Life was often difficult for the Iguanodon. It couldn't fight larger dinosaurs with sharp teeth or pointy spikes. Even thunderstorms could pose a danger. Learn how Iguanodon survived on Earth for nearly twenty million years and why its fossils have been discovered all over the planet. Additional features to enhance comprehension include informative sidebars, a glossary of key words and phrases, sources for further research, a Did-You-Know section, and an overview of the geologic time scale.