''Hesperocyon'' is an extinct

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of canids (subfamily Hesperocyoninae, family

Canidae Canidae (; from Latin, ''canis'', "dog") is a family (biology), biological family of caniform carnivorans, constituting a clade. A member of this family is also called a canid (). The family includes three subfamily, subfamilies: the Caninae, a ...

) that was endemic to

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, ranging from southern

Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...

Colorado Colorado is a U.S. state, state in the Western United States. It is one of the Mountain states, sharing the Four Corners region with Arizona, New Mexico, and Utah. It is also bordered by Wyoming to the north, Nebraska to the northeast, Kansas ...

. It appeared during the Uintan age, – Bridgerian age (NALMA) of the Mid-

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

– 42.5 Ma to 31.0 Ma. ( AEO). ''Hesperocyon'' existed for approximately .

Taxonomy

''Hesperocyon'' was assigned to Borophagini by Wang et al. in 1999 and was the earliest of the canids to evolve after the Caniformia- Feliformia split some 42 million years ago.

Fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

evidence dates ''Hesperocyon gregarius'' to at least 37 mya, but the oldest ''Hesperocyon'' has been dated at 39.74 mya from the Duchesnean North American land mammal age. The

subfamily Hesperocyoninae probably arose out of ''Hesperocyon'' to become the first of the three great dogs groups: Hesperocyoninae (~40–30 Ma), Borophaginae (~36–2 Ma), and the Caninae lineage that led to the present-day canids (including grey wolves, foxes, coyotes, jackals and dogs). At least 28 known species of Hesperocyoninae evolved out of ''Hesperocyon'', including those in the following five genera: '' Ectopocynus'' (32–19 mya), '' Osbornodon'' (32–18 mya), '' Paraenhydrocyon'' (20–25 mya), '' Mesocyon'' (31–15 mya) and '' Enhydrocyon'' (31–15 mya).

Evolution

This genus of primitive canids is the ancestor of all later canids.

Morphology

This early, canine looked more like a civet or a small

raccoon The raccoon ( or , ''Procyon lotor''), sometimes called the North American, northern or common raccoon (also spelled racoon) to distinguish it from Procyonina, other species of raccoon, is a mammal native to North America. It is the largest ...

. Its body and tail were long and flexible, while its limbs were weak and short. Still, the build of its ossicles and distribution of its teeth showed it was a canid. It may have been an omnivore—unlike the hypercarnivorous Borophaginae that later split from this canid lineage. Unlike modern canids, ''Hesperocyon'' had five fingers and toes and a dew claw deeply set enough to suggest tree climbing capabilities. Hesperocyon skull Smithsonian

Fossil record

The oldest fossil evidence was recovered from

Saskatchewan Saskatchewan is a Provinces and territories of Canada, province in Western Canada. It is bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, to the northeast by Nunavut, and to the south by the ...

dating from 42.5 mya to 31.0 Ma. The youngest fossil was recovered from the Dog Jaw Butte site, Goshen County, Wyoming dating to the Arikareean age (NALMA) of the

Oligocene The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that defin ...

and

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

42.5 mya—31.0 Ma. (AEO).Paleobiology Database
Collection 17492, Dog Jaw Butte site, Goshen County, Wyoming. Authorized and entered by Dr. John Alroy, March 26, 1995.

References

{{Taxonbar, from=Q1947861 Hesperocyonines Eocene carnivorans Oligocene canids Transitional fossils Prehistoric carnivoran genera Paleogene mammals of North America Fossil taxa described in 1890