A bipedal dinosaur with a massive jaw filled with giant teeth.

The ground beneath you shakes. A Tyrannosaur passes through the portal into the arena, and the crowd thunders with applause. - Tome of Encounters (RPA-SQ1) 

Tyrannosaurs have difficulty changing their direction after beginning a charge;

Watching the other gladiators face off against the beast, you notice that the creature is able to sprint forward with great speed but is considerably slower when she needs to turn around. She should have great difficulty responding to an attack from behind. - Tome of Encounters (RPA-SQ1)

A Tyrannosaur is brought to the Colosseum of Ashes:

• Rally the guards to assist you:
  • You lead them to victory.
  • You fail to band them together and suffer grave injuries.
• Let the guards lead the charge to find its weak point:
  • You figure out a way to take her down.
  • You fail to come up with a good strategy and suffer grave injuries.