Anconodon
Scientific classification
Kingdom: Animalia
Therapsida
Class: Mammalia
Order: Multituberculata
Superfamily:Ptilodontoidea
Family:Cimolodontidae
Genus:Anconodon
Species
  A. cochranensis
  A. gidleyi
  A. lewisi

Ref.

Anconodon is a mammal genus from the Paleocene of North America, and thus lived just after ‘the age of the dinosaurs'. It was a member of the extinct order of Multituberculata.
For those of a technical inclination, it's within the Suborder of Cimolodonta, and possibly the family Cimolodontidae.

Genus: Anconodon Jepsen GL, 1940
Aka: Ectopodon Russell, 1967; Ectypodus (partly); Liotomus (partly); Ptilodus (partly)
Reference: Jepsen (1940), Paleocene faunas of the Polecat Bench formation, Park County, Wyoming. Pro. Amer. Philos. Soc, 83, p.217-340, 21 figs., 5pls.

Species: Anconodon cochranensis (Russell, 1929) Van Valen & Sloan, 1966
Aka: A. russelli (Simpson, 1935) Jepsen, 1940; Ectopodon cochranensis Russel, 1967; Ectypodus cochranensis Simpson, 1937a; Ectypodus russelli Simpson, 1935d; Liotomus russelli; Ptilodus cochranensis Russell, 1929
Place: Alberta & Montana & Wyoming
Country: Canada & USA
Age: Tiffanian, Middle-Upper Paleocene
Remarks: Has been cited as a descendant of A. gidleyi. The holotype is in the University of Alberta collection. Body mass of about two standard mice, (55g).
Reference:

Species: Anconodon gidleyi (Simpson GG, 1935) Jepsen GL, 1940
Aka: A. gibleyi; Ptilodus?gidleyi Simpson, 1935d
Place: Gidley Quarry, Montana & Wyoming & New Mexico & Alberta
Country: USA & Canada
Age: Torrejonian, Middle-Upper Paleocene
Remarks: Cited as a possible descendant of Cimolodon nitidus.
Reference: Simpson (1935), New Paleocene mammals from the Fort Union of Montana. Proc. US Nation. Museum 83, p.221-244.

Species: Anconodon lewisi Sloan RE, 1987
Place: Keefer Hill, Wyoming & Douglass Quarry, Montana
Country: USA
Age: Middle-Upper Paleocene
Remarks: The holotype is from Wyoming.
Reference:

Page references: 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)