Temporal range: late Miocene–Pleistocene
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 Mya, existing for about 7 million years.
Indarctos (10.7—9.2 Mya) 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 million — 11,000 years ago) and shared its habitat.
- Specimen 1 was estimated to weigh 165.5 kg (360 lb).
- Specimen 2 was estimated to weigh 25.3 kg (56 lb).
Sites and specimen ages:
- Ile de Ratonneau Breccia, Provence, France about ~800,000—100,000 years ago
- Fort Green Mine, Polk County, Florida paleontological sites about 10.3—4.9 Mya
- Taunton site, Adams County, Washington (P. harroldorum) about 4.9—1.8 Mya (Plionarctos harroldorum)
- Pipe Creek Sinkhole, Grant County, Indiana (P. edensis) about 10.3—1.8 Mya
- Palmetto Mine, Polk County, Florida 7.9—7.8 Mya
- Gray Fossil Site, Washington County, Tennessee about 7.0-4.5 Mya
- 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. 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 0-521-35519-2.
- S. Legendre and C. Roth. 1988. Correlation of carnassial tooth size and body weight in recent carnivores (Mammalia). Historical Biology 1(1):85-98