Astrapotherium

Astrapotherium ("lightning beast") is an extinct genus of large astrapotherian ungulate native to South America during the early-middle Miocene. It is the best known member of the group. The type species. A. magnus have been found in the Santa Cruz Formation in Argentina. Other fossils have been found in the Deseado, Sarmiento, and Aisol Formations of Argentina and Chile (Cura-Mallín Group).

Description
Astrapotherium had an elongated body, with a total length around 2.5 m, a weight of nearly 1000 kg, and relatively short limbs. Larger estimates suggest its body mass was up to 1600 - 3500 kg. It had small plantigrade feet, and the hind limbs were significantly weaker than the fore limbs. Its four canine teeth were elongated to form short tusks, and it had broad, protruding lower incisors, which likely ground against a horny pad in the upper jaw, as in many modern ruminants. Astrapotherium has been inferred to have had a tapir-like proboscis, based on its retracted narials and short upper jaw.

Classification
Cladogram based in the phylogenetic analysis published by Vallejo-Pareja et al., 2015, showing the position of Astrapotherium:

Paleobiology
The animal was probably at least partially aquatic, living in shallow water and feeding on marsh plants in a similar manner to a modern hippopotamus.