Dinotherium (Gr. terrible, and beast), an extinct pachyderm of immense size, some of whose bones have been found in the middle tertiary or miocene deposits of Europe, Asia, and Australia. A few teeth were found in France during the last century and the early part of the present. In 1829 Kaup discovered at Eppelsheim, S. of Mentz, a sufficient number of bones to lead him to form a new genus for it. In 1836 the discovery of a cranium by Klipstein seemed to settle the position of the dinotherium among the pachyderms. This head (of which casts are very generally found in cabinets) is nearly 4 ft. long, 2 ft. broad, and 1 1/2 ft. high, its summit divided into two parts by a well marked ridge, and its occipital surface wide and oblique, with a globular occipital condyle; the nasal aperture is very large, as in the elephant and mastodon, with the large suborbital foramina indicating the possession of a proboscis. The lower jaw is remarkable for its curve downward, and its two tusks pointing in the same direction, forming a hook 3 ft. in length and describing a quarter of a circle.
The primary teeth appear to have been 12, 3 on each side of each jaw, and the permanent teeth 20, 5 on each side of each jaw; the front 2 on each side, making 8, are premolars, and resemble those of the tapir; the upper 12 teeth, the true molars, resemble those of the mastodon in their transverse ridges, but differ from them in their square form; they are developed vertically, as in man and most mammals, while those of the elephant family are developed horizontally. If the bones of the trunk and extremities attributed to this animal really belong to it, it would have a length of 18 ft. and a height of 14, 2 ft. longer and higher than the largest mastodon discovered. The shoulder blade is like that of the mole, indicating that the fore feet were adapted for digging. It is not very easy to decide whether this animal was more terrestrial or aquatic in its habits. Pictet expresses the opinion that it was a herbivorous cetacean. On the contrary, Owen, Kaup, and Do Blainville consider it a terrestrial proboscidian, intermediate between the mastodon and tapir.
These two opinions are really not very different, since it is now generally agreed that the manati and dugong, or the herbivorous cetacca, must be removed from the order of cetaceans and placed among the pachyderms, of which last they are the embryonic type. Considering then the dinotherium to be a true pachyderm, or perhaps a connecting link between this order and the herbivorous cetaceans, its favorite element, air or water, may be a matter of question. It has no incisor teeth; its inferior tusks seem admirably adapted to drawing its heavy body out of water upon the banks of rivers, and would also serve for rooting up aquatic plants, assisted by the mole-shaped fore feet. Buckland suggests that the tusks served to anchor the animal to the shore, while it slept in the water. It cannot be far from the truth to call it an aquatic pachyderm, similar in habits to the hippopotamus. The best known species (D. giganteum, Kaup) was found at Eppelsheim, in clayey marl about 18 ft. below the surface, in connection with bones of other pachyderms; their remains have been found only in the miocene strata.
Other smaller species are described, as the D. Cuvieri (Kaup), D. minutum (II. do Meyer), and D. proavum (Eichwald), in Europe; D. Indicum (Cautley and Falconer), from the Sivalik hills; and the D. australe (Owen), of Australia.