NOTICE OF THE MEGATHERIUM. 
13 
earth at the moment when the forces of the fore-limb3 were exerted. The hind-foot, a full 
yard in length, stood at right angles with the leg, and, with its inward turned heel, gave a 
suitable base to the massive column above. The rugged ilium and spinal crest proclaim the 
pelvis to have been the centre of muscular masses of enormous power, which diverged to act 
upon the trunk, the tail, and the hind-legs. These muscles, if we may judge from the great 
size of the spinal cord, which in this region is 4 inches in diameter, must have been charac- 
terized by the extreme energy of their vital contractility * The unusual size of the sacral 
foramina, — far larger in their proportions to the other nervous canals than we find them in 
other animals, — shows the concentration of force in the posterior extremities. The acetabu- 
lum is excavated in a very exceptional manner, its concavity facing directly downwards. 
Setting in this way over the head of the femur, there is a great increase of strength for sus- 
taining vertical pressure, but attended with a diminished capability of rapid motion. But the 
animal had no need of agility, for it was not carnivorous ; neither for flight, for any cotempo- 
rary foe that ventured to cope with him could be laid in the dust by a single blow of his paw. 
We are anxious to know the daily habits, food, &c., of an animal whose bony frame-work 
offers so many and exceptional peculiarities of structure, united to such colossal dimensions. 
That the Megatherium was not carnivorous is settled by the structure of its molar teeth, — the 
only ones of the whole series which it possesses. Its lack of incisive teeth forbids our seeking 
its living analogue among those Ruminants or Pachyderms whose food is grass. We have 
already noticed the similarity of its teeth to those of the Sloth ; and, following the safe physi- 
ological rule, that animals having the same dental structure have the same kind of food, we 
come to the conclusion that, like the modern tardigrade, the Megatherium lived upon the 
foliage of trees. The elephant and the Giraffe, — the largest of the few leaf feeders of the 
present day, — present remarkable modifications of their organic structure relating to the 
acquisition of such food ; the one gathered in the branches with its long proboscis ; the other, 
standing on its stilt-like fore-legs, and reaching out its attenuated neck, plucked the higher 
boughs with its long and flexible lips and muscular tongue. The Megatherium jaossessed both 
of these prehensile organs (as we have judged from the pre-nasal and inter-buccal orifices for 
the passage of their nerves), yet with a much less development of the proboscis. We must 
evidently look to some other parts of its body for its most efficient instruments in obtaining 
its food. The question arises as to whether the animal sought its leafy pabulum after the 
mode of the modern Sloth, — by climbing. Was it scansorial ? We have before noticed 
the conjecture of Dr. Lund, that the huge monster once climbed, like a Bear, along the 
branches of the giant trees which then clothed the continent of South America, steadying 
itself, and even swinging from bough to bough, by means of a prehensile tail. The most 
obvious objection to this view is the immense bulk and weight of the creature, as well as its 
clumsy make. The large and well-developed clavicle indicates only the freedom with which 
the monster moved its fore-limbs, as we now see in those animals which carry their food to 
their mouths in their paws. It does not prove the Megatherium a climbing animal ; for the 
Bear, the heaviest animal now gifted with this faculty, has not even the rudiments of a clavicle, 
* The few modern Sloths which have been kept alive in menageries have astonished every spectator by the 
immense muscular force which they exerted with their fore and hind legs. 
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