CONTENTS ONE Out of the Water 4 SIX Salamanders 66 TWO Becoming Tetrapods 16 SEVEN Caecilians 80 THREE Ancient Amphibians 28 EIGHT Studying Amphibians Today 90 FOUR Early Frogs 42 FIVE Modern Frogs 54 Essential Facts 100 Glossary 102 Additional Resources 104 Source Notes 106 Index 110 About the Author 112
CHAPTER ONE Out of the Water Approximately 360 million years ago MYA in what is now Greenland a brawny animal about three feet 1 m long swam in a river Ichthyostega looked like a short alligator or a large iguana but it had a thick neck and a wide head Using its four squat limbs and tail it propelled itself through the currents eating small fish and breathing with its gills Sometimes it walked along the bottom of the river and sometimes it left the river entirely and stepped onto land How did it do this Why did it leave the water Perhaps there was a long rainy period and the animal found itself in the shallow waters of a floodplain Maybe it just wandered onto dry land An artist depicts what Ichthyostega may have looked like
