The Multituberculata (commonly known as multituberculates, named for the multiple tubercles of their teeth) were a group of rodent-like mammals that existed for approximately one hundred and twenty million years —the second longest fossil history of any mammal lineage, after Haramiyida— but eventually declined from the late Palaeocene onwards, disappearing in the early Oligocene. At least 200 species are known, ranging from mouse-sized to beaver-sized.