220 VERTEBRATE ZOOLOGY 



thew says: "It reached a length of 47 feet and in bulk must have 

 equalled the mastodon or the largest living elephants. The massive 

 hind limbs, supporting the whole weight of the body, exceeded the 

 limbs of the great proboscidians in bulk." It stood about 20 feet 

 high, had a head over four feet long, teeth three to six inches long 

 and an inch wide. The claws on the hind feet were about eight 

 inches in length and of massive proportions. One can readily im- 

 agine a scene of carnage, the like of which the modern animal world 

 cannot afford, when such a reptilian dreadnought went into action 

 against one of those huge, heavily armed, monitor-like reptiles such 

 as the herbivorous dinosaur, Triceratops (Fig. 128). Such a struggle 

 would decide the question of supremacy between offensive andcie- 

 fensive armaments. 



THE HERBIVOROUS DINOSAURS (Sauropoda). The contrast be- 

 tween the carnivorous dinosaurs and the herbivorous dinosaurs in- 

 volves largely the matter of relative speed, of offensive and defensive 

 equipment. While haste is the essence of success in raptorial 

 life, no time element is involved in securing plant food. It ap- 

 pears to be certain that the early herbivores and early carnivores 

 were quite similar and that both were more or less bipedal. While 

 the carnivores carried this cursorial tendency to such an extreme that 

 the fore limbs were reduced to weak grasping appendages, useless for 

 locomotion, the herbivores eventually underwent a reversed evoluv 

 tion and became secondarily quadrupedal. Evident traces of the bi- 



FIG. 125. Brontosaurus. (From Lull.) 



pedal habit, however, are to be noted in the general body form and the 

 relative proportions of the fore and hind limbs, the latter in most forms 

 being much larger. An interesting series of massive forms appeared 

 of which Brontosaurus (Fig. 125) is typical. This great creature, 

 with a total length of nearly a hundred feet, has comparatively small 

 fore legs, but they more nearly equal the hind limbs than in some of 

 the earlier members of this group. Evidently the fore limbs later 



