Essonodon

Essonodon is a mammal genus from the Upper Cretaceous of North America. It was a member of the extinct order of Multituberculata and lived towards the end of 'the age of the dinosaurs'.
For those of a technical inclination, it's within the Suborder of Cimolodonta, and perhaps the family Cimolomyidae.

Genus: Essonodon Simpson GG, 1927
Aka: Cimolodon (partly)
Remarks: The inclusion of this taxon within Cimolomyidae is tentative, (Kielan-Jaworowska & Hurum 2001, p.408).

Species: Essonodon browni Simpson GG, 1927
Aka: Cimolodon nitidus Marsh, 1889 (partly)
Place: Hell Creek, Montana & San Juan Basin, New Mexico & Wyoming
Country: USA
Age: Maastrichtian, Upper Cretaceous
Remarks: A mighty multi, which weighed in at over 2,5 kilos. Further material has been reported from the Frenchman Formation of Canada.
Reference: Simpson (1927), Mammalian fauna of the Hell Creek Formation of Montana. Amer. Mus. Novit. 267, p.1-7, 6 figs.

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] (http://home.arcor.de/ktdykes/cimolod.htm) MESOZOIC MAMMALS; 'basal' Cimolodonta, Cimolomyidae, Boffiidae and Kogaionidae, an internet directory. As that's my webpage, there are no issues of copyright. Trevor Dykes)