5 8o EOCENE AND OLIGOCENE PERIODS 



appeared in North America in the White River stage, and con- 

 tinued into the Miocene. An interpretation of their general 

 appearance is shown in Fig. 487. Artiodactyls were prominent, 

 represented by various extinct forms, and by ancestral peccaries, 

 camels, ruminants, and other forms. 



Marine life. The fauna of the Oligocene on the Atlantic coast 

 of North America has the same general aspect as that of the Eocene. 

 Later, however, provincialism became pronounced. By this time, 

 the foraminifers had declined greatly, and the fauna was over- 

 whelmingly molluscan. On the Pacific coast, the Oligocene fauna 

 shows closer relation to the Miocene fauna than to the Eocene, and 

 suggests a climate intermediate between the climates of those 

 periods. 



