THE EVOLUTION OF THE HORSE AND THE 



ELEPHANT 



By Frederic Brewster Loomis 



Professor of Geology, Amherst College 



The horse and the elephant are so well known and their 

 characteristic features are so striking that a study of the 

 changes which have taken place in their ancestors to bring 

 them to their present forms should be of general interest. 

 The horse and his associates, unlike other animals, has on 

 each foot only a single toe — the hoof — and the elephant is 

 unique in possessing that wonderful organ, the trunk, which 

 is adapted to so many uses. In our study of the evolution of 

 these animals we shall have to turn to the geologist for the 

 evidence, which consists of bones entombed in beds of sand 

 and clay, most of them now hardened to rock, laid down in 

 different parts of the world during what is called the Tertiary 

 period (see the accompanying geologic time table) and part 

 of the succeeding Quaternary period, in which we are now 

 living. The order of succession of the animals whose forms 

 are thus revealed must be determined by the order of the 

 deposition of the beds in which the bones are found. In a 

 series of such beds the one at the bottom was laid down first 

 and the overlying beds were laid down in the order in which 

 they appear, one above another. The bones found in these 

 beds belonged to animals that lived and died about the time 

 the beds were formed. Each bone found occupied a certain 

 known position in the skeleton of the animal, had certain 



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