Basal non-placental eutherians are a weird off-shoot of the extant group of eutherians, which are typically known to be placental mammals. One of the best known of those mammals was the Cretaceous scamperer Cimolestes. A North American fossil mammal of the trees the size of a rat, Cimolestes is thought to have chased insects around the arboreal habitats it called home and, probably often, temporary forays into the undergrowth below. Either way, Cimolestes may have been in a transitional place in the fossil history of mammals between marsupials and placental mammals. Additionally, look at how fuzzy and mammaly this animal has finally gotten to be. About time that mammals have started to look like mammals in this jumpy history we have been following lately!