Marsh — Restorations of Claosdurus and Ceratosaurus. 347 



Ceratosaurus, Marsh, 1884.* 



In the same horizon of the Jurassic in which Brontosaurus 

 and Stegosarus were found, the skeleton restored in Plate YII 

 was likewise discovered. It is a typical carnivorous Dinosaur 

 of moderate size, and doubtless was one of the various enemies 

 of the large herbivorous forms. The restoration represents 

 the reptile one-thirtieth natural size, and in a position it must 

 have frequently assumed. 



The skull of Ceratosaurus nasicornis is very large in 

 proportion to the rest of the skeleton. The posterior region 

 is elevated, and moderately expanded transversely. The facial 

 portion is elongate, and tapers gradually to the muzzle. Seen 

 from above, the skull resembles in general outline that of a 

 crocodile. The nasal openings are separate and lateral, and 

 are placed near the end of the snout, as shown in Plate YII. 



Seen from the side, this skull appears Lacertilian in type, 

 the general structure being light and open. From this point 

 of view, one special feature of the skull is the large, elevated, 

 trenchant horn-core situated on the nasals. Another feature is 

 the large openings on the side of the skull, four in number. 

 The first of these is the anterior nasal orifice ; the second, the 

 very large triangular antorbital foramen ; the third, the large 

 oval orbit ; and the fourth, the still larger lower temporal 

 opening. 



The parietal bones are of moderate size, and there is no 

 parietal foramen. The median suture between the parietals is 

 obliterated. The frontal bones are rather short, and are 

 closely united on the median line. The nasal bones are more 

 elongate than the frontals, and are firmly coossified. These 

 bones support the large, compressed, elevated horn-core, on 

 the median line. The lateral surface of this elevation is very 

 rugose, and furrowed with vascular grooves. It evidently 

 supported a high, trenchant horn, which must have formed a 

 most powerful weapon for offense and defense. 



The premaxillaries are separate, and each contained three 

 functional teeth. The maxillary bones are large and massive, 

 as shown in Plate YII. They are provided each with fifteen 

 functional teeth, which are large, powerful, and trenchant, 

 indicating clearly the ferocious character of the animal when 

 alive. These teeth have the same general form as those of 

 3fegalosaurus, and the dental succession appears to be quite 

 the same. Above the antorbital foramen on either side is 

 a high elevation composed of the prefrontal bones. These 

 protuberances would be of service in protecting the orbit, 

 which they partially overhang. 



*This Journal, vol. xxvii, p. 329, April, 1884; and vol. xxviii, p. 161, August, 

 1884. 



