Rhizocyon

Rhizocyon ("root dog") is an early member of the subfamily Borophaginae, an extinct subgroup of canids that were endemic to western North America during the Oligocene epoch, living from ~31—24.5 Ma., existing for approximately 6.5 million years.

Rhizocyon Temporal range: early Oligocene
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Carnivora
Family:	Canidae
Subfamily:	†Borophaginae
Genus:	†Rhizocyon Wang, Tedford, & Taylor, 1999
Species:	†R. oregonensis
Binomial name
†Rhizocyon oregonensis (Merriam, 1906)
Range of Rhizocyon based on fossil distribution

Rhizocyon was similar to a contemporary species, Archaeocyon leptodus, from the Great Plains, but it shows a few subtle differences in the structure of the skull and dentition that indicate that Rhizocyon may be close to the ancestry of later borophagines. Only a single species, R. oregonensis, is known and all fossils come from the John Day Formation in Oregon.

References

• Wang, Xiaoming., R.H. Tedford, and B.E. Taylor. 1999. Phylogenetic systematics of the Borophaginae (Carnivora, Canidae). Bulletin of the American Museum of Natural History, 243:1-391.
• Balisi, Mairin and B. Van Valkenburgh. 2020. Iterative evolution of large-bodied hypercarnivory in canids benefits species but not clades. Communications Biology 3(461).