The canines, in contrast to those of Thylacosmilus which had an "almond-shaped" section and a sharp margin, were ovoid in cross-section and thus must have been much more robust.

[6] Proborhyaena was first described by Florentino Ameghino in 1897, based on fossils found in Patagonia in deposits dating to the Late Oligocene (Deseadan).

[9] In addition, fossils assigned to Proborhyaena have been found in the Agua de la Piedra Formation of Mendoza Province, Argentina.

[10] Proborhyaena is the eponymous genus of the family Proborhyaenidae, also including smaller forms such as Callistoe and Arminiheringia these animals belonged to the sparassodonts, a group of metatherian mammals akin to marsupials that in South America occupied the ecological niches typical of other carnivorous mammal groups on other continents.

Both Proborhyaena and numerous large ungulates became extinct during the Oligocene, and it is likely that this predator-prey ratio was influenced by climate change.