Janumys
Scientific classification
Kingdom: Animalia
Therapsida
Class: Mammalia
Order: Multituberculata
Family: Affinities unclear
Species
  J. erebos

Ref.

Janumys is an extinct mammal of the middle Cretaceous. It was a member of the also extinct order of Multituberculata. It lived in North America during the 'age of the dinosaurs'.
It's been previsionally placed within the informal suborder "Plagiaulacida".

Genus: Janumys Eaton & Cifelli, 2001

Species: Janumys erebos Eaton & Cifelli, 2001
Place: Cedar Mountain Formation, Utah
Country: USA
Age: Albian-Cenomanian, Lower-Upper Cretaceous boundary
Remarks: Further info welcome.
Reference: Eaton & Cifelli (2001), Multituberculate mammals from near the Early-Late Cretaceous boundary, Cedar Mountain Formation, Utah. Acta Palaeontologica Polonica 46 (4), p.453-518.

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