A T-Rex comes through an anomaly during the 2011 Convergence and rampages through London, eating fleeing citizens. It then fatally attacks Lucy and leaves her friend, Jenna, traumatized. When Jenna tries to return to Lucy's body, the T-Rex attacks her, but Matt drives his car right in front of it and trips it as it snaps its jaws towards Jenna before getting back up. Jenna hides in the car and the T-Rex bumps it until Matt shoots it until it collapses.
It is presumably either returned through the anomaly or kept in the menagerie. However, the last option is not likely because Tyrannosaurus can´t be kept in the menagerie, not only because of the high chances of an escape, but the hard time in transporting a huge T-rex to the ARC. It´s likely it was returned or perhaps killed, since Matt said in Series 4 that an EMD can take down a Tyrannosaurus Rex. It may have even been forgotten and is possibly still roaming somewhere in London killing and eating more people, like what happened to Baby Yaga.
Tyrannosaurus rex featured in the sixth and final episode of Walking with Dinosaurs - Death of a Dynasty. An adult Tyrannosaurus rex was first seen scavenging for carcasses amongst poisonous fumes. This was a male. A female had some eggs which she had to protect from egg-eating mammals likeDidelphodon. Three eggs hatched successfully out of a clutch of twelve, and three offspring reach an age of just a few months before the extinction event claims them, in which time one of them is singled out as a weakling (possibly killed by its bullying siblings) Later, the remaining pair of babies continued explore their surrounding habitat increasingly wandering off from the powerful protection of their mother. Dinilysia, a type of prehistoric snake, is seen to view seen to view the young Tyrannosaurus rex siblings as fully warm blooded animals - animals that happen to pester it incessently. At the end of the episode, just after the snake leaves, an Ankylosaurus stomps through the area occupied by the Mother Tyrannosaurus and her offspring, by complete turn of misfortune. In defence of her cowering infants, the Mother Tyrannosaurus is obliged to stand and fight, although it is stated she would usually retreat. In a fatal move, the Mother Tyrannosaurus charges the Ankylosaurus with a mighty roar that blasts through the air like thunder. Though this devastating last ditch effort would see off virtually every other Dinosaur in its habitat - even horned Dinosaurs - the impregnable Ankylosaurus has no fear and responds with a literally traumatic strike of its multi-kilogram tailclub swung at high velocity. The Mother Tyrannosaurus is mortally wounded with a shattered femur and internal organs ruptured. Its appears that after she limped away from the area (with her offspring in tow) she collapsed on the ashfields - perhaps she stumbled into this desolate area away from her usual hunting areas in the forests in a delirious state of agony - and slowly died in agony, perishing under a volcanic sunset with terrible haunting whimpers. By the next morning, her body lay strewn on the baking ashfields, her dismayed offspring standing by her colossal corpse. However, they are killed along with all giant Dinosaurs shortly after, in the blast front of the K-T Extinction Event, literally blown away. Even the huge 6 tonne giant of the Mother Tyrannosaurus is whipped into the air as though a toy. Even the mighty Tyrannosaurus rex becomes a victim of the inordinate power of conspiring geological and astronomical forces.