EVOLUTION OF THE HORSE 



39 



every tooth, and every part of the skeleton had been changed 

 by slow degrees during unmeasured periods of past time. 



Moreover, with this knowledge as their basis, they knew 

 they had in hand a key which would help unlock the mys- 

 tery of all change in all animals, both ancient and modern. 



Head 



Fore Foot 



HindFoot 



Teeth 



OneToe. 



Splints of 



2nd and 4th 



digits 



OneToe 



Splints of 



2nd and 4th 



digits 



Protohippus 



Mesohippus 



ThreeToes 



SidTtoes 



not touching 



the ground 



ThreeToes 



Side~toes 



not touching 



the ground 



Long- 

 Crowned, 

 Cement- 

 covered 



ra ThreeToes 

 Side toes 

 Aft touching the 



ground; 

 Splint of Sthdigit 



Protorohippus 



ThreeToes 



Side toes 



touching the 



ground 



Four Toes 



Short- 

 Crowned, 

 without 

 Cement 



Hyrac other ium 

 (Eohippus) 



FourToes 

 Splint of 

 1st digit 



ThreeToes 

 Splint of 

 5th digit 



DRAWING OF SKULLS, FEET, AND TEETH OF PREHISTORIC HORSES, 

 GROUPED FOR COMPARISON 



They show the development of the horse by evolution. (Reproduced, by permission, 

 from " Origin and History of the Horse," by H. F. Osborn) 



As might be supposed, it takes two sets of scientists to 

 make out the truth about buried bones. 



i. There is the geologist. He studies the earth itself, 

 knows which parts of it were formed first, which later, and 

 by knowing just where the bones came from, he tells us which 



