''Prohesperocyon'' ("before ''

Hesperocyon ''Hesperocyon'' is an extinct genus of canids (subfamily Hesperocyoninae, family Canidae) that was endemic to North America, ranging from southern Canada to Colorado. It appeared during the Uintan age, – Bridgerian age (NALMA) of the Mid-Eocen ...

''") is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

of the first

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 ...

endemic to North America appearing during the

Late Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', "d ...

around 36.6 mya ( AEO).

Fossil distribution

''Prohesperocyon wilsoni'' was unearthed at the Airstrip (TMM 40504) site,

Presidio County, Texas Presidio County is a county located in the U.S. state of Texas. As of the 2020 census, its population was 6,131. Its county seat is Marfa. The county was created in 1850 and later organized in 1875. Presidio County (K-5 in Texas topological ind ...

dating between 36.6 and 36.5

million years ago The abbreviation Myr, "million years", is a unit of a quantity of (i.e. ) years, or 31.556926 teraseconds. Usage Myr (million years) is in common use in fields such as Earth science and cosmology. Myr is also used with Mya (million years ago) ...

.Paleobiology Database Collection 16888
revised on 2002-06-03,

John Alroy John Alroy is a paleobiologist born in New York in 1966 and now residing in Sydney, Australia. Area of expertise Alroy specializes in diversity curves, speciation, and extinction of North American fossil mammals and Phanerozoic marine inver ...

. This fossil species bears a combination of features that definitively mark it as a Canidae, including teeth that include the loss of the upper third molar (a general trend in canids toward a more shearing bite), and the characteristically enlarged bony bulla (the rounded covering over the middle ear). Based on what we know about its descendants, ''Prohesperocyon'' likely had slightly more elongated limbs than its predecessors, along with toes that were parallel and closely touching, rather than splayed, as in bears.

References

Eocene carnivorans Transitional fossils Prehistoric carnivoran genera Prehistoric mammals of North America Taxa named by Xiaoming Wang Fossil taxa described in 1986 {{paleo-carnivora-stub