The occurrence of vertebrate fossils from the Ravenscrag Formation near Roche Perce, southeastern Saskatchewan, Canada, documents the presence of a large and diverse assemblage of early late Paleocene (approximately 58 million years) mammals. Previous studies of the Roche Perce localities have examined only a small portion of the fauna, with the vast majority of taxa remaining undescribed. The current research centers on the identification, description and, where appropriate, evolutionary relationships of these undescribed mammals. Significant discoveries, to date, include two new species of the rare viverravid carnivoran Raphictis, a new species of the phenacodontid condylarth Ectocion, a large collection of a probable new species of the semi-aquatic pantolestid Palaeosinopa, and only the second known occurrence of the predominantly European lipotyphlan Adapisorex in North America. This research provides an improved understanding of mammalian diversity and evolution in the northern part of the Western Interior during this important time interval. / Systematics and Evolution