- "Tyrannosaurus was a bipedal carnivore with a massive skull balanced by a long, heavy tail. Compared to the large and powerful hind limbs, Tyannosaur's forelimbs were small, and bore two clawed digits used for holding struggling prey to be dispatched by the massive jaws. It was one of the larger known land predators that roamed the Earth."
- —Loading screen description.
It is encountered twice in the campaign, once in its respective mission "The Tyrant King" and once more in "Enter: Spike", where it falls victim to the main antagonist, the Spinosaurus, known as Spike.
The T. rex appears in two variants, both function the same, but feature differing aesthetics. The first encountered variant is the green variant, which has dark forest green skin. The second, is a blood-red Tyrannosaurus with orange-yellow stripes. In the Wii version of the game, there is no red T. rex, instead there is another green one.
The Tyrannosaurus body is much like that of any average tyrannosaur, featuring the large skull, the two fingered claws it's famous for, and a distinctive roar, that only this dinosaur possesses, in game.
Its body size is average for its species, with a height of approximately 20 feet, and a length of 40 feet. They have yellow eyes and they also have a ridge of small spines running down the base of their skulls, to the end of their tails.
In gameplay, these dinosaurs don't show much versatility in combat. They possess only one attack, and the player is constantly stationary, leading to a rather static fight.
When the boss battle starts, the T. rex will run forward towards the player, before roaring, and then lunging at them, trying to bite the player to death. The bite will kill the player in two hits on the game's normal difficulty, and in one on the game's hard difficulty. Upon being injured enough, the dinosaur will slip, fall and then run off, leaving the Pterosaurs to do the work for the creature.
When combating these creatures, Adrenaline Mode will help the player immensely, as it can reveal internal organs, which, upon being hit, will amplify damage done to the T. rex.
It will take about four runs for the T. rex to finally fall, before the second appears, the same strategy should be employed for the second appearance.
The T. rexe's health pool is massive, and while being numerically unknown, is able to take mass amounts of gunfire from the player's .50 turret.
after defeating Spike, a T.rex will arrive to fight him but he is then killed in a similar fashion to the T.rex from jurassic park III