving her plenty of space to hide. While this was one favor InGen did her, it meant that she was able to take advantage of the forest cover and remain out of sight. Tyrannosaurus was surprisingly one of Jurassic Park’s less troublesome inhabitants, preferring to stay concealed and making fewer active escape attempts than the problematic Velociraptors held in the nearby paddock. It seems as though she did not really understand what the purpose of restraining technology was, simply viewing it as an inconvenience instead of an injustice. This was also the biggest challenge to keeping her contained: should the power fail, she would leave her paddock reasonably quickly once she realized the obstacle was gone. Having no sense of challenge to her authority, she saw no need to respect the little boundaries her keepers set.

Many of the exhibit issues of Jurassic Park were addressed when she was recaptured for Jurassic World in 2002. She was held in Paddock 9, and was one of the dinosaurs never relocated back to Isla Sorna during construction. By 2005, Paddock 9 was reassigned to an attraction near Main Street which included T. rex Kingdom. The eldest tyrannosaur was its only inhabitant; while other Tyrannosaurus were brought from Isla Sorna and more were bred between 2005 and 2015, she was the only one held in a major attraction. This new exhibit had insurmountable concrete walls containing a lush simulated redwood environment. Such solid boundaries kept her from wandering freely during a power outage, and the use of redwoods rather than dense cloud forest flora meant that her visibility was kept high while also maintaining the forest environment she preferred. She was still fed tethered goats, depriving her of the opportunity to hunt, but she could now also benefit from advances in paleoveterinary medicine made since she was created. Her diet mostly consisted of live food, but periodically she was fed prepared meat enhanced with vitamins. Apparently each tyrannosaur will have a preferred type of food; the eldest maintained goat meat as her favorite dish.

Behavioral conditioning is possible in this dinosaur as it is relatively intelligent, curious, and even playful. Jurassic World staff learned from the 1993 incident survivors’ accounts that the tyrannosaur was fascinated by flares, which at the time were a much-needed change from the monotony of her existence in the Park. She was conditioned to associate flares with food, and would direct her attention to anything flares were thrown at. This gave her a simple game to play, which alleviated her boredom and kept her stimulated. Now she had fewer reasons to be aggressive toward her handlers, though firsthand accounts describe her as refusing to accept their authority. According to dinosaur experts at InGen, tyrannosaur respect is hard to earn, and few achieve it.

Younger tyrannosaurs were kept in Jurassic World, but no evidence currently exists that any were exhibited. However, Jurassic World did manage to keep the peace between the juveniles for ten years, avoiding any major fights. This is in contrast to tyrannosaurs seen in the wild on Isla Sorna; it was common for males to have facial scars gained in combat with rivals during the mating season. Preventing uncontrolled breeding would obviously have been paramount to Jurassic World’s security and animal welfare goals, so reducing intraspecific combat might have been a welcome side effect.

Some InGen documentation misspells its genus name as “Tyranosaurus.”

Science

Tyrannosaurus seems to have been one of the most abundant giant theropods of the Cretaceous period in North America and a great many fossils of it have been discovered. Its awe-inspiring nature means that any research linked to it is sure to generate a lot of attention from the public, guaranteeing funding for scientific institutions. Together, these factors make Tyrannosaurus not just one of the most well-researched dinosaurs, but one of the most well-researched animals, be they living, dead, or de-extinct.

The nature of study into T. rex has spanned all manner of scientific fields including biomechanics, population dynamics, ecology and evolution, and reproductive biology. Scientific unknowns about its traits, such as how much of its body was feathered or whether it hunted or scavenged more often, are often overblown in the media but do reflect actual debates in the paleontological community. (For those curious, it was probably mostly feathered as a juvenile but became less so as it matured, and it likely hunted and scavenged in equal measure.) When theropod research focuses on other species, it can benefit the researchers for funding purposes if the name Tyrannosaurus is at least mentioned in comparison to the subject species, as this immediately attracts public attention. Famous fossils are often given names, allowing scientists to popularize individual animals as characters in the story of life on Earth.

De-extinction has allowed further research to go into it, but its paleontological applications are limited. InGen’s most famous specimen is its oldest, and is only Version 1.0; this is the de-extinct Tyrannosaurus without any corrections or modifications, and is noticeably different from our modern understanding of the animal. It has led to some amount of misinformation, such as the discredited hypothesis that cannot distinguish stationary objects from a stationary background; this disability in InGen’s Tyrannosaurus is almost certainly due to genetic engineering. However, some of its traits are unchanged: it shares its ancestor’s superb sense of smell. It has also lent itself to genetics research, with its full genome being known by 2012. This dinosaur was utilized as the genetic template for the hybrid species Indominus rex.

It has also, since being brought back to life via cloning of ancient DNA, given irreplaceable insight into theropod cognition and the ways in which dinosaurs perceive their world. Most of this research has involved the eldest specimen, whose decades of life have seen her through all manner of events and encounters. InGen and other parties have observed her for all these years and used her reactions to the world as a way of understanding how she experiences it. Such research can be applied to other theropods to a degree.

Politics

With the popularity of this dinosaur is is unavoidable that it will become embroiled in legal difficulties such as fossil poaching and ownership disputes. The famous specimen “Sue” was subject to a legal debate regarding who could claim the right to the fossil when it was discovered. This debate was settled in 1997 with courts assigning ownership to Maurice Williams, the landowner where the fossil was found in 1990.

Although it has been subject to all of the de-extinction and cloning controversies, the fame of Tyrannosaurus shields it from most criticism. It is possibly the only de-extinct animal capable of evading political controversy through sheer charisma and star power alone. Even Dr. Laura Sorkin, who often criticized the phenotypic errors resulting from Dr. Henry Wu‘s genetic engineering shortcuts, made some exception for Tyrannosaurus. She ascribed its visual disability to Wu’s techniques, but essentially admitted that the error made the dinosaur safer to observe and did not complain further.

A male tyrannosaur and his offspring were heavily involved with the 1997 San Diego incident, which was the eventual result of an effort by big-game hunter Roland Tembo to hunt and kill an adult male Tyrannosaurus. This event was central in the history of de-extinction politics for many reasons: it was the first attempt (though failed) at trophy hunting of de-extinct animals, the first incident of a de-extinct animal confirmed on the American mainland, and the event which revealed de-extinction as fact to the general public. It was the precipitating event for the modern de-extinct animal rights movement, which was popularized by InGen’s former CEO John Hammond. However, the damage to person and property was later used by groups such as Extinction Now! to promote dinosaurian re-extinction.

Promotional poster released by the DPG

The Tyrannosaurus exhibited in Jurassic World was the only publicly-accessible park animal known for certain to have killed people in the past, but somehow this added to her reputation rather than detract from it. She was established as a part of Isla Nublar’s mysterious history rather than a confirmed maneater. The incident of 2015 was a sobering reminder for the world that all animals can indeed be dangerous, and for plenty of people it was the nail in the coffin for the de-extinction issue: others suggested saving only the herbivorous dinosaurs and leaving the carnivores to die in the impending Mount Sibo eruption. In response to this, the Dinosaur Protection Group‘s Klayton S. wrote an article entitled “Saving the Carnivores of Isla Nublar” on June 5, 2018 which focused heavily on the tyrannosaur’s life history and the role she played in her ecosystem. Relying on her fame and popularity was a sure way to increase support for the DPG; they also featured her as an adoptable dinosaur on their website. Not only was this dinosaur already famous, she had been instrumental in ending the 2015 incident by driving the escaped Indominus rex to its death in the Jurassic World Lagoon. This conflict took place just across the Lagoon from the hotel complex where countless visitors waited for evacuation, and was probably witnessed by hundreds or even thousands of people. The fact that the Indominus was engineered from the Tyrannosaurus genome does not seem to have had any impact on her reputation.

The United States government opted to take no action with regards to Mount Sibo, citing Isla Nublar’s status as foreign territory on lease to a multinational corporation. For its own part, Masrani Global had also refused to take action on the grounds that it would be expensive. The DPG’s mission was then funded illegally by the Lockwood Foundation, though the tyrannosaur’s status as of June 2018 was unknown. During the expedition on June 23, the tyrannosaur was encountered alive and healthy; she was captured by the mercenary team employed by the Lockwood Foundation. Their lead hunter Ken Wheatley made a last-minute move to catch and contain this theropod, understanding that it would be highly valuable. Rather than relocate the dinosaurs to Sanctuary Island as intended, the Foundation’s manager Eli Mills went against his employer Benjamin Lockwood‘s orders and brought the animals to the Lockwood estate for sale on the black market. The tyrannosaur was not brought up for auction before animal rights activists disrupted it, meaning she was still held in the laboratory sub-basement during those events. Had she been sold, she would surely have gone for many tens of millions of dollars, providing funding for Henry Wu‘s research. While the live tyrannosaur did not go up for sale, a sample of Tyrannosaurus DNA was sold among eleven other specimens to a Russian buyer, probably gangster Anton Orlov. This means Tyrannosaurus DNA will likely go open-source soon enough.

Due to a hydrogen cyanide leak, the tyrannosaur and the other dinosaurs were released from their containment cells by the young Maisie Lockwood to save their lives. This act indirectly led to the death of Eli Mills and the loss of the last known Indominus rex specimen, preventing Henry Wu from continuing his research. The tyrannosaur has since made only sporadic appearances among the pine forests of the Pacific Northwest.

Resources

As such a popular dinosaur, it is only fitting that Tyrannosaurus is ascribed incredible amounts of intrinsic value (whether it is alive or fossilized). Especially complete skeletons have sold for many millions of dollars, and biological material is now available thanks to de-extinction, making this dinosaur all the more valuable.

Its applications have mainly been for entertainment and education, and Jurassic World has proven that a sufficiently well-funded facility can make excellent use of it. Between 2005 and 2015, the park’s biggest moneymaker was consistently the tyrannosaur, which drew in more tourists to Isla Nublar than any other animal. Once issues surrounding its containment and satisfaction were dealt with, it was actually a fairly easygoing resident, especially compared to the temperamental Velociraptors. Juveniles are also very popular, as the prospect of seeing one hatch drew many tourists to the Hammond Creation Lab. The tyrannosaur was also valuable to science; it was the first theropod confirmed to have been added to InGen’s genetic library and the first known to be brought back from extinction, lending it to decades of scientific study. It is believed to be a valuable source of biopharmaceutical compounds found in no other animals, which was one of the reasons it was collected in 2018 for sale on the black market by Ken Wheatley working under Eli Mills.

The DNA of this dinosaur was used as a template for building the Indominus rex by Dr. Henry Wu, who also engineered that hybrid animal’s descendants. Tyrannosaurus DNA is therefore extremely valuable; samples were sold in 2018 to a Russian black-market buyer, most likely Anton Orlov. The money generated from this was intended to fund Wu’s continued research, as he had been driven underground by inquiries into bioethical misconduct by the U.S. government.

Tyrannosaurus frequently sheds and replaces its teeth, like all theropods. These teeth are enormous in size and visually stunning, so they make quite good souvenirs.

Safety

An encounter with a Tyrannosaurus rex is a breathtaking experience, but can turn deadly in an instant. Many people would consider a tyrannosaur attack to be certain death. Survival is actually possible, though, and there are several stories of both experts and amateurs making it through a tyrannosaur encounter and living to tell about it. While this animal is assuredly intimidating, recalling basic survival strategies for dealing with animal attacks can mean the difference between escaping with your life and suffering a rapid, crushing death.

First of all, know where an encounter is more likely to take place. Tyrannosaurus prefers the edges of forests, where it can conceal itself to better ambush prey. It mainly feeds on medium-sized to large animals, though it will gladly eat smaller food items if that is what is most available; it is not a picky eater. For many people, avoiding a tyrannosaur attack is as simple as staying away from uninhabited woodland and areas where large animals herd, but for others (such as people living in rural areas, or farmers with outdoor livestock) this may not be possible. In such situations, it helps to know a bit more about tyrannosaur biology and behavior patterns.

Tyrannosaurus takes its prey by surprise, ambushing it from the edges of forests. You may not be its usual prey, but if you are traveling in areas where it would have the benefit of forested land to hide its huge body, the danger still exists. For farmers with livestock, reducing the chances of a tyrannosaur attack may be vital to your livelihood. Any large stands of trees near your fields or barns will be a risk, so ensure that your livestock are not able to graze too close to someplace they might be ambushed. Cutting back forested areas on your property might be prudent if tyrannosaurs are known to live in your area. Physical barriers are of limited use; tyrannosaurs never really become accustomed to being restrained, and they view all but the most insurmountable obstacles as mere inconveniences. If the worst does happen and one of your animals is killed, do not confront the dinosaur: Tyrannosaurus is extremely defensive of its food. For other people, when traveling near forest, remember that the Tyrannosaurus hunts chiefly using its senses of smell and hearing. InGen Tyrannosaurus depend less on their vision, since they struggle to differentiate stationary objects from stationary backgrounds.

Some people assume that just standing still would be enough to avoid a tyrannosaur attack, but it is not this simple. Humans are highly visual animals, so it is easy for most of us to forget that the other senses play a large role in how we interpret the world. Tyrannosaurs can still smell and hear you, as well as whatever you are carrying. If you have food on your person, especially meat, they can tell. They can also detect you easily if you are injured or bleeding. The smell range for an adult Tyrannosaurus reaches up to ten miles, so they will smell you long before you know they are there. If you make a lot of noise while traveling in the woods, this will also attract their attention. Prey animals need to avoid predator attention in order to survive, and you are no longer an apex predator in this environment. In fact, it may be prudent to watch other prey animals nearby. If they suddenly become skittish and wary, or if they quickly leave an area, you should follow suit.

Some tyrannosaurs have even figured workarounds for their visual disability. In the wild, it is common for them to issue an alarming roar to startle other creatures into motion. Those that have experience with humans often encounter standing still as an evasion tactic frequently and can teach themselves to recognize it. Jurassic World’s famous Tyrannosaurus is a good example: by the time the park closed, she had figured out how to interpret stationary human shapes as actual humans through repeated exposure. Better ways to hide yourself involve disguising your scent, either by cleansing yourself with water or applying a scent a tyrannosaur would not be interested in.

A Tyrannosaurus attack will come quickly, and you will probably have only moments to react. If it wants to eat you, it will strike with a sudden, incapacitating bite from its jaws. Any action you can take to dodge this initial lunge will buy you precious time to make a more thorough escape. Outrunning it on flat ground is unlikely; InGen has clocked this animal’s top speed at 32 miles per hour, though paleontologists estimate that its walking speed could reach fifteen miles per hour. This is faster than you can go, so instead of relying on speed alone, find ways to hinder it. Make your escape through the densest brush you can find, squeeze between thick trees, and make for the sturdiest and narrowest shelter you can fit deep into (you will need to be deep enough to escape the strong tongue). Some obstacles that really can stop it include thick rock obstructions, well-built concrete walls, and heavily-armored vehicles. You can also try climbing to evade it, if you can get up fast enough. It cannot climb trees, though it can probably tear down smaller ones, and cliffs will stop it. Ensure you actually can get far up enough to avoid its head; otherwise you are only putting yourself at a convenient biting height.

If you are bitten, you may as well make a last attempt to fight back. The interior of the mouth is sensitive and you may be able to surprise it into dropping you by pummeling the mouth from inside. Other vulnerable spots include the eyes and the nostrils. A tyrannosaur will often handle its prey for a few seconds to get it into an ideal position to make a killing bite, so you have a brief moment of time to cause as much trouble as you can. By making yourself difficult or unpleasant to eat, you may save yourself; if you do not, you will at least give the dinosaur reason to hesitate before making another human its meal. There is precedent for this: Jurassic World’s Tyrannosaurus gained serious wounds preying on Velociraptors, and since then has been wary of attacking them.

Food is not the only reason for an attack. They are very territorial towards anything they perceive as a threat, though they will tolerate animals that either do not endanger them or are not worth the effort in driving away. You might be able to reduce the changes of a Tyrannosaurus attack by being harmless enough. As discussed above, a common provocation is getting too close to a tyrannosaur’s food; they will chase away any scavengers they see. Another reason for territorial attacks is defense of their nests or offspring. Tyrannosaurus nests are rarely seen, as they are usually well-hidden and breeding is quite a rare event owing to their small population size, but one way you can determine if there is a nest nearby is to keep track of how frequent their kills are. An adult Tyrannosaurus rex will eat a few hundred pounds of meat in a day. If you see it making regular kills in excess of this, especially if there is more than one Tyrannosaurus, they may have other mouths to feed. They stockpile meat near their nests for their offspring to choose from, often taking more than they need as to provide their young with a surplus. If your local tyrannosaurs are breeding, they will be far more aggressive than usual.

Tyrannosaurus attempts to use Dr. Alan Grant as a source of stimulation, Isla Nublar (6/11/1993). Note that the eyes are not focused on him; she locates him using her sense of smell. Moments after this image, she became frustrated at his lack of movement and rammed the nearby vehicle instead.

There is one other reason tyrannosaurs attack humans, and it is a leading cause of unprovoked attacks: enjoyment. This is an intelligent animal, naturally curious and exploratory, investigating any new environment it finds itself in as well as any new curiosities it discovers. Tyrannosaur play behavior was first documented during the 1993 Isla Nublar incident, in which the dinosaur was drawn to one of the electric Ford Explorers by a bright flashlight. She made the Explorer and its two human passengers into a much-needed plaything, ramming and eventually flipping the vehicle. She attempted to extract the humans from inside, but failed, instead pushing the vehicle over a cliff. During the encounter, she also became fascinated with the light and smoke given off by road flares, which she chased after. In June 2016, this same tyrannosaur encountered a vulnerable human, roaring at him to get him to run so she could chase him down Main Street; she subsequently engaged in a tug-of-war with a helicopter ladder. Her intent appears not to have been to eat these targets, but rather to turn them into sources of stimulation, much like with the Ford Explorer and its human passengers during the 1993 incident.

However, the sheer size and power of the Tyrannosaurus means that even playful interactions can be fatal. During her initial foray outside of her paddock, Jurassic Park’s Tyrannosaurus severely wounded Dr. Ian Malcolm after ramming him through a faux-thatch restroom wall, and then gripped Donald Gennaro and flung him back and forth until his body flew apart. As she did not eat him, this behavior was not predatory but instead a form of play. Lacking powerful hands, this animal mostly interacts with its environment using its mouth, which is filled with seven-inch serrated teeth, so it usually kills what it is playing with. To avoid this kind of fate, you will want to redirect the tyrannosaur’s behavior to something else. Flares have proven effective in the past, so you can try carrying these with you if you believe tyrannosaurs to live in the area. Ensure that once you have the tyrannosaur distracted, you do not recapture its attention. Be boring, and let it find something else to play with. Staying still is actually an effective defense against a playful tyrannosaur, as opposed to a hungry or territorial one.

Unfortunately, though these dinosaurs are a majestic sight, having them live near human habitation is detrimental for all creatures involved. Some communities might learn to live in peace with these giant carnivorous neighbors, but for many people, it will probably be impossible. Instead of dealing with the issue yourself, contact state or federal authorities (in the United States, the department dealing with this the longest has been the Department of Wildlife) to contain and relocate the dinosaur somewhere secure. Our relationship with this breathtaking theropod is better left at a distance, so that both of our species may live safe and enjoyable lives.

Notable Individuals

Eldest Tyrannosaurus – first known specimen bred in 1988, known as “Rexy”

Male Tyrannosaurus – male individual involved in the 1997 San Diego incident

Female Tyrannosaurus – mate to the male involved in the 1997 San Diego incident

Infant Tyrannosaurus – first confirmed Tyrannosaurus bred in the wild

Lone Male Tyrannosaurus – male individual, deceased in 2001

Gray and Red Tyrannosaurus – individual which controlled a coastal territory of Isla Sorna

Sick Tyrannosaurus – female individual suffering from health issues; deceased in 2001

Disambiguation Links

Tyrannosaurus rex (S/F-Ride)

Tyrannosaurus rex (JN)

Tyrannosaurus rex (C/N)

Tyrannosaurus rex (CB-Topps)