The genus contains two species, B. macrodonta and B. tuberata. Compared to other sparassodonts, Borhyaena was found to have more adaptations towards cursoriality, however it still likely wasn’t a specialized cursorial predator as seen with wolves. It’s believed like striped hyenas, it is believed that Borhyaena searched and hunted for smaller prey without cooperation from individuals. Although other experts believed it was capable of hunting prey larger than itself.
Classification
Borhyaena was a genus part of the order known as Sparassodonta, an extinct order of metatherian predators. It’s dotted in the family, Borhyaenidae, which is part of the superfamily Borhyaenoidea. This superfamily includes other families such as Proborhyaenidae and Thylacosmilidae.[3]
Description
Borhyaena was a predator and had a large head and a long, powerful neck similar to living hyenas. Its legs were cursorial, albeit less specialized than those of wolves or the marsupialthylacine. The most complete specimen is estimated to have weighted 23 kilograms (51lb) and stood 50 centimetres (1.6ft) at the shoulders.[4] One study suggested that Borhyaena may have been even larger, weighing 36.42 kilograms (80.3lb).[5]
It was believed that Borhyaena may have had digitgrade locomotion,[6] although this has been questioned by some experts.[7] The tail of Borhyaena is believed to have been lighter and less muscled than Prothylacinus.[4]
Paleobiology
Predatory behavior
While having some adaptations of cursoriality, Borhyaena wasn’t a true cursorial predator due to the generalized morphology of the autopodials, femur, and tibia, instead it may have been a long distance traveler but not a fast runner.[8] Compared to modern day pursuit predators, its legs were shorter and heavier.[9][10] A 2010 paper estimated that B. tuberata had an estimated bite force of 538N or 121lbf, with a BFQ of 165, similar that of thylacine and American black bear.[10] The dentition of Borhyaena suggests it wasn’t a specialist in bone-crusher. One expert suggested that the foraging behavior of the animal is believed to have been comparable to the striped hyena, searching for smaller foods in denser vegetation without cooperation from individuals.[9] However, other experts suggested Borhyaena was capable of hunting larger animals.[10][5]
Brain anatomy and senses
A 2025 study found that B. tuberata had an encephalization quotient score of 0.21 to 0.24. From dorsal view, cerebrum of B. tuberata is slightly gyrencephalic and ovoid in shape.[11] Compared to early sparassodonts, later diverging sparassodonts such as Borhyaena and Thylacosmilus had lower hearing ranges of frequency compared to other metatherians in the study.[12]
Paleoecology
Restoration of Theosodon garretorum and Borhyaena tuberata
↑ Riggs, Elmer S. (1934). "A New Marsupial Saber-Tooth from the Pliocene of Argentina and Its Relationships to Other South American Predacious Marsupials". Transactions of the American Philosophical Society. 24 (1): 1–32. doi:10.2307/3231954. JSTOR3231954.
1 2 Argot, Christine (April 2004). "Evolution of South American mammalian predators (Borhyaenoidea): anatomical and palaeobiological implications". Zoological Journal of the Linnean Society. 140 (4): 487–521. doi:10.1111/j.1096-3642.2004.00110.x.
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