394 ORIGIN OF LIFE IN AMERICA 



westward. During part of Secondary times eastern Brazil 

 was most likely united by land with West Africa. During the 

 Cretaceous age already, the southern Atlantic rapidly advanced 

 northward, invading eastern Brazil, so that the land bridge 

 then joined only northern South America and a small tract 

 of West Africa. In Eocene times the southern trans -Atlantic 

 land connection had ceased to exist, yet the South American 

 continent must have extended still far eastward of its present 

 coast-line. Eastern Brazil continued to receive new additions 

 to its fauna from' the northern States of South America while 

 its area extended gradually westward. When Brazil finally 

 became joined to Argentina a faunistic interchange took 

 place, although Brazil and Chile remain to the present day 

 two fundamentally distinct countries. 



