There were plenty of giant animals around during the Age of Dinosaurs. This epoch ended 65 million years ago when a huge meteor hit the Earth and ushered in our current Age of Mammals. The Age of Dinosaurs saw herds of Triceratops move through what would become the western United States, eating ferns, cycads, and other exotic Cretaceous plants. Tyrannosaurus rex, one of the most powerful, huge meat-eaters ever to live on Earth lived in the same place...