Stegosaurus had spikes along its back. Triceratops had long, sharp horns. Tyrannosaurus rex was enormous. Millions and millions of years before the first people lived, these fascinating creatures ruled the Earth. To find out where they came from, you have to look way back in time . . . 3.5 billion years ago! Come explore the biggest mystery of all: Where did dinosaurs come from? Read and find out!