104 MIGHTY ANIMALS 



fossil hunters are continually working in the Dakota 

 Bad Lands in the hope of making new discoveries 

 concerning all the different members of this strange 

 family of beasts. 



It must not be supposed that these different sizes 

 of Titanotheres are found buried in neat layers, one 

 below the other. On the contrary, the different 

 layers are often in different bluffs. But the farther 

 down a layer is in a bluff, the smaller are the animals 

 it contains. So it is known that, from the time the 

 Titanotheres first appeared on earth until they dis- 

 appeared, they made their homes in this part of 

 Dakota. They lived in other parts of that western 

 country, also, but not in such large numbers as 

 around the lakes that once made beautiful the now 

 dreary and uninhabited Bad Lands. 



Tens of thousands of years, yes, perhaps, even a 

 million of years, passed between the time when the 

 first Titanotheres lived and the time when the last of 

 the family — the Titanotherium — became extinct. 

 The general estimate is that it takes nine hundred 

 and ninety-six years for one foot of rock to be formed 

 through the action of water on mud. When we re- 



