Zofiabaataridae
Scientific classification
Kingdom: Animalia
Therapsida
Class: Mammalia
Order: Multituberculata
Family: Zofiabaataridae
Genus:Zofiabaatar
Species
  Z. pulcher

Ref.

Zofiabaatar is an extinct mammal of the Upper Jurassic. It was a relatively early member of the also extinct order of Multituberculata, suborder "Plagiaulacida". It lived in North America along with dinosaurs such as Diplodocus and Allosaurus.

Genus: Zofiabaatar Bakker RT & Carpenter K, 1990
'Zofia’s hero' (Zofia Kielan-Jaworowska)
Family: Zofiabaataridae Bakker RT, 1992

Species: Zofiabaatar pulcher Bakker RT & Carpenter K, 1990
Place: Morrison Formation, Wyoming
Country: USA
Age: Upper Jurassic
Remarks: The animal was reportedly about 30cm long, (which sounds suspiciously large to me). Be that as it may, it seems to have been a rather specialised creature, judging by the dentary, which is all that's known. "We regard the Zofiabaataridae as belong to the allodontid line", (Kielan-Jaworowska & Hurum, 2001, p.401).
Reference: Simpson (1927), Mesozoic Mammalia. VII. Taxonomy of Morrison multituberculates. Am. J. Sci. (5) xiv: p.36-38.

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; Basal Multituberculata, an internet directory. As that's my webpage, there are no issues of copyright. Trevor Dykes)