The ancient elasmobranchs (sharks + rays) have the potential to provide great insight into evolutionary processes over large timescales, but this potential is limited by a poor understanding of the relationships between living and extinct groups and the timing of major divergence events. In this project I will address these knowledge gaps by combining new 3D tomographic data on key Mesozoic elasmobranch body fossils with genomic and anatomical data from their living relatives. I will then use this and a dataset of 3D elasmobranch lower jaws to investigate the dynamics of elasmobranch macroevolution, using the rate and mode of lower jaw shape evolution as a case study. In doing so I will build on my existing background in palaeobiology and 3D methods by learning new skills in genomics-based phylogenetics and 3D geometric morphometrics, while developing my skills as a supervisor, communicator, and leader. These new skills, along with the scientific groundwork laid by this project, will give me the tools to pursue an independent programme of research in the longer term, investigating the early evolution of elasmobranchs by combining data from animals both living and extinct.