Read about the largest mammal ever to walk on land, about a tiger with teeth longer than your hand, and about a horse the size of a dog!Mammals -- some strange and some strangely familiar -- ruled the earth after the dinosaurs. These compelling creatures are introduced to beginning readers by the team who created The Day the Dinosaurs Died. Paleontologist Charlotte Lewis Brown's easy-to-read and fascinating descriptions of these ancient animals are brought to life in Phil Wilson's detailed illustrations.