The tyrannosaurus rex, according to science, lived during the Cretaceous., 68 to 66 million years ago. It is one of the most popularly represented dinosaurs that has been featured in movies. It’s ominous size and formidable set of teeth are the source of many nightmares. Tyrannosaurus rex means “tyrant lizard.” It was a bipedal carnivore. It walked on two legs and ate meat. It was about 40 feet long and about 12 feet at the hips.