SOUTHERN MEXICO AND CENTRAL AMERICA 



to: 



Permian reptiles and flora were isolated and did not migrate from one 

 continent to the other (Schuchert, 1935). The separation continued 

 through the Triassic. Little can be said of the Jurassic and Early Cre- 

 taceous. 



At the same time as land migration routes are established between 

 North and South America, so are migration routes of marine invertebrates 



severed between the Atlantic and Pacific. The conclusions reached In tin- 

 invertebrate paleontologist should therefore dovetail those of tin- verte 

 brate paleontologist. According to Schuchert ( L935) not all invertebrate 

 paleontologists agree on the relation of Atlantic or Gulf and Pacific forms, 

 but most evidence points to a portal in Early and Middle Tertian time, 

 and thus supports the mammalian record. 



