[5] The type species, Astraponotus assymetrum, comes from Eocene terrains known as Gran Barranca, in Patagonia (Argentina).

The area was later nicknamed capas Astraponotenses ("Astraponotus' layers" in Spanish) due to the abundance of the peculiar fossils of this animal.

[3] The features observed in the teeth of Astraponotus are intermediate between the Middle Eocene astrapotheres and those of the Oligocene-Miocene in the degree of hypsodonty, the reduced dental formula, and the development of accessory occlusal elements.

These features seem surprisingly derived for an Eocene astrapothere, and suggest that these extreme cranial specializations were developed independently during the evolution of this order; Astraponotus could represent a lineage distinct from Astrapotherium and other Miocene forms.

[3] Cladogram based in the phylogenetic analysis by Vallejo-Pareja et al., 2015, showing the position of Astraponotus:[6] Eoastrapostylops Trigonostylops Tetragonostylops Albertogaudrya Scaglia Astraponotus Maddenia Comahuetherium Parastrapotherium Astrapotherium Astrapothericulus Uruguaytherium Hilarcotherium Xenastrapotherium Granastrapotherium