I Will Here Give Only A Brief Outline Of Their Nature.
First, parts of three heads and other bones of the Megatherium,
the huge dimensions of which are expressed by its
name.
Secondly, the Megalonyx, a great allied animal.
Thirdly, the Scelidotherium, also an allied animal, of which
I obtained a nearly perfect skeleton. It must have been as
large as a rhinoceros: in the structure of its head it comes
according to Mr. Owen, nearest to the Cape Anteater, but
in some other respects it approaches to the armadilloes.
Fourthly, the Mylodon Darwinii, a closely related genus of
little inferior size. Fifthly, another gigantic edental quadruped.
Sixthly, a large animal, with an osseous coat in compartments,
very like that of an armadillo. Seventhly, an
extinct kind of horse, to which I shall have again to refer.
Eighthly, a tooth of a Pachydermatous animal, probably the
same with the Macrauchenia, a huge beast with a long neck
like a camel, which I shall also refer to again. Lastly, the
Toxodon, perhaps one of the strangest animals ever discovered:
in size it equalled an elephant or megatherium, but
the structure of its teeth, as Mr. Owen states, proves
indisputably that it was intimately related to the Gnawers, the
order which, at the present day, includes most of the smallest
quadrupeds: in many details it is allied to the Pachydermata:
judging from the position of its eyes, ears, and nostrils,
it was probably aquatic, like the Dugong and Manatee,
to which it is also allied. How wonderfully are the different
Orders, at the present time so well separated, blended together
in different points of the structure of the Toxodon!
The remains of these nine great quadrupeds, and many
detached bones, were found embedded on the beach, within
the space of about 200 yards square. It is a remarkable
circumstance that so many different species should be found
together; and it proves how numerous in kind the ancient
inhabitants of this country must have been. At the distance
of about thirty miles from Punta Alta, in a cliff of red earth,
I found several fragments of bones, some of large size.
Among them were the teeth of a gnawer, equalling in size
and closely resembling those of the Capybara, whose habits
have been described; and therefore, probably, an aquatic
animal. There was also part of the head of a Ctenomys; the
species being different from the Tucutuco, but with a close
general resemblance. The red earth, like that of the Pampas,
in which these remains were embedded, contains, according
to Professor Ehrenberg, eight fresh-water and one salt-water
infusorial animalcule; therefore, probably, it was an estuary
deposit.
The remains at Punta Alta were embedded in stratified
gravel and reddish mud, just such as the sea might now wash
up on a shallow bank. They were associated with twenty-
three species of shells, of which thirteen are recent and four
others very closely related to recent forms. [1] From the bones
of the Scelidotherium, including even the knee-cap, being
intombed in their proper relative positions, and from the
osseous armour of the great armadillo-like animal being so
well preserved, together with the bones of one of its legs, we
may feel assured that these remains were fresh and united by
their ligaments, when deposited in the gravel together with
the shells. [2] Hence we have good evidence that the above
enumerated gigantic quadrupeds, more different from those
of the present day than the oldest of the tertiary quadrupeds
of Europe, lived whilst the sea was peopled with most
of its present inhabitants; and we have confirmed that remarkable
law so often insisted on by Mr. Lyell, namely, that
the "longevity of the species in the mammalia is upon the
whole inferior to that of the testacea." [3]
The great size of the bones of the Megatheroid animals,
including the Megatherium, Megalonyx, Scelidotherium, and
Mylodon, is truly wonderful. The habits of life of these
animals were a complete puzzle to naturalists, until Professor
Owen [4] solved the problem with remarkable ingenuity. The
teeth indicate, by their simple structure, that these Megatheroid
animals lived on vegetable food, and probably on the
leaves and small twigs of trees; their ponderous forms and
great strong curved claws seem so little adapted for locomotion,
that some eminent naturalists have actually believed,
that, like the sloths, to which they are intimately related,
they subsisted by climbing back downwards on trees, and
feeding on the leaves. It was a bold, not to say preposterous,
idea to conceive even antediluvian trees, with branches
strong enough to bear animals as large as elephants. Professor
Owen, with far more probability, believes that, instead
of climbing on the trees, they pulled the branches down to
them, and tore up the smaller ones by the roots, and so fed on
the leaves. The colossal breadth and weight of their hinder
quarters, which can hardly be imagined without having been
seen, become on this view, of obvious service, instead of
being an incumbrance: their apparent clumsiness disappears.
With their great tails and their huge heels firmly fixed like
a tripod on the ground, they could freely exert the full force
of their most powerful arms and great claws. Strongly
rooted, indeed, must that tree have been, which could have
resisted such force! The Mylodon, moreover, was furnished
with a long extensile tongue like that of the giraffe, which,
by one of those beautiful provisions of nature, thus reaches
with the aid of its long neck its leafy food. I may remark,
that in Abyssinia the elephant, according to Bruce, when it
cannot reach with its proboscis the branches, deeply scores
with its tusks the trunk of the tree, up and down and all
round, till it is sufficiently weakened to be broken down.
The beds including the above fossil remains, stand only
from fifteen to twenty feet above the level of high-water;
and hence the elevation of the land has been small (without
there has been an intercalated period of subsidence, of which
we have no evidence) since the great quadrupeds wandered
over the surrounding plains; and the external features of
the country must then have been very nearly the same as
now.
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