The great bulk of the Deseado fauna is made up, so far as individual abundance is concerned, of hoofed animals belonging to the typically South American groups. The †Toxodonta were represented partly by genera which were the direct ancestors of the common Santa Cruz genera (_†Pronesodon_, _†Proadinotherium_), and, more numerously, by a very peculiar family, the †Notohippidæ, which had highly complex, cement-covered grinding teeth. Still a third family of this suborder, the †Leontiniidæ, was highly characteristic of the Deseado fauna and is not known from the Santa Cruz. These were large animals, with a small horn on the tip of the nose and low-crowned, comparatively simple grinding teeth. Even more abundant were the †Typotheria, small forms which were ancestral to the Santa Cruz genera, larger ones which died out without leaving successors and one quite large animal (_†Eutrachytherus_) which seems to have been the ancestor of the Pliocene and Pleistocene _†Typotherium_. This series is not known to have been represented in the Santa Cruz and may have withdrawn from Patagonia at the end of the Deseado stage. [Illustration: FIG. 138.—Horned †toxodont (_†Leontinia gaudryi_), Deseado stage. Restored from a skull in the Ameghino collection.] The †Entelonychia, those strange toxodont-like animals with claws instead of hoofs, were much more numerous and varied than they were afterward in the Santa Cruz, when they were on the verge of extinction, and included both very small and very large species. The †Pyrotheria, a suborder which is not met with in the Santa Cruz or later formations, likewise included some very large forms. The typical genus, _†Pyrotherium_, included large, relatively short-legged and very massive animals; the upper incisors formed two pairs of short, downwardly directed tusks, and in the lower jaw was a single pair of horizontally directed tusks; the grinding teeth were low-crowned and had each two simple, transverse crests. These grinding teeth and the lower tusks so resemble those of the ancestral Proboscidea in the Oligocene of Egypt, that the †pyrotheres have actually been regarded as the beginnings of the †mastodons and elephants, but this is undoubtedly an error. The †Astrapotheria, another group which became extinct at or soon after the end of the Santa Cruz, were relatively abundant in the Deseado and counted some very large species. Finally, the †Litopterna were represented by the same two families as continued through the Pliocene and one of them far into the Pleistocene. The horse-like †proterotheres were present, but not enough of them has been obtained to show whether or not they were in a notably less advanced stage of development than those of the Santa Cruz. The †macrauchenids were quite similar to those of the latter formation, though considerably smaller. In addition, there were a few genera, survivals from earlier times, which were not referable to either of these families.