FOSSIL EDENTATES 401 



dences of man's presence, along with the remains of the 

 ground sloth, it was concluded that the cavern was an old 

 corral in which the ground sloths had been kept and tended 

 by some primitive human race.* 



The survival of many of such large creatures until recent 

 geological times implies that, as in the northern hemisphere, 

 there must have been ample food available in Argentina 

 during the Pliocene and Pleistocene Periods to nourish these 

 mammals, the climatic conditions having since become more 

 varied and unfavourable. Compared with the Santa Cruz 

 edentates, the less ancient groups were mostly larger. 



In spite of the fact that the fossil mammalian fauna of 

 Argentina presents so many features pointing to long isola- 

 tion, the relationship of certain forms to those found in far 

 distant regions is of extreme interest and importance from a 

 zoogeographical point of view, as elucidating the geological 

 history of the South American continent. The diversity in 

 shape and character between the Santa Cruz armadillos 

 (Dasypoda), for example, is very notable, according to Pro- 

 fessor Scott,t no less than three families and seven genera 

 having been described so far. And yet a genus of armadillo 

 (Metacheiromys) makes its appearance in the Middle Eocene 

 beds of western North America. Dr. Wortman's theory that 

 the edentates were of North American origin, having sub- 

 sequently spread to South America, has not been adopted by 

 any later authors. Dr. Wortman assumed that their earliest 

 appearance in South America did not antedate the Santa Cruz 

 epoch, whereas Professor Scott points out that they also 

 occur in the oldest known Tertiary and possibly even pre- 

 Tertiary deposits of Patagonia, and that there is every 

 appearance of their having been indigenous in that region. 

 It is, in fact, generally assumed now that South America was 

 the original home of the edentates. If it is correct, as I have 

 endeavoured to show, that Central America has only come into 

 existence in comparatively recent geological times, and that 

 the whole continent of South America in the dawn of the 

 Tertiary Era consisted of several distinct masses, Patagonia 



* Woodward, A. Smith, " Grypotherium listai," p. 64. 

 t Scott, W. B., " Princeton Expedition to Patagonia," Vol. V., p 7. 

 L.A. O D 



