Stegoceras validus

Figure 9 N, 0

A number of teeth recovered from the Judith River Formation closely resemble those of Stegoceras validus, an ornithopod not previously reported from the Judith River Formation, but quite frequent in the Oldman Formation of Alberta. Specimen AMNH 8530, from Clambank Hollow, is representative of the group. The tooth is small with a crown height of 5.2 mm., a length of 4.8 mm., and a transverse width 3.6 mm. (fig. 9 N, 0). The crown is conical with a pointed apex showing a horizontal wear surface. Denticles are large compressed cones, better separated on the labial than on the lingual side. Valleys between the denticles extend as flutings to the base of the crown. The base is swollen on the internal face, thereby considerably increasing the basal width of the crown. The crown is markedly constricted at its junction with the cylindrical root. These teeth are distinctly different from those of Troodon. Gilmore (1924) put the genus Stegoceras in synonymy with Troodon and this was followed by Brown and Schlaikjer (1943). Sternberg (1945), on the basis of his comparative study of the teeth of T. formosus and Stegoceras, maintained that the genera were distinct. Later, Russell (1948), in his description of the dentary of Troodon, also supported the separation of the ornithopod Stegoceras from the theropod Troodon.