Alticonodon lindoei, new gen. and sp., a triconodont mammal from the early Campanian Upper Milk River Formation, Alberta, is the first known triconodont of Late Cretaceous age, and only the second recorded from post-Jurassic rocks. Progressive specializations in Alticonodon suggest a more highly developed shearing of the postcanine dentition than in geologically older members of the order.