Genus: Agathaumas COPE,1872
Etymology: Greek, agan, “much” and Greek, thaumas, personified form of Greek, thauma, “wonder, prodigy”: “great wonder”.
= Agathaumus HAY, 1901 (sic)

Species: sylvestris COPE, 1872
Etymology: Latin, sylvestris, "forested, wooded."
= Agathaumas silvestre COPE, 1892 (sic)
= Agathaumas sylvestre COPE, 1890 (not 1889) (sic)
= Triceratops sylvestris (COPE, 1872) KUHN, 1936 (nomen dubium)
= Triceratops silvestris (COPE, 1872) (KUHN, 1936 (nomen dubium)

Holotype: AMNH 4000

Locality: 1/2 miles east of Black Buttes station on the Union Pacific Railroad, Black Buttes, 52 miles east of Green River, Sweetwater County, sec. 9, T18N, R100W, Wyoming.

Horizon: Lance Formation.

Biostratigraphy:

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

Material: Right ilium, 8 posterior dorsal and sacral centra, right ilium, and ribs, proximal portion of a pubis? and other fragments.

Figs. 1-16. A continnous series of dorsal, lumbar, and sacral vertebrae, viewed from the right side; one

only of the neural archs found in place

Fig. 2. Second vertebra of teh series: a, viewed from behind.

Fig. 7. Antepenultimate lumbar vertebra; c, viewed from before; d, viewed from behind.

Figs. 10-16. a the sacral series viewed from above.

10-16b. The same viewed from below.

Fig. 10, c, Proximal end of sacrum.

14, c. Distal end of the fifth vertebra of the same.

16. Seventh sacral vertebra; c, anterior view; d, posterior view, both exhibiting teh inferior position of the articular surface of the diapophysis.

17. A more disatal sacral vertebra; b, from below.

18. The neural arches of two consecutive ?sacral vertebrae, coosified, and with diapophyses free from the centrum; a, from above.

Figs. 19-20. undetermined bones.

Fig. 21. Lateral view of the acetabular portion of the ilium, with the base of the ischium continuous with it; a, the same, viewed from below.

Figs. 1-3. Agathaumas sylvestre, three views of the ilium. a, the outer side; b, the inferior edge, c, the inner side; the iliac acetabular face retaius some of the matrix.

Figs. 1-4. Agathaumas sylvestre.

Fig. 1. A rib.

Figs 2-3. Undetermined bones.

Fig 4. Neural arch of a dorsal vertebra minus the processes.

Referred material:

COPE, 1892

Locality: Dakota.

Horizon:

Biostratigraphy:

Age: Late Cretaceous.

Material:

Number: Not given: Ilium and tibia.