DESC: Did you know that mammals can range in size from just a few ounces to more than 200 tons? Learn the two subclasses of the class Mammalia and the characteristics common to all members of it. Discover which mammal is the only one capable of flying. This informative title introduces koalas, monkeys, orangutans, armadillos, rabbits, prairie dogs, beavers, mice, dolphins, blue whales, and much more.