150 STORY OF THE REPTILES 



their motion, perhaps all were capable of rearing up, 

 many of sitting np 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, 

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

 protected and armed in the tail, and the Triceratops — 

 which was three-homed (Fig. 69) — are eKamples of 



Fio. 69. — Triceratops prorsus (after Marsh), x A, 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, Brontosawus, shows by its small fore limbs 

 (Fig. YO) 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 Laosaurus (Fig. 71) walked 

 erect. All of these noted were herbivorous — brows- 



