Hyaenodonta ("hyena teeth") is an extinct order of mostly carnivorous placental mammals of clade Pan-Carnivora from mirorder Ferae. Hyaenodonts were important mammalian predators that are believed to have arose either in the Late Cretaceous or Early Paleocene within Europe or North America, and persisted well into the Late Miocene. Hyaenodonts were found across Africa, Eurasia, and North America throughout the Cenozoic and occupied a variety of ecosystems, from forests to coastlines. They displayed a variety of body shapes, diet, and sizes, ranging from ambush predators like Hyainailouros to pounce-pursuit predators like some species of Hyaenodon.
The order currently consists of three superfamilies, Hyaenodontoidea, Hyainailouroidea, and Limnocyonoidea, in addition to smaller groups such as the Galecyon clade. The hyaenodontoids consisted of Hyaenodontidae, the hyainailouroids consisted of Hyainailouridae, Prionogalidae, and Teratodontidae, and with the limnocyonoids consisted of Limnocyoninae, Sinopinae, and Arfiinae. Hyaenodonts saw their diversification peak during the Middle-Late Eocene, before seeing a significant decline in diversity following the Eocene-Oligocene extinction event. In Afro-Arabia and Europe, they saw a recovery in diversity following the extinction event before seeing a terminal decline something during the Late Oligocene and Early Miocene respectively. The last hyaenodont would go extinct 7.5 Ma.
The extinction of the order has been debated by experts, many experts argued that their extinction was the result of competition with carnivorans. But over the recent years, many experts have questioned that hypothesis and argued their decline and extinction in most of their range was due to climatic changes.
Classification and phylogeny History of taxonomy Hyaenodonts were considerably more widespread and successful than the oxyaenids, the other clade of mammals originally classified along with the hyaenodonts as part of Creodonta. (1985): The Field Guide to Prehistoric Life. Facts on File Publications, New York. In 2015 phylogenetic analysis of Paleogene mammals, by Halliday et al., the monophyly of Creodonta was supported and was placed in the clade Ferae, closer to Pholidota than to Carnivora. However, most experts consider Creodonta to be considered to be a polyphyletic order as it contains two unrelated clades. Most experts have now recovered Hyaenodonta and Oxyaenodonta as distinct orders within Pan-Carnivora.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 Recent phylogenetic modeling suggests hyaenodonts were sister group to the Oxyaenodonta-Carnivoraformes clade.
Hyaenodonta currently consists of three superfamilies, Hyaenodontoidea, Hyainailouroidea, and Limnocyonoidea. The hyaenodontoids consisted of Hyaenodontidae and Proviverrinae, the hyainailouroids consisted of Hyainailouridae, Prionogalidae, and Teratodontidae, and with the limnocyonoids consisted of Limnocyoninae, Sinopinae, and Arfiinae. It also contained smaller groups unrelated to the superfamilies such as the Galecyon clade, Boualitominae, and Indohyaenodontinae.Borths, Matthew R., Al-Ashqar, Shorouq F., Sallam, Hesham M., Seiffert, Erik R. (2022.) "The Oldest Hypercarnovore (Placentalia, Mammalia, Hyaenodonta) from the Fayum Depression, Egypt", in "The Society of Vertebrate Paleontology 82th annual meeting" Hyainailourines were historically considered to be a subfamily within Hyaenodontidae, however Sole et al. (2015) proposed the clade Hyainailouridae, uniting the Hyainailourinae and Apterodontinae under the family.
Classification Order: †Hyaenodonta (unranked): †Eoproviverra/Tinerhodon clade Genus: †Eoproviverra Genus: †Tinerhodon (unranked): †Galecyon clade Genus: †Galecyon Genus: †Gazinocyon Genus: †Pyrocyon Family: †Wyolestidae Superfamily: †Hyaenodontoidea Family: †Hyaenodontidae Superfamily: †Limnocyonoidea Clade: †Arfiinae Clade: †Limnocyoninae Clade: †Sinopinae (unranked): †Afro-Arabian clade Genus: †Furodon Genus: †Glibzegdouia (unranked): †Kyawdawia clade Genus: †Kyawdawia Genus: †Paratritemnodon (unranked): †Lahimia clade Genus: †Parvavorodon Clade: †Boualitominae (paraphyletic clade) (unranked): †Tritemnodon clade Genus: †Tritemnodon Family: †Indohyaenodontidae Superfamily: †Hyainailouroidea (polyphyletic superfamily) Family: †Hyainailouridae (paraphyletic family) Family: †Prionogalidae Family: †Teratodontidae
ichnotaxa of Hyaenodonta: Ichnogenus: †Creodontipus Ichnogenus: †Dischidodacylus Ichnogenus: †Sarcotherichnus Ichnofamily: †Sarjeantipodidae Ichnogenus: †Hyaenodontipus Ichnogenus: †Quiritipes Ichnogenus: †Sarjeantipes
Phylogeny Phylogeny from Dubied et al. (2019) and Al-Ashqar et al. (2025) showing differences in more recent publications
Dubied et al. (2019)
Al-Ashqar et al. (2025)
Evolution
When the order arose exactly has changed over the years, Solé and Smith (2013) suggested hyaenodonts arose in the Late Paleocene roughly 58 Ma. Solé et al. (2009), as well as Borths and Stevens (2019), suggested an Early Paleocene origin for the order. However, majority of phylogenetic modeling over the recent years had support a Late Cretaceous origin for the order.
The biogeographic origin of the group has also been hotly debated by experts. Solé et al. (2009) suggested an African origin for the order as the known oldest hyaenodonts were recovered there, in additional to the diversity of hyaenodonts within the Ouarzazate basin. Bayesian analysis by various studies had found strong evidence of hyaenodonts originating from Europe. Borths et al. (2016) noted while European and North America origins were problematic due to hyaneodonts not being recorded before the Paleocene-Eocene boundary, European Paleocene records were poor unlike North America. They also noted Afro-Arabian origins for the order have never been tested using phylogenetic analysis and was based on the assumption that Lahimia was a basal hyaenodont although more recent analysis suggest it wasn't a basal hyaenodont. On the other hand, Bayesian analysis by Al-Ashqar et al. (2025) found stronger evidence of a North American origin than a European origin.
From Europe, hyaenodonts would have dispersed into Africa and from there dispersed into India. The oldest known hyaenodonts were Lahimia and Tinerhodon from the middle Paleocene of Morocco. Afterwards, hyaenodonts dispersed into Asia from either Europe or India, and dispersed into North America from either Europe or Asia. Proviverrines experience a radiation in diversity during the Early Eocene, due to the lack of competition and the Early Eocene Climatic Optimum. In Africa, hyaenodonts saw an increase in subfamilial richness after the end of the Early Eocene Climatic Optimum. During the middle to late Eocene, hyaenodonts, along with carnivorans, replaced oxyaenids, mesonychians, and miacoids in North America and Europe. With the former, the extinction of European mesonychids and oxyaenids resulted in the diversification of hyaenodonts, as well as an increase in body size. For most of the Paleogene, hyaenodonts were the dominant group of mammalian carnivores in Africa and Europe.
The order saw a massive decline globally during the Eocene-Oligocene extinction event due to the decline of favorable prey and the expansion of open environments. Following the boundary event, hyaenodonts experienced a rebound in diversity in Europe and Afro-Arabia. During the Early Miocene, the formation of the Gomphotherium land bridge saw the dispersal of hyaenodonts into Eurasia.
Anatomy Size
They generally ranged in size from at the shoulder, with most hyaenodonts weighing within the range, equivalent to a mid-sized dog. However, hyaenodonts have been known to reach larger sizes. Hyaenodon horridus was one of the largest North American species, with limb regressions suggesting the adults weighed on average, with the largest adults weighing no more than . Hyaenodon megaloides was the largest North American Hyaenodon species being three times heavier than Hyaenodon horridus, weighing . However, Van Valkenburgh (1994) suggested this species may have weighed , making it about the size of a lion. Simbakubwa kutokaafrika may have weighed up to , with Megistotherium estimated to have reached an even larger size of . However estimate is suspect due to being based on skull-body size ratios derived from felids, which have much smaller skulls for their body size. Additionally, it was estimated that the maximum size a terrestrial mammalian carnivores could reach was , further suggesting the higher body mass estimates for Megistotherium was unlikely.
Other large hyaenodonts include the hyainailourine Hyainailouros and the much earlier-living Hyaenodon gigas and Hyaenodon mongoliensis (two of the largest species of the genus, Hyaenodon), all three taxa had a skull length of .
Skull and dentition
Compared to carnivorans, who have one pair of carnassial teeth, hyaenodonts possessed as many as three sequential pairs of carnassials or carnassial-like molar teeth in their jaws. Their skulls are known to have high sagittal crests which supported attachment for powerful temporalis muscles.Wang, Xiaoming; and Tedford, Richard H. (2008). "Dogs: Their Fossil Relatives and Evolutionary History." New York: Columbia University Press Hyaenodonts, like all "creodonts", lacked post-carnassial crushing molar teeth, such as those found in many carnivoran families, especially the Canidae and Ursidae.
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. Hyaenodonts differed from Carnivora in that they replaced their deciduous dentition slower in development than carnivorans. Studies on Hyaenodon show that juveniles took 3 to 4 years in the last stage of tooth eruption, implying a very long adolescent phase. In North American forms, the first upper premolar erupts before the first upper molar, while European forms show an earlier eruption of the first upper molar.
Postcranial anatomy
While the neck of Hyaenodon was relatively short, the body and tail were longer in comparison. Compared to Hyainailouros, the spine of Hyaenodon was longer and more robust, suggesting it didn't bore its head as low. Cervical vertebrae of Hyaenodon was relatively short and resembled that of a felid than a canid. The femur of Hyaenodon was found to have been nearly as long as the humerus, which was short and massive, supporting a large, rounded head. Compared to carnivorans, the greater tuberosity has a more irregular shape and faces anteromedially. It would've been an insertion site for the infraspinatous muscles, which isn't seen in carnivorans. Despite this, the humerus of Hyaenodon was similar to that of wolves and hyenas. Compared to hyenas, it shows an anconeal fossa, a well-developed brachial flange and a similarly elongated trochlea shape. Despite this, the trochela shape of Hyaenodon is more similar in to the red fox.
Regressions found Hyainailouros had a humerus as robust as an average felid. Compared to the humerus of a tiger, the deltoid scar of Hyainailouros was more distally than tigers. The ulna of Hyainailouros sulzeri was arched and supported a high, well-developed olecranon, as well as a long, but strong diaphysis to the distal end of ulna. Compared to carnivorans, the fibula of Hyainailouros was thicker in comparison, with the diaphysis being twice as antero-posteriorly elongated in its distal area compared to the proximal area.
Paleobiology Locomotion