Paul Barrett – Natural History Museum. Dinosaurs are justly famous for their huge sizes and total domination of Jurassic and Cretaceous terrestrial ecosystems. However, they started their evolutionary journey as small, rare animals that were overshadowed by our own early ancestors and other earlier-appearing reptile groups. Until recently, palaeontologists had relatively information on dinosaur origins, but new discoveries are starting to shed much-needed light on when dinosaurs appeared, how they started to explore new ways of life and, ultimately, how they went on to become some of the most successful animals of all time. This talk will outline our current knowledge of dinosaur origins, drawing on the latest findings from both the lab and field.