The Tyrannosaurus Rex, or T-Rex was a species of carnivorous dinosaur. It lived at the end of the reign of the dinosaurs and it's name means "terrible lizard." Like the rest of the dinosaurs, the T-Rex was killed off once and for all when a meteor hit planet Earth 65 million years ago. In Ook and Gluk: Kung Fu Cavemen from The Future Mog Mog and her daughter Lily are T-Rexes that have befriended Ook and Gluk. In the 10th Captain Underpants book, Tippy Tinkletrousers rides one to capture the five protagonists and after a meteor hits the earth and one of Tippy's clones is killed, the T-Rex is killed along with the rest of the dinosaurs.