Stones and Bones

For three billion years, the only life forms on this planet were tiny, single-celled bacteria. But then, about 500 million years ago, something amazing happened. The atmosphere filled with oxygen and life exploded, with many different kinds of creatures coming into existence. Scientists called palaeontologists study fossils to find clues about how the earth and all the living things that inhabit it have evolved over time. From primitive sponge-like creatures to huge dinosaurs, fossils tell us amazing tales about how life has changed in the past and might change in the future.