Aelurodon montanensis, sp. nov. (Carnivora, Canidae, Borophaginae), is described from a new locality, Aelurodon Cut, near Pipestone Springs in Jefferson County, Montana. The new species is a primitive representative of the previously recognized Aelurodon mcgrewi–A. stirtoni clade, one of the most hypercarnivorous, relatively rare clades in the subfamily Borophaginae. It shares with this clade such derived characters as a broadened posterior cingulum of p3, initial development of a posteriorly expanded M1 internal cingulum, and similarities in dental proportions. Evolutionary trends within this clade include reduction in size, increasingly hypercarnivorous dentition with lengthened shearing blades on the upper and lower carnassials, a more trenchant talonid on m1, a reduced grinding part of upper and lower molars, and a posteriorly expanded M1 internal cingulum. Based on the stage of evolution of the new canid and on an associated metapodial fragment of Aepycamelus, we tentatively assign an early Barstovian age to the Aelurodon Cut locality.