Species: montanus MARSH, 1888
Etymology: In reference to the state of Montana.
= Proceratops montanus (MARSH, 1888) LULL, 1906
= Triceratops montanus (MARSH, 1888) [sic; typographical error in OSTROM & WELLNHOFER, 1986; J. H. Ostrom, pers. comm.to OLSHEVSKY]

Holotype: USNM 2411

Locality: Cow Creek, about 10 miles above the confluence of that stream with the Missouri River, Fergus County, Montana.

Horizon: Judith River Formation.

Biostratigraphy:

Age: Judithian age, Campanian Stage, Senonian subepoch, Upper Gulf epoch, Late Cretaceous.

Material: Occipital condyle and a pair of frontal horns.

Referred material:

MERRELL, 1907

Locality: Cow Island, Fergus County, Montana.

Horizon: Judith River Formation.

Biostratigraphy:

Age: Judithian age, Campanian Stage, Senonian subepoch, Upper Gulf epoch, Late Cretaceous.

Material:

USNM 4802: Squamosal.

 

TREXLER, 1995

Locality: Along the Milk River, Montana.

Horizon: Judith River Formation.

Biostratigraphy:

Age: Judithian age, Campanian Stage, Senonian subepoch, Upper Gulf epoch, Late Cretaceous.

Material:

MOR: Fragmentary skull.