Extant mammals move in many ways, from walking and running to swimming and climbing. How can we compare locomotion across taxa, both extant and extinct, to understand how these different styles of movement evolved through time? For any organism, locomotion is a complex combination of (1) its capacity for movement as constrained by its morphology, (2) the behaviors that the organism employs within its biomechanical limits, and (3) the habitat(s) through which the organism moves. Traditionally, this complexity is collapsed into several broad locomotor categories, like arboreal, terrestrial, or cursorial, because postcranial fossils and modern ecological data are often extremely limited. I will present two cases where exceptional data allows for more nuanced comparison of locomotion across mammals. First, in extant mammals, GPS tracking data records locomotor behavior: how far and where individuals choose to travel. I used data from an online database, Movebank, to measure the daily distance travelled by different species of mammals. I took skeletal measurements from specimens in the University of Michigan Museum of Zoology (UMMZ) for the same species to look at how morphology corresponded with distance moved. For the second case, I will discuss the preservation of partial skeletons in the Eocene Bridger Formation of Wyoming. Often, postcranial fossils are isolated bones without good identifiers and locomotion must be inferred from the function of a single bone or joint. The Bridger Formation, however, has produced a number of exceptional partial skeletons, including for “archaic” mammals, groups which have gone completely extinct. I will show how these can be used to examine the interaction between different elements of the skeleton in relation to locomotion.