Mammals were scrambling around during the Age of Dinosaurs and they're usually seen as small, shrew-like animals waiting for their chance to become diverse. But recent research, including three new fossils discovered in 160 million-year-old rocks from China, show our mammalian cousins were ecologically specialized creatures. Arboroharamiya was climbing through the trees while Megaconus scrambled along the ground, and Rugosodon lead the way for the diverse radiation of mammals called Multituberculates. In this episode, Matt tries to show Adam why these new, tiny mammals are so interesting and where they fit into the mammalian tree of life.