An exceptional specimen of Cimexomys judithae (Mammalia : Multituberculata) from the Campanian Two Medicine Formation of Montana, and the phylogenetic status of Cimexomys

We here describe a near-complete dentition, partial rostrum, and associated lumbar vertebrae of the multituberculate mammal Cimexomys judithac, discov ered on a dinosaur nest horizon at Egg Mountain, in Montana's Campanian Two Medicine Formation. This specimen confirms associations of isolated teeth made by previous authors and provides a wealth of phylogenetically useful i nformation. A phylogenetic analysis including this specimen indicates that Cimexomys is diagnosed on the basis of primitive and widely distributed cha racter states, is probably not monophyletic, and that C. judithae is more d erived than other species of Cimexomys. Species of Cimexomys are too primit ive to be included in the suborders Taeniolabidoidea or Ptilodontoidea, and are thus useful as outgroups in future analyses, but they must be scored s eparately to insure monophyly.