One of the largest predatory dinosaurs of all time, Tyrannosaurus was a deadly predator with a massive skull and a bite more powerful than any land animal before or after it. Tyrannosaurus was shown to hunt its prey using stealth and cunning surprising for such a large animal. (Extinction Event) However, as seen with the T. rex that appeared during Convergence, Tyrannosaurus would lose its stealth when in a panic. (Episode 5.5)
Once it locked its sights on a prey item, Tyrannosaurus would pursue its victim swiftly and silently despite its large size, with little chance of escape. T. rex was so deadly that its very presence could be disturbing to some smaller animals, who would go into a state of complete silence when the predator was nearby. (Extinction Event) Tyrannosaurus was a very resistant creature, as it took nearly a dozen direct EMD shots to knock a T. rex out. (Episode 5.5) Tyrannosaurus apparently also had a very strong metabolism, as the Baba Yaga T. rex recovered from a tranquiliser within minutes. (Extinction Event)
At least two Tyrannosaurus came through an Anomaly to the forests of Siberia in the 20th - 21st Century, including a female referred to as Baba Yaga. The Baba Yaga T. rex wreaked havoc, killing a Torosaurus infant and eleven people in June 2008, before killing a male Tyrannosaurus which killed Medyevin.
Baby Yaga also attacked a Russian military camp and killed three of the Russian military before giving chase to Abby Maitland and Nick Cutter, who tranquilised her only for her to awake and recover within a matter of minutes. The Baba Yaga T. rex continued to live in the Siberian forests even after the forest fire.
In the Late Cretaceous, one Tyrannosaurus killed a Pachycephalosaurus directly in front of Jenny Lewis, Helen Cutter and their military escorts. Nick Cutter, Connor Temple, Abby Maitland, and a team of scientists and Russian military saw another Tyrannosaurus killing an Anatotitan in the Cretaceous.Convergence started, a T. rex came through an Anomaly into Central London in the present and rampaged through Baker Street Plaza. It ate fleeing citizens in the streets and fatally attacked Lucy. Later, when Jenna tried to return to Lucy's body, the T. rex attacked her, but Matt Anderson drove his car right in front of it, and tripped it up for a few moments before it got back up.
Jenna hid in Matt's car as the T. rex investigated, and Matt shot it multiple times directly in its mouth with an EMD until it collapsed. Presumably, the T. rex either died from the EMD shots, was put in the ARC's Menagerie, or was returned through the Anomaly.
When Tom and Duncan were under the false impression that the Home Office was cloning Dodos, Tom mentioned it as being more logical to first clone Dodos than a large and dangerous predator such as T. rex.
Matt Anderson mentioned that the largest version of the EMD, when at full power, could take down a full-grown T. rex.
- Eleven unnamed people
- One Torosaurus infant
- Nikolai Medyevin
- Three Russian soldiers
- One Pachycephalosaurus
- One Anatotitan
- One or more London citizens
- Tyrannosaurus caused more deaths than any other creature in the Primeval novels. It also caused more deaths than any other dinosaur in the entire Primeval series. However, if one included the twelve people the Spring-Heeled Jack Raptor killed in the initial timeline before Matt stopped it, then the Raptors would have killed more people than the T. rex.
- Tyrannosaurus was mentioned more times than any dinosaur. In fact, T. rex has been mentioned seven times, but has only appeared three times.
- The scene in Episode 5.5 where the T. rex tripped on Matt's car was reminiscent of a scene in Episode 3.4 where the Giganotosaurus tripped on Connor's truck while chasing him.
- Even though Baba Yaga from Extinction Event was described as a very silent and stealthy predator, the Tyrannosaurus from Episode 5.5 was very noisy in comparison, spending most of its time stomping around and roaring. This was speculated to be because it was a panicked animal in an unfamiliar environment, whereas Baba Yaga had been living in the Siberian woods for some time and had become used to it.
- The T. rex in Episode 5.5 was a different colour from Baba Yaga in Extinction Event. While Baba Yaga was described as black with darker black stripes, the T. rex in the show was lighter in color. It's possible that Tyrannosaurus rex exhibits melanism, like modern leopards and jaguars, in which some individuals are darker than others due to a genetic mutation.
- The models used for Tyrannosaurus in Primeval Series 5 promos were similar to the one used in the actual show but not identical.
- The Tyrannosaurus from Episode 5.5 was able to get up quickly after tripping. An trip in real life would've caused greater disorientation.