Pentacosmodon

Pentacosmodon is a mammal genus from the Paleocene of North America, so it lived somewhat 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 the family Microcosmodontidae.

Genus: Pentacosmodon Jepsen GL, 1940

Species: Pentacosmodon pronus Jepsen GL, 1940
Place: Wyoming & Porcupine Hills Formation, Bow River, Alberta
Country: USA & Canada
Age: Upper Paleocene
Remarks: This genus was previously placed within Djadochtatherioidea.
Reference: Jepsen (1940), Paleocene faunas of the Polecat Bench Formation, Park County, Wyoming. Proc. of the Am. Philos. Soc., 83, p.217-341.

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/taenio.htm) MESOZOIC MAMMALS; Eucosmodontidae, Microcosmodontidae and Taeniolabidoidea, an internet directory. As that's my webpage, there are no issues of copyright. Trevor Dykes)