CERATOPSIDAE, Marsh, 1888

Sahni, Ashok, 1972, The vertebrate Fauna of the Judith River formation, Montana, Bulletin of the American Museum of Natural History 147 (6), pp. 319-416 : 361-363

FAMILY CERATOPSIDAE

Figure 9G, H

Although worn ceratopsian teeth form a sizable portion of the ornithischian remains, they cannot be differentiated at the generic level. Unworn teeth indicate that at least two genera of ceratopsians may have been present. The ceratopsians of the Judith River Formation have been discussed by, among others, Lull and Hatcher (1907) and Lull (1933). Based mostly on fragmentary material, a number of species of Monoclonius and Ceratops , the only two genera known from the formation, have been described. Brachyceratops montanensis was described by Gilmore (1917) from the Two Medicine Formation of Montana. The Oldman Formation of Alberta has produced better known forms such as Eoceratops , Brachyceratops , Monoclonius , Centrosaurus , Styracosaurus , Chasmosaurus , and Anchiceratops ( Sternberg, 1940 a; Langston, 1965, p. 4).

An unworn tooth, AMNH 8540, from Clambank Hollow, has a sharply pointed apex (fig. 9G, H). The sides of the crown are serrated toward the apex, and a strong median keel must have been present but it is broken away in the specimen.

A much larger tooth, AMNH 8541, also from Clambank Hollow, with rougher ornamentation, probably belongs to a distinct genus.

Figures

FIG. 9. A, B. Edmontonia lorngiceps, AMNH 8543, lateral views of an isolated tooth, x 1. C, D. Palaeoscincus costatus, AMNH 8542, lateral views of an isolated tooth, x 12. E, F. Thescelosaurus cf. T. neglectus, AMNH 8536, lateral views of an isolated tooth, x 10. G, H. Ceratopsidae, AMNH 8540, lateral views of an unworn tooth, x 12. I. Dromaeosaurus albertensis, AMNH 8516, lateral view of an isolated tooth, x 12. J, K. Paronychodon lacustris, AMNH 98523, lateral views of an isolated tooth, x 12. L, M. Troodon formosus, AMNH 8518, lateral ~~~~~~~~~~~~~~~~~~~~~~~~~~~~3. views of an isolated tooth, x 12. N. 0,?Stegoceras validus, AMNH 8530, lateral views of an isolated tooth, x 1-. Dinosaur egg shell fragments. P. AMNH 8545, external view of shell (Class B). Q. Internal view. Both x 10. R. AMNH 8546, external view of shell (Class B). S. Internal view. Both x 10. T. AMNH 8548, external view of shell (Class C). U. Internal view. Both x 10. V. AMNH 8547, external view of shell (Class B). W. In- ternal view. Both x 10. X. AMNH 8544, external view of shell (Class A), x 10.