288 EXTINCT MONSTERS 
Darwin obtained an almost entire skeleton of one of these. It 
was as large as a polar bear. Speaking of his discovery, he says, 
“The beds containing the fossil skeletons consist of stratified 
gravel and reddish mud; a proof that the elevation of the land 
has been inconsiderable since the great quadrupeds wandered 
over the surrounding plains, and the external features of the 
country were then very nearly the same as now. The number of 
the remains of these quadrupeds embedded in the vast estuary 
deposits which form the Pampas and cover the granitic rocks 
of Banda Oriental must be extraordinarily great. I believe a 
straight line drawn in any direction through the country would 
cut through some skeleton or bones. As far as I am aware, not 
one of these animals perished, as was formally supposed, in the 
marshes or muddy river-beds of the present land, but their bones 
have been exposed by the streams intersecting the subaqueous 
deposit in which they were originally embedded. We may con- 
clude that the whole area of the Pampas is one wide sepulchre of 
these extinct gigantic quadrupeds.” ! 
The genus Scelidotherium comprises a number of species and 
presents characters more or less intermediate between Mega- 
therium and some other genera. The skull is low and elongated, 
and shows an approach to that of the modern ant-eater. The 
feet also are different from those of Megatherium (see Fig. 109). 
These monster sloths inhabited South America during the 
latest geological period, known as the Pleistocene. During part 
of that time North America, as well as Northern Europe and 
Asia, were invaded by a great ice-sheet, and an arctic climate 
prevailed, It is therefore very probable that while the mammoth 
and the mastodon were roaming over North America, giant sloths 
and armadillos were monarchs of the southern continent. What 
1 Journal of Researches. 
