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extensive distribution, ranging from the highlands of Ecuador and Peru, along the Andes, to the open plains of Patagonia ; while the Vicugna (L. vicugna), which is a somewhat smaller animal, is found only in Ecuador, Peru, and Bolivia

In addition to the Lamas, this Sub-region possesses a species of thickly haired mountain Tapir, differing from the lowland forms, and two or three peculiar Deer, of the sub-genus Furcifer, which are likewise densely furred. A third diminutive deer found in Chili is distinguished from Cariacus, the ordinary American forin of deer, by anatomical characters, and belongs to a special genus, Pudua. A second species of this form (P. mephistopheles) from the highlands of Ecuador has lately been described by Mr. De Winton.

The Rodents of the Patagonian Sub-region almost all belong to the Hystricomorphine section of the Order. Amongst them are the Chinchillas (Chinchilla and Lagidium), noted for their delicate fur, the Viscacha (Lagostomus), and the Patagonian Cavy (Dolichotis). Out of the eighteen genera of this division known to occur in the Patagonian Sub-region, ten are restricted to it.

Of the carnivorous Mammals of this Sub-region, one of the most interesting is the Spectacled Bear of the Andes (Ursus oratus), which affords an instance of that rare phenomenon in nature “discontinuous distribution, the nearest allied species of bear (the black bear of North America) only coming as far south as Mexico. The presence of a bear in the Andes can only be explained by the supposition that the ancestral form migrated southwards along the line of the Cordilleras, but has died out in the intermediate district. The Bats of the Patagonian

Sub-region present but few features of interest; they are, with one exception, all of genera found also in the GuianoBrazilian Sub-region.

As might have been expected from the dearth of forests and the generally severe climate, the American monkeys and marmosets are entirely unrepresented in the Patagonian Sub-region. On the other hand, at least two small species of Opossum (Didelphys and Dromiciops) occur in Chili, and a very remarkable form of Armadillo (Chlamydophorus) is peculiar to Argentina and the high plateau of Bolivia.

The following list of the mammal genera of the Patagonian Sub-region is constructed on the same plan as that of the preceding tables :

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SECTION VIII.—THE PAST HISTORY OF THE

NEOTROPICAL MAMMAL-FAUNA

During the last few years our knowledge of the extinct mammals of the Neotropical Region has been enormously increased by the discoveries of the palæontologists of the Argentine Republic, more particularly by the labours of

Burmeister, Moreno, and Ameghino. A few words about this branch of the subject may be added.

The oldest formation containing well-preserved remains of mammals yet investigated is in the neighbourhood of Santa Cruz, in Southern Patagonia, where the deposits are about 200 feet in thickness. The exact age of the Santa Cruz beds it is very difficult to determine, but the best authorities consider that they cannot be of earlier date than the Upper Eocene or Oligocene of Europe. Following these in point of time, are the so-called “Patagonian" beds of Patagonia and Uruguay, which are probably of Miocene age. The “Araucanian” formation of Ameghino, which is well developed at Monte Hermoso, near Bahia Blanca, in Southern Argentina, seems to correspond approximately with the older European Pliocene. Finally, the later Pliocene is apparently represented by the “Pampas” formation of Argentina and Uruguay. Our knowledge of the extinct mammal-faunas of these beds is mainly due to the efforts of the Argentine palæontologists just mentioned, but a clear résumé of the work done will be found in a recent number of the Geological Magazine (12).

In the “Santa Cruz” beds have been found remains of about 120 genera of mammals referable to the following groups :

Marsupials.
Edentates.

Perissodactyles.
Toxodonts.

Rodents.
Monkeys.

Among the Marsupials the most prominent forms in this formation are the Opossums (Didelphyidx), which are still found all over America, and in Tertiary times appear to have been distributed nearly all over the northern hemisphere. But accompanying these are other forms of the same Order, which seem to be more nearly related to the Australian marsupials of other families; in fact, Ameghino has placed some of them in the (hitherto supposed to be) exclusively Australian family Dasyuridæ.

The fossil Edentates of this formation are all of the American section of the group. The Perissodactyle Ungulates are represented by two families (Proterotheriidæ and Macraucheniidæ)not very definitely connected with other Perissodactyles, and unknown elsewhere; and the Toxodonts (another group forming a distinct sub-order of the Ungulata) are also quite unrecognised outside South America, where, indeed, they appear to have existed for a short period only.

The Rodents of this formation all belong to the Hystricomorphine section of the order, and the Monkeys are all Platyrrhine, so that, except in the case of the Marsupials where the results are to a certain extent doubtful, no clue to the origin of the Neotropical fauna is shown by this extinct fauna. When these results are compared with the Eocene Mammal-fauna of the northern hemisphere, the absence of Artiodactyles, Insectivores, Bats, Carnivores, and Lemurs, is very striking.

The “Patagonian” beds contain a Mammal-fauna only to be distinguished from the previous “Santa Cruz" series by a further differentiation of genera belonging to the same orders without any traces of foreign admixture. When, however, we reach the more recent Araucanian formation, we find, in addition to the Edentates, Toxodonts, and other typical South American forms, a number of foreign intruders, such as Tapirs, Lamas, Elephants (Mastodon), and Wild Dogs (Canis), of an entirely different aspect. There can be little doubt that these animals had migrated

here southwards from North America, where their remains (or those of closely allied species) have been likewise found in the nearly contemporaneous formations of the United States.

Moreover, it would seem that in these bygone days, not only did the northern forms move southwards, but that also some of the southern forms emigrated northwards. This is evidenced by the fauna of the so-called Equus-beds” and “ Megalonyx-beds” of a slightly later date in the United States, which contain a composite Mammal - fauna of northern forms mixed with forms usually considered to be exclusively South Americansuch as the gigantic armadillo-like Glyptodon, the Capybara (Hydrochorus), Toxodon, and others.

Finally, in the age of the “Pampas” beds, the peculiar South American Mammal-fauna seems to have reached its culminating-point, and to have far exceeded that of the present day both in number of species and in the size of the individuals. This great increase in size, which is, as a rule, accompanied by an extreme specialisation of individual organs, seems to have had a fatal effect on its possessors, as none of the larger Edentates or Toxodonts appear to have outlived the end of the pampas formation. Along with most of the larger arrivals from the north, such as Mastodon and Equus, they became extinct. All the conclusions to be derived from this much-abbreviated account of the extinct Mammals of South America, confirm in a remarkable way the evidence of the present fauna as to this history of the Neotropical Region. Up to the last period of the Tertiary epoch, South America was certainly isolated from the rest of the world, and the connections with Australia and with Africa, if they ever did exist, must have been previous to this

ever

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