THE EVOLUTION OF MAN 



brought face to face with another historical 

 fact. 



We have now arrived at the beginning of the 

 Tertiary period. One step further back and we 

 find ourselves in the age of the great saurians. 

 The geological picture has now completely 

 changed. We enter the Secondary period of the 

 earth's history, that inconceivably long epoch in 

 which the chalk cliffs of the Island of Rugen, the 

 Jurassic' slate of Suabia, and the reddish sand- 

 stone used in building the Strasburg Munster 

 were formed. The greater part of the large fossil 

 bones belonging to these days were the remains 

 of giant reptiles, some of them resembling 

 dragons. Those saurians swam around in the 

 ocean like our present day whales, or they rolled 

 around in the mud like our hippopotami. Some 

 of them, resembling colossal kangaroos, grazed 

 on the prairies like cows, lumbered about on their 

 heavy hind legs, or jumped after their prey, and 

 some of the most daring even rocked themselves 

 on batlike wings high up in the air. It was not 

 until gradually in the course of this geological 

 period, which probably lasted many millions of 

 years, that birds appeared for the first time first 

 of all, the lizard-bird Archaeopteryx. This transi- 

 tion form shows very plainly in its structure that 



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