Tyrannosaurus rex
Name meaning:                      Tyrant Lizard King
Area:                                    Canada and western USA
Period:                                      Late Cretaceous, 68 to 66 million years ago
Diet:                                                         Carnivore
Lenght:                                     12 meters (40 ft)
Height:                                         4 meters (13 ft)
Weight:                                                      6-9 tons (12,000 to 18,000 pounds)

Tyrannosaurus rex (pronounced tie-RAN-oh-SOR-us REX) is a tyrannosaurid theropod dinosaur that appeared roughly 68 million years ago and went extinct in the K-T extinction, about 66 million years ago in North America. Tyrannosaurus is one of the heaviest land predators of all time, and is the largest known land predator ever to roam the Northern Hempisphere. 


The overall size of Tyrannosaurus is somewhat debated, but the most dependable estimates put it in the 40 foot (12 meters), 6-9 ton (12,000 focus 18,000 lb) range.  The most complete Tyrannosaurus specimen, FMNH PR 2081 (nicknamed 'Sue', after her discoverer, Sue Hendrickson) measures 40 feet (12.3 meters) in length and is 13 feet (4 meters) tall at the hips.

The lowest size estimates for T.rex are about 36-37 feet (11-11.3 meters) in length and short 5 tons (10,000 lbs) in weight. Some specimens including Thomas, Devil Rex, C-Rex, F-Rex, and UCMP 118742 shows possibilities of even bigger sizes than Sue. Some have even been estimated to be 13 meters (43 ft) in length! The problem with these specimens is that they are very fragmentary; thus showing inconclusive evidence.

T.rex model by Saurian dev team

T.rex compared with an average sized Human.

Hunting and DietEdit

The question of whether T.rex was a hunter or scavenger has been the subject of debate for decades, though most scientist today agree that T.rex may have been an opportunistic predator: hunting when necessary, and scavenging when given the opportunity. A hypothesis by Philip Currie suggests that T.rex hunted in packs, where the agile juveniles would chase prey right into the jaws of the larger, more powerful adults. Currie's hypothesis however has been criticized by the scientific community due to it's lack of solid evidence in the fossil record.

Tyrannosaurus' prey varied from large hadrosaurs to ceratopsians, ankylosaurs, sauropods, and practically any animal in it's environment it could get it's jaws on. It had to compete with Nanotyrannus, Dakotarapto, and Alamotyrannus.


While early tyrannosaurs such as Dilong and Yutyrannus are known to have had feathers as adults, it is also reasonable to assume that T.rex (and other large Tyranosaurs) may have had feathers. Multiple theories suggest that juvenile T.rex had feathers, but lost them upon reaching maturity. However this could be proven otherwise due to the fact that Yutyrannus (a large Tyrannosaur) sports feathers. With the usage of phylogenetic bracketing, we can safely say that Tyrannosaurus rex may have had feathers. 
T.rex infograph by Suarian dev team

An infograph explaining the possible integument of T.rex.

Hell Creek's annual temperature was around 7 to 11 degrees Celsius during the dry season; around the same temperature as the Liaoning Province that Yutyrannus lived 61 million years earlier. The temperate area during the dry season would have allowed Tyrannosaurus to have a coating of feathers without overheating since feathers can insulate heat for the animal during such time.


Tyrannosaurus' speed is a heavily debated subject. Estimates as low as 5 mph have been suggested, as well as estimates up to 45 mph.  The most generally accepted top speed for an adult T-rex is in the 10-15 mph range for a short period of time. However, juvenile T.rexes probably could've ran faster. Due to their shinbones being proportionately longer than their thigh bones in juveniles, they could've achieved a top speed of a whopping 30 mph for short distances; slightly faster than Usain Bolt. Who's current speed record is 28 mph.


At 3 feet (1 meter) long, the arms of T.rex are tiny compared to the animal's 40 foot body. Despite their small size, studies suggest that the arms of an adult T.rex could lift some 200 - 450 pounds. Scientists are unsure about what the arms were used for; suggestions include mating, feeding, and combat.  Whether or not T.rex utilized its arms at all remains a mystery.

Bite ForceEdit

Tyrannosaurus had a skull reaching 1.3-1.5 m long. Its massive jaws were backed by huge muscles that allowed it to bite down with bone-crushing force. Minimally, Tyrannosaurus had a bite force of 1,800 pounds (816 kilograms) per square inch; with an estimated maximum bite exceeding 12,800 pounds (6.4 tons) per square inch.  

T-rex Bite

Computer model of T.rex's bite force

T.rex has the strongest bite force of any land animal (other predators had bite forces comparable to or exceeding T.rex's, but they were mainly aquatic or semi-aquatic animals), ranking among one of the strongest in the animal kingdom.

In Popular CultureEdit

Tyrannosaurus rex is perhaps one of the most famous and feared dinosaurs ever to be discovered, and has been featured in many movies, books, documentaries, and TV shows. One of its most famous film 

Roaring rex

T.rex from Walking With Dinosaurs

roles was in the widely popular Jurassic Park trilogy. Scientific documentaries featuring T.rex include When Dinosaurs Roamed America, Walking With Dinosaurs, and Jurassic Fight Club.  


See AlsoEdit