150 STORY OF THE REPTILES 



their motion, perhaps all were capable of rearing up, 

 many of sitting up permanently, and a large propor- 

 tion could move about on the hind feet with or with- 

 out touching the tail to the ground. In all, however, 

 the tail was an important member — the third leg 

 often of a three-cornered support. The Stegosaurus, 

 ajready described (see page 135, Fig. 62) as so well 

 protected and armed in the tail, and the Triceratops — 

 which was three-horned (Fig. 69) — are examples of 



Fig. 69. — Tricerat02)S prorsus (after Marsh), x g\j, Cretaceous, 



Wyoming. 



the four-footed walkers of this group. This last is 

 the one which had a collar of spines also. It had a 

 beak which was tortoiselike in some respects. The 

 next one, Brontosaurus^ shows by its small fore limbs 

 (Fig. 70) that it arose on its hind legs ; but a glance 

 at its neck bones and the set of its skull shows that its 

 head was held horizontal by the spines of the back- 

 bone. Observe that the elongation of rear limbs, the 

 slim neck vertebrae, and the long head, set at an angle 

 with the neck, show that Laosaurits (Fig. 71) w^alked 

 erect. All of these noted were herbivorous — brows- 



