Life on Earth can be traced back over three billion years into the past. Many examples of the Earths former inhabitants are to be found in rocks, preserved as beautiful and fascinating fossils. The earliest life forms were bacteria and algae; these produced the oxygen that enabled more complex life forms to develop. About 600 million years ago multi-cellular organisms appeared on Earth, some of which could protect themselves with hard parts such as shells. Many of these life forms were readily fossilized and are used to subdivide geological time. Numerous species have evolved and most are now extinct. Lineages can be traced and extinctions explained as a consequence of terrestrial and extra-terrestrial events.Now in a revised, updated and expanded Second Edition Introducing Palaeontology will continue to provide readers with a concise and accessible introduction to the science of palaeontology.