Most readers are familiar with small lizards they see at the zoo and the fluffy pet mammals they may keep, from dogs to bunnies. But in prehistoric times, some reptiles and mammals were enormous, terrifying creatures! In this volume, readers can discover reptiles, mammals, sea creatures, and birds of the prehistoric era they may have never heard of. Fascinating details accompany illustrations of what each creature was likely to look like, and what it would have eaten, where it lived, and its size. A concluding timeline aids understanding of prehistory.