Species: crassus COPE, 1876
Etymology: Latin, crassus, "thick."
Holotype: AMNH 3998
Locality: Opposite the mouth of Dog Creek, Missouri River, Montana.
Note: HATCHER, MARSH & LULL, 1907, Near the mouth of Birch Creek.
Horizon: Near the base of the Judith River Formation.
Biostratigraphy:
Age: Judithian age, Campanian Stage, Senonian subepoch, Upper Gulf epoch, Late Cretaceous.
Material: Teeth?, parietal, right ilium, ischium, right femur, right humerus, tibia, and fibula, sacrum, anterior dorsal, caudal vertebrae and parietal.
Referred material:
AMNH 3998a: Right scapula and coracoid.
AMNH 3997: Prefrontal and postfrontal with brow horn.
LULL, 1933
Locality: 3 miles Southwest of the mouth of Little Sandhill Creek, Red Deer River, Newell County, Alberta Province, Canada.
Horizon: Dinosaur Park Formation, upper Judith River Group.
Biostratigraphy:
Age: Judithian age, Middle Campanian Stage, middle Senonian subepoch, upper Gulf Epoch, Late Cretaceous.
Material:
NMC: Central portion of crest.
= Monoclonius sphenocerus COPE, 1889 (nomen dubium)
Etymology: Greek, sphenos, "wedge" and Greek, ceras, "horn."
= Agathaumas sphenocerus (COPE, 1889) BALLOU, 1898 (nomen dubium)
= Styracosaurus sphenocerus (COPE, 1889) (nomen dubium)
Note: LAMBE, 1915 has been attributed for the renaming Monoclonius sphenocerus as Styracosaurus sphenocerus. This is incorrect. He never coined the name, but said there maybe a possibility that M. sphenocerus is Styracosaurus, but he never published that name.
= Monoclonius sphenoceras KEYES, 1894 (sic)Holotype: AMNH 3989
Locality: On Missouri River near Cow Island, Fergus County, Montana.
Horizon: Judith River Formation.
Biostratigraphy:
Age: Judithian age, Campanian Stage, Senonian subepoch, Upper Gulf epoch, Late Cretaceous.
Material: Nasals and left premaxilla.
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Species: ? fissus COPE, 1889
Etymology: Latin, fissus, past participle of findere, "to split, cleave."
Holotype: AMNH 3988
Locality: North side of the Missouri River, Montana.
Horizon: Judith River Formation.
Biostratigraphy:
Age: Judithian age, Campanian Stage, Senonian subepoch, Upper Gulf epoch, Late Cretaceous.
Material: Right pterygoid.
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Species: ? lowei STERNBERG, 1940
Etymology: In honor of field assistant Harold D'acre Robinson Lowe from Drumheller who had worked six field seasons (1925-1937), across southern Alberta, Canada.
Holotype: NMC 8790
Locality: Near south-central part of NE 1/4, sec.2, T5, R5, west of 4th mer., About 7 miles southeast of Manyberries, Forty Mile County, Alberta Province, Canada.
Horizon: Uppermost Dinosaur Park Formation, upper Judith River Group.
Biostratigraphy:
Age: Judithian age, Middle Campanian Stage, middle Senonian subepoch, upper Gulf Epoch, Late Cretaceous.
Material: Skull complete except for rostral, left maxilla, quadrate and quadratojugal and palatial bones.
Note: Shows possible trauma to the right side of the parietal (TANKE & ROTHSCHILD, 2010)
Note: Possibly a growth series of Styracosaurus?
