j 32 THE CERATOPSIA 



"The openings may be due to tumors arising in the medullary portion of the bone. Such pathological condi- 

 tions appear first in the Triassic and are found in later reptiles and among Tertiary and Pleistocene mammals." 



Torosaurus gladius Marsh 97 

 PI. XVI 



Holotype: 98 No. 1831 Y.P.M.; nearly complete parietal, right squamosal, nasal horn and both brow horns, an 



epijugal, occipital condyle, and other fragments of the skull. 

 Horizon: Lance formation, No. 3 from the summit of the Niobrara County sequence. 

 Locality: Niobrara County, Wyoming, very near that of Torosaurus lotus, on the divide midway between 



Lightning and Cow creeks and about a mile from their confluence. 

 Collector: J. B. Hatcher, 1891. 



This is a huge skull, measuring, as restored, about 8 feet 5 inches over all, and hence the 

 largest known skull of a land animal, actually exceeded in size by only a few of the greater of the 

 modern whales. The animal was apparently adult, but not extremely old. It was a younger indi- 

 vidual than the latus type. 



The dorsal profile of the skull, as restored, is flatter than that of latus, the line of face and 

 crest being continuous, although the latter rises slightly toward the posterior margin. The orbit is 

 nearly circular, in contrast to the oval one of latus. The descending limb of the jugal is preserved in 

 part on the left side, is of medium width, and flat on the outer aspect. There is a fairly large, 

 rounded, rugose epijugal. The limits of the infratemporal fossa are unknown except on its anterior 

 side, but it seems to have been somewhat larger in proportion than that of latus. Its actual form 

 cannot be determined. The nasal horn is conical, with an elliptical basal section, rugose, and with 

 the anterior face nearly vertical. 



The brow horns are slender for the size of the skull, and arise behind the orbits, the forward 

 margin of the horn being immediately over the posterior limit of the orbit. This position of the 

 horns is unique. The horns are flattened transversely at their base, and are elliptical in cross-section 

 throughout. The right one curves toward the median line when viewed from in front, the left 

 being & straight. Laterally, the posterior margin curves more than the forward one, and in the less 

 perfect left there is some indication of a reversal of the curve toward the tip. How much of this is 

 postmortem cannot be determined. 



The crest is immense. The median bar of the parietal, convex above, concave below, is very 

 thin and bears four low undulations. Marsh states that in this species the parietals entirely enclose 

 the fenestrae, while in latus the sauamosal forms a portion of the outer limit of the aperture. But 

 I find the evidence in the two skulls is about the same; in Radius, the distal part of the inner border 

 of the squamosal shows a distinct sutural surface, about 300 mm. long, and in latus 270 mm., in 

 front of which the border in each is smoothly rounded for a lesser distance when indications of 

 sutural connection with the parietal begin again. In the presumably ancestral Chasmosaurus there 

 is generally an overlapping suture in that portion of the parietal which lies between the fenestra and 

 the squamosal (see p. 68), except in the Yale specimen No. 2016 Y.P.M. in which the contact 

 between the two portions of the parietal is incomplete so that the squamosal resembles that of 

 Torosaurus in having a smoothly rounded portion interrupting the sutural continuity for the parietal. 

 The rear margin of the parietals is thin and undulatory, but there is no sure indication that Toro- 

 saurus ever possessed epoccipitals. The squamosal is extremely long, reaching the maximum length 

 ever attained by this bone. At the forward end there are three slight undulations, but the remainder 

 of the outer margin is smooth and rounded. There is no trace of vascular impressions on the entire 

 crest. . 



The pseudopineal fontanelle is single, as in Trkeratops, in contrast to its paired condition in 

 latus, with two radiating grooves terminating in large foramina, only one of which is preserved. 



97 Marsh, O. C, 1891, pp. 266-267. 



98 Hatcher, Marsh, Lull, 1907, Fig. 119. 



