196 F. B. LOOMIS ORIGIN OF SOUTH AMERICAN FAUNAS 



know), should we be surprised if the same sort of thing was true in the 

 Permian, especially when we know of the great change in climate during 

 that period. My feeling, then, is that until it is demonstrated that the 

 fruiting of Glossopteris and similar genera is really distinct from that of 

 other seed ferns, it is just as well not to postulate a great continental 

 connection joining all the lands of the southern hemisphere, based on this 

 group at least. 



Conclusion : Mammals the first Vertebrates fully adapted to 



Land Life, and Faunas of South America 



CAME from North America 



In concluding, might I emphasize the statement made early in the 

 paper, that among vertebrates it is not until we come to the mammals 

 that we have a great class which has fully adapted itself to living on land 

 plants. In this we see the reason why this group so suddenly expanded 

 into luxuriant and diverse adaptations. For the first time food supplies 

 were well-nigh unlimited, and animals were not going back through a 

 series of preying on each other to the water plants for their ultimate 

 source of food ; but, having cut out an indefinite number of interme- 

 diaries, each such intermediary, taking some 90 per cent toll in passing 

 the food along, went directly to the land plants so abundant about them 

 for their food. 



Among the mammals, it is the herbivores which have progressed in the 

 most manifold and astonishing ways, and this is not to be wondered at; 

 for they have the direct access to the world of new plants which arose as 

 iiiscct pollination came in. They are the ones which lived in great num- 

 bers, bizarre forms, and bewildering changes. 



Then I have reviewed the evidence on which some of the most typic:al 

 arguments of the land connection between Africa and South America are 

 founded. In each great group there is in South America some form or 

 forms for Avhich a land connection would be convenient, but in no group 

 is the number for which such a bridge is postulated large, and for none 

 of them is the demand overwhelming. In all cases it is difficult to ex- 

 plain why the migrations did not go out as well as into South America. 

 As we should expect, there are some forms in each group the past history 

 of which we do not know. The better we know the history, the less de- 

 mand there is for such a bridge. To me it seems that the bridge in each 

 case was called into being for the purpose of making the discussion of a 

 group complete, when the wise method would have been to mark the 

 group and wait for further knowledge. Perhaps I can say these things, 

 for I postulated this land bridge, and now wish I had left the discussion 

 a paragraph shorter. 



