Hyainailouridae

Hyainailouridae Temporal range: Middle Eocene to Late Miocene 47.8–10  Ma PreꞒ Ꞓ O S D C P T J K Pg N (Suspected Early Eocene origin, unconfirmed by fossils yet) [1]
Megistotherium osteothlastes life restoration
Apterodon macrognathus life restoration
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	† Hyaenodonta
Superfamily:	† Hyainailouroidea
Family:	† Hyainailouridae Pilgrim, 1932 [2]
Type genus
† Hyainailouros (polyphyletic genus) Biedermann, 1863
Subfamilies
[see classification]
Synonyms
list of synonyms: Hyaenaelurinae (Pilgrim, 1932) Hyainailourindae (Solé, 2015) Pterodontidae (Polly, 1996) [3] Pterodontinae (Polly, 1996)

Hyainailouridae ("hyena-like cats") is a paraphyletic family of extinct predatory mammals within the polyphyletic superfamily Hyainailouroidea within extinct order Hyaenodonta. Fossil records show hyainailourids arose during the Middle Eocene, although Early Eocene origin is suspected, ^[4] the family persisted into the Late Miocene. ^[5] Fossils of this group have been found in Asia, Africa, North America and Europe.

General characteristics

Hyainailourids are characterized by long skulls, slender jaws, slim bodies, and a plantigrade stance. They generally ranged in size from 30 to 140 cm at the shoulder. While some measured as much as 1.4 m high at the shoulder with head-body length up to 3.2 m and weighed up to 500–880 kg (1,100–1,940 lb), ^{[6] [7]} were in the 5–15 kg range, equivalent to a mid-sized dog. The anatomy of their skulls show that they had a particularly acute sense of smell, while their teeth were adapted for shearing, rather than crushing.

At least one hyainailourid lineage, Apterodontinae, was specialised for aquatic, otter-like habits. ^[8]

Range

The oldest member of the Hyainailouridae is Orienspterodon from the middle Eocene of China. ^[9] They were important hypercarnivores in Eurasia and Africa during the Oligocene, but by middle Oliogcene, the family went extinct in the northern continents, only persisting in Afro-Arabia. Only Simbakubwa , Megistotherium and several of its sister genera, including Hyainailouros and Sivapterodon , survived into the Miocene. ^[10] Traditionally this has been attributed to competition with carnivorans, but no formal examination of the correlation between the decline of hyaenodontids and the expansion of carnivorans has been recorded, and the latter may simply have moved into vacant niches after the extinction of hyaenodontid species.

Classification and phylogeny

Relations

Hyainailouridae used to be considered a subfamily of Hyaenodontidae, but cladistic study by Sole et al., (2013, 2015) treats it as a distinct family. Two subfamilies are recognized, Apterodontinae and paraphyletic Hyainailourinae. ^{[11] [12]}

Taxonomy

Family: †Hyainailouridae(paraphyletic family)(Pilgrim, 1932) Subfamily: † Apterodontinae (Szalay, 1967) Genus: † Apterodon (Fischer, 1880) †Apterodon altidens(Schlosser, 1910) †Apterodon gaudryi(Fischer, 1880) †Apterodon langebadreae(Grohé, 2012) †Apterodon macrognathus(Andrews, 1904) †Apterodon rauenbergensis(Frey, 2010) †Apterodon saghensis(Simons & Gingerich, 1976) †Apterodon sp. [Dur At-Talah escarpment, Libya] (Grohé, 2012) Genus: † Quasiapterodon (Lavrov, 1999) †Quasiapterodon minutus(Schlosser, 1910) Subfamily: † Hyainailourinae (paraphyletic subfamily)(Pilgrim, 1932) Genus: † Ekweeconfractus (Savage, 1973) †Ekweeconfractus amorui(Flink, 2021) Genus: † Leakitherium (Savage, 1965) †Leakitherium hiwegi(Savage, 1965) Genus: † Megistotherium (Savage, 1973) †Megistotherium osteothlastes(Savage, 1973) Genus: † Mlanyama (Rasmussen & Gutierrez, 2009) †Mlanyama sugu(Rasmussen & Gutierrez, 2009) Genus: † Pakakali (Borths & Stevens, 2017) †Pakakali rukwaensis(Borths & Stevens, 2017) Genus: † Simbakubwa (Borths & Stevens, 2019) †Simbakubwa kutokaafrika(Borths & Stevens, 2019) Genus: † Thereutherium (Filhol, 1876) †Thereutherium thylacodes(Filhol, 1876) (unranked): †Akhnatenavus clade Genus: † Akhnatenavus (Holroyd, 1999) †Akhnatenavus leptognathus(Osborn, 1909) †Akhnatenavus nefertiticyon(Borths, 2016) Genus: † Hemipsalodon (Cope, 1885) †Hemipsalodon grandis(Cope, 1885) †Hemipsalodon viejaensis(Gustafson, 1986) Genus: † Ischnognathus (Stovall, 1948) †Ischnognathus savagei(Stovall, 1948) (unranked): †Maocyon/Orienspterodon clade Genus: † Maocyon (Averianov, 2023) †Maocyon peregrinus(Averianov, 2023) Genus: † Orienspterodon (Egi, 2007) †Orienspterodon dahkoensis(Chow, 1975) †Orienspterodon mianchiensis(Sheng, Bi & Li, 2024) Tribe: † Hyainailourini (polyphyletic tribe)(Ginsburg, 1980) Genus: † Bastetodon (Al-Ashqar, 2025) †Bastetodon syrtos(Holroyd, 1999) Genus: † Exiguodon (Morales & Pickford, 2017) †Exiguodon pilgrimi(Savage, 1965) Genus: † Falcatodon (Morales & Pickford, 2017) †Falcatodon schlosseri(Holroyd, 1999) Genus: † Hyainailouros (polyphyletic genus)(Biedermann, 1863) †Hyainailouros bugtiensis(Pilgrim, 1912) †Hyainailouros napakensis(Ginsburg, 1980) †Hyainailouros sulzeri(Biedermann, 1863) Genus: † Isohyaenodon (polyphyletic genus)(Savage, 1965) †Isohyaenodon andrewsi(Savage, 1965) †Isohyaenodon zadoki(Savage, 1965) Genus: † Parapterodon (Lange-Badré, 1979) †Parapterodon lostangensis(Lange-Badré, 1979) Genus: † Sectisodon (Morales & Pickford, 2017) †Sectisodon markgrafi(Holroyd, 1999) †Sectisodon occultus(Morales & Pickford, 2017) Genus: † Sekhmetops (Al-Ashqar, 2025) †Sekhmetops africanus(Andrews, 1903) †Sekhmetops phiomensis(Osborn, 1909) Genus: † Sivapterodon (Ginsburg, 1980) †Sivapterodon lahirii(Pilgrim, 1932) (unranked): †Pterodon clade Genus: † Kerberos (Solé, 2015) †Kerberos langebadreae(Solé, 2015) Genus: † Pterodon (Blainville, 1839) †Pterodon dasyuroides(Blainville, 1839) Incertae sedis : †"Pterodon" sp. [DPC 5036] (Holroyd, 1999) Tribe: † Metapterodontini (Morales & Pickford, 2017) Genus: † Metapterodon (Stromer, 1926) †Metapterodon brachycephalus(Osborn, 1909) †Metapterodon kaiseri(Stromer, 1926) †Metapterodon stromeri(Morales, 1998) Tribe: † Paroxyaenini (Lavrov, 2007) Genus: † Paroxyaena (Martin, 1906) †Paroxyaena galliae(Filhol, 1881) †Paroxyaena pavlovi(Lavrov, 2007) Incertae sedis : †"Pterodon" sp. [BC 15'08] (Pickford, 2008) †Hyainailourinae sp. [GSN AD 100'96] (Morales, 1998) †Hyainailourinae sp. [UON 84-359] (Solé, 2016) †Hyainailourinae sp. A [DPC 6555] (Holroyd, 1999) †Hyainailourinae sp. C [DPC 9243 & DPC 10315] (Holroyd, 1999) †Hyainailourinae sp. D [DPC 6545] (Holroyd, 1999)

References

1. 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.
2. Pilgrim G. E. (1932). "The fossil Carnivora of India. Memoirs of the Geological Survey of India" . Palaeontologica Indica. 18 (1–232). doi:10.1017/S0016756800096448. Archived from the original on April 13, 2023.
3. P. D. Polly (1996). "The skeleton of Gazinocyon vulpeculus gen. et. comb nov. and the cladistic relationships of Hyaenodontidae (Eutheria, Mammalia)" (PDF). Journal of Vertebrate Paleontology. 16 (2): 303–319. Archived (PDF) from the original on June 25, 2023.
4. 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.
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6. Sorkin, Boris (2008). "A biomechanical constraint on body mass in terrestrial mammalian predators" . Lethaia. 41 (4): 333–347. doi:10.1111/j.1502-3931.2007.00091.x. ISSN   0024-1164.
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9. Averianov, Alexander; Obraztsova, Ekaterina; Danilov, Igor; Jin, Jian-Hua (2023). "A new hypercarnivorous hyaenodont from the Eocene of South China". Frontiers in Ecology and Evolution. 11. doi: 10.3389/fevo.2023.1076819 . ISSN   2296-701X.
10. Borths, M. R.; Stevens, N. J. (April 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 e1570222. Bibcode:2019JVPal..39E0222B. doi:10.1080/02724634.2019.1570222. S2CID   145972918.
11. 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.
12. Solé, Floréal; Amson, Eli; Borths, Matthew; Vidalenc, Dominique; Morlo, Michael; Bastl, Katharina (2015). "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. Bibcode:2015PLoSO..1035698S. doi: 10.1371/journal.pone.0135698 . PMC   4580617 . PMID   26398622.