22 THE CERATOPSIA 



ing and chopping one, which is one reason for the need of muscular cheeks to retain within the 

 mouth that portion of the food which would fall outside the teeth. A well-developed mobile 

 tongue is also a necessary part of the buccal mechanism. The form of the muzzle varied somewhat 

 in its degree of lateral compression, being very narrow and deep in Monoclonius, but broader and 

 shallower in Chasmosaurus. Whether this indicates a difference of food and the manner of its pre- 

 hension it is difficult to say. There is no marked specific distinction in the teeth themselves other 

 than of size and a small variation in the number of vertical rows. 



Tait and Brown 6 have given us a vivid picture of a feeding ceratopsian, derived not only from a 

 study of the mouth, but also from that of the ball and socket articulation of the skull and neck and 

 the length of the unprotected area of the spinal cord. Of course, a ball and socket joint is a uni- 

 versal one in the mechanical sense, but whether it implied a ninety-degree rotation of the skull on 

 its long axis, which their picture calls for, I seriously doubt. They say, "From its bodily configura- 

 tion .... it must have attacked the plants and plant stems near their base, and the wedge-shaped 

 beak .... was no doubt the instrument employed in seizing these stems. Tricerato-ps is possessed of 

 forward projecting horns, and it is conceivable that these may also have been used as an accessory 

 mechanism in the process of food collecting. 



"Throwing its beak laterally towards the cluster of vegetation, in which position it could seize 

 and grip vertically growing objects, it picked, let us say, one of these stems, the recurved beak clos- 

 ing either lightly or firmly around the column. Next with violence it wrenched the selected stem 

 towards the open A nasal horn such as Monoclonius possesses may have played some part." 



I agree with Nopsca 7 that the horns of the Ceratopsia could have had little or no part in food 

 getting, but were offensive and defensive weapons, and I do not see why, with its great weight and 

 widespread fore limbs, a horned dinosaur could not have ridden down the stems of desirable vegeta- 

 tion, in addition to that within easy reach, exactly as does a moose. This seems to me far more 

 consonant with structural limitations than the remarkable cervical gymnastics postulated by Tait and 

 Brown (see p. 73). 



METHODS OF COMBAT 



That the ceratopsians were pugnacious animals is attested first by their possession of horns and 

 neck shield, and secondly by the injuries which they carried, such as puncture wounds and broken 

 horns, all of which were premortem. These are in addition to the manifestations of bone tumors or 

 other disease. (See Torosaurus latus, Fig. 42 and PI. XV, which shows a puncture wound above 

 and in front of the right orbit, visible in the plate, in addition to the diseased condition of the right 

 squamosal.) 



Nopsca 8 stresses the heavy, broad-gauged position of the fore feet in contrast with the more 

 movable hind limbs. This permitted a freer rotation about the fore limbs, the creature swinging 

 the stern over to present the head to the enemy, rather than moving laterally the more cumber- 

 some forward part. What it strove to do, I imagine, was to charge the enemy head on, and at 

 the same time protect its own flank from attack. The long, more or less erect nose horn of Mono- 

 clonius must have implied a somewhat different mode of attack from that of Triceratofs with its short 

 nasal and long brow horns. The variation in curvature of the latter in the various species which 

 possessed them implies either that some of the difference is due to postmortem conditions or that 

 the individual tactics varied. The reinforcement of the skull, together with the powerful muscula- 

 ture of neck and shoulder, indicates a very decided survival value in these horns. There is never 

 any evidence of immensely long spinous processes in the anterior dorsal vertebrae of these animals, 

 however, such as certain horned mammals — the bison, titanotheres and rhinoceroses — possess. The 

 great extent of the crest, together with the mechanical advantage of increased leverage of the head 

 may have offset this in the ceratopsians. 



6 Tait, J., and Brown, B., 1928. 



7 Nopsca, F., 1929, A, pp. 69-70. 



8 Op. cit. 



