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Temporal range: late Miocene–Pleistocene
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Suborder: Caniformia
Superfamily: Arctoidea
Family: Ursidae
Subfamily: Tremarctinae
Genus: Plionarctos
Frick, 1926
Type species
Plionarctos edensis
Frick, 1926

P. harroldorum (Tedfored & Martin, 2001)
P. edensis (Frick, 1926)

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.

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.


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]


Body mass[edit]

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

  • Specimen 1 was estimated to weigh 165.5 kg (360 lb).
  • Specimen 2 was estimated to weigh 25.3 kg (56 lb).

Fossil distribution[edit]

Sites and specimen ages:


  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. 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. 
  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