Sharks have an ancient pedigree extending more than 400 million years, but we know surprisingly little about their origins and subsequent evolution. Dr. John Maisey studies extremely rare shark fossils, including some of the earliest shark-like fishes, in order to discover answers to these mysteries. An important aspect of his work involves the use of high-resolution CT-scanning to reveal the internal structure of the braincase in both extinct and modern sharks. He is now collaborating with colleagues around the world on the earliest shark fossils, from the Devonian of Bolivia, South Africa, Canada and Western Australia.