178 EXTINCT MONSTERS 
provided. Thus the vertebre have their “neural spines ” 
expanded at the summit to aid in supporting part of the armour. 
(See Fig. 62.) The fore limbs were short and massive, but 
provided with five fingers ; the hind limbs were very much larger 
and more powerful. These and the powerful tail show that the 
monster could support itself on them as on a tripod, in an 
upright position, and this position must have been easily assumed 
in consequence of the massive hind quarters. As in Iguanodon, 
there were three toes to the hind feet, and these were probably 
Fic. 62.—Tail vertebree of Stegosawrus. (After Marsh.) 
1, Side view. 2. Front view. 
covered by strong hoofs. The fore limbs could move freely in 
various directions like a human arm, and were probably used in 
self-defence. (See Fig. 63.) But for this purpose the tail with 
its four pairs of huge spines would be very effective, and one 
could easily imagine that a single deadly blow from such a tail 
would be sufficient to drive away, if not kill, one of the 
carnivorous enemies of the species. All the plates and spines 
were, during life, protected by a thick horny covering, which 
