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,f 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. Workman 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,” Yol. V., p 7. 
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