Astraponotus

Astraponotus is an extinct genus of herbivorous mammals, belonging to the family of astrapotherids. It lived during the late Late Eocene (in the Divisaderan and Tinguirirican of the South American land mammal ages (SALMA), 37.2-33.9 million years ago) and its fossil remains have been found in the Sarmiento Formation of Argentina, South America.
Description.
This animal was probably similar in shape and size to a modern tapir. Unlike most astrapotheres, "Astraponotus" was equipped with an unusually high, short, narrow skull. The nasal bones were quite withdrawn, which suggests the presence of a short proboscis. Other unusual features of "Astraponotus" includes the extreme reduction of the premaxillary and nasal bones, the absence of an antorbital circle, and the reduction of the frontal region. The canines were long and strong, as in all astrapotheres.
Classification.
"Astraponotus" was first described in 1901 by Florentino Ameghino, based on teeth fossils. The type species, "Astraponotus assymetrum", comes from Eocene terrains known as Gran Barranca, in Patagonia (Argentina). The area was later was nicknamed "capas Astraponotenses" (""Astraponotus"' layers" in Spanish) due to the abundance of the peculiar fossils of this animal. Other species were described later (for example, "A. dicksoni" and "A. holdichi"), but always based just on the remains of the teeth and jaws. A a nearly complete skull was not described until 2010, which has allowed hypothesis of the phylogenetic relationships of this animal more precisely.
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 hypsodoncy, the reduced dental formula, and the development of accessory occlusal elements. Moreover, the skull retains plesiomorphic features also observed in the archaic genus "Trigonostylops", while the auditory region and the skull base are much closer to those of "Parastrapotherium", "Astrapotherium", and "Granastrapotherium". Furthermore, the "Astraponotus" skull differs from all astrapotheres known in its disproportionate height, the narrowness of the skull, and other numerous cranial specializations that are opposite to "Astrapotherium". 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.
Phylogeny.
Cladogram based in the phylogenetic analysis by Vallejo-Pareja "et al"., 2015, showing the position of "Astraponotus":