Ptilodontidae is a family of primitive mammals within the extinct order Multituberculata. Representatives are known from the Upper Cretaceous and Paleocene of North America.The Ptilodontidae family was originally named Ptilodontinae and classified as a subfamily by Edward Drinker Cope in 1887. It was amended by Gregory and Simpson in 1926 to its current status.In addition, Cope mistakenly classified the Ptilodus genus as a marsupial.