Dinocrocuta spp.

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Dinocrocuta spp.


Life restoration of Dinocrocuta. © @ Mauricio Antón.

Temporal range: Late Miocene (Tortonian; Bahean age[1]; ~8.7-7.75Ma[2])

Scientific classification:

Life
Domain: Eukaryota
(unranked): Unikonta
(unranked): Opisthokonta
(unranked): Holozoa
(unranked): Filozoa
Kingdom: Animalia
Subkingdom: Eumetazoa
(unranked): Bilateria
Clade: Nephrozoa
Superphylum: Deuterostomia
Phylum: Chordata
Clade: Olfactores
Clade: Craniata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Clade: Eugnathostomata
Clade: Teleostomi
Superclass: Tetrapoda
Clade: Reptiliomorpha
Clade: Amniota
Clade: Synapsida
Clade: Eupelycosauria
Clade: Sphenacodontia
Clade: Sphenacodontoidea
Order: Therapsida
Clade: Eutheriodonta
Suborder: Cynodontia
Clade: Epicynodontia
Infraorder: Eucynodontia
Parvorder: Probainognathia
Superfamily: Chiniquodontoidea
Clade: Prozostrodontia
Clade: Mammaliaformes
Class: Mammalia
Clade: Holotheria
Superlegion: Trechnotheria
Legion: Cladotheria
Sublegion: Zatheria
Infralegion: Tribosphenida
Subclass: Theria
Clade: Eutheria
Infraclass: Placentalia
Subcohort: Exafroplacentalia
Magnorder: Boreoeutheria
Superorder: Laurasiatheria
(unranked): Ferae
(unranked): Carnivoramorpha
Order: Carnivora
Suborder: Feliformia
Family: †Percrocutidae? (or Hyaenidae)
Genus: †Dinocrocuta
Species: †D. gigantea
†D. macrodonta

Dinocrocuta is an extinct genus of hyena-like carnivoran that lived in the Hezheng Basin of central China[1] during the late Miocene ~8.7-7.75 million years ago[2].

Description:
Dinocrocuta was a large hyena-like predator. According to Mauricio Antón, Dinocrocuta likely doubled, if not tripled, the mass of the largest living hyenas (which is around 80 kilograms).[1]


Skeletal restoration of Dinocrocuta. © @ Mauricio Antón.

It was found that the skulls of Dinocrocuta gigantea and Crocuta crocuta would be better at dissipating and distributing stress than Canis lupus. The highly domed frontal region of the former two would have facilitated stress dissipation and would be consistent with bone-cracking behavior. By contrast, the grey wolf, though it is capable of bone-crushing behavior*, is clearly not as adapted for this behavior as Dinocrocuta and the spotted hyena due to its very shallow forehead.[3] However, analysis of the mandibular biomechanics of these three carnivorans has yielded some noteworthy facts. During biting at P3, P4, and M1 (third premolar; fourth premolar; and first molar; respectively), mandibular stress was lowest in the spotted hyena and elevated in both the grey wolf and Dinocrocuta. Stress dissipation patterns of the pre-M1 corpus are similar in Dinocrocuta and the spotted hyena. But Dinocrocuta’s post-M1 corpus was slender and actually relatively weaker than that of the spotted hyena and grey wolf, meaning that the extinct carnivoran had a weaker mandible when performing a similar bone-cracking task as in the spotted hyena. It is worth noting that the individual studied in both of the aforementioned studies was a subadult individual. As such, the increase in biting performance in spotted hyenas throughout the course of their ontogeny may suggest that complete bone-cracking ability was relatively more delayed in Dinocrocuta than in the spotted hyena.[4]

*As noted by the author, a difference between bone-cracking and bone-crushing in ossiphageous mammalian carnivores is established by Werdelin (1989).

Predatory and scavenging behavior:
There is a specimen of a female Chilotherium wimani (an extinct rhinocerotid) whose skull was bitten by Dinocrocuta gigantea. The damage to the skull was interpreted as an injury inflicted by the percrocutid. This suggests that Dinocrocuta was an active predator, just like the extant spotted hyena.[5]

With its skeleton that was efficient for terrestrial locomotion, Dinocrocuta could have traveled far distances to search for carrion or prey. With its large body size and formidable armament, it could have evicted other carnivores from their kills.[1]


Skull of Dinocrocuta

Ecological implications:
According to Mauricio Antón, Dinocrocuta was the dominant large carnivore in Bahean-aged sediments. But by the Baeodean age, it was either very rare or extinct and was replaced by the much smaller true hyaenid Adcrocuta. The machairodont Amphimachairodus also became much more common after the extinction of Dinocrocuta. These facts suggest that Amphimachairodus’ frequency and dominance in the habitat were held back by competition from Dinocrocuta and that competition from Adcrocuta was not as suppressive on the cat.[1]

The actual cause of Dinocrocuta’s extinction is currently unknown.[1]

References:

[1] Sabertooth’s Bane: Introducing Dinocrocuta (article by Mauricio Antón)
[2] Fossilworks page on Dinocrocuta
[3] Tseng, Z.J. (2009). Cranial function in a late Miocene Dinocrocuta gigantea (Mammalia: Carnivora) revealed by comparative finite element analysis. Biological Journal of the Linnean Society, 2009, 96, 51–67. doi:10.1111/j.1095-8312.2008.01095.x
[4] Tseng, Z.J.; Binder, W.J. (2010). Mandibular biomechanics of Crocuta crocuta, Canis lupus, and the late Miocene Dinocrocuta gigantea (Carnivora, Mammalia). Zoological Journal of the Linnean Society. 158 (3): 683–696. doi:10.1111/j.1096-3642.2009.00555.x
[5] Deng, T.; Tseng, Z.J. (2010). Osteological evidence for predatory behavior of the giant percrocutid (Dinocrocuta gigantea) as an active hunter. Chinese Science Bulletin, June 2010, Volume 55, Issue 17, pp 1790–1794. doi:10.1007/s11434-010-3031-9

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A recent study on basicranial morphology suggests that Dinocrocuta is, in fact, a true hyena, and that Percrocutidae is probably an invalid taxon.

Dinocrocuta gigantea was once moved out of the Hyaenidae based on its peculiar deciduous teeth and placed in a separate family – the Percrocutidae. A D. gigantea skull from Fugu, Shaanxi Province is scanned with the internal structures of its bulla reconstructed, described in detail, and compared with other feliforms. The basicranium of D. gigantea shows a typical hyaenid pattern, which supports the traditional view that it should remain within the Hyaenidae and questions the validity of the Percrocutidae. The basicranium of D. gigantea also possesses a number of unique features, suggesting that it could be an early side-branch of the Hyaenidae.

However, as is noted in the earlier work of Schmidt-Kittler (1976), the feloid pattern of dp4, i.e. backwards migrating metaconid and its close association with talonid could result from a rapid reduction of molars. In his investigation, this pattern occurs in not only Stenoplesictis, felids, Percrocuta and Dinocrocuta but also the nimravid Nimravus and a primitive carnivoran Palaeogale. In Wintershof-West materials of Semigenetta elegans, he observed both feloid and viverroid patterns. Moreover, the feloid pattern is recorded in the myrmecophagous hyaenid Proteles by Baryshnikov and Averianov (1995) who group it with Percrocuta and Dinocrocuta in a separate Protelidae. The dp4 of the euplerid Cryptoprocta, figured by Carlsson (1911), is probably similar to that of “Proailurus sp.” described by Chen and Schmidt-Kittler as an ancestral type of the feloid pattern. These taxa are unlikely to form a monophyletic group altogether, and the feloid pattern of dp4 must have evolved many times in different lineages of Carnivora, which is also the original conclusion drawn by Schmidt-Kitter (1976:99). Therefore, the shape of dp4 is not convincing enough as the only evidence of founding a separate family for Percrocuta, Dinocrocuta or Proteles. Given the basicranial morphology, Percrocutidae is probably invalid and could be relegated to Percrocutinae before the relationship between Percrocuta, Dinocrocuta and other hyaenids is better clarified.

www.researchgate.net/profile/Vertebrata-Palasiatica/publication/336578352_Basicranial_morphology_of_Late_Miocene_Dinocrocuta_gigantea_Carnivora_Hyaenidae_from_Fugu_Shaanxi/links/5da6bcbd299bf1c1e4c38532/Basicranial-morphology-of-Late-Miocene-Dinocrocuta-gigantea-Carnivora-Hyaenidae-from-Fugu-Shaanxi.pdf