Oxyaenidae

Not to be confused with Oxyclaeninae.

Oxyaenidae Temporal range: Late Paleocene to Middle Eocene 58.9–39.7 Ma PreꞒ Ꞓ O S D C P T J K Pg N
skull of Palaeonictis occidentalis
reconstruction of Patriofelis ferox
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Mirorder:	Ferae
Clade:	Pan-Carnivora
Order:	†Oxyaenodonta Van Valen, 1971[2]
Family:	†Oxyaenidae Cope, 1877[1]
Type genus
†Oxyaena Cope, 1874
Subfamilies
†Machaeroidinae †Oxyaeninae †Palaeonictinae †Tytthaeninae
Synonyms
synonyms of order: Oxyaenida (Van Valkenburgh, 2007) synonyms of family: Oxyaenoidea (Osborn, 1910)

Oxyaenidae ("sharp hyenas") is a family of extinct carnivorous placental mammals.^[3] Traditionally classified in order Creodonta, this group is now classified in its own order Oxyaenodonta ("sharp tooth hyenas") within clade Pan-Carnivora in mirorder Ferae. The group contains four subfamilies comprising fourteen genera. Oxyaenids first appeared during the late Paleocene in North America, with smaller radiations of oxyaenids in Eurasia occurring during the Eocene.^[4][5]

Etymology

The name of order Oxyaenodonta comes from Ancient Greek ὀξύς (oxús) 'sharp', name of hyena genus Hyaena and from Ancient Greek ὀδούς (odoús) 'tooth'.

The name of family Oxyaenidae comes from Ancient Greek ὀξύς (oxús) 'sharp', name of hyena genus Hyaena and taxonomic suffix "-idae".^[6]

Characteristics

Skull of Patriofelis ulta at Muséum national d'Histoire naturelle, Paris

They were superficially otter- or badger-like placental mammals that walked on flat feet, in contrast to most modern Carnivora, which walk and run on their toes. Though most genera were medium-sized by modern standards, they may have been the earliest group of large carnivorous mammals.^[7][8] The largest known oxyaenid was Sarkastodon mongoliensis, which could have weighed 800 kg (1,800 lb). However, this may have been an overestimate.^[9] All had two molars on each side of both the upper and lower jaw.^[10] While many oxyaenids, such as Patriofelis, were hypercarnivores,^[11] some such as Oxyaena were more omnivorous, with meat-based but varied diets similar to modern brown bears and racoons.^[12] Of the four families:

• The Tytthaeninae were the earliest representatives of the group, generally smaller and with more unspecialized bodies and primitive features.^[13]
• The Paleonictinae included intermediate-sized hypercarnivores and mixed feeders.^[13]
• The Oxyaeninae included the largest genera, such as Sarkaskadon, Patriofelis, and Oxyaena. Some genera showed Hunter-Schrager bands on their molars, typical of bone-cracking. They were adapted for terrestrial locomotion and probably hunted or scavanged on forest floors.^[11]
• The Macheroidinae were a small number of specialized hypercarnivores adapted for arboreal locomotion, with long slender bodies and strong grappling forelimbs^[14] This group was the first saber-toothed mammals in the fossil record. A flange on the lower jaw partially protected their long, slender saber canine teeth. They ranged from civet- to leopard-sized, probably lived in the trees of closed-canopy forests, and ambushed prey larger than their bodies. Since most large herbivores at the time were terrestrial, it is likely they dropped from trees onto their prey.^[15]

Overall, oxyaenids had long, flat heads, long bodies with short legs, large claws, and reinforced, inflexible lower spines. The forelimbs were strong and flexible, and could twist to embrace and grapple, like the forelimbs of cats and unlike those of dogs. These adaptations suggest that hunting Oxyaenids were solitary ambush predators that would capture larger prey.^[7][14] Their extinction in the Eocene may be connected to the reduction of closed-canopy tropical jungles, which dominated the world in the hothouse of the Paleocene-Eocene Thermal Maximum. No modern carnivoran has an inflexible spine, which would reduce maneuverability and running speed in more open environments.^[16]

Evolution

Oxyaenodonts were believed to have evolved in the middle Paleocene in North America with the oldest known oxyaenodont, Tytthaena, being found there.^[17][18] Oxyaenodonts would disperse into Europe near the Paleocene-Eocene boundary via the De Geer route, however the timing of arrival in Asia is unknown.^[17]

Classification and phylogeny

Taxonomy

Order: †Oxyaenodonta Van Valen, 1971 Family: †Oxyaenidae Cope, 1877 Subfamily: †Machaeroidinae Matthew, 1909 Genus: †Apataelurus Scott, 1938 †Apataelurus kayi Scott, 1938 †Apataelurus pishigouensis Tong & Lei, 1986 Genus: †Diegoaelurus Zack, Poust & Wagner, 2022 Diegoaelurus vanvalkenburghae Zack, Poust & Wagner, 2022 Genus: †Isphanatherium Lavrov & Averianov, 1998 Isphanatherium ferganensis Lavrov & Averianov, 1998 Genus: †Machaeroides Matthew, 1909 †Machaeroides eothen Matthew, 1909 †Machaeroides simpsoni Dawson, 1986 Incertae sedis: †Machaeroidinae sp. [CM 2386] Zack, 2019 †Machaeroidinae sp. [FMNH PM 1506] Tomiya, 2021 †Machaeroidinae sp. [USNM 173514] Zack, 2019 Subfamily: †Oxyaeninae Cope, 1877 Genus: †Argillotherium Davies, 1884 †Argillotherium toliapicum Davies, 1884 Genus: †Dipsalidictis ^(paraphyletic genus) Matthew & Granger, 1915 †Dipsalidictis aequidens Matthew & Granger, 1915 †Dipsalidictis krausei Gunnell & Gingerich, 1991 †Dipsalidictis platypus Matthew & Granger, 1915 †Dipsalidictis transiens Matthew & Granger, 1915 Genus: †Malfelis Stucky & Hardy, 2007 †Malfelis badwaterensis Stucky & Hardy, 2007 Genus: †Oxyaena Cope, 1874 †Oxyaena forcipata Cope, 1874 †Oxyaena gulo Matthew & Granger, 1915 †Oxyaena intermedia Denison, 1938 †Oxyaena lupina Cope, 1874 †Oxyaena pardalis Matthew & Granger, 1915 †Oxyaena simpsoni Van Valen, 1966 †Oxyaena woutersi Lange-Badré & Godinot, 1982 †Oxyaena sp. [Europe] Solé, 2011 Genus: †Patriofelis Leidy, 1870 †Patriofelis ferox Marsh, 1872 †Patriofelis ulta Leidy, 1870 Genus: †Protopsalis Cope, 1880 †Protopsalis tigrinus Cope, 1880 Genus: †Sarkastodon Granger, 1938 †Sarkastodon henanensis Tong & Lei, 1986 †Sarkastodon mongoliensis Granger, 1938 Subfamily: †Palaeonictinae Denison, 1938 Genus: †Ambloctonus Cope, 1875 †Ambloctonus major Denison, 1938 †Ambloctonus priscus Matthew & Granger, 1915 †Ambloctonus sinosus Cope, 1875 Genus: †Dipsalodon ^(paraphyletic genus) Jepsen, 193) †Dipsalodon churchillorum Rose, 1981 †Dipsalodon matthewi Jepsen, 1930 †Dipsalodon sp. [UM 71172] Rose, 1981 Genus: †Palaeonictis de Blainville, 1842 †Palaeonictis gigantea de Blainville, 1842 †Palaeonictis occidentalis Osborn, 1892 †Palaeonictis peloria Rose, 1981 †Palaeonictis wingi Chester, 2010 Subfamily: †Tytthaeninae Gunnell & Gingerich, 1991 Genus: †Tytthaena Gingerich, 1980 †Tytthaena lichna (Rose, 1981) †Tytthaena parrisi Gingerich, 1980

Phylogeny

Cladogram according to Gunnel in 1991:^[19]

Oxyaenidae	Tytthaena parrisi Tytthaena lichna Palaeonictis occidentalis Palaeonictis peloria Dipsalodon matthewi Dipsalodon churchillorum Dipsalidictis krausei Dipsalidictis transiens Dipsalidictis platypus Dipsalidictis aequidens Oxyaena gulo Oxyaena intermedia Oxyaena forcipata

Temporal distribution

Within clade Pan-Carnivora

Within family Oxyaenidae

See also

• Mammal classification
• Ferae
• Creodonta

References

1. E. D. Cope (1877.) "Report upon the extinct Vertebrata obtained in New Mexico by parties of the expedition of 1874." Report upon United States Geographical Surveys West of the One Hundredth Meridian, in charge of First Lieut. G.M. Wheeler, Corps of Engineers, U.S. Army, Vol. IV Paleontology, Part II, pp. 1-365. Government Printing Office, Washington, D.C.
2. Van Valen, Leigh (1971). "Adaptive Zones and the Orders of Mammals". Evolution. 25 (2): 420–428. Bibcode:1971Evolu..25..420V. doi:10.1111/j.1558-5646.1971.tb01898.x. PMID 28563121.
3. Halliday, Thomas J. D.; Upchurch, Paul; Goswami, Anjali (2015). "Resolving the relationships of Paleocene placental mammals" (PDF). Biological Reviews. 92 (1): 521–550. doi:10.1111/brv.12242. ISSN 1464-7931. PMC 6849585. PMID 28075073.
4. Gunnel, Gregg F.; Gingerich, Philip D. (30 Sep 1991). "Systematics and evolution of late Paleocene and early Eocene Oxyaenidae (Mammalia, Creodonta) in the Clarks Fork Basin, Wyoming" (PDF). Contributions from the Museum of Paleontology. 28 (7). The University of Michigan: 141–180. Retrieved 2010-01-03.
5. F. Solé, E. Gheerbrant and M. Godinot (2011.) New Data on the Oxyaenidae from the Early Eocene of Europe; biostratigraphic, paleobiogeographic and paleoecologic implications Palaeontologia Electronica, Vol. 14, Issue 2; 13A: Pages 1-41
6. Dixon, Dougal (2008). World Encyclopedia of Dinosaurs & Prehistoric Creatures. Lorenz Books. ISBN 978-0754817307.
7. Kort, Anne E.; Ahrens, Heather; David Polly, P.; Morlo, Michael (2021-10-01). "Postcrania and paleobiology of Patriofelis ulta (Mammalia, Oxyaenodonta) of the Bridgerian (lower–middle Eocene) of North America". Journal of Vertebrate Paleontology. 41 (6) e2045491. Bibcode:2021JVPal..41E5491K. doi:10.1080/02724634.2021.2045491. ISSN 0272-4634.
8. Gebo, Daniel L.; Rose, Kenneeth D. (1993). "Skeletal Morphology and Locomotor Adaptation in Prolimnocyon atavus, an Early Eocene Hyaenodontid Creodont". Journal of Vertebrate Paleontology. 13 (1): 125–144. Bibcode:1993JVPal..13..125G. doi:10.1080/02724634.1993.10011492. ISSN 0272-4634. JSTOR 4523490.
9. Sorkin, B. (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.
10. Morlo, M.; Habersetzer, J. (1999). "The Hyaenodontidae (Creodonta, Mammalia) from the lower Middle Eocene (MP 11) of Messel (Germany) with special remarks on new x-ray methods" (PDF). Courier-Forschungsinstitut Senckenberg: 31–74.
11. Kort, Anne E.; Ahrens, Heather; David Polly, P.; Morlo, Michael (2021-10-01). "Postcrania and paleobiology of Patriofelis ulta (Mammalia, Oxyaenodonta) of the Bridgerian (lower–middle Eocene) of North America". Journal of Vertebrate Paleontology. 41 (6) e2045491. Bibcode:2021JVPal..41E5491K. doi:10.1080/02724634.2021.2045491. ISSN 0272-4634.
12. Wesley-Hunt, Gina D. (2005). "The Morphological Diversification of Carnivores in North America". Paleobiology. 31 (1): 35–55. Bibcode:2005Pbio...31...35W. doi:10.1666/0094-8373(2005)031<0035:TMDOCI>2.0.CO;2. ISSN 0094-8373. JSTOR 4096983. S2CID 10989917.
13. Floréal Solé, Emmanuel Gheerbrant and Marc Godinot. "New data on the Oxyaenidae from the Early Eocene of Europe; biostratigraphic, paleobiogeographic and paleoecologic implications". Palaeontologia Electronica.
14. Zack, Shawn P. (2019). "A skeleton of a Uintan machaeroidine 'creodont' and the phylogeny of carnivorous eutherian mammals". Journal of Systematic Palaeontology. 17 (8): 653–689. Bibcode:2019JSPal..17..653Z. doi:10.1080/14772019.2018.1466374.
15. Zack, Shawn P.; Poust, Ashley W.; Wagner, Hugh (2022). "Diegoaelurus, a new machaeroidine (Oxyaenidae) from the Santiago Formation (late Uintan) of southern California and the relationships of Machaeroidinae, the oldest group of sabertooth mammals". PeerJ. 10 e13032. doi:10.7717/peerj.13032. ISSN 2167-8359. PMC 8932314. PMID 35310159.
16. "The Paleoecology of Patriofelis ulta and Implications for Oxyaenid Extinction - ProQuest". www.proquest.com. Archived from the original on 2025-01-21. Retrieved 2025-12-19.
17. Solé, Floréal & Smith, Thierry (2013). "Dispersals of placental carnivorous mammals (Carnivoramorpha, Oxyaenodonta & Hyaenodontida) near the Paleocene-Eocene boundary: a climatic and almost worldwide story" Geologica Belgica 16/4: 254–261
18. P. D. Gingerich. (1980.) "Tytthaena parrisi, Oldest Known Oxyaenid (Mammalia, Creodonta) from the Late Paleocene of Western North America." Journal of Paleontology 54(3):570-576
19. Gunnel, Gregg F.; Gingerich, Philip D. (1991). "Systematics and evolution of late Paleocene and early Eocene Oxyaenidae (Mammalia, Creodonta) in the Clarks Fork Basin, Wyoming" (PDF). Contributions from the Museum of Paleontology. 28 (7). The University of Michigan: 141–180.

Further reading

• David Lambert and the Diagram Group. The Field Guide to Prehistoric Life. New York: Facts on File Publications, 1985. ISBN 0-8160-1125-7