This series of books look in detail at those animals that are now extinct and those that are endangered. What is extinction? And when does an animal become classified as endangered? Starting with the known mass extinctions including the dinosaurs, the series looks at the five main biomes of the world and explores the extinct and endangered animals in each. We look optimistically at what can be done to save the precious species. PREHISTORIC BEASTS: We look at certain dramatic extinctions caused naturally by such things as volcanoes, ice sheets and meteorites. At one point in time the North American plains were teeming with mammoths, camels as well as sabre-toothed cats and long-legged bears. We look at where they and the flightless birds went.