In the wake of the Permian mass extinction, the prehistoric world was ripe for the taking. All the world’s landmass was consolidated into the single supercontinent: Pangaea. With no seas standing in their way, new terrestrial animal lineages were able to exploit new habitats all across the globe. Archosaurs, meaning ‘ruling reptiles’, came to dominate Triassic ecosystems. However, dinosaurian archosaurs were not the top predators. Instead, crurotarsans sat undisputed at the top of the food chain. The first theropods were small, but agile carnivores, and although they started out as the Darwinian equivalent of the mail room clerks, by the next geological period (the Jurassic), they were large and in charge. In Lesson 2, we will introduce you to some of the earliest theropods, and explore the anatomical secrets to their survival and eventual success. We will also meet the largest land predators of all time.