Ichthyosaurs are large marine reptiles that existed for most of the Mesozoic Era. The most familiar forms superficially represent dolphins, but some earlier ichthyosaurs were more eel like. They could attain huge proportions, with some genera reaching up to 21m long. They were active predators feeding on belemnite, fishes and even other marine reptiles! In this episode, we talk to Dr Ben Moon and Fiann Smithwick, researchers at the University of Bristol, UK. Both have recently been involved in producing a documentary with the BBC entitled ‘Attenborough and the Sea Dragon’, so we have used this as an opportunity to discuss in great detail what ichthyosaurs are and get insights into the kind of work required to produce such a documentary.