Synapsids, the precursors to modern mammals, undergo a strange transition in their tails, where the earliest members of the group have relatively long tails compared to the rest of their body, while the later groups, such as the therapsids, have significantly shorter tails. While this transition has been previously noted in the literature, there has been little to no research attempting to explain why this trend takes place, what the evolutionary drivers behind it might have been, and if there was a clear functional difference between tail lengths within the group that might explain the discrepancy. This question is the focus of my PhD research at the University of Oxford.