Borophagus[1] Temporal range: MiddleMiocene -Early Pleistocene12–2 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Borophagus secundus skull
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Carnivora
Family:	Canidae
Subfamily:	†Borophaginae
Tribe:	†Borophagini
Subtribe:	†Borophagina
Genus:	†Borophagus Cope, 1892
Type species
†Borophagus diversidens
Other species
†B. dudleyi †B. hilli †B. littoralis †B. orc †B. parvus †B. pugnator †B. secundus
Synonyms
†CynoguloKretzoi, 1968 †HyaenognathusMerriam, 1903 †PorthocyonMerriam, 1903 †Osteoborus

Borophagus ("gluttonous eater") is an extinctgenus of thesubfamilyBorophaginae, a group ofcanids endemic toNorth America from the MiddleMiocene to theearly Pleistocene (12—2Mya).^[1]

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 asEpicyon, which seems to be an evolutionary trend of the group (Turner, 2004). During the Pliocene epoch,Borophagus began being displaced by otherCanid species such asCanis edwardii and later byAenocyon dirus. Early species ofBorophagus were placed in the genusOsteoborus until recently, but thegenera are now considered synonyms.^[1]

Typical features of this genus are a bulging forehead and powerful jaws;Borophagus has been considered to be probably ascavenger by paleontologists in the past.^[2] Its crushingpremolar teeth and strong jaw muscles would have been used to crack open bone, much like thehyena of the Old World. However,Borophagus fossils are so abundant and geographically widespread that some paleontologists now argue thatBorophagus 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.^[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.^[3] Coprolites fromBorophagus 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 thatBorophagus may have been a social pack-hunter.^[4]

The adult animal is estimated to have been about 80 cm in length, similar to acoyote, although it was much more powerfully built.^[5]

• Borophagus diversidens existed for2.5 million years (synonymous withFelis hillianus,Hyaenognathus matthewi,Hyaenognathus pachyodon,Hyaenognathus solus,Porthocyon dubius)
• Borophagus dudleyi existed for2 million years
• Borophagus hilli existed for0.5 million years (synonymous withOsteoborus crassapineatus,Osteoborus progressus)
• Borophagus littoralis existed for3 million years (syn.Osteoborus diabloensis)
• Borophagus orc existed for2 million years
• Borophagus parvus existed for2 million years
• Borophagus pugnator existed for4 million years (synonymous withOsteoborus galushai)
• Borophagus secundus existed for4 million years (synonymous withHyaenognathus cyonoides,Hyaenognathus direptor,Osteoborus secundus)

Existence based on Figure 141 of Wang et al. (1999).^[1]

In North America, in places such asCoffee Ranch in Texas,Borophagus was contemporary with the bearAgriotherium as well as the feliformBarbourofelis, the saber-toothedmachairodont catAmphimachairodus coloradensis and fellow canidEpicyon. All of these animals were potential competitors that would have occasionally conflicted withBorophagus for food and territory, though it may also have readily scavenged their kills. Prey forBorophagus included herbivores like the camelAepycamelus, the pronghorn antelopeCosoryx, horses likeNeohipparion andNannippus, the ancient peccaryProsthennops and even rhinoceroses like the hippo-likeTeleoceras, all of which could provide a suitable meal through hunting or scavenging.^[6][7]

• Alan Turner, "National Geographic: Prehistoric Mammals" (Washington, D.C.: Firecrest Books Ltd., 2004), pp. 112–114.ISBN 0-7922-7134-3
• Xiaoming Wang,"The Origin and Evolution of the Dog Family" Accessed 1/30/06.

• Picture of anOsteoborus skull in a museum, from "World of the Wolf." (Accessed 6/19/06)
• Russell Hunt,"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)Archived 2007-03-20 at theWayback Machine
• Xiaoming Wang, Richard H. Tedford, Mauricio Antón,Dogs: Their Fossil Relatives and Evolutionary History, New York : Columbia University Press, 2008;ISBN 978-0-231-13528-3

• Borophagines
• Miocene canids
• Pliocene carnivorans
• Neogene mammals of North America
• Prehistoric carnivoran genera
• Fossil taxa described in 1892
• Taxa named by Edward Drinker Cope
• Prehistoric canines

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