30 WAITING IN THE WILDERNESS 



time, in what is called the Miocene, grass for 

 the first time grew and the teeth of horses later 

 changed to grass-eating teeth such as horses now 

 have." 



That evening I talked about prehistoric horses 

 with one of the geologists until everyone else 

 had turned in. Then early the following morn- 

 ing I climbed along canon walls hoping to see the 

 fossil of a tiny Oligocene horse sticking out of 

 the rocks. 



The oldest discovered fossil of the horse be- 

 longs to the Eocene Epoch, perhaps four million 

 years ago. He is known as Eohippus or Dawn 

 Horse. At that time he was not more than a foot 

 high, had four toes and a rudimentary fifth one 

 on each foot. Someone wrote of him : 



Said little Eohippus, 



"I am going to be a horse, 

 And on my middle finger-nail 



I'll run my earthly course." 



By the following epoch, the Oligocene, he had 

 grown to the height of two feet and had reduced the 

 number of toes to three. During the next epoch, 

 the Miocene, the Great Plains region of the West 

 was uplifted and became a vast, grassy prairie. 

 The horse, evidently benefited by grass, changed 

 and developed rapidly. His legs lengthened, he 

 at last came to his middle finger-nail one toe; 



