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Tyrannosaurus Rex
JW T-Rex
'Tyrannosaurus as it appeared in Jurassic World'



Name Translation:

Tyrant Lizard King


Late Cretaceous (68-65 mya)


42-49 feet long(13-15 meters)


15-21 feet tall (5-7 meters)


6.6-9 tonnes

Tyrannosaurus meaning "king tyrant lizard" (Greek tyrannos = tyrant + sauros = lizard + rex = king), also known and simply as T. rex, was a large carnivorous theropod dinosaur that lived from 68-66 million years ago. Tyrannosaurus is the most-known- and famous dinosaurs that has ever lived. Its fossil remains are relatively rare, as of 2012 only 44 specimens had been found, including three complete skulls.
What's more is it's speculated that dinosaurs grew their whole lives, so its possible we'll find even bigger specimens in the near future. It lived throughout what is now western North America, with a much wider range than most other tyrannosaurids, including the states of Wyoming, Montana, North and South Dakota, Colorado, Canada, and even Texas. It was among the last non-avian dinosaurs to exist prior to the Cretaceous–Tertiary   Extinction Event. While Tyrannosaurus and its relatives ruled the north, abelisaurs such as Carnotaurus ruled the south. In fact, the tyrannosaurids were so successful, that whenever a tyrannosaur moved into an area anywhere within the northern hemisphere, all other large theropods were soon wiped out due to being in direct competition with them. So people have speculated about whether there may be more than one type of tyrannosaur in T.rex's environment.
File:Tyrannosaurus rex by teratophoneus-d5bn6z5.jpg

Tyrannosaurus rex is one of the most most well-known dinosaurs, ranging from toys to television shows. Its name still brings fear even today, and it's also celebrated as the "King of the Dinosaurs". It has become the quintessential dinosaur/monster, and an icon in dinosaur culture. In 1892, Edward Cope described the first known Tyrannosaurus rex skeleton as Manospondylus gigas, but this is now considered a Nomen oblitum. Barnum Brown's 1902 discovery of "Dynamosaurus imperiosus," is also now called Tyrannosaurus rex, Tyrannosaurus' type species. He found two more specimens, in 1902 and 1905. Tarbosaurus was at one point considered to be a second Asian species of Tyrannosaurus, but was later reclassified as either Tarbosaurus bataar or Tyrannosaurus bataar.

File:638px-T-rex ve triceratops.svg.png

Tyrannosaurus rex was not the undisputed biggest carnivorous dinosaur, however. Spinosaurus may have been the biggest carnivore ever discovered, with the largest estimates being 52 feet (16 m), long though its habits indicate a more aquatic than terrestrial lifestyle, similar to those of crocodilians, and it's only based on fragments for the time being, so its exact size isn't truly known, but Tyrannosaurus was by far the biggest carnivore ever in North America. Three carnosaurs called Mapusaurus, Giganotosaurus and Carcharodontosaurus also compete against T. rex for the title of largest carnivorous dinosaur, but recent study on body structure shows that due to excessive body mass, the tyrant lizard was likely heavier than either contenders.

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Skin and feathers

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In 2004, the scientific journal Nature published a report describing an early tyrannosauroid, Dilong paradoxus, from the famous Yixian Formation of China. As with many other theropods discovered in the Yixian, the fossil skeleton was preserved with a coat of filamentous structures which are commonly recognized as the precursors of feathers. It has also been proposed that Tyrannosaurus and other closely related tyrannosaurids had such protofeathers. However, skin impressions

File:800px-Young Tyrannosaurus rex 02.jpg

from large tyrannosaurid specimens show mosaic scales. While it is possible that protofeathers existed on parts of the body which have not been preserved, a lack of insulatory body covering is consistent with modern multi-ton mammals such as elephants, hippopotamus, and most species of rhinoceros. And in 2012, another feathered tyrannosaurid, Yutyrannus huali, was discovered.

As an object increases in size, its ability to retain heat increases due to its decreasing surface area-to-volume ratio. Therefore, as large animals evolve in or disperse into warm
into warm climates, a coat of fur or feathers loses its selective advantage for thermal insulation and can instead become a disadvantage, as the insulation traps excess heat inside the body, possibly overheating the animal. Protofeathers may also have been secondarily lost during the evolution of large tyrannosaurids like Tyrannosaurus, especially in warm Cretaceous climates. If anything, the feathers would've been used to show off during courtship to attract mates in large tyrannosaurs. Even though the larger adult tyrannosaurs probably didn't have any feathers, the babies, which were much smaller and needed more warmth than the adults, probably hatched with a full coat of downy feathers and lost them as they grew.

Killer Instinct

There has been ongoing debate as to how Tyrannosaurus found its food. Most people believe it was a predator, hunting down and killing its food in the same way modern lions do. However, others believe it was a scavenger, as evidenced by its large olfactory bulbs (which indicate a phenomenal sense of smell). The best
possible conclusion is that T. rex was both a part time hunter and scavenger, since no carnivore relies on just one of those things alone. Evidence has shown that T. rex was also cannibalistic when the sitiuation demanded it, or after killing its own kind for mating or territory. There's also evidence that Tyrannosaurus rex hunted in groups, from when Phil Currie found a large number of Tyrannosaurus' close, more primitive relative Albertosaurus in Canada that were all of different ages, and since Albertosaurus, which was more primitive and not as smart as its more famous cousin, hunted in groups, then why shouldn't T. rex have done the same?
File:Tyrannosaurus 3D Model.jpg

The concept that makes Tyrannosaurus rex so deadly is that it had a huge 5 foot (1.5 metre) long skull that weighed well over 500 lbs (225 kg) in weight and great jaws that could dislocate like a snake to swallow large pieces of meat. It also had banana-sized teeth (12 in. or 30 cm), some of the largest in the animal kingdom, and could bite 500-600 lbs. (227-273 kg.) of meat off at a time and swallow it whole, sometimes breaking the teeth off when biting but growing them back repeatedly. Unlike most predators, T. rex would also eat basically the whole carcass, bones and all. We know because we've found Tyrannosaurus coprolites (fossilized poop) with ceratopsian and hadrosaur bones in it. The teeth made Tyrannosaurus different from most predators, because these teeth were blunter, stronger, and more suited to crush bone and penetrate armor instead of slice through flesh. Another discovery seems to show that T. rex also had a very infectious bite from the teeth, since the serrations in the them were much larger than other theropoods, and probably held pieces of rotten meat in them, which allowed harmful bacteria to grow and cause disease when the Rex bit down on prey items, so even if the T. rex didn't get the kill on the first bite, the prey would eventually die of infection and the T. rex would just track it down using its keen sense of smell and eat it after it'd died or became too weak to fight. It


also seems as though T. rexes in the North fought against Triceratops, Ankylosaurus, Edmontosaurus, and Pachycephalosaurus, while ones in the South fought against all of those plus a large sauropod called Alamosaurus.

The average bite force of Tyrannosaurus rex astounded scientists when they used calculations from crocodile bite forces to find out that Tyrannosaurus rex had a bite force of 60,000 newtons (6.8 tons) of pressure and perhaps even more. Higher estimates were made by professor Mason B. Meers of the University of Tampa in 2003. In his study, Meers estimated a possible bite force of around 183000 to 235000 newtons or 18.3 to 23.5 metric tons; a bite force equivalent to that of the largest Megalodon shark specimens. Other studies say the neck could lift 5 tons. This tremendous amount of force is enough to easily crush bone and bite through a steel oil drum, and also is by far the most powerful bite force of any terrestrial animal that ever lived, surpassing any modern-day animal, such as sharks, crocodiles, or hippos. Tyrannosaurs could probably use hunting tactics which required lunging at prey from short distances, and then crushing them with its jaws. It also could break bones with it's tail, teeth, and could also do so by ramming into

File:Kd pop big1.jpg

prey with its rock-hard head. T. rex was also the most muscularly built theropod ever, even its tiny arms were strong, being able to lift 500 lbs. (227 kg.) with each arm, crushing any Olympic record for weight-lifting. The exact use for its arms are unknown, but most scientists agree it was to grab onto struggling prey with those 2-inch (5-cm.) long, hook-like claws while its huge jaws finished it off with a bite to the neck. They also could've been used to grab on at first while mating or to help lift itself up off the ground. Most scientists agree that T. rex's arms got so small throughout evolution from its jaws becoming so big and powerful, so the arms were less needed, and if T. rex hadn't gone extinct, the arms might've completely disappeared all together.


Although it was the top predator, Tyrannosaurus rex had a very tough life, most not even living past their early 30's (even Sue died at 29), but T. rex has proven to also be a very resilient dinosaur. Nearly every adult Tyrannosaurus specimen found has wounds that it have been healed, but would've killed nearly any other animal.For instance, in one specimen named Sue, it had suffered and survived injuries such as broken ribs, infections in the vertebrae and legs, and also had arthritis. Other specimens have also been healed from Triceratops horns, Ankylosaurus clubs, and even bitemarks from other tyrannosaurs. In fact one specimen nicknamed Stan even had a piece of the back of his skull and brain case bitten out of and he still lived for several more years. Aside from fighting some of the toughest herbivores that nature's ever produced, like Triceratops and Ankylosaurus, they also fought amongst themselves frequently. Nearly every complete or mostly complete skull found has bite marks from the only large theropod around, another T. rex. They most likely fought over mates, territory, or food. Tyrannosaurus and its cousins were so successful that whenever a tyrannosaur moved into a territory, it drove out any other large predator, and were soon the only large predators in the area.

T. rex's speed has been a topic of discussion for a while. The scientists that believe T. rex was a scavenger
say that it was a slow-moving, lumbering animal that could barely run 15 mph. However, some speculate, that since T. rex had some of the longest and most muscular legs of any bipedal dinosaur, it was a fast runner. In fact its legs and pelvis alone made up half of the tyrant lizard's body weight, and the tail alone weighed a full ton, designed to hold extra muscle mass and counter-balance its enormous head. Another study on the famous Tyrannosaurus specimen nicknamed Sue also shows how deep indentations on the leg bones where muscle once was, suggesting high concentration of the tissue. Also, unlike most other large theropods, T. rex had a longer shin bone than a femur bone, giving it an ostirich-like build and shows that T. rex possibly was fairly fast. Scientists that believe T. rex was a predator say that it could run 25-28 mph (40-45 km/h), faster than Olympic sprinters! Ao far it was confirmed that T.rex was a slow reptile, running up to 11 mph (18 kph). Even though T. rex wasn't that fast, it was still capable of taking down large prey. It also seems as though if T. rex was a predator, than it held its prey down with one of its feet, using the other one and its long tail for balance, and then taking a bite out if its prey's neck, severing the spine. T. rex also likely had specialized pads on the soles of its feet like elephants today to feel low frequencies in the ground to find and locate its prey like ceratopsians or ankylosaurs.

Another terrifying aspect about Tyrannosaurus rex was the size of its brain. It was the smartest of the large theropods, and its brain was about the size of a gorilla's or a coconut. Recent studies show that T. rex was probably about as smart as a lion, meaning this dinosaur could use strategic thinking to take down tough prey like Triceratops and Ankylosaurus. T. rex probably became so smart because unlike other large theropods, which hunted large, small-brained sauropods, it hunted tough animals that were about the same size, like Triceratops, so it would need to come up with a plan to kill it. That can also explain why the teeth were so much broader, thicker, and stronger than other carnivores, since there was more armor that needed to be bitten through. This brain size may also have led T. rex to be able to form a family pack, letting the juveniles chase after the prey items into the jaws of the adults, like lions do today. Hunting in packs or pairs could also be a factor in being able to take down tough prey. If T. rex hunted in a pack, most likely the juveniles would chase the prey towards the more powerful adults, where they would kill it. If it hunted in pairs, they probably attacked together on each side. If it was alone, then the tyrannosaur probably waited until it was ready to attack, and then would charge and repeatedly bite down until thge prey became weak and died. The large brain also helped T. rex take better care of its young, so the next generation of killers had a greater chance of surviving. The skull of T. rex also shows that it had large eyes that faced forward, giving it three-dimensional binocular vision, while most theropods had eyes that were on the sides of their heads. Considering how large its eyes were and how good of a sense of smell it had, there's also been debate as to whether Tyrannosuarus was a part-time nocturnal hunter.


For a long time T. rex was considered part of the carnosaur genus, like Allosaurus, but a closer analysis a

File:Tyrannosaurus triceratops1.jpg

few years ago showed that it was actually part of its own genus; the tyrannosaurids, which descended from coelurosaurs like Velociraptor. While Tyrannosaurus was by far the biggest tyrannosaurid, it wasn't the only one. It had numerous relatives; Daspletosaurus, Albertosaurus, and Tarbosaurus are all part of the tyrannosaur family.

The earliest known tyrannosaurs were actually small hunters from the Jurassic Period, like Guanlong. Of all it's relatives, Daspletosaurus is believed to be the direct ancestor of T. rex, due to its very similar appearance. The skull of a small tyrannosaur, Nanotyrannus, found in South Dakota, was later thought to be from an adolescent T. rex but it is still possibly a separate species or genus. T. rex had a relatively short neck for such a large theropod, but was
File:Tyrannosaurus-rex new.jpg
very well muscled and designed to withstand much more force from its powerul bite than other theropods were. Although Tyrannosaurus rex was the peak of tyrannosaur and carnivourous dinosaur evolution, it was an evolutionary dead end, with its closest descendants being birds, because of the K-T Extinction caused by a massive asteroid or comet.

Of the 31 specimens found, the most famous, most complete, and largest T. rex skeleton on display is Sue, a 42 foot (13 m) long Tyrannosaurus found in the badlands of South Dakota in 1990 by Susan Hendrickson. Sue's the most complete skeleton of any tyrannosaur, and was auctioned off in Washington D.C. for over $8,000,000. The skeleton is now on display in the Field Museum in Chicago, Illinois for everyone to see, but its

skull is on a seperate case because it was too heavy to put on the actual skeleton, so they made a lighter replica and put it on the frame instead. Sue was named after the paleontologist who found it, but scientists aren't quite sure what its gender is. Not only is Sue the most complete and largest displayed T. rex, but it's also the oldest, dying at the age of 28. This seems to suggest tyrannosaurs grew continuously as they aged. Sue has given the most information of any T. rex skeleton yet, and is one of only a few Tyrannosaurus with a complete skull and forelimb. Despite being so large and ferocious, Sue's bones have shown just how tough its life was. It has healed rib fractures, healed infected
File:Tyrannosaurus Sue.JPG
broken leg bones, bites taken out of its vertebrae by other tyrannosaurs, and even arthritis. Another significant specimen found by Dr. Jack Horner, curator of the Museum of the Rockies in Bozeman, Montana, shows medullary tissue in the bone sctructure, tissue only found in modern-day pregnant birds. This is a very significant find because it's the first dinosaur ever discovered to show that dinosaurs (or at least coelurosaurs) had a birth cycle much closer to birds than previously thought, and also shows the first proven male or female Tyrannosaurus. Some other famous T. rex specimens are Stan, Thomas, Samson, and Jane.

Popular Culture

  • Tyrannosaurus is possibly the most famous of dinosaurs, ever since its discovery in 1902, it's been extremely popular, and it's almost always the first dinosaur that comes to mind when the word "Dinosaur" is mentioned, being one of the only dinosaurs where nearly everyone actually fully knows its name.
  • It is shown in every single dinosaur movie involving dinosaurs barring Walking with Dinosaurs: The 3D Movie. Its first appearance in the movies was in the 1925 film The Lost World, where it battles an Agathaumas.
  • It also played an important role in the 1990 book and 1993 famous movie Jurassic Park.
  • It also appeared in the sequel to 1997 Jurassic Park The Lost World: Jurassic Park. In this movie it rampaged through San Diego in an attempt to find its offspring.
    File:Tyrannosaurus rex bites Spinosaurus.jpg.jpg
  • It later appeared in the 2001 third sequel of Jurassic Park Jurassic Park 3. Here a sub-adult male Tyrannosaurus ate the remains of a Parasaurolophus and was killed by a fully grown adult Spinosaurus.
  • It also starred in an episode of the reknown documentary series Walking With Dinosaurs, and two shows from the same producers called Prehistoric Park and Primeval.
  • It also appeared in several episodes of the well known documentary Jurassic Fight Club, Animal Armageddon, Dinosaurs Decoded, Truth About Killer Dinosaurs, T. rex: New Science, New Beast, Prehistoric Denver, Dino Gangs, Ultimate Guide: Tyrannosaurus rex, Last Day of the Dinosaurs, and Clash of the Dinosaurs.
  • Another documentary it's been in is Dinosaur Revolution, where it showed how a family of tyrannosaurs lived until the K-T Extinction.
  • File:Tyrannosaurus new.png
    A Tyrannosaurus named Heart serves as the main protaganist of the 2010 anime film You Are Umasou and as antagonists in the books and TV shows of Dinotopia.
  • It's also featured in many games involvong dinosaurs, including all Jurassic Park Games, all Dino Crisis Games, and also Primal Carnage. It has also been featured in the Fossil Fighters series, appearing on the cover of the seque, Fossil Fighters Champions. Tyrannosaurus appears in Turok, as there is a T. rex that has grown to intense size, as it is nicknamed "Mama Scarface", for the scar on its right eye.
  • It was also in the IMAX movie, T. rex: Back to the Cretaceous. A giant robotic Tyrannosaurus is piloted by the red ranger in both the Mighty Morphin' Power Ranger series and the Dino Thunder series.
  • Tyrannosaurus is also the antagonist of nearly every episode of The Land Before Time.
  • It also starred in a Hollywood parody called T. rex: A Dinosaur in Hollywood, where they talk about how T. rex gained its fame throughout its discovery to modern-day movies, and also was in the Disney movie Fantasia where it fought a Stegosaurus while the song "The Rite of Spring" played.
  • It was also a main source for evolution in many episodes of the History Channel show Evolve.
  • It also served as the main dinosaur in a documentary called Tyrannosaurus Sex, where they talked
    File:Tyrannasaurus Spitter.gif
    about how T. rex and other dinosaurs may have reproduced.
  • Tyrannosaurus was also an antagonist in the comedy movie Land of the Lost and the Korean film Speckles: the Tarbosaurus, where it was named "One Eye" and killed the family of the main character "Speckles", a Tarbosaurus.
  • Jack Horner also talked about T. rex and why he believes it's mostly a scavenger in Valley of the T. rex.
  • Tyrannosaurus also made a short cameo in Dinosaur Planet.
  • A T. rex named Rex is the main protagonist of We're Back! A Dinosaur's Story
  • T. rex is one of the main dinosaurs in the Dinosaur themed restaurant T-Rex Cafe located in Disney World and Kansas City. It's mascot is also a T. rex named Dexter.
  • File:T-Rex 3.png
    A T.rex named Grumpy by the characters appeared in the 2009 film Land of the Lost.
  • Tyrannosaurus rex is seen as The Disneyland train travels to the Primeval World diorama. In it, he is seen reenacting his battle from Fantasia.
  • In Walt Disney World's Epcot there is a ride known as Ellen's Energy Adventure staring Ellen DeGeneres and Bill Nye the Science Guy, who explore the world of energy, including the use of fossil fuels. During the ride, Bill Nye brings DeGeneres "back in time" to the age of dinosaurs to explain the origin of fossil fuels. During this portion of the ride, several dinosaurs can be seen that are similar to the ones during Fantasia's The Rite of Spring. Most notably, there is a large Tyrannosaurus attacking a Stegosaurus over a cliff. This is obviously in reference to Fantasia. At Downtown Disney's T-Rex Cafe, there is a large Tyrannosaurus with his young.



Websites: (Username: University Password: Trojans)


Walking with Dinosaurs Walking With Beasts

Dinosaur Revolution

Clash of the Dinosaurs

T. rex: New Science, New Beast

Prehistoric Park

Jurassic Fight Club

Dinosaurs Decoded

The Truth About Killer Dinosaurs

Animal Armageddon


Dino Gangs

Ultimate Guide: Tyrannosaurus rex

Prehistoric Park

The Last Days Of The Dinosaurs

Tyrannosaurus Sex

T. rex: Back to the Cretaceous

T. rex: A Dinosaur in Hollywood


Prehistoric Denver

Valley of the T. rex

T. rex: Warrior or Wimp?

Bizarre Dinosaurs

Dinosaurs Unearthed

Dinosaur 13


The Complete Guide To Prehistoric life ;by Tim Haines and Paul Chambers

Ultimate Book of Dinosaurs; by Paul Dowswell, John Malam, Paul Mason, Steve Parker

Dino Wars; by Jinny Johnson, consulted by Michael J. Benton

Vertebrate Paleontology; by Michael J. Benton

How do We Know Dinosaurs Existed; by Mike Benton

The Audubon Society Pocket Guides Familiar Dinosaurs; by Alfred A. Knopf

Uncover T. rex; by Dennis Schaz

The Dinosaur Heresies; by Robert T. Bakker

Life-Sized Dinosaurs; David Bergen

Rise and Fall of the Dinosaur; Joseph Wallace

Tyrannosaurus Sue; Steve Fiffer

See also

Trex gallery

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