''Otarocyon'' ("large eared dog") is an extinct genus of the

Borophaginae The extinct Borophaginae form one of three subfamilies found within the canid family. The other two canid subfamilies are the extinct Hesperocyoninae and extant Caninae. Borophaginae, called "bone-crushing dogs", were endemic to North America ...

subfamily of

canid Canidae (; from Latin, '' canis'', " dog") is a biological family of dog-like carnivorans, colloquially referred to as dogs, and constitutes a clade. A member of this family is also called a canid (). There are three subfamilies found withi ...

s native to North America. It lived during the Oligocene epoch, about 34—30 Ma (million years ago). Fossils have been found only in

Montana Montana () is a state in the Mountain West division of the Western United States. It is bordered by Idaho to the west, North Dakota and South Dakota to the east, Wyoming to the south, and the Canadian provinces of Alberta, British Columb ...

Wyoming Wyoming () is a state in the Mountain West subregion of the Western United States. It is bordered by Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho to the west, Utah to the southwest, and Colorado to the s ...

, and

South Dakota South Dakota (; Sioux: , ) is a U.S. state in the North Central region of the United States. It is also part of the Great Plains. South Dakota is named after the Lakota and Dakota Sioux Native American tribes, who comprise a large porti ...

. ''Otarocyon'' was a small borophagine characterized by a short, broad

skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, th ...

, a specialized

middle ear The middle ear is the portion of the ear medial to the eardrum, and distal to the oval window of the cochlea (of the inner ear). The mammalian middle ear contains three ossicles, which transfer the vibrations of the eardrum into waves in the ...

, simple, tall premolar teeth, and

molars The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name ''molar'' derives from Latin, ''molaris dens'', meaning "millstone to ...

that are incipiently adapted to a hypocarnivorous diet. Despite its Oligocene age, the skull of ''Otarocyon'' shows several striking similarities to the living

fennec fox The fennec fox (''Vulpes zerda'') is a small crepuscular fox native to the deserts of North Africa, ranging from Western Sahara to the Sinai Peninsula. Its most distinctive feature is its unusually large ears, which serve to dissipate heat and ...

, particularly in the structure of its middle ear. The similarities are probably convergent, but they suggest that ''Otarocyon'' may have been similar in its appearance and habits.Phylogenetic systematics of the Borophaginae (Carnivora, Canidae)
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Species

*''O. macdonaldi'' Wang ''et al.'' 1999, Early Oligocene *''O. cooki'' Macdonald 1963, Late Oligocene In addition to its earlier age, ''O. macdonaldi'' differs from ''O. cooki'' in being smaller and in showing lesser development of the specializations that characterize the genus. ''O. macdonaldi'' is also the earliest known member of the subfamily Borophaginae, although the later appearing ''

Archaeocyon ''Archaeocyon'' ("ancient dog") is an extinct genus of the Borophaginae subfamily of canids native to North America. It lived during the Oligocene epoch 32-24 Ma., existing for approximately . Species of ''Archaeocyon'' are among the earliest k ...

'' was more primitive.

References

{{Taxonbar, from=Q583006 Borophagines Oligocene carnivorans Chattian genus extinctions Oligocene mammals of North America Prehistoric carnivoran genera Fossil taxa described in 1999