152 EXTINCT MONSTERS. 
and it may be that in the course of subsequent ages such promi- 
nences as those developed into true ‘horn cores,” such as sheep 
or goats have, while the thick bosses of skin that covered them 
slowly developed into the true horns that are attached to these 
cores. If this is so, then we have here another instance of a 
“generalised” structure. Again, the limbs with their five toes 
tell us at once that the creature’s place in Nature is outside of 
those two great groups of modern ungulates, or hoofed quadru- 
peds, the odd-toed and the even-toed, represented on the one 
hand by the horse, rhinoceros, and tapir, on the other by the pig, 
camel, deer, ox, and many other forms. Probably the two groups 
Fic. 44.—Cast of brain-cavity of Dznxoceras mirabile. (After Marsh.) 
had not at this early period branched off from the primitive 
ungulate stock with five toes in each foot, of which the elephant 
is a living descendant, and from which also the Dinoceras must 
have come. 
The limbs were strong and massive, but the brain was 
remarkably small, so that our Dinoceras cannot be credited 
with any high degree of intelligence: and here again we see 
an absence of ‘‘specialisation” compared with the sagacious 
elephant. Professor Marsh has taken casts of its brain-cavity 
(see Fig. 44). These casts show that the brain was smaller (in 
proportion to the size of the animal) than in any other mammal, 
whether living or extinct—and even less than in some reptiles ! 
