98 ANNALS NEW YORK ACADEMY OF SCIENCES 



none of the typical South African Permian land reptiles have been found 

 in South America. 



MAMMALS 



Is an Antarctic connection between Patagonia and the Australian 

 realm needed to explain the distribution of any of the South American 

 extinct mammals? 



The best evidence which has been used to support the Antarctica 

 theory is derived from the mammals. It is the best evidence, because 

 slow-moving mammals need land connections more than do either flying 

 or aquatic animals and because the Tertiary record of the mammals is 

 fairly well known. There is, however, a great blank in the fossil record 

 in the entire lack of pre-Oligocene mammals of Asia and northern South 

 America. 



The absence of pre-Oligocene animals in both Asia and northern South 

 America is either due to imperfection of the fossil record or to the lack 

 of exploration, because the existence of pre-Oligocene mammals in Xorth 

 America, Patagonia and Africa could not be explained unless the mam- 

 mals entered both Asia and northern South America; for otherwise we 

 must assume the separate origin of mammals in two or three different 

 places. The works of Sclater, Wallace, Lydekker, Matthew, Osborn and 

 others indicate that the most of the orders of mammals directly or indi- 

 rectly originated in the northern hemisphere, which has embraced the 

 bulk of the land at least during the age of mammals. It is true that 

 South America and Africa have been separate centers of origin of many 

 mammals, but even many of these can be remotely traced back to the 

 northern hemisphere. The presence of primitive mammals in the Tri- 

 assic of North America and the Jurassic of North America and Europe 

 taken in connection with the geology of Europe is sufficient evidence to 

 show that the pre-Oligocene animals must have existed in both Asia and 

 northern South America. The distribution of mammals, as I see it, in- 

 volves, unfortunately, exactly the above regions from which we have no 

 fossil evidence. These are transitional regions between the northern and 

 southern hemispheres. Until the known fossil-bearing region of Bahia, 

 Brazil, is examined and until mammalian fossils have been found in the 

 early Eocene of northern South America and southern Asia, the distribu- 

 tion of the Mammalia will never be satisfactorily settled. Nevertheless, 

 on account of its profound geological significance, I think that a brief 

 re-examination of the materials of the distribution of South American 

 mammals should be attempted. 



The only support for the Antarctica theory from the standpoint of the 

 Mammalia is derived from the affinities in the common presence of both 



