The transition of fins to limbs is one of the most significant in the history of vertebrate evolution. These were the first steps that would eventually allow tetrapods to go on to dominate so many terrestrial ecosystems. Fossils that help fill the gaps in this crucial time are invaluable, so how do we go about finding them and what happens when we do discover one? Joining us to give an overview of some of the fossils involved in this transition, and to provide insights into the fieldwork that goes into finding them, is Dr Ted Daeschler, Academy of Natural Sciences of Drexel University.