Hyainailouros

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Hyainailouros
Temporal range: Early to Late Miocene (Burdigalian to Tortonian) 20.0–11.4  Ma
Hyainailouros sulzeri.jpg
Lower jaw of Hyainailouros sulzeri
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order:† Hyaenodonta
Superfamily:† Hyainailouroidea
Family:† Hyainailouridae
Subfamily:† Hyainailourinae
Tribe:† Hyainailourini
Genus:† Hyainailouros
Biedermann, 1863
Type species
†Hyainailouros sulzeri
Biedermann, 1863 [1]
Other Species
  • †H. bugtiensis(Pilgrim, 1912) [2]
  • †H. napakensis(Ginsburg, 1980) [3]
  • †H. osteothlastes?(Savage, 1973)
Synonyms
synonyms of genus:
  • Hainailouros(Lavrov, 1999) [4]
  • Hyaenaelurus(Stehlin, 1907)
  • Hyaenailurus(Rütimeyer, 1867)
synonyms of species:
  • H. napakensis:
    • Hyainailouros nyanzae(Ginsburg, 1980)
    • Pterodon nyanzae(Savage, 1965) [5]
  • H. sulzeri:
    • Hyainailouros maximus(Meyer, 1837)
    • Hyaenailurus sulzeri(Biedermann, 1863)

Hyainailouros ("hyena-cat") is an extinct polyphyletic genus of hyaenodont belonging to the family Hyainailouridae that lived during the Early to Late Miocene from 20.0 to 11.4 million years ago, making it one of the last known hyaenodonts. This genus comprises at least three species spread across Eurasia and Africa. [6] [7] Currently, there’s a debate whether or not Megistotherium was synonymous to Hyainailouros or a separate genus entirely. [8] [9] [10] [11] The genus currently consists of at least 3 species, H. bugtiensis, H. sulzeri, and H. napakensis. H. sulzeri was the type species of the genus and may have been the largest species weighing 500 kg (1,100 lb). On the other hand, H. napakensis was believed to have been the smallest weighing 202–271 kg (445–597 lb).

Contents

Due to their large size and massive skulls, Hyainailouros and other large hyainailourines were thought to have specialized on preying on probsocideans and rhinoceroses. The extinction of large hyainailourines such as Hyainailouros, may have been due to the decline of large herbivores and competition with social carnivorans, as their larger, more complex brains, would’ve enabled them to steal kills from large, solitary hyainailourines like Hyainailouros.

Taxonomy

Hyainailouros is the type genus of the superfamily Hyainailouroidae, one of the two known superfamilies of the order Hyaenodonta, with Hyaenodontoidea representing the other superfamily. The genus is part of the subfamily known as Hyainailourine, within the family known as Hyainailouridae. [12] This family of hyaenodonts was diverse, while hyainailourines consisted of terrestrial predators, the subfamily Apterodontinae consisted of hyainailourids with otter-like adaptations for a semi-aquatic lifestyle. [13] [14] [15] The classification between Hyainailouros and Megistotherium has been debated by experts. [8] Some experts consider H. bugtiensis to be synonymous with H. sulzeri. [16]

Hyainailourine based on results by recovered by Matthew R. Borths and Nancy J. Stevens (2019): [12]

Hyainailourinae

Falcatodon schlosseri

Simbakubwa kutokaafrika

Hyainailouros sulzeri

Arrisdrift hyainailourine

Hyainailouros napakensis

Isohyaenodon andrewsi

Sivapterodon

Hyainailouros bugtiensis

Evolution

Hyainailouroids were thought to have evolved during the Early Eocene, [12] although a Middle Paleocene origin was also suspected for the superfamily. [17] Hyainailourines were believed to have evolved during the Middle Eocene around 43.55 Ma, with the Miocene lineage evolving during the Early Oligocene around 29.73 Ma. [17]

Despite its large size, Hyainailouros may have evolved from small-bodied hyainailourines weighing less than 15 kg (33 lb). [14] Due to the appearance of the Gomphothere Land Bridge, the Hyainailouros lineage was able to disperse into Eurasia around 19.6 Ma, and would later disperse into Europe around 16.9 Ma. [12]

Description

Size comparison of H. sulzeri, Amphicyon giganteus and Crocuta crocuta Africa - the evolution of a continent and its large mammal fauna (2006) fig. 7.png
Size comparison of H. sulzeri, Amphicyon giganteus and Crocuta crocuta

The type species, H. sulzeri, was one of the largest members of the order Hyaenodonta. This species stood 100 cm (3 ft 3 in) at the shoulders, [18] with a 2019 study estimating this species weighing between 266–1,276 kg (586–2,813 lb). H. bugtiensis was around the same size of H. sulzeri, if not slightly larger, weighing 267–1,744 kg (589–3,845 lb). Both species were similar in size to the closely related Simbakubwa. H. napakensis, on the other hand, was the smallest species of the genus, weighing just around 202–271 kg (445–597 lb). [12] But this regression is problematic as hyaenodonts possessed very large heads in proportion to their body size. Many experts argue smaller sizes. Based on postcranial remains, some experts argued Hyainailouros was about the size of a tiger, [19] although other experts still suggest higher estimates for H. sulzeri, suggesting it weighed 500 kg (1,100 lb). [20] H. bugtiensis (referred as H. sulzeri) according to a 2025 study, was estimated to have weighed 430 kg (950 lb). [16]

Paleobiology

Molar Hyaenaelurus molar.jpg
Molar

Much like Simbakubwa , Hyainailouros walked had semidigitigrade locomotion and was probably capable of large, leaping bounds, although it likely wasn’t a fast runner. [12] [14] Early hyainailourines were plantigrade walkers, as seen with Kerberos , however later hyainailourines, such as Hyainailouros and Simbakubwa, shifted to semidigitigrade locomotion as digitigrade conserves more energy and is more efficient in open environments than plantigrade locomotion. [12]

While Hyainailouros showed less adaptation for meat shearing compared to Hyaenodon , it did show more adaptations towards osteophagy, cracking and eating bone. [18] The evolution of large hyainailourines was likely due to the evolution of large herbivores, which resulted in adaptations to hunt and scavenge proboscideans and rhinoceroses, which were typically ignored by carnivorans due to their large size. This specialized niche remains largely unoccupied in modern ecosystems populated by more socially complex carnivorans and may have allowed them survive into the Neogene. [12] Additionally, fossil evidence shows that Hyainailouros appeared in Europe around the same time as proboscideans, suggesting Hyainailouros followed their prey as they dispersed out of Africa. [14] [21]

Regressions found that humerus of Hyainailouros is found to be as robust as an average felid, but less robust than Smilodon and American lion. Compared to the humerus of tigers, the deltoid scar was located more distally in the humerus of the hyainailourine than the humerus of tigers. [19]

Paleoecology

Restoration of H. sulzeri (far left), Cynelos eurydon, Afrosmilus africanus and H. napakensis (far right) Africa - the evolution of a continent and its large mammal fauna (2006) fig. 8.png
Restoration of H. sulzeri (far left), Cynelos eurydon , Afrosmilus africanus and H. napakensis (far right)

Hyainailouros sulzeri was found in Europe and some parts of Africa, [22] [20] from 18 to 15 Ma. [23] Including supplementary materials Within Grand Morier of Miocene France, H. sulzeri coexisted with mammalian predators such as the hyena Protictitherium gaillardi , felids such as Miopanthera lorteti and Styriofelis , amphicyonids such as Agnotherium grivense , Amphicyon giganteus , Pseudarctos bavaricus, and Pseudocyon sansaniensis , the mustelid Trocharion albanense , and early ursid Hemicyon sansaniensis . Herbivores present in this locality include proboscideans such as the gomphothere Gomphotherium angustidens , deinothere Prodeinotherium bavaricum , and mammutid Zygolophodon turicensis , an ochotonid, extinct beavers Anchitheriomys and Steneofiber depereti , the early horse Anchitherium aurelianense , the chalicothere Anisodon grande , and rhinoceroses such as Lartetotherium sansaniense , as well aceratheriinaes Brachypotherium brachypus , Plesiaceratherium lumiarense , and Prosantorhinus . [24] Due to its rarity, H. sulzeri probably wasn’t serious competitor towards Amphicyon in Europe. [20]

Within Arrisdrift, Namibia, H. sulzeri coexisted with carnivorans such as the felid Diamantofelis , amphicyonids such as Amphicyon giganteus and Namibiocyon ginsburgi , and viverrids such as Orangictis gariepensis and Africanictis . Contemporary herbivores include proboscideans such as the deinothere Prodeinotherium hobleyi, amebelodont Afromastodon , and the gomphothere Gomphotherium, the hyracoid Prohyrax hendeyi , the bovid Homoiodorcas , the tragulid Dorcatherium pigotti , and the rhino Diceros . Other faunas found within Arrisdrift include reptiles such as the crocodilian Crocodylus gariepensis , tortoises such as Namibchersus namaquensis and Mesochersus orangeus , the boid Central African rock python, and monitor lizards. Birds present in this locality include accipitrids and struthionid. [25]

H. bugtiensis was found in the Siwalik Hills and lived from 19 to 11.4 Ma. [16] Within the Bugti Hills of Pakistan, Hyainailouros coexisted with proboscideans such as the mammutid Zygolophodon metachinjiensis, the deinothere Prodeinotheriumpentapotamiae, the choerolophodontid Choerolophodon corrugatus , and gomphotheres such as Gomphotherium and Protanancus chinjiensis , the giraffid Progiraffa , and rhinoceroses such as Brachypotherium, Hoploaceratherium , Dicerorhinus , and Aprotodon fatehjangense . Contemporary predators included the amphicyonid Amphicyon and Crocodylus . [26]

Extinction

The extinction of large hyainailourines is hypothesized to have been the result of changing ecosystems and competition with carnivorans. [12] [27] While hyaenodonts in Namibia declined due to the inability to adapt to environments such as steppes, savannas, and deserts, a few lineages such as Megistotherium continued to persist despite the increase in aridity. [28] Some experts argued that the presence of carnivorans may have resulted in some hyaenodonts to become larger and more hypercarnivorous. [29] [27] [30] However, the discovery of Simbakubwa suggests the key factor of the large sizes of hyainailourines was changes in the herbivore fauna due to changes in the Afro-Arabia landscape instead of competition with carnivorans as they diversified later in the Miocene. Experts believed that large hyainailourines may have declined due to the decline of large herbivores, who tend to have slow generation times and may be particularly sensitive to environmental changes. [12]

Since they were specialized on these herbivores, even if their population declined briefly, the large hyainailourines would’ve been affected by the changing resources, more so than the smaller carnivorans. This is seen in modern ecosystems where large hypercarnivores are affected more dramatically with environmental shifts than smaller mescarnivores. [12] Although they were likely effective scavengers, [20] [12] experts argued social carnivorans may have been adept at stealing large carcasses from large, solitary hyainailourines, due their larger, more complex brains. This would’ve resulted in the extinction of large hyainailourines as they wouldn’t be able to obtain large amounts of food needed for survival. [12] However, studies have shown that larger brains have little to no roles in sociality among carnivorans, [31] [32] [33] instead within carnivoran families, sociality tends to correlate the anterior cerebrum volume relative to overall brain size. [34] [35] [36]

References

  1. ↑ W. G. A. Biedermann (1863.) "Petrefacten aus der Umgegend von Winterthur. II Heft: Die Braunkohlen von Elgg. Anhang: Hyainailouros sulzeri". Bleuler-Hausheer, Winterthur, 23 pp.
  2. ↑ Pilgrim, G. E. (1912.) "The Vertebrate Fauna of the Gaj Series in the Bugti Hills and the Punjab", Memoir of the Geological Survey of India, Palaeontologia Indica, New Series, 4: 1–83
  3. ↑ Ginsburg, L. (1980.) "Hyainailouros sulzeri, mammifère créodonte du Miocène européen." Annales de Paléontologie, 66: 19–73.
  4. ↑ A. V. Lavrov (1999.) "Adaptive Radiation of Hyaenodontinae (Creodonta, Hyaenodontidae) of Asia." in 6th Congress of the Theriological Society, Moscow, April 13–16, p. 138 [in Russian].
  5. ↑ R. J. G. Savage (1965.) "Fossil Mammals of Africa: The Miocene Carnivora of East Africa." Bulletin of the British Museum (Natural History) Geology 10(8):241-316
  6. ↑ Morlo, M.; Miller, E. R.; El-Barkooky, A. N. (2007). "Creodonta and Carnivora from Wadi Moghra, Egypt". Journal of Vertebrate Paleontology. 27: 145–159. doi:10.1671/0272-4634(2007)27[145:CACFWM]2.0.CO;2. S2CID   86235694.
  7. ↑ Solé, F.; Lhuillier, J.; Adaci, M.; Bensalah, M.; Mahboubi, M.; Tabuce, R. (2013). "The hyaenodontidans from the Gour Lazib area (?Early Eocene, Algeria): implications concerning the systematics and the origin of the Hyainailourinae and Teratodontinae". Journal of Systematic Palaeontology. 12 (3): 303–322. doi:10.1080/14772019.2013.795196. S2CID   84475034.
  8. 1 2 J. Morales, M. Pickford, S. Fraile, M. J. Salesa and D. Soria (2003.) "Creodonta and Carnivora from Arrisdrift, early Middle Miocene of southern Namibia" Mem. Geol. Surv. Namibia 19 177–194.
  9. ↑ Morlo, Michael; Friscia, Anthony; Miller, Ellen; Locke, Ellis; Nengo, Isaia (2021). "Systematics and paleobiology of Carnivora and Hyaenodonta from Buluk, Early Miocene, Kenya". Acta Palaeontologica Polonica. 66. doi:10.4202/app.00794.2020.
  10. ↑ Borths, Matthew R.; Stevens, Nancy J. (2 January 2019). "Simbakubwa kutokaafrika, gen. et sp. nov. (Hyainailourinae, Hyaenodonta, 'Creodonta,' Mammalia), a gigantic carnivore from the earliest Miocene of Kenya". Journal of Vertebrate Paleontology. 39 (1) e1570222. Bibcode:2019JVPal..39E0222B. doi:10.1080/02724634.2019.1570222. ISSN   0272-4634.
  11. ↑ Borths, Matthew R.; Holroyd, Patricia A.; Seiffert, Erik R. (10 November 2016). "Hyainailourine and teratodontine cranial material from the late Eocene of Egypt and the application of parsimony and Bayesian methods to the phylogeny and biogeography of Hyaenodonta (Placentalia, Mammalia)". PeerJ. 4 e2639. doi: 10.7717/peerj.2639 . ISSN   2167-8359. PMC   5111901 .
  12. 1 2 3 4 5 6 7 8 9 10 11 12 13 Borths, M. R.; Stevens, N. J. (2019). "Simbakubwa kutokaafrika, gen. et sp. nov. (Hyainailourinae, Hyaenodonta, 'Creodonta,' Mammalia), a gigantic carnivore from the earliest Miocene of Kenya" . Journal of Vertebrate Paleontology. 39 (1) e1570222. Bibcode:2019JVPal..39E0222B. doi:10.1080/02724634.2019.1570222. S2CID   145972918.
  13. ↑ Solé, Floréal; Lhuillier, Julie; Adaci, Mohammed; Bensalah, Mustapha; Mahboubi, M'hammed; Tabuce, Rodolphe (2013). "The hyaenodontidans from the Gour Lazib area (?Early Eocene, Algeria): implications concerning the systematics and the origin of the Hyainailourinae and Teratodontinae". Journal of Systematic Palaeontology. 12 (3): 303–322. doi:10.1080/14772019.2013.795196. S2CID   84475034.
  14. 1 2 3 4 Solé, Floréal; Amson, Eli; Borths, Matthew; Vidalenc, Dominique; Morlo, Michael; Bastl, Katharina (2015-09-23). Friedman, Matt (ed.). "A New Large Hyainailourine from the Bartonian of Europe and Its Bearings on the Evolution and Ecology of Massive Hyaenodonts (Mammalia)". PLOS ONE. 10 (9) e0135698. doi: 10.1371/journal.pone.0135698 . ISSN   1932-6203. PMC   4580617 . PMID   26398622.
  15. ↑ Laudet, V.; Grohé, C.; Morlo, M.; Chaimanee, Y.; Blondel, C.; Coster, P.; Valentin, X.; Salem, M.; Bilal, A. A.; Jaeger, J. J.; Brunet, M. (2012). "New Apterodontinae (Hyaenodontida) from the Eocene Locality of Dur At-Talah (Libya): Systematic, Paleoecological and Phylogenetical Implications". PLOS ONE. 7 (11) e49054. Bibcode:2012PLoSO...749054G. doi: 10.1371/journal.pone.0049054 . PMC   3504055 . PMID   23185292.
  16. 1 2 3 Morgan, Michèle E.; Flynn, Lawrence J.; Pilbeam, David (January 2025). "Siwalik Mammalian Community Structure and Patterns for Faunal Change". At the Foot of the Himalayas: Paleontology and Ecosystem Dynamics of the Siwalik Record. pp. 432–480. ISBN   978-1421450278.
  17. 1 2 Borths, Matthew R.; Stevens, Nancy J. (2017). "The first hyaenodont from the late Oligocene Nsungwe Formation of Tanzania: Paleoecological insights into the Paleogene-Neogene carnivore transition". PLOS ONE. 12 (10) e0185301. Bibcode:2017PLoSO..1285301B. doi: 10.1371/journal.pone.0185301 . PMC   5636082 . PMID   29020030.
  18. 1 2 Wang, Xiaoming; Tedford, Richard H. (2008). Dogs: Their Fossil Relatives and Evolutionary History. New York: Columbia University Press. p. 17. doi:10.7312/wang13528. ISBN   978-0-231-13528-3. JSTOR   10.7312/wang13528.
  19. 1 2 Sorkin, Boris (2008). "A biomechanical constraint on body mass in terrestrial mammalian predators" . Lethaia. 41 (4): 333–347. Bibcode:2008Letha..41..333S. doi:10.1111/j.1502-3931.2007.00091.x.
  20. 1 2 3 4 M. T. Antunes; et al. (2006). "Ichnological evidence of a Miocene rhinoceros bitten by a bear-dog (Amphicyon giganteus)" (PDF). Annales de Paléontologie. 92 (1): 31–39. Bibcode:2006AnPal..92...31A. doi:10.1016/j.annpal.2005.10.002.
  21. ↑ Putshkov, P. V. (2001). ""Proboscidean agent" of some Tertiary megafaunal extinctions" (PDF). Terra Degli Elefanti Congresso Internazionale: The World of Elephants: 133–136.
  22. ↑ Morlo, Michael; Friscia, Anthony; Miller, Ellen R.; Locke, Ellis; Nengo, Isaiah Odhiambo (2021). "Systematics and paleobiology of Carnivora and Hyaenodonta from Buluk, Early Miocene, Kenya" (PDF). Acta Palaeontologica Polonica. 66 (2): 465–484. doi: 10.4202/app.00794.2020 .
  23. ↑ Borths, Matthew R.; Holroyd, Patricia A.; Seiffert, Erik R. (2016). "Hyainailourine and teratodontine cranial material from the late Eocene of Egypt and the application of parsimony and Bayesian methods to the phylogeny and biogeography of Hyaenodonta (Placentalia, Mammalia)". PeerJ. 4 e2639. doi: 10.7717/peerj.2639 . PMC   5111901 . PMID   27867761.
  24. ↑ Paleobiology Database: Grand Morier, assemblage no. 6
  25. ↑ PaleoBiology Database: Arrisdrift (Miocene of Namibia)
  26. ↑ PaleoBiology Database: Bugti Hills
  27. 1 2 Frisica, Anthony R.; Macharwas, Mathew; Muteti, Samuel; Ndiritu, Francis; Rasmussen, D. Tab (2 November 2020). "A Transitional Mammalian Carnivore Community from the Paleogene–Neogene Boundary in Northern Kenya" . Journal of Vertebrate Paleontology. 40 (5) e1833895. Bibcode:2020JVPal..40E3895F. doi:10.1080/02724634.2020.1833895.
  28. ↑ Morales, J.; Pickford, M.; Salesa, M. J. (2008). "Creodonta and Carnivora from the Early Miocene of the Northern Sperrgebiet, Namibia". Memoir of the Geological Survey of Namibia. 20 (20): 291–310.
  29. ↑ Friscia, Anthony; Van, Valkenburgh B. (2010). "Ecomorphology of North American Eocene carnivores: evidence for competition between Carnivorans and Creodonts". Carnivoran Evolution. Cambridge University Press. pp. 311–341. doi:10.1017/CBO9781139193436.012. ISBN   978-0-521-51529-0.
  30. ↑ Borths, Matthew R.; Stevens, Nancy J. (2017). "The first hyaenodont from the late Oligocene Nsungwe Formation of Tanzania: paleoecological insights into the Paleogene-Neogene carnivore transition". PLOS ONE. 12 (10) e0185301. Bibcode:2017PLoSO..1285301B. doi: 10.1371/journal.pone.0185301 . PMC   5636082 . PMID   29020030.
  31. ↑ Finarelli, J. A.; Flynn, J. J (2009). "Brain-size evolution and sociality in Carnivora". Proc. Natl. Acad. Sci. U.S.A. 106 (23). doi: 10.1073/pnas.0901780106 .
  32. ↑ Chambers, Helen Rebecca; Heldstab, Sandra Andrea; O'Hara, Sean J. (2021). "Why big brains? A comparison of models for both primate and carnivore brain size evolution". PLOS ONE. 16 (12). doi: 10.1371/journal.pone.0261185 . PMC   8691615 .
  33. ↑ Benson-Amram, Sarah; Dantzer, Ben; Stricker, Gregory; Swanson, Eli M.; Holekamp, Kay E. (2016). "Brain size predicts problem-solving ability in mammalian carnivores". Proceedings of the National Academy of Sciences. 113 (9): 2532–2537. doi: 10.1073/pnas.1505913113 .
  34. ↑ Vinuesa, Víctor; Iurino, Dawid A.; Madurell-Malapeira, Joan; Liu, Jinyi; Fortuny, Josep; Sardella, Raffaele; Alba, David M. (August 2016). "Inferences of social behavior in bone-cracking hyaenids (Carnivora, Hyaenidae) based on digital paleoneurological techniques: Implications for human–carnivoran interactions in the Pleistocene" . Quaternary International. 413: 7–14. Bibcode:2016QuInt.413....7V. doi:10.1016/j.quaint.2015.10.037.
  35. ↑ Sakai, Sharleen T.; Arsznov, Bradley M.; Hristova, Ani E.; Yoon, Elise J.; Lundrigan, Barbara L. (2016). "Big Cat Coalitions: A Comparative Analysis of Regional Brain Volumes in Felidae". Front Neuroanat. 10: 1–12. doi: 10.3389/fnana.2016.00099 .
  36. ↑ Sakai, Sharleen T.; Whitt, Blake; Arsznov, Bradley M.; Lundrigan, Barbara L. (2018). "Endocranial Development in the Coyote (Canis latrans) and Gray Wolf (Canis lupus): A Computed Tomographic Study". Brain Behavior and Evolution. 91 (2): 1–17. doi:10.1159/000487427.
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