Leptauchenia Sespia Leptaucheniinae Protoceras Oreonetes Merycoidodontoidea List of the Cenozoic life of South Dakota List of the Cenozoic life of North Dakota List of the prehistoric life of North Dakota List of the Cenozoic life of Nebraska List of the Cenozoic life of Montana List of the prehistoric life of Nebraska List of the prehistoric life of South Dakota List of the prehistoric life of Montana List of the prehistoric life of Colorado List of the prehistoric life of Wyoming List of the Cenozoic life of Wyoming List of the Cenozoic life of Colorado List of prehistoric mammals Brule Formation White River Fauna