Alternative combination: Agathaumas prorsus
Full reference: O. C. Marsh. 1890. Description of new dinosaurian reptiles. The American Journal of Science, series 3 39:81-86
Sister taxon: Triceratops horridus
Type specimen: YPM 1822, a skull. Its type locality is Middle Fork, Dry Creek (YPM), which is in a Maastrichtian terrestrial sandstone/sandstone in the Laramie Formation of Wyoming.
Ecology: ground dwelling herbivore