We live on a beautiful and ever-evolving planet — both in its geography, living and extinct species. Whether you study palaeontology (Brits & Canadians) or paleontology (USA and much of the rest of the world...) much of our Earth's history is dramatic in its changing role call for living and extinct species. We have had Five Mass Extinction Events in the Earth's 3.5 billion year history. These are cataclysmic events where more than 75% of the Earth's species have become extinct. The most recent of these is the Cretaceous mass extinction where we lost the dinosaurs, our mighty marine reptiles and beloved ammonites. The loss of the dinosaurs gave rise to the age of mammals and eventually, the world you and I know today.