Proborhyaena was very large in size, with the skull alone reaching up to 60 cm (2.0 ft),[1] and the whole animal may have been as large as a present-day spectacled bear.[2] Sorkin (2008) speculated that Proborhyaena gigantea may have weighed up to 600 kg (1,300 lb),[3] but subsequent studies consider this an overestimate and argue that it would have weighed up to 90–200 kg (200–440 lb).[4][2][5]
Proborhyaena was a massive animal, with a robust and powerful body. Its skull was equipped with a short, high snout, and its caniniform teeth were saber-shaped, although not as developed as those of the later Thylacosmilus. 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. Like the thylacosmilids, Proborhyaena possessed only one pair of lower incisors.[6]
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. Proborhyaena may be the largest carnivorous metatherians that ever lived.
Paleobiology
This animal must have been a fearsome marauder that certainly did not chase prey for long; it probably fed on large, slow-moving prey, such as Pyrotherium. 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.[11]
References
^Shockey, B. J. (1999). "Postcranial osteology and functional morphology of the Litopterna of Salla, Bolivia (Late Oligocene)". Journal of Vertebrate Paleontology. 19 (2): 383–390. Bibcode:1999JVPal..19..383S. doi:10.1080/02724634.1999.10011149.
^ abPrevosti, Francisco J.; Forasiepi, Analía M. (2018). "South American Endemic Mammalian Predators (Order Sparassodonta)". Evolution of South American Mammalian Predators During the Cenozoic: Paleobiogeographic and Paleoenvironmental Contingencies. Springer Geology. p. 67. Bibcode:2018esam.book.....P. doi:10.1007/978-3-319-03701-1. ISBN978-3-319-03700-4. S2CID134939823.
^A. M. Forasiepi; M. Judith Babot; N. Zimicz (2014). "Australohyaena antiqua (Mammalia, Metatheria, Sparassodonta), a large predator from the Late Oligocene of Patagonia". Journal of Systematic Palaeontology. 13 (6): 503–525. Bibcode:2015JSPal..13..503F. doi:10.1080/14772019.2014.926403. hdl:11336/59430.
^Ameghino, Florentino (1897). "Mammiféres crétacés de l'Argentine (Deuxième contribution à la connaissance de la fauna mammalogique de couches à Pyrotherium) [Cretaceous mammals of Argentina (second contribution to the knowledge of the mammalian fauna of the Pyrotherium Beds)]". Boletin Instituto Geografico Argentino. 18 (4–9): 406–521.
