| Hesperocyon | |
|---|---|
 | |
| Skeleton ofH. gregarius at theSmithsonian National Museum of Natural History | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Carnivora |
| Family: | Canidae |
| Subfamily: | †Hesperocyoninae |
| Genus: | †Hesperocyon Scott, 1890 |
| Type species | |
| †Hesprocyon gregarius | |
| Species | |
| |
Hesperocyon is an extinctgenus ofcanids (subfamilyHesperocyoninae, familyCanidae) that was endemic toNorth America, ranging from southernCanada toColorado. It appeared during theUintan age, –Bridgerian age (NALMA) of the Mid-Eocene– 42.5 Ma to 31.0 Ma. (AEO).[1]Hesperocyon existed for approximately11.5 million years.
Hesperocyon was assigned to Borophagini by Wang et al. in 1999[2] and was the earliest of the canids to evolve after theCaniformia-Feliformia split some 42 million years ago.Fossil evidence datesHesperocyon gregarius to at least 37 mya, but the oldestHesperocyon has been dated at 39.74 mya from theDuchesneanNorth American land mammal age.[3]
TheCanidae subfamily Hesperocyoninae probably arose out ofHesperocyon to become the first of the three great dogs groups: Hesperocyoninae (~40–30 Ma), Borophaginae (~36–2 Ma), and theCaninae lineage that led to the present-day canids (includinggrey wolves,foxes,coyotes,jackals anddogs). At least 28 known species of Hesperocyoninae evolved out ofHesperocyon, including those in the following five genera:Ectopocynus (32–19 mya),Osbornodon (32–18 mya),Paraenhydrocyon (20–25 mya),Mesocyon (31–15 mya) andEnhydrocyon (31–15 mya).[2][4]
This genus of primitive canids is the ancestor of all later canids.[5]
This early, 80-centimeter-long (2 ft 7 in) canine looked more like acivet or a smallraccoon. Its body andtail were long and flexible, while its limbs were weak and short. Still, the build of itsossicles and distribution of itsteeth showed it was a canid. It may have been anomnivore—unlike thehypercarnivorousBorophaginae 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.[5]
The oldest fossil evidence was recovered fromSaskatchewan 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 theArikareean age (NALMA) of theOligocene andMiocene 42.5 mya—31.0 Ma. (AEO).[6][failed verification –see discussion]
Therefore, Hesperocyon has played a central role in the history of the Canidae and is ancestral to all the subsequent canids.
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