BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 

 Vol. 32, pp. 187-196 March 31, 1921 



PROCEEDINGS OF THE PALEONTOLOGICAL SOCIETY 



OEIGIN OF SOUTH AMERICAN FAUNAS ^ 



PRESIDENTIAL ADDRESS BY F. B. LOOMIS 



{Read before the Paleontological Society Decemher 29, 1920) 



CONTP]NTS 



Page 



Relations of earlj' vertebrates to plants 187 



Land connections of South America 189 



Comparison of Eocene faunas of North and Soutli America 189 



Review of Gondwanaland data: Reptilian, fish, land snails, and flora.... 193 

 Conclusion : Mammals the first vertebrates fully adapted to land life, and 

 faunas from South America came from North America 196 



Relations of early Vertebrates to Plants 



The background against which the early history of the South Amer- 

 ican animals unrolls includes the food supplies, the climate, and the 

 migration possibilities. The time when the various groups begin to as- 

 sume modern aspects and when the mammals begin to flourish is the 

 latter part of the Cretaceous and the beginning of the Eocene. 



The prime influence controlling any group of animals is the food sup- 

 ply. While the origin of mammals goes at least back to the Comanchean, 

 it is not until the Eocene that they flourish and spread out into luxuriant 

 lines of adaptation. The evolution of flowering plants started in a man- 

 ner which, to those of us who study mostly mammals, is strange ; for the 

 early angiosperms are trees of considerable size, while the herbaceous 

 plants coming later are smaller by far. Just before the beginning of the 

 Eocene, sedges and grasses spread over the arid country, but it is not 

 until the Eocene is really begun that the modern luxuriance of vegeta- 

 tion is characteristic, when the heretofore wind-pollinated trees and 

 grasses adapt themselves also to insect fertilization. Thus, then, just 

 about the beginning of the Eocene, to the forests is added a carpet of 

 grass on the prairies, ponds and streams are bordered and even occupied 

 by soft herbs, mountain slopes up to the snow-line blossom with both 



^Manuscript received by the Secretary of the Society March 3, 1921. 



(187) 



