A new eutypomyid rodent from the Arikareean (Miocene) of Montana

Abstract

Four localities northwest of Deer Lodge, Montana, produce Arikareean early Miocene fossils of the Tavenner Ranch Local Fauna. A fifth, with apparently identical lithology, has produced two specimens of Oligocene aspect, one tentatively identified as Leptomeryx, which, while predominantly Oligocene, is also Arikareean. Eutypomys montanensis, new species, is more advanced than the previously known (Oligocene) members of the family and could readily be Arikareean. The relationships of the Eutypomyidae are discussed. The family is still considered to be more closely related to the beavers than to any other rodents.