The time is the Pleistocene epoch, about 2 million to 10,000 years ago. Continent-size ice sheets cover 30 percent of the earth's landmass, and strange creatures rove the landscape. Ice Age Mammals of North America transports you to the world of saber-tooth cats, woolly mammoths, four-hundred-pound beavers, and twenty-foot-tall ground sloths. Illustrated descriptions of the animals form the heart of the book and the final chapter explores why so many of these animals were extinct by the end of Pleistocene time.