BRACHVCERATOPS MONTANEN3IS 97 



The brow horns which constitute the type are large and, as reoriented by Hatcher, curve sharply 

 outward from their base, when viewed from in front. From the oblique rear, they are straight, but 

 taper rather abruptly. The only possible comparisons with contemporary forms are with Mono- 

 clonius recurvicomis Cope, Eoceratops canadensis Lambe, and Chasmosaurus kaiseni Brown, of 

 which the first only is Judith River, the others being Belly River forms. In the first of these, the 

 brow horns are much shorter, truncated, and erect, without axial curvature, hence differing decidedly 

 from the widely curved horns of Ceratops montanus. The comparison with Eoceratops canadensis is 

 nearer; in fact, Hatcher says the horns "are strikingly similar." 88 They are nearly the same length 

 in each species, that of Eoceratops being a little the shorter, but much more slender and backwardly 

 curved. These distinctions may be specific only. Comparison with Chasmosaurus kaiseni (see Fig. 

 38) also shows about the same degree of likeness and difference, the latter having to do with the 

 greater relative slenderness and curvature, for here the horns slope outward and forward at their 

 base, and curve upward toward their summit in a single curve. Fortunately, Chasmosaurus kaiseni 

 is founded upon a perfect skull, and its reference to Chasmosaurus is unquestioned on the basis of 

 the crest, but it and one other (No. 40, Univ. of Alberta (see p. 95)) are the only instances, in any 

 of the nine Chasmosaurus skulls known to me, in which long brow horns occur, all of the others, in 

 which they are preserved, having rudimentary horns. One cannot, therefore, accept the synonymy 

 of Ceratops and Chasmosaurus on such slender evidence as this, especially as the latter is a well 

 defined genus, and from a different region, although perhaps of nearly equivalent age. Ceratops 

 montanus comes from the summit of the Judith River series and may represent a more advanced 

 evolutionary stage of the same phylum as Chasmosaurus, but until more perfect diagnostic material, 

 including the entire crest, is collected from this horizon and locality, the status of Ceratops cannot be 

 solved. The relationship between Monoclonius and Centrosaurus is more nearly proved, but the 

 inferred assumption that if these genera are nearly related, Ceratops and Chasmosaurus must also 

 be, is based upon no evidence whatever. No fragment of a long squamosal, such as that of Chasmo- 

 saurus, has come to light in the Judith River collections. 



Genus BRACHYCERATOPS Gilmore 

 Brachyceratops montanensis Gilmore 39 



PI. IX, B 



Holotype: No. 7951 U.S.N.M., considerable portion of a disarticulated skull with which is provisionally asso- 

 ciated a fragmentary part of the crest and a right dentary and predentary. 



Paratopes: No. 7952, U.S.N. M., rostral and portions of the premaxillaries; No. 7953, U.S.N. M., sacrum, pelvis, 

 articulated caudal series of 50 vertebrae, with which are provisionally associated dorsal vertebrae and ribs; 

 No. 7957, U.S.N. M., tibia, fibula, and partly articulated hind foot from the left side, consisting of an 

 astragulus, calcaneum, and 2 tarsals of the distal row, 4 metatarsals and a portion of a fifth, and 1 1 

 phalanges. 



Horizon: Two Medicine formation. 



Locality: N.E. l /\ sec. 16, Township 37N., Range 8 W., Milk River, Blackfeet Indian Reservation, Glacier 

 County, Montana. 



Collector: C. W. Gilmore, 1913. 



The original description of generic and specific characters, as emended by Gilmore, 40 is as 

 follows: "Typically of small size. [Note. The small size of the animal, Gilmore says, may be 

 due to some extent to the immaturity of the individuals. I should say to a large extent, for the 

 impression one gets from the open sutures and general proportions is that of a creature not half 

 grown. A very Monoclonius-Wke squamosal in the collection, which is nearly if not quite as large 



38 Hatcher, Marsh, Lull, 1907, p. 102. 



39 Gilmore, C. W., 1 9 1 4, pp. 1 - 1 0. 



40 Gilmore, C. W., 191 7, p. 7. 



