Genus: Polyonax COPE, 1874 (nomen dubium)
Etymology: Greek, poly, "many, and Greek, anax, "master, ruller."
= Polponax OSBORN, 1902 (sic)
= Polygonax HATCHER, 1902 (sic)

Species: mortuarius COPE, 1874 (nomen dubium)
Etymology: Greek, mortuarius, "belong to the dead."
= Agathaumas mortuarius (COPE, 1874) HAY, 1901 (nomen dubium)

Holotype: AMNH 1568 (3950?)

Locality: Bijou Crteek, Denver Basin, Colorado.

Horizon: Laramie Formation.

Biostratigraphy:

Age: Lancian Age, upper Maastrichtian Stage, uppermost Senonian Subepoch, Upper Upper Gulf Epoch, Late Cretaceous.

Material: 3 dorsal vertebrae, caudal centra, rig fragment, fibual fragment and fragments of horncores.