Hesperocyoninae
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The extinct Hesperocyoninae are one of three
subfamilies In biological classification In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, ...
found within the
canid Canidae (; from Latin, ''canis'', "dog") is a biological family Family ( la, familia, plural ') is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy; it is classified between order (biology), order and genus. A family ...
family. The other two canid subfamilies are the extinct
Borophaginae The extinct Borophaginae form one of three subfamilies found within the canid Canidae (; from Latin, ''canis'', "dog") is a biological family of dog-like carnivora Carnivora is an order of placental mammals that have specialized in prim ...
and extant
Caninae The Caninae, known as canines, are one of three subfamily, subfamilies found within the Canidae, canid family. The other two canid subfamilies are the extinct Borophaginae and Hesperocyoninae. The Caninae includes all living canids and their most ...
.


Taxonomic history

Hesperocyoninae are basal canids that gave rise to the other two canid subfamilies, the Borophaginae and Caninae. This subfamily was endemic to
North America North America is a continent A continent is any of several large landmasses. Generally identified by convention (norm), convention rather than any strict criteria, up to seven geographical regions are commonly regarded as continen ...

North America
, living from the
DuchesneanThe Duchesnean North American Stage on the geologic timescale is a North American Land Mammal Ages, North American Land Mammal Age (NALMA), with an age from 42 to 38 million years Before Present, BP, representing . It falls within the Eocene epoch. T ...
stage of 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 Ancient ...
through to the early
Barstovian The Barstovian North American Stage on the geologic timescale The geologic time scale (GTS) is a system of chronological dating that classifies Geology, geological strata (stratigraphy) in time. It is used by geologists, paleontology, paleontolo ...
stage of the
Miocene The Miocene ( ) is the first of the Period and extends from about (Ma). The Miocene was named by Scottish geologist ; its name comes from the Greek words (', "less") and (', "new") and means "less recent" because it has 18% fewer modern sea s ...
, lasting around 20 million years. It comprises 10 recognized genera and 26 recognized species. Four major lineages can be defined based on shared characteristics: *'' Mesocyon''-''Enhydrocyon'' clade (includes ''Cynodesmus, Sunkahetanka, Philotrox'') *''Osbornodon'' clade *''Paraenhydrocyon'' *''Ectopocynus clade'' The genus ''Caedocyon'', which is only known from a single partial cranium that shows some ''Paraenhydrocyon'' affinities, probably represents another independent lineage. ''Hesperocyon'', which lacks the shared derived characters that would include it within any of the aforementioned clades, is possibly ancestral to many of the lineages. Some evidence indicates the ''Paraenhydrocyon'' clade may be directly descended from ''Hesperocyon gregarius''. According to Xiaoming Wang, ''Hesperocyon coloradensis'' provides an important link between ''H. gregarius'' and the ''Mesocyon-Enhydrocyon'' clade.Wang, X. 1994
Phylogenetic systematics of the Hesperocyoninae (Carnivora, Canidae)
Bulletin of the American Museum of Natural History, 221:1-207.


Extinction

According to an analysis of the fossil record of North American fossil carnivorans, the decline of hesperocyonines to extinction during the period from about 20 to 10 million years ago was driven by competition with felids and borophagines. File:Canidae Species Divesity.png, Fluctuation of species within Canidae over 40 million years File:Wang Borophagine Construct.png, Phylogeny of Hesperocyoninae related to
Borophaginae The extinct Borophaginae form one of three subfamilies found within the canid Canidae (; from Latin, ''canis'', "dog") is a biological family of dog-like carnivora Carnivora is an order of placental mammals that have specialized in prim ...
and Canidae, canines by R.L. Tedford, 1977 File:Hesperocyoninae species.png, Hesperocyoninae species per unit of time


References


Further reading

* Xiaoming Wang, Richard H. Tedford, Mauricio Antón, ''Dogs: Their Fossil Relatives and Evolutionary History'', New York : Columbia University Press, 2008; Hesperocyonines Miocene extinctions Eocene first appearances {{Canid-stub