(Argentina) size: 8 ft/2.5 m long Except for its greater size, Astrapotherium was typical of the family as a whole. The head was quite short, with a dome over the forehead created by enlarged air sinuses.
The canine teeth continued to grow throughout life and formed 4 tusks. As in a hippopotamus, the larger top pair of tusks sheared against the lower pair. The broad lower incisors protruded, and probably worked against a horny pad in the upper jaw to crop plants.
Evidence for a trunk is somewhat contradictory. The nose bones were certainly very short, and opened high on the forehead, which suggest a trunk. Yet there seems to have been no clear reason for a proboscis: Astrapotherium's neck was not particularly short, and its head could easily have reached the ground. It is possible that the "trunk" was really an inflated nose.
Astrapotherium had a long, low body with a weak back and legs, the hind legs feebler than the front ones. The feet were small and plantigrade — the weight was borne on the flat of the foot.
Taken together, the features seem to indicate that the animal was largely aquatic, wallowing in shallow water and rooting about with its tusks and trunk for water plants. Such a lifestyle and physical structure is reminiscent of the amyndont rhinoceroses found in the northern hemisphere (see pp. 262-265).
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