TRICEPATOPS. 



133 



Triceratops sulcatus Marsh. 1890. 



Type consists of a fragmentary skull, vertebrae, etc. (No. 4276, U. S. National Museum), from Laramie of Converse County, 

 Wyo. 



Original description in Am. Jour. Sci., vol. 39, May, 1890, p. 422. 

 Nopcsa, F. Baron, Foldtani Kozlony, Budapest, 1901, vol. 31, p. 271. 

 Osborn, H. F., Contr. Canadian Pal., vol. 3 (quarto), pt. 2, 1902, p. 14. 

 Walcott, C. D., Science, new ser., vol. 11, 1900, p. 23. 



The type (No. 4276, U. S. National Museum) of this species was found by me at a somewhat 

 higher horizon in the Laramie of Converse County, Wyo., than any remains yet mentioned. 

 Professor Marsh's original description was as follows: 



One of the largest skulls of Triceratops secured during the past season was not in good preservation, although nearly the 

 whole was recovered, and with it various vertebras and other portions of the skeleton. The animal was fully adult, as shown 

 by the ossification of the epoccipital and epijugal bones with the portions of the skull on which they rest. The epijugal bones 

 are especially prominent and rugose, and the sutures uniting them with the jugals are nearly obliterated 



The most distinctive character of the skull is seen in the horn cores of the frontal region, which are very large and elon- 

 gate. On the posterior surface of the upper half of each horn core there is a deep groove, which has suggested the specific 

 name. The horn cores are narrow in front, and in the upper portion become distinctly ridged. 



The antero-posterior diameter of the horn cores at the base is about 9 inches, and 

 above, where the groove begins, about 4| inches. 



The caudal vertebras in this species are unusually short, and the median caudais 

 have a deep longitudinal groove on the bottom of the centra. 



This type specimen was found in the Ceratops beds, in Wyoming, by Mr. J. B. 

 Hatcher. 



The exact locality at which the type of this species was found 

 is shown at +5, PI. LI. It consisted of a fragmentary skull with 

 lower jaw, humerus, several vertebrae, and other portions of the 

 skeleton. The lower jaw is in a good state of preservation, but the 

 other portions of the skull are for the most part in a very fragmen- 

 tary condition. External, internal, and superior views of the left 

 ramus are shown in PI. VI. These show the animal to have been 

 fully adult. The splenial is firmly coossihed with the dentary, and 

 the angular, surangular, and articular are in position. The ramus 

 is massive. The inferior border is nearly straight and the coronoid 

 process rises upward, slopes backward, and curves inward. It is 

 pointed at the apex and is only moderately expanded antero- 

 posteriorly. I am unable to detect the presence of a distinct 

 coronoid bone, this element, if it existed, having become completely 

 fused with the coronoid process of the dentary. 



Thirty-two foramina enter the dental magazine from the inner side of the ramus. All the 

 teeth in use during the life of the animal have fallen out and are wanting, but the crowns of a num- 

 ber of unused teeth may be seen in the dental chamber. These are of the usual pattern and of 

 moderate size, not nearly so large as in the cotype a of Triceratops elatus Marsh (No. 4805, U. S. 

 National Museum). 



Only one of the supraorbital horn cores is at present accessible, and this does not agree very 

 well with Marsh's statement : 



The most distinctive character of the skull is seen in the horn cores of the frontal region, which are very large and elongate. 

 On the posterior surface of the upper half of each horn core there is a deep groove, which has suggested the specific name. 



It seems quite likely that Professor Marsh based his description of the horn cores in the 

 present species on that one of the two supraorbital horn cores pertaining to the type which is at 

 present unavailable and that the two differ materially in size and form, this difference apparently 

 having been due to an injury received by the one now available during the life of the animal. 

 This horn core is very stout, but not elongate. It is truncated above in a peculiar wedge-shaped 

 manner, as though the superior portion had. been broken off in life and the injured bone had 



Fig. 112.— Supraorbital horn core of 

 Triceratops sulcatus Marsh, type, 

 No. 4276, U. S. National Muse- 

 um. A, Side view; B, cross sec- 

 tion. One-eighth natural size. 



a See footnote on p. 130.— R. S. L. 



