Ungulata.—Equus, Tapirus, Dicotyles, Auchenia, Cervus, Leptotherium, and Antilope, are the cave-genera of this order. Equus and Antelope are particularly interesting, as representing groups forming no part of existing South American zoology; while the presence also of Leptotherium, an extinct genus of antelopes, shows that the group was fairly represented in South America at this comparatively recent period.
Proboscidea.—A species of Mastodon, found also in the Pliocene of La Plata, represents this order.
Rodentia.—These abound. Dasyprocta, Cælogenys, Cavia, Kerodon, all living genera of Caviidæ, are represented by extinct species. Cercolabes, the 'tree porcupine' (Cercolabidæ) has two species, one as large as a peccary; Myopotamus, Loncheres, Carterodon, are existing genera of spiny rats (Echimyidæ); and there are two extinct genera of the same family, Lonchophorus and Phyllomys. Lagostomus (Chinchillidæ), the viscacha of the Pampas, is represented by an extinct species. There is also an extinct species of Lepus; several species of Hesperomys and Oxymycterus; and a large Arvicola, a genus not living in South America.
Edentata.—These, which constitute the great feature of the existing South American fauna, were still more abundant and varied in the Cave period, and it is remarkable that most of them are extinct genera. The armadillos are alone represented by living forms, Dasypus, and Xenurus; Eurydon and Heterodon, are extinct genera of the same family, as well as Chlamydotherium—huge armadillos the size of a tapir or rhinoceros, and Pachytherium, which was nearly as large. The ant-eaters are represented only by Glossotherium, an extinct form allied to Myrmecophaga and Manis. The sloths were more numerous, being represented by the extinct genera Cælodon, Sphenodon and Ochotherium, the last of large size. The huge terrestrial sloths—Megatheridæ, also abounded; there being species of Megatherium and Megalonyx, as well as the allied Scelidotherium, supposed to have some affinity for the African Orycteropus.
Marsupials.—No new forms of these appear, but numerous species of Didelphys, all closely allied to opossums still living in South America.
The preceding sketch of the wonderful cave fauna of Central Brazil, is sufficient to show that it represents, in the main, a period of great antiquity. Not only are almost the whole of the species extinct, but there are twenty extinct genera, and three others not now inhabitants of South America. The fact that so few remains of the living animals of the country are found in these caves, indicates that some change of physical conditions has occurred since they were the receptacles of so many of the larger animals; and the presence of many extinct genera of large size, especially among the Edentata and American families of Rodents, are additional proofs of a very high antiquity. Yet many of these cave animals are closely allied to those which are found in North America in the Post-Pliocene deposits only, so that we have no reason to suppose the cave-fauna to be of much earlier date. But the great amount of organic change it implies, must give us an enlarged idea of the vast periods of time, as measured by years, which are included in this, the most recent of all geological epochs.
Pliocene Period of Temperate South America.—We have now to consider the numerous remains of extinct animals found in various deposits in the Pampas, and in Patagonia, and a few in Bolivia. The age of these is uncertain; but as they are very similar to the cave-fauna, though containing a somewhat larger proportion of extinct genera and some very remarkable new forms, they cannot be very much older, and are perhaps best referred at present to the newer portion of the Pliocene formation.
Carnivora.—The genus Machairodus or sabre-toothed tigers, represents the Felidæ. There are several species of wolves (Canis); a weasel (Mustela); two bears of the Brazilian cave-genus Arctotherium; and the extinct European genus Hyænarctos.
Ungulata.—There are two species of Equus, found in the Pampas, Chili, and Bolivia; two of Macrauchenia, an extraordinary extinct group allied to the tapir and Palæotherium, but with the long neck, and general size of a camel. A second species found on the highlands of Bolivia is much smaller.
A more recent discovery, in Patagonia, is the almost perfect series of teeth of a large animal named Homalodontotherium; and which is believed by Professor Flower, who has described it, to have been allied to Rhinoceros, and still more to the Miocene Hyracodon from North America; and also to present some resemblances to Macrauchenia, and though much more remotely, to the curious genus Nesodon mentioned further on.