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Borhyaena

Borhyaena
Temporal range: Early-Middle Miocene (Colhuehuapian-Friasian)
~21.0–15.5 Ma[1]
B. tuberata skull
Scientific classification Edit this classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: †Sparassodonta
Family: †Borhyaenidae
Genus: †Borhyaena
Ameghino 1887
Species
  • B. macrodonta (Ameghino 1902)
  • B. tuberata (Ameghino 1887)
Synonyms
  • Conodonictis Ameghino 1891
  • Dinamictis Ameghino 1891
  • Pseudoborhyaena Ameghino 1902

Borhyaena is an extinct genus of South American metatherian known as borhyaenaid, a family of mammalian predators part of the now extinct order, Sparassodonta. The genus lived from 21 to 15.5 million years ago from the Early to Middle Miocene.[2]

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.

Classification

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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

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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 marsupial thylacine. The most complete specimen is estimated to have weighted 23 kilograms (51 lb) and stood 50 centimetres (1.6 ft) at the shoulders.[4] It was believed that Borhyaena may have had digitgrade locomotion,[5] although this has been questioned by some experts.[6] The tail of Borhyaena is believed to have been lighter and less muscled than Prothylacinus.[4]

Paleobiology

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Predatory behavior

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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.[7] Compared to modern day pursuit predators, its legs were shorter and heavier.[8][9] A 2010 paper estimated that B. tuberata had an estimated bite force of 538 N or 121 lbf, with a BFQ of 165, similar that of thylacine and American black bear.[9] However, the dentition of Borhyaena suggests it wasn’t a specialist in bone-crusher. 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.[8]

Brain anatomy and senses

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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.[10] 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.[11]

Paleoecology

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Restoration of Theosodon garretorum and Borhyaena tuberata

The genus has been found in Patagonia, Argentina (Santa Cruz and Sarmiento Formations) and Chile (Río Frias Formation).[12] Santa Cruz Formation had a heterogeneous environment with patches forests, semi-arid forests, and open areas. Within this formation, B. tuberata coexisted with other sparassodonts. This included fellow borhyaenoids such as Acrocyon sectorius, Artodictis munizi, Lycopsis torresi, and Prothylacynus patagonicus. Hathliacynids were also present including Acyon tricuspidatus, Cladosictis patagoncia, Pseudonotictis pusillus, Perathereutes pungens, and Sipalocyon. Because of its large size, it would’ve been capable of displacing Acrocyon and Cladosictis. Borhyaena also coexisted with birds such as Brontornis, cariamid Cariama santacrucensis, the terror birds Patagornis marshi, Phorusrhacos, and Psilopterus bachmanni. Terror birds and sparassodonts likely niche partitioned due to locomotive differences. Herbivores present in Santa Cruz Formation included litoperns Diadiaphorus, Theosodon, and Tetramerorhinus, sloths Eucholoeops and Hapalops, and notoungulate toxodontid Adinotherium. Borhyaena may have typically preyed on animals that weighed 17–48 kilograms (37–106 lb), such as Hapalops.[13]

References

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  1. ^ Marshall, Larry G. (1978). Evolution of the Borhyaenidae, extinct South American predaceous marsupials. University of California Publications in Geological Sciences. Vol. 117. University of California Press. pp. 1–89. ISBN 9780520095717.
  2. ^ Marshall, Larry G. (1978). Evolution of the Borhyaenidae, extinct South American predaceous marsupials. University of California Publications in Geological Sciences. Vol. 117. University of California Press. pp. 1–89. ISBN 9780520095717.
  3. ^ Forasiepi, Analía M. (2009). "Osteology of Arctodictis sinclairi (Mammalia, Metatheria, Sparassodonta) and phylogeny of Cenozoic metatherian carnivores from South America". Monografías del Museo Argentino de Ciencias Naturales. 6: 1–174.
  4. ^ a b Argot, C. (2003). "Functional adaptations of the postcranial skeleton of two Miocene borhyaenoids (Mammalia, Metatheria), Borhyaena and Prothylacinus, from South America". Palaeontology. 46 (6): 1213–1267. Bibcode:2003Palgy..46.1213A. doi:10.1046/j.0031-0239.2003.00339.x.
  5. ^ 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. JSTOR 3231954.
  6. ^ Forasiepi, Analía M. (2009). "Osteology of Arctodictis sinclairi (Mammalia, Metatheria, Sparassodonta) and phylogeny of Cenozoic metatherian carnivores from South America". Monografías del Museo Argentino de Ciencias Naturales. 6: 1–174.
  7. ^ Ercoli, Marcos D.; Prevosti, Francisco J.; Álvarez, Alicia (May 2012). "Form and function within a phylogenetic framework: locomotory habits of extant predators and some Miocene Sparassodonta (Metatheria)". Zoological Journal of the Linnean Society. 165 (1): 224–251. doi:10.1111/j.1096-3642.2011.00793.x.
  8. ^ a b 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.
  9. ^ a b Blanco, R. Ernesto; Jones, Washington William; Grinspan, Gustavo (2011). "Fossil marsupial predators of South America (Marsupialia, Borhyaenoidea): Bite mechanics and palaeobiological implications". Alcheringa an Australasian Journal of Palaeontology. 35 (3): 377–387. Bibcode:2011Alch...35..377B. doi:10.1080/03115518.2010.519644.
  10. ^ Gaillard, Charlène; Prevosti, Francisco J.; Forasiepi, Analía M.; Babot, M. Judith (14 June 2025). "The braincase endocast of Sparassodonta (Mammalia, Metatheria) reveals that some of today's morphological characters of marsupial brains were already present in stem Marsupialia". Journal of Mammalian Evolution. 32 (2) 26. doi:10.1007/s10914-025-09763-6. ISSN 1064-7554. Retrieved 16 June 2025 – via Springer Nature Link.
  11. ^ Damico, Sophia (May 2024). Endocranial, Basicranial, and Inner Ear Anatomy of a Middle Miocene Sparassodont (Metatheria) from Bolivia (MS (Master of Science) thesis).
  12. ^ Borhyaena at Fossilworks.org
  13. ^ Ercoli, Marcos D.; Prevosti, Francisco J.; Forasiepi, Analía M. (8 October 2013). "The Structure of the Mammalian Predator Guild in the Santa Cruz Formation (Late Early Miocene)" (PDF). Journal of Mammalian Evolution. 21 (4): 369–381. doi:10.1007/s10914-013-9243-4. hdl:11336/19136. S2CID 6240294.
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  • Media related to Borhyaena at Wikimedia Commons


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