Glirodon

Glirodon 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 during the 'age of the dinosaurs'.

Genus: Glirodon Engelmann GF & Callison G, 1999
'gliriform tooth'

Species: Glirodon grandis Engelmann GF & Callison G, 1999
Place: Dinosaur National Monument, Utah
Country: USA
Age: Upper Jurassic
Remarks: Other than being a large, early American multituberculate, (see Multituberculata), the nature of this beast is somewhat unclear. It's an "allodontid (two families and the genus Glirodon)", (Kielan-Jaworowska & Hurum, 2001). It had gliriform incisors; incisors with the "enamel reduced to a stripe on the front side." Apparently, this condition evolved several times among multis. (Personal communication and with thanks for the info to David Marjanovic).
It's based on a portion of snout. "Glirodon retains the plesiomorphic 'plagiaulacidan' ("Plagiaulacida") dental formula and shares with Allodontidae the structure of the upper premolars (Pl.1 fis 2-4). It differs from the Paulchoffatiidae and Plagiaulacidae in having a single-cusped I3," (Kielan-Jaworowska & Hurum, 2001, p.401-402). I3 refers to an upper incisor and 'plsiomorphic' means 'basal'.
Reference: Engelmann & Callison, (1999), Glirodon grandis, a new multituberculate mammal from the Upper Jurassic Morrison Formation. Vertebrate Paleontology of Utah, pp.161-178, in Utah Geological Survey, (ed. Gillette DD), 8/99.

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