EOCERATOPS CAN \M N'SIS 91 



restored. M. {(.'.) nasicornus is not Styracosaurus^ for the crests, while possessing processes and 



short squamosals, are otherwise totally different, as are the general proportions of the entire skull. 

 The two cannot be congeneric, and there is no more assurance that Styracosaurus albertensis and 

 Monoclormu sphenocerus were. On the other hand, Styracosaurus, being a short squamosal form, 

 lies nearer Monoclonius (Centrosaurus) in relationship than any other contemporary genus, evi- 

 dently representing a highly aberrant offshoot of the same ancestral stock as that of Monoclonius. 

 Certainly, no known Lance genus or species gives any evidence of relationship. The evolutionary 

 trend in Styracosaurus, as shown by the available material, seems to be toward a shortening, broad- 

 ening, and straightening, together with a convergence, of the posterior processes. 



Genus EOCERATOPS Lambe 

 Eoceratops canadensis Lambe 20 



Holotypc: Right squamosal, No. 1254a G.S.C.; the right posterior lateral extension of the parietal, No. 1254b; 



the right postfrontal and prefrontal with the supraorbital horn core rising from the former bone, No. 1254d; 



the right nasal including the right half of the nasal horn core, No. 1254c; the left dentary without teeth, 



No. 1254e; and an anterior dorsal vertebra, No. 1254. 

 Horizon: Belly River formation. 



Locality: On the east side of Red Deer River, Alberta, a short distance below the mouth of Berry Creek. 

 Collector: L. M. Lambe, 1901. 



Generic characters are: "Skull small, short, compact; supraorbital horn-core moderately large, 

 slender, overhanging the orbit, circular in cross section, tapering to a point and directed upward, and 

 slightly inward and backward above; nasal abbreviated and deep; nasal horn-core short, contributed 

 to by the nasals and two separate, anterior ossifications; crest or neck-frill slightly longer than half 

 the total length of the head; squamosal broadly triangular, longer than broad, with a smooth, 

 undulating outer border, without epoccipitals, forming the greater part of the crest laterally; fenes- 

 trae of the crest long, enclosed without by the squamosal, and behind by a slender parietal bar which 

 passes forward beneath the inner posterior border of the squamosal; dentary robust, with about 

 twenty-five vertical series of teeth." 



The type material upon which the genus Eoceratops is based consists of several isolated bones, 

 pertaining to an immature individual, which might well account for such features as the absence of 

 epoccipitals, and the character of the nasal horn core. Lambe's outline of the skull, with the short 

 and very deep muzzle, is highly conjectural except for the fact that a deep facial region generally 

 goes with a short broad squamosal. It is noteworthy that in the presence of so many nearly perfect 

 skulls of the other Belly River genera, especially of Monoclonius (Centrosaurus) and Chasmosaurus, 

 this should be the only recognizable specimen referable to this genus. The full understanding of 

 relationships in this instance, as in that of Alonoclonius dawsoni and the Judith River genera, must 

 await further discovery. 



The skull, as at present understood, differs from all other Belly River genera in the nature 

 and position of the nasal horn core. The character may be partly juvenile, but the position over 

 the forward margin of the narial opening, instead of over the rear, separates it from Monoclonius 

 (Centrosaurus), Chasmosaurus, and Styracosaurus, and likens it to the Lance Triceratops. 



The form of the squamosal also resembles that in Triceratops. It is short like that of Mono- 

 clonius (Centrosaurus), but differs in being generally triangular instead of quadrangular, as in the 

 latter genus. The long fenestra, apparently but partly enclosed by the parietal element, is sugges- 

 tive of an imperfect Chasmosaurus crest rather than of Monoclonius (Centrosaurus) in which the 

 fenestrae are widely removed from the squamosal. The absence of epoccipital bones is not invari- 

 ably diagnostic, since they are lacking in several Triceratops skulls, notably that on the mounted 

 skeleton at the American Museum, in which they have probably been lost through lack of coossifi- 

 cation before fossilization. 



26 Lambe, L. M., 1915, pp. 1-25. 



