Ptilodontidae
Scientific classification
Kingdom: Animalia
Therapsida
Class: Mammalia
Order: Multituberculata
Family: Ptilodontidae
Genera
  Ptilodus
  Baiotomeus
  Kimbetohia
  Prochetodon

Ref.

Ptilodontidae is a family of fossil mammals within the extinct order Multituberculata. Representatives are known from the Upper Cretaceous and Paleocene of North America.
For the technically minded, this family is part of the suborder of Cimolodonta, within the superfamily of Ptilodontoidea.

Taxon: Ptilodontidae (Cope ED, 1887) Gregory & Simpson, 1926
Remarks: This grouping has also been seen as a subfamily; Ptilodontinae (Cope, 1887). Chirogidae Cope ED, 1887 is a synonym. Despite Cope's original title, Chirox, a synonym of Ptilodus, was no more a marsupial than I am. It was much more distantly related.
Reference: Cope ED, (1887), The marsupial genus Chirox. American Naturalist, 21, p.566-567.

Page reference: Page reference: Kielan-Jaworowska Z & Hurum JH (2001), Phylogeny and Systematics of multituberculate mammals. Paleontology 44, p.389-429.

(This information has been derived from [1] MESOZOIC MAMMALS; Ptilodontoidea, an internet directory. As that's my webpage, there are no issues of copyright. Trevor Dykes)