ANTMALS OF THE PAST 



351 



.six feet. Many of them had no wings but depended on their 

 strong legs for locomotion. 



Mammals. — As we have already said, these are the 

 highest animals on the earth. They appeared for the first 

 time in the early mesozoic. But the first representatives 

 were of a low type; and the earliest that have been found 

 in this country belong to the marsupials antl monotremes, 

 the same groups as those to which the kangaroo and duck- 

 bill belong, respectively. Toward the end of the mesozoic 

 higher types of mammals came into existence. 



Animals of the Cenozoic Era 



We have seen how life fjegan with very low forms in the 

 archean, and gratlually grew higher and higher by the ex- 



FiG. 233. — Mainmotli. Redrawn, by permission, from an illustration 

 by Knight in McClure's Magazine, 1900. 



tinction of old and low forms and the formation of new and 



higher forms, until now, in 



the beginning of the cenozoic 



