400 
ORIGIN OF LIFE IN AMERICA 
remarkable and instructive examples of convergent develop¬ 
ment among mammals. Finally the Santa Cruz beds contain 
the remains of monkeys of South American type. The earliest 
traces of mammalian remains in Patagonia were supposed to 
have been found together with the bones of dinosaurs. Since 
these reptiles are characteristic of the Mesozoic Era, the state¬ 
ment that they were contemporaneous with rather advanced 
types was at first treated with little credence, especially as 
the actual deposits were not examined by Dr. Ameghino * 
but by his brother. Dr. Roth, however, has since re-examined 
the localities in question and has met with mammalian re¬ 
mains partly mixed with those of dinosaurs, and partly resting 
actually below the latter, so that there is scarcely any doubt 
as to the correctness of the original observation. The 
mammals belong to peculiar mastodon-like ungulates, having 
been placed in the order Pyrotheria which is now extinct and 
quite confined to Patagonia. Others, such as Notostylops, be¬ 
long to the Toxodontia above alluded to. 
I think there is a general agreement now that, at any rate 
at the dawn of the Tertiary Era, a number of rather 
specialized groups of mammals lived in Patagonia, and, 
although some of them became extinct, others continued 
to inhabit the country until recent geological times. A few 
of the largest edentates, like the giant ground sloth Mega¬ 
therium, which was about the size of an elephant, and is 
supposed to have dragged down trees in order to feed on the 
leaves, rather than climb up like its modern diminutive rela¬ 
tion the tree-sloth, still roamed about the country in 
Pleistocene times.f A few years ago the dried skin, with hair 
still attached to it, of a huge creature was discovered in a cave 
in southern Patagonia, near the boundary between Argentina 
and Chile. It proved to belong to the ground sloth Neorny- 
lodon, now known as Grypotherium listai.J Later on, the 
bones of the animal were disinterred, along with those of an 
extinct horse and a large carnivore. Traces of a fire were 
also noticed and an enclosure with cut hay. From these evi- 
* Ameghino, FI., “ Formations sedimentaires,” p. 80. 
f Lankester, Ray, “ Extinct Animals,” p. 172. 
X Moreno, F. P., and A. Smith Woodward, “Neomylodon listai.” 
