Borophagus

''Borophagus'' ("gluttonous eater") is an extinct genus of the subfamily Borophaginae, a group of canids endemic to North America from the Middle Miocene epoch through the Early Pleistocene epoch 12—1.8 Mya.

Evolution

''Borophagus'', like other borophagines, are loosely known as "bone-crushing" or " hyena-like" dogs. Though not the most massive borophagine by size or weight, it had a more highly evolved capacity to crunch bone than earlier, larger genera such as ''Epicyon'', which seems to be an evolutionary trend of the group (Turner, 2004). During the Pliocene epoch, ''Borophagus'' began being displaced by other ''Canid'' species such as ''Canis edwardii'' and later by ''Aenocyon dirus''. Early species of ''Borophagus'' were placed in the genus ''Osteoborus'' until recently, but the genera are now considered synonyms.

Description

Typical features of this genus are a bulging forehead and powerful jaws; ''Borophagus'' has been considered to be probably a scavenger by paleontologists in the past. Its crushing premolar teeth and strong jaw muscles would have been used to crack open bone, much like the hyena of the Old World. However, ''Borophagus'' fossils are so abundant and geographically widespread that some paleontologists now argue that ''Borophagus'' must have been both the dominant carnivore of its time, and thus an active predator because carrion feeding alone could not have sustained such a large population.Wang, Xiaoming; and Tedford, Richard H. Dogs: Their Fossil Relatives and Evolutionary History. New York: Columbia University Press, 2008. pp112-3 They note that not all carnivores with bone-cracking ability are scavengers, such as the modern spotted hyena; instead, they interpret the bone-cracking ability as an adaptation to social hunting where complete utilization of a carcass was favored. Coprolites from ''Borophagus'' further vindicate its bone-crushing abilities, while simultaneously indicating it occupied a niche no longer seen in the present-day ecosystems of North America. The discovery of these coprolites also indicates that ''Borophagus'' may have been a social pack-hunter.

The adult animal is estimated to have been about 80 cm in length, similar to a coyote, although it was much more powerfully built.

Species

*''Borophagus diversidens'' existed for (synonymous with ''Felis hillianus'', ''Hyaenognathus matthewi'', ''Hyaenognathus pachyodon'', ''Hyaenognathus solus'', ''Porthocyon dubius'')
*''Borophagus dudleyi'' existed for
*''Borophagus hilli'' existed for (synonymous with ''Osteoborus crassapineatus'', ''Osteoborus progressus'')
*''Borophagus littoralis'' existed for (syn. ''Osteoborus diabloensis'')
*''Borophagus orc'' existed for
*''Borophagus parvus'' existed for
*''Borophagus pugnator'' existed for (synonymous with ''Osteoborus galushai'')
*''Borophagus secundus'' existed for (synonymous with ''Hyaenognathus cyonoides'', ''Hyaenognathus direptor'', ''Osteoborus secundus'')
Existence based on Figure 141 of Wang et al. (1999).

Paleoecology

In North America, in places such as Coffee Ranch in Texas, ''Borophagus'' was contemporary with the bear ''Agriotherium'' as well as the feliform ''Barbourofelis'', the saber-toothed machairodont cat '' Amphimachairodus coloradensis'' and fellow canid ''Epicyon''. All of these animals were potential competitors that would have occasionally conflicted with ''Borophagus'' for food and territory, though it may also have readily scavenged their kills. Prey for ''Borophagus'' included herbivores like the camel ''Aepycamelus'', the pronghorn antelope ''Cosoryx'', horses like ''Neohipparion'' and ''Nannippus'', the ancient peccary '' Prosthennops'' and even rhinoceroses like the hippo-like ''Teleoceras'', all of which could provide a suitable meal through hunting or scavenging.

References

*Alan Turner, "National Geographic: Prehistoric Mammals" (Washington, D.C.: Firecrest Books Ltd., 2004), pp. 112–114.
*Xiaoming Wang
"The Origin and Evolution of the Dog Family"
Accessed 1/30/06.

Further reading

*Russell Hunt, [https://web.archive.org/web/20110926205607/http://darkwing.uoregon.edu/~rhunt/publications.htm "Ecological Polarities Of the North American Family Canidae: A New Approach to Understanding Forty Million Years of Canid Evolution" (Accessed 1/30/06)].
Wang et al., "Phylogenetic Systematics of the Borophaginae (Carnivora:Canidae)." ''Bulletin of the American Museum of Natural History'', No. 243, Nov. 17 1999. (PDF) (Accessed 4/11/06)
*Xiaoming Wang, Richard H. Tedford, Mauricio Antón, ''Dogs: Their Fossil Relatives and Evolutionary History'', New York : Columbia University Press, 2008;

{{Taxonbar, from=Q137418

Borophagines
Miocene canids
Pliocene carnivorans
Neogene mammals of North America
Prehistoric carnivoran genera
Fossil taxa described in 1892