A giant meteor blasts an enormous crater into Earth's surface, causing the end of what scientists call the Age of Dinosaurs. Here are the most recent theories about the history of dinosaurs, along with amazing facts about dinosaur discoveries. Gail Gibbons discusses the Triassic, Jurassic, and Cretaceous periods and many of the non-bird dinosaurs that lived during each of those times. Each dinosaur is described with lots of detail for aspiring paleontologists, bringing to life again these magnificent creatures.