Step back in time and discover a world where whales once walked, crocodiles were warm-blooded and snakes had legs! Meet terrifying giant birds, and tiny elephants living on islands in this fascinating creature guide like no other. Learn how whales once walked on four legs before taking to the oceans; how dinosaurs evolved into birds; and how the first cats were small and lived in trees.

Includes index.

Introduction : What is evolution? -- A timeline of life on Earth -- Working out the evolutionary tree -- Nature's big experiment -- When fins became feet - When lizards went back into the water -- When reptiles grew wings -- When crocodiles ruled the world -- When snakes had legs -- When birds had teeth -- When whales walked on land -- When rhinos grew huge -- When elephants were tiny -- When birds stopped flying -- When mammals began to hunt -- When primates came down from the trees -- Evolution continues.