EPOCH 



Pre- 

 Archaic Cambrian 



Man 



Mastodon 



Univalves 



Conifers 



(Angiosperms) 



(Tapir) 



Nummulite 



(Birds) 



Univalve 



(Palms) 



Pearl mussel 



Bivalves 

 Ammonites 



Crustacea 

 Cycads 



Winged 



reptiles 

 Crinoid 

 Gryphaea 



Crocodile 

 Bivalves 

 Lamp shells 

 Insects 

 Amphibia 

 Tree ferns 



Ganoid fish 



Starfish 

 Trilobites 



Sponge 

 spicules 



Graptolites 

 ofjellyfish 



FIG. 248. Geology and evolution 



In the oldest rocks no remains of plant or animal life are to be found. In each succeed- 

 ing age of the earth more and more highly developed plant and animal forms lived, as 

 shown by the remains of the organisms preserved in the rocks 



