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PLATE I. Pachyrhinosaurus eanadensis Sternberg. NMC 9485, skull lacking cheek and frill. Above,

left lateral view; below, palatal aspect. Scale equals 10 cm.

the only positively associated material of one individual yet found in the Scabby Butte area.

Site 6 — This locality includes Scabby Butte 'badlands as a whole. The number is applied to all surface finds. Specimens so designated have been transported unknown distances from their

solll'ces.

Ceratoysian dinosaurs hem Scabby Suite Because Pachyrtu'nosaurus is, in terms of its

morphological contribution to the present study,

1579

LANGSTON: CERATOPSIAN DINOSAURS

PLATE II

PLATE II. Pachyrhinosaurus canadensis Sternberg. NMC 9485, skull lacking cheek and frill.
Left, superior aspect; right, anterior aspect. In anterior view, relative width of the nasofrontal boss
is diminished by parallax. Scale equals 10 cm.

River rocks on Little Bow River in southern Alberta, some 10 miles ( 16 km) from Scabby Butte. A relatively good skull displayed in the Drumheller Museum is from the Lower Edmon- ton on the Red Deer River near Drumheller (Langston 1967, 1968). The fourth (and first-

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P. canadensis Sternberg (NMC 8867) is fairly complete, but is fiattened laterally to only a fraction of its normal width; a paratype speci- men (NMC 8866) comprises only the central part of the cranium and some of the mandible. These specimens are from Lower Edmonton/St. Mary

the most significant element in the Scabby Butte vertebrate assemblage, I am departing from cus- tomary systematic procedures to deal with it and certain associated ceratopsians before turning to other forms.

Pachyrhinosaurus Sternberg, 1950

P. canadensis Sternberg, 1950

Four skulls of Pachyrhinosaurus have been discussed previously in the literature (Sternberg 1950; Langston 1967, 1968). The holotype of