Genus: Prenocephale MARYANSKA & OSMOLSKA, 1974
Etymology: Greek, prenes, “inclined, sloping", and Greek, kephale, “head”; “sloping head”, because of the anterior sloping profile of the head.
= Sphaerotholus WILLIAMSON & CARR, (2002) 2003
Etymology: Greek, sphaira, ‘ball’, and Greek, tholos, ‘dome’: referrig to the sphere-like shape of the dome of subadult and adult specimens in dorsal view.

Species: prenes MARYANASKA & OSMOLSKA, 1974
Etymology: Greek, prenes, “inclined, sloping".

Holotype: Z. Pal. No. MgD-I./104

Locality: Nemegt, Nemegt basin, Ömnögov (South Gobi), Mongolia.

Horizon: Nemegt Formation.

Biostratigraphy: Tarbosaurus bataar and Saurolophus angustirostris.

Age: Lower Maastrichtian Stage, Uppermost Senonian, Uppermost Gulf Epoch, Late Cretaceous.

Material: Perfectly preserved skull with dentition, without mandibles, several fragmentary dorsal vertebrae, 1 caudal vertebra, fragmentary dorsal ribs, badly damaged left femur, right femur lacking greater and lesser trochanters, and lateral condyle, numerous free caudal tendons, several of them in natural arrangement.


_____________________________________________________________________________________

Species: brevis (LAMBE, 1918) SULLIVAN, 2000
Etymology:
= Stegoceras brevis LAMBE, 1918
= Stegoceras breve LAMBE, 1918
= Troodon brevis (LAMBE, 1918) HAY, 1930

Syntype: CMN (old NMC) 1423

Locality: Below the mouth of Berry Creek, east side of Red Deer River, Dinosaur Provincial Park, 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: Frontoparietal area of a juvenile.

Plesiotypes:

CMN (old NMC) 121: Frontoparietal area.

CMN (old NMC) 193: Frontoparietal area of a juvenile.

CMN (old NMC) 194: Frontoparietal area without the posterior tips of the parietals of a juvenile.

CMN (old NMC) 8819: Frontoparietal area of a juvenile.

Referred material:

SULLIVAN, 2000

Locality: Dinosaur Provincial Park, 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:

RTMP 85.36.292: A well-preserved frontoprietal dome with endocast.

RTMP 91.36.262: Nearly complete frontoparital dome.

RTMP 95.55.122: Nearly complete frontoparietal dome.

RTMP 2000.12.01: Incomplete frontoparietal dome.

SULLIVAN, 2003

ROM 2960, 2961, 31616, RTMP 81.16.480, 91.36.265, UALVP-8501, -8508:

Cf. Prenocephale brevis

CMN 1535, 1593, RTMP 74.10.74, 81.27.40, 85.43.69, UALVP-5, -8504, -8506:

?Prenocephalus brevis

RTMP 85.43.62:

 

RUSSELL & CHAMNEY, 1967

Locality: Alberta Province, Canada.

Horizon: Horseshoe Canyon Formation, Edmonton Group.
Note: Formerly Member A of the Edmonton Formation.

Biostratigraphy:

Age: Edmontonian age, lower Maastrichtian Stage, Upper Senonian subepoch, Upper Gulf Epoch, Late Cretaceous.

Material:

NMC 11316:

_____________________________________________________________________________________
Species: edmontonense (BROWN & SCHLAIKJER, 1943) SULLIVAN, 2000
emend WILLIAMSON & CARR, (2002) 2003 (= Sphaerotholus sp)
Etymology:
= Troodon edmontonensis BROWN & SCHLAIKJER, 1943
= Stegoceras edmontonensis (BROWN & SCHLAIKJER, 1943) STERNBERG, 1945

Holotype: CMN (formerly GSC and NMC) 8830

Locality: Opposite mouth of Big Valley Creek below Scollard Ferry, Steller County, Red Deer River, Alberta Province, Canada.

Horizon: Horseshoe Canyon Formation, Edmonton Group.

Biostratigraphy:

Age: Edmontonian age, lower Maastrichtian Stage, Upper Senonian subepoch, Upper Gulf Epoch, Late Cretaceous.

Material: Frontoparietal area of an adult.

Paratypes:

CMN (NMC) 8831: A frontoparetal area with the anterior margin broken away.

CMN (NMC) 8832: The anterior two-thirds of a frontoparietal area.

Referred material:

= Stegoceras cf. edmontonensis WALL & GALTON, 1979

Locality: Billy Creek, Montana.

Horizon: Hell Creek Formation.

Biostratigraphy:

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

Material:

LACM 15345: Fragmentary skull.

 

Locality: Garfield County, Montana.

Horizon: Hell Creek Formation.

Biostratigraphy:

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

Material:.

LACM 15342, LACM 64000: Skull caps.

 

= Sphaerotholus buchholtzae WILLIAMSON & CARR, (2002) 2003
Etymology: In honor of Emily A. Buchholtz, for her extensive contributions to pachycephalosaurian research.

Holotype: RTMP 87.113.3

Locality: SE 1/4, T1S, R55E, west side of Dry Creek Road, 0.2 miles (.l32km) north of its intersection with Powder River [sic. Powderville] road, Carter County, Montana.

Horizon: Hell Creek Formation.

Biostratigraphy:

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

Material: Fragmentary skull cap.

_____________________________________________________________________________________

Species: goodwini (WILLIAMSON & CARR, (2002) 2003) SULLIVAN, 2003
Etymology: In honor of Mark Goodwin for his contributions to the study of pachycephalosaurians.
= Pachycephalosaurian nova WILLIAMSON, 1999
= Sphaerotholus goodwini WILLIAMSON & CARR, (2002) 2003

Holotype: NMMNH P-27403

Locality: NMNH locality L-3921, Head of Willow Wash, within the Bisti/De-na-zin Wilderness area, San Juan Basin, San Juan County, New Mexico.

Horizon: De-na-zin Member, Lower Kirtland Formation.

Biostratigraphy:

Age: Kirtlandian age, Upper Campanian Stage, Senonian Subepoch, Gulf Epoch, Late Cretaceous.

Material: A partial skull lacking the facial and palatal bones.

Referred material:

= cf. Sphaerotholus goodwini WILLIAMSON & CARR, (2002) 2003

Locality: NMMNH Locality L-3097, head of Pinabete Arroyo, on the lands of the Havajo Nation, San Juan Basin, San Juan County, New Mexico.

Horizon: Farmington Member, Kirtland Formation.

Biostratigraphy:

Age: Kirtlandian age, Upper Campanian Stage, Senonian Subepoch, Gulf Epoch, Late Cretaceous.

Material:

NMMNH P-30068: A nearly complete dentary, a fragment of a squamosal and additional skull fragment.
Note: Found with the new species of Daspletosaurus.