38 MIGHTY ANIMALS 



skull was buried in the mud the jaws were still 

 apart, leaving the teeth exposed. But, although 

 the weight of the water was sufficient to cement the 

 mud into solid rock, the teeth in this skull were not 

 even bent. For, just as rapidly as the mud had 

 turned to stone, so had the bones within them been 

 changed into the same material. How this could 

 happen no one has ever been able to explain. We are 

 told that as the animal matter in all such buried bones 

 disappears, its place is taken by lime and silica, but 

 how this change comes about we do not know. It 

 remains one of Nature's many beautiful mysteries. 



Thus it was, that, after countless years, the bones 

 of the Dinosaur which had fought for its life in this 

 lake were changed into what is called a " fossil' ' and 

 lay imbedded in the solid rock beneath the water. 

 All the other things, whether they were bones, or 

 twigs, or leaves, that had fallen into the mud soon 

 after the Dinosaur had died, had been turned to 

 fossils also. And as more mud was carried into the 

 lake and settled to the bottom, more animals and 

 leaves and twigs found their way into this mud, and, 

 in this manner, layer after layer of rocks containing 



