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Temporal range: Early Miocene
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Family: Canidae
Subfamily: Borophaginae
Genus: Protomarctus
Wang, 1999
Type species
P. optatus

Protomarctus is an extinct member of the Borophaginae and a small terrestrial canine (bear-dog) which inhabited most of North America during the Burdigalian stage of the Miocene epoch 20.4—15.9 Mya, existing for approximately 4.5 million years.[1]


Protomarctus was named by Wang et al. (1999). It was assigned to Borophagini by Wang et al. (1999). One species, Tomarctus optatus, is known and was named by Matthew in 1924. The first specimen was found in Thomson Quarry, Sheep Creek Formation, Nebraska in a Hemingfordian layer.


Protomarctus were short-faced, heavy-jawed canines usually massive in size. It would have shared its early existence with a variety of bear dogs like bone crushing canidae Aelurodontina, Tomarctus, Phlaocyonini, and Rhizocyon.

Body mass[edit]

Fossil specimens of two individuals' body mass were examined by Legendre and Roth. The first specimen was estimated to weigh 11.8 kg (26 lb). The second specimen was estimated to weigh 11.1 kg (24 lb).[2]

Sister genera[edit]

Fossil range[edit]

Protomarctus specimens have been found in present-day Nebraska, Colorado, as far west as California and as far southwsest as New Mexico.[3]


  1. ^ PaleoBiology Database: Protomarctus Taxonomy, Species
  2. ^ S. Legendre and C. Roth. 1988. Correlation of carnassial tooth size and body weight in recent carnivores (Mammalia). Historical Biology
  3. ^ PaleoBiology Database: Protomarctus optatus

Further reading[edit]

  • Martin, L.D. 1989. Fossil history of the terrestrial carnivora. Pages 536 - 568 in J.L. Gittleman, editor. Carnivore Behavior, Ecology, and Evolution, Vol. 1. Comstock Publishing Associates: Ithaca.