Dinosaurs ruled the Earth for nearly 165 million years, living in widely different climates - from the cool Arctic to the hot tropics - on what is now all seven continents. When dinosaurs first appeared, there was a single warm and wet super continent called Pangea that subsequently split apart, separating and causing evolutionary changes among dinosaur groups. The remains of plants and pollen found with dinosaur fossils tell scientists much about those dinosaurs' habitats. In many cases, these ancient environments are as long gone as the dinosaurs themselves. The Sahara was a forest during the Jurassic era, and western North America was an ocean. Something - probably an asteroid impact - killed off land-living dinosaurs 66 million years ago. Many of the birds (which evolved from dinosaurs), reptiles, and mammals that existed at the time survived and flourished following the original dinosaurs' disappearance. For ages 7 and up. WARNING: CHOKING HAZARD - Small Parts. Not for children under 3yrs.