Mammals are only the living representatives of an incredibly diverse group known as Synapsida whose history goes back over 310 million years. Given the depth of this evolutionary history, it is difficult to truly appreciate the uniqueness of mammals without understanding the full context that gave way to the group. For example, living mammals have evolved to fill every conceivable ecological niche on the planet – mammals can swim, fly, run, burrow, and everything in between. My research helps to pinpoint when this astounding breadth of form and functional originated and contextualizes this group among a larger mosaic of tetrapod evolutionary history. My work has shown that the origins of synapsid diversity lies extremely far back in time, likely in the group’s earliest radiations during the Permian and Carboniferous periods of the Phanerozoic. Through a combination of linear and multivariate geometric morphometric analyses on the appendicular skeleton, primarily on the limbs and girdles, I work to critically test the geologic and phylogenetic timing of the massive diversity that many tetrapod groups, both living and extinct, are known for.