Plionarctos

Plionarctos; Temporal range: late Miocene–Pleistocene PreꞒ Ꞓ O S D C P T J K Pg N
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Carnivora
Suborder:	Caniformia
Superfamily:	Arctoidea
Family:	Ursidae
Subfamily:	Ursinae
Tribe:	Tremarctini
Genus:	†Plionarctos; Frick, 1926
Species
	P. edensis (type); P. harroldorum;

Plionarctos is an extinct genus of mammals of the family Ursidae (bears) endemic to North America and Europe during Miocene through Pleistocene, living from ~10.3—3.3 Ma, existing for approximately 7.1 million years.

Indarctos (10.7—9.2 Ma) preceded Plionarctos by only a few thousand years and was a contemporary of that bear and shared its habitat. Plionarctus preceded and was also contemporary with Tremarctos floridanus (4.9 Ma.—11,000 years ago) and shared its habitat.

Plionarctos is the oldest known genus within the subfamily of the short-faced bears (Tremarctinae) endemic to the Americas, and is believed to be ancestral to the clade.

Taxonomy

Plionarctos was named by Frick (1926). Its type is Plionarctos edensis. It was assigned to Ursidae by Frick (1926) and Carroll (1988); and to Tremarctini by Hunt (1998).^[1]^[2]

Morphology

Body mass

Two specimens were examined by Legendre and Roth for body mass.^[3]

Specimen 1 estimated to weigh: 165.5 kg (360 lb)
Specimen 2 estimated to weigh: 25.3 kg (56 lb)

Fossil distribution

Sites and specimen ages:

Ile de Ratonneau Breccia, Provence, France ~800,000—100,000 years ago.
Fort Green Mine, Polk County, Florida paleontological sites ~10.3—4.9 Ma.
Taunton site, Adams County, Washington (P. harroldorum) ~4.9—1.8 Ma. (Plionarctos harroldorum)
Pipe Creek Sinkhole, Grant County, Indiana (P. edensis) ~10.3—1.8 Ma.
Palmetto Mine, Polk County, Florida ~7.9—7.8 Ma.
Gray Fossil Site, Washington County, Tennessee ~7.0-4.5 Ma.

References

^ R. L. Carroll. 1988. Vertebrate Paleontology and Evolution. W. H. Freeman and Company, New York 1-698
^ Hunt, R. M. (1998). "Ursidae". In Jacobs, Louis; Janis, Christine M.; Scott, Kathleen L. (eds.). Evolution of Tertiary Mammals of North America: Volume 1, Terrestrial Carnivores, Ungulates, and Ungulate like Mammals. Cambridge, UK: Cambridge University Press. pp. 174–195. ISBN 0521355192.
^ S. Legendre and C. Roth. 1988. Correlation of carnassial tooth size and body weight in recent carnivores (Mammalia). Historical Biology 1(1):85-98

[1] R. L. Carroll. 1988. Vertebrate Paleontology and Evolution. W. H. Freeman and Company, New York 1-698

[2] Hunt, R. M. (1998). "Ursidae". In Jacobs, Louis; Janis, Christine M.; Scott, Kathleen L. (eds.). Evolution of Tertiary Mammals of North America: Volume 1, Terrestrial Carnivores, Ungulates, and Ungulate like Mammals. Cambridge, UK: Cambridge University Press. pp. 174–195. ISBN 0521355192.

[3] S. Legendre and C. Roth. 1988. Correlation of carnassial tooth size and body weight in recent carnivores (Mammalia). Historical Biology 1(1):85-98

[1]

[2]

[3]