408 P. S. MARTIN 



mut, mastodon; Paramylodon, Nothrotherium, and Megalonyx, 

 ground sloths; Glyptotherium, glyptodont; Platygonus, peccary; 

 Tanupolama, long-legged llama; Camelops, camel; Sangamona, 

 extinct deer; Breameryx, tar-pit pronghorn; Stockoceros, pronghorn; 

 Euceratherium and Preptoceras, shrub-oxen; Bootherium, musk-ox; 

 Equus, horse and ass, various species. 



Surviving. Antilocapra, pronghorn; Odocoileus, mule deer; Bison, 

 buffalo, one species only. 



Extinction intensity. Heavy. 



In addition to these three cases it is obvious that other regional 

 faunas fulfill the requirements. For example, the Greater Antilles ex- 

 perienced complete extinction of all beaver-sized and larger animals 

 and partial survival only among the small mammals and reptiles. 

 In Alaskan tundra and Mexican steppe there was a high extinction 

 rate for large herbivores (pronghorn size and over) , but not for small 

 or medium-sized mammals. Applying the model to South America 

 we would expect heavier extinction on the pampas and campo 

 cerrado savannas than in the Amazonian rainforest. 



Paleontology of the Pampean formation (Simpson, 1940) showed 

 that a variety of ground sloths, glyptodonts, and other edentates, 

 horses, certain camels, and the native ungulates, as the macra- 

 ucheniids, toxodonts, mesotheres, and hegetotheres, disappeared 

 from the plains areas. Some extinction of forest forms must have 

 occurred, probably more than the scanty fossil record of mastodonts 

 and bears would indicate (tropical forest Pleistocene sediments are 

 all but unknown) . However, survival in the forest exceeds that on the 

 plains. Peccaries, large edentates, monkeys, tapirs, capybaras, and 

 various deer in the forest and forest margin contrast with the pres- 

 ence of only two large native herbivores in the pampas and in Pata- 

 gonia, the guanaco or wild llama and the pampas deer. 



If the model is adequate in these cases, it by no means explains 

 lack of extinction under certain circumstances that call for it. The 

 survival of four species of native camamelids in South America, at 

 least two of them with relatively narrow ranges in the i\ndean Puna 

 is mystifying, both in terms of the model and the extermination of 

 the camamelids in North America. The survival of Capromys ingra- 

 hami on one of the smaller Bahaman Keys and of Testudo, the giant 

 tortoises of the Galapagos, introduce an additional problem that 

 appears worthy of special treatment. 



