T. rex poster
Creature information
Scientific name : Tyrannosaurus rex
Time period : Late Cretaceous
Primary diet : Carnivore
In the documentary
Fatalities caused : One Edmontosaurus
Tyrannosaurus rex (or T. rex for short) was a species of large theropod dinosaur that lived during the very end of the late Cretaceous period.


T. rex was the 4th largest land predator ever at 13 meters (43 ft) long and 7 tons. Carcharodontosaurus, Giganotosaurus,and Spinosaurus were all bigger. Evidence has been found though that Tyrannosaurus rexes often fed on ceratopsids. It is now clear that T. rex is both a predator and a scavenger. They were also potential cannibals, eating their own kind.

Michael Crichton, the author of the novel version of Jurassic Park, called the creature Tyrannosaurus Rex, or for short T-Rex. In most media and film or television subtitles, the creature is called T-Rex or T. Rex.

However popular, this spelling is wrong. Dinosaur names are created according to the rules of the Binomial nomenclature. Binomial names consist of two parts. Tyrannosaurus is the genus name, while rex is the species name. Genus names must be written with a capital letter but the species name don't. In many cases the (mostly long names) are shortened. In that case, only the first letter of the Genus name is written. That letter is followed by a period, not a "-". All binomial nomenclatural taxon should be written in italics.

Therefore, the taxa should be written like this: Tyrannosaurus rex or for short: T. rex.

In When Dinosaurs Roamed AmericaEdit

Rex face

Tyrannosaurus rex

In the late Cretaceous segment, Tyrannosaurus is first seen stalking some Triceratops, Edmontosaurus, and Ornithomimus. Later, a young T. rex charges at a herd of Triceratops but the herd fend him off. He soon sees a Quetzalcoatlus feeding on a Triceratops carcass. The prince soon chases the pterosaur to hunt him, but the Quetzalcoatlus escapes. He walks away and soon walks home in the dark, thanks to his night vison. We see a pack of T. rexes made of the prince's family. We see that the mom that has a twisted ankle, but when the kids are play-fighting, 1 of them hits her ankle, making her roar in pain. Then the pack leave. The next morning, the pack of T. rexes is hunting the herd of Edmontosaurus. The prince chases them into the trap with his two larger siblings coming out, surprising 3 Edmontosaurus. Soon the mother attacks and kills 1 of the hadrosaurs. She roars into the air in victory. While eating, she sees an asteriod coming to the earth. It hits the earth, causing the Tyrannosaurus rexes to ditch their kill. Lastly, after the extinction, some mammals called Purgatorius crawl on a T. rex skull. 


  • Evidence that females were bigger than males isn't solid anymore.
  • They are depicted featherless. In reality, they probably had feathers when they were very young. Although there are no really young T. rexes in this program, the juveniles should have been at least been molting their feathers off.
  • Tyrannosaurus's hands should be facing inwards, not downwards. Also they couldn't pivot without breaking them. The pivot error is seen when we meet T. rex.
  • Recent studies showed Tyrannosaurus had strong lips.
  • Tyrannosaurus probably did not roar but probably coos.
  • Tyrannosaurus was shown a little less Bulky then in reality



Mother T. rex with a dead Edmontosaurus

  • It is the most famous and popular of all the dinosaurs, known for it's cultural impact, even more than Brontosaurus(who is now its' own genus again).
  • It is also called the King of the Dinosaurs (in fact its species name Rex means "King" in Latin).
  • Most footage of T. rex from Valley of the T. rex is used from When Dinosaurs Roamed America.


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