THE LIFE OF MAMMALS 
apparent that these comparatively pygmy ground sloths were 
the ancestors of the megatheres and their relatives, which 
later were among the most gigantic beasts of the ancient 
world. 
Some of these huge edentates became known long ago, for in 1789 a 
nearly complete skeleton of one of them, named Aegatherium by Cuvier, 
was exhumed near Buenos Aires and sent to Paris, where it was mounted 
Megathe- and may still be seen at the Museum of Natural History. 
rium. Many other specimens, and the skeletons of allied species, 
have since been found in the Pampean formations of Pleistocene age, when 
these mighty animals flourished. The megatheres were very bulky, the 
largest measuring about eighteen feet in total length (yet the tail was not 
long, although extremely massive), and had big, roundish, slothlike heads, 
and short, massive limbs, especially as to the hinder pair, where the haunches 
were of enormous breadth and strength. The structure of the fore foot is 
essentially that of the modern ant-eater, the inner toe being rudimentary, 
the next three, and more especially the middle one, enormously enlarged 
and furnished with huge claws; and during life the creature rested on the 
outside of the fifth claw and the backs of the three large toes in ant-eater 
fashion. Its hind foot, however, was not at all ant-eaterlike, for that ani- 
mal stands upon a flat sole while the megathere walked only on its outer 
edge; the great middle toe, which constituted nearly the whole foot and 
was armed with a terrible claw, does not seem to have touched the ground 
in walking, and so the claw was not dulled. ‘Some idea of the gigantic 
proportions of the megatheres,”’ Lydekker tells us, ‘may be gathered from 
the circumstance that its hind foot measured nearly a yard in length.” 
The mouth of the megathere contained teeth in the form of square 
prisms, with a length of more than ten inches and a diameter of one and a 
half inches. These teeth were rootless and continued growing, and their 
arrangement shows that between them lay a huge tongue that probably 
could be stretched far out. The structure of these teeth and of other parts 
shows that the megatheres were far removed from being sloths; but the 
gap is somewhat filled by the mylodons, contemporary and somewhat 
smaller animals of the same general appearance, the special feature of which 
was the presence in their skins, near the outer surface, of a great number 
of bony nodules like beans. There was still another group of related ani- 
mals at that time, — the great scelidotherces, — differing decidedly from 
those already mentioned in having elongated narrow skulls, so that when 
alive they must have resembled ant-eaters. 
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