The T-rex is one of the deadliest animals in the game,as well as being the most famous of all dinosaurs.
Tyrannosaurus Rex is mainly called "A Roadrunner From Hell" by most paleontologists. Tyrannosaurus Rex means "Tyrant King". The T-Rex appears in the game 3 or more times, with three different rexes, two green ones and one red. The first and the second one are in a boss battle where Dylan is on a heavily loaded turret,you then are in a face to face battle with a green rex, when it sudden leaves and comes back, only to leave you with a flock of Pterosaurs swooping down at you. When you defeat the green T-Rex,and you think its over,a second T-Rex comes running right at you.This T-rex is Red,instead of Green.It is not known for sure if the Red T-rex is another gender,or another variant of T-rex.
Later in the game when you are fighting the Spinosaurus,when it's nearly in the end of it's health,another T-rex comes in and the two titans fight.The Spinosaurus manages to break the T-rex neck quite similar to the movie Jurassic park III,killing it.