As in the other typical South American edentates, there are no teeth in the front of the jaws, while those of the cheek-series usually comprise five pairs in the upper and four in the lower.
By many palaeontologists a group of North American Lower Tertiary mammals, known as Ganodonta, has been regarded as representing the ancestral stock of the ground-sloths and those of other South American edentates; but according to Professor W.
If this be so, we are still in complete darkness as to the stock from which the South American edentates are derived.
Non-committal as regards evolution, he vastly broadened the field of vertebrate palaeontology by his descriptions of the extinct fauna of England, of South America (including especially the great edentates revealed by the voyage of the " Beagle "), of Australia (the ancient and modern marsupials) and of New Zealand (the great struthious birds).
The edentates are represented by the pangolin (Manis sp.?) of the Palawan group. In the seas are found the dolphin, cachalot and dugong.
Lydekker, "The Extinct Edentates of Argentina," An.
Very generally the tail has distinctly the appearance of an appendage, but in some of the lower mammals, such as the thylacine among marsupials, and the aard-vark or ant-bear among the edentates, it is much thickened at the root, and passes insensibly into the body, after the fashion common among reptiles.