Oldest occurrence of the genusStegoceras (Dinosauria: Pachycephalosauridae) from the Foremost Formation (Campanian) of South Alberta, Canada

Three pachycephalosaurid frontoparietals from the Foremost Formation (Campanian) of South Alberta, Canada, are described and assigned to the genusStegoceras Lambe 1902 on the basis of measurements. Measurements and indices suggest that all of the specimens originate from male animals. The specimens are the oldest fossil record of this genus. The possibility is discussed, that they represent a species that could be an ancestor of the North AmericanStegoceras validum and/or the MongolianPrenocephale prenes.