NO. 3 NEW CERATOPSIAN DINOSAUR GILMORE 3 



Ceratopsians of the Lance formation. It is to this shortening that 

 the generic name refers. The narial opening, as in other known 

 Judith River and Belly River forms, is situated well forward and 

 under the nasal horn, whereas in the later and more, highly special- 

 ized Tricciatops this orifice is ^entirely posterior to that horn. The 

 distance between the nasal and supraorbital horns, as seen in the 

 upper outline, is exceedingly short, due largely to the shortened 

 nasal bones and the great fore and aft development of the basal 

 portion of the nasal horn and also to the forward position over the 

 orbits of the small brow horns. 



The exact pitch of the frill portion in relation to the anterior part 

 of the skull cannot be positively determined, though in the drawing 

 it has been placed in accordance with the evidence of articulated 

 skulls. 



This specimen brings to light an entirely new phase of nasal horn 

 development and one which, so far as our previous knowledge goes, 

 appears to be unique among dinosaurs. Reference is made here to 

 the longitudinal separation of the horn core into two halves by the 

 nasal suture. This also indicates the nasal horn to be an outgrowth 

 from the nasal bones instead of having originated from a separate 

 center of ossification, as is the case in the more specialized Tricera- 

 tops. It appears quite probable there are some of the described 

 Belly River species that will also show a similar mode -of nasal horn 

 development when juvenile specimens are found. 



The nasals are especially deep and massive, due to the develop- 

 ment on their superior surfaces of the nasal horn cores. Posteriorly 

 they present a pointed process with a beveled underlapping surface 

 for contact with the prefrontals (the frontals and lachrymals of 

 authors). Laterally they send down a deep extension to meet the 

 premaxillary, and anteriorly the arched ventral borders of the nasal 

 bones form the upper half of the boundary of the narial ori- 

 fice. Anteriorly they send out vertically flattened processes (see p, 

 fig. i) between which are received the ascending processes of the 

 premaxillas. This nasal process appears to end about 32 mm. in ad- 

 vance of the forward line of the horn core, so that the upper outline 

 of the beak is formed largely by the premaxillaries. The horn has 

 a broad fore and aft extent at its base, but tapers rapidly to a bluntly 

 pointed horn of moderate height. Transversely it is much com- 

 pressed at the base, though inclined to expand somewhat toward 

 the summit. The horn as a whole is directed somewhat forward, 

 but the curve of the posterior side is such as to give the impression 



