PROBABLE HABITS. 193 



Triceratops was extremely deficient mentally, and was probably of comparatively peace- 

 able disposition except, perhaps, at the breeding season. Then the combats between rival 

 males which probably took place must have been prompted and carried out by blind, unrea- 

 soning instinct solely. This would make such weapons and defensive armor very efficient, 

 for the Ceratopsia were evidently not intelligent enough to use weapons requiring skill in their 

 manipulation. 



The question of other skin protection can not yet be settled, for while certain dermal scutes 

 and ossicles have been found which may have been borne by Triceratops, we have no knowledge 

 of their position or arrangement. It is unreasonable to suppose that the skin was naked, for 

 such condition is found only among exclusively aquatic reptiles, such as the ichthyosaurs. 



The limbs were doubtless somewhat elephantine except that the ulna, with its huge olecranon 

 process, gives evidence of having been flexed to a greater degree, as shown in the restoration. 



Of the feet we have but little trustworthy knowledge. The hoof-like claws are clearly 

 indicated by the form of the ungual phalanges and, if Hatcher's very reasonable conception of 

 the creature's habitat be correct, one would expect a somewhat spreading foot, which would 

 bear the animal up in soft ground. 



Of. Triceratops only have we any idea of general form and proportions, its contemporaries 

 Diceratops and Torosaurus being known only from the skull. 



Diceratops, it will be remembered, had no nasal horn, and the supraorbitals were erect 

 instead of forward projecting as in Triceratops. Its mode of fighting must have differed some- 

 what from that of the latter, probably in lowering the head much more. The peculiar fenestra? in 

 the squamosals are unequal in size, and the one in the right parietal, near the margin of the 

 frill (the corresponding portion of the left having been destroyed), may have been due to wounds 

 caused by the penetration of an adversary's horn. In the Yale Museum there is a scapula of 

 Diclonius with a clean-cut perforation, the edges of which have healed so as to give the appear- 

 ance of a normal foramen. It is absent in the other scapula of the same animal, and Professor 

 Marsh used to say that it was made by the horn of a Triceratops. This is certainly very suggestive 

 of the Diceratops fenestra?. The left squamosal of the type of Triceratops elatus also shows a 

 perforation near the parietal suture, which is of pathologic character. (See PL XLIII, p. 284.) 



In Torosaurus the cranium was of proportions so different, with its immense though weak 

 frill and its wedge-shaped facial region, that the aspect of the head must have differed greatly 

 from that of Triceratops. The upper surface of the frill does not bear the deep vascular impres- 

 sions of the last-mentioned genus nor are there marginal ossicles, indicating that instead of 

 being somewhat free with a dense horny or tegmentary covering, the crest was more or less 

 buried in the flesh of the neck. It was evidently used to obtain leverage for the head and not 

 like the neck guard of a helmet, to protect the cervical region. The presence of the large vacui- 

 ties is further evidence in favor of this belief. The two known species of Torosaurus are huge 

 creatures, larger than the average Triceratops though of less proportions than the giant specimen 

 of the latter genus alluded to on page 185. The supraorbital horns of Torosaurus were well 

 developed, though the nasal horn was proportionately reduced and acutely pointed. 



PROBABLE HABITS. 



The feeding habits of the Ceratopsia are manifest from the tooth structure and from the 

 character of the vegetation preserved with ceratopsian remains. The forward part of the 

 mouth was edentulous and was sheathed on both the upper and the lower jaw, with a cutting 

 beak like that of a turtle. Within the mouth were the magazines of teeth, each series presenting 

 a vertical though slightly twisted wearing surface toward that of the opposing series, the worn 

 surface of the lower teeth facing outward, that of the upper row inward. There is no possibility 

 of a lateral grinding movement, as in herbivorous mammals; the lower jaw must have been 

 moved entirely in a vertical plane. The beak probably served for cropping the more succulent 

 leaves and shoots of low trees or shrubs, while the teeth were used to chop the food into short 

 pieces before it was swallowed. As such pieces would naturally fall outside of the teeth of the 



MON XLIX — 07 13 



