Dinosaurs are primitively bipedal, but various dinosaur groups (e.g. ankylosaurs, ceratopsians) became secondarily quadrupedal.
During the course of this NERC-funded project, Paul Barrett and Susannah Maidment are aiming to investigate the factors that may have led to this transition, including body size, changes in body proportions and the development of extensive armour and cranial ornamentation.