Vertebrates dominate the vast majority of present day ecosystems, but have an obscure early history with the fossil record indicating the prevalence of jawless ‘agnathans’ for the first 50 million years of their evolution. The anatomy of these early jawless vertebrates, and in particular how they fed, is of great importance to understand the origins of modern vertebrates and the acquisition of evolutionary novelties such as the head. However, previous studies have largely been limited to observations of the surface of the fossils, including mechanical or acid preparations. The application of propagation phase contrast synchrotron X-ray μCT imaging of specimens from the Ordovician and Devonian will enable the evaluation some of the key proposals of the ‘New Head’ hypothesis and the subsequent evolution of jaws, with a particular focus on the development of the cranium and associated feeding mechanisms.