Protomarctus is an extinct member of the Borophaginae

Borophaginae

The subfamily Borophaginae is an extinct group of canids called "bone crushing dogs" that were endemic to North America during the Oligocene to Pliocene and lived roughly 36—2.5 million years ago and existing for approximately .-Origin:...

 and a small terrestrial

Terrestrial animal

Terrestrial animals are animals that live predominantly or entirely on land , as compared with aquatic animals, which live predominantly or entirely in the water , or amphibians, which rely on a combination of aquatic and terrestrial habitats...

 canine

Canidae

Canidae is the biological family of carnivorous and omnivorous mammals that includes wolves, foxes, jackals, coyotes, and domestic dogs. A member of this family is called a canid . The Canidae family is divided into two tribes: Canini and Vulpini...

 (Bear-dog) which inhabited most of North America

North America

North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

 during the Burdigalian

Burdigalian

The Burdigalian is, in the geologic timescale, an age or stage in the early Miocene. It spans the time between 20.43 ± 0.05 Ma and 15.97 ± 0.05 Ma...

 stage of the Miocene

Miocene

The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...

 epoch 20.4—15.9 Mya, existing for approximately .

Taxonomy

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.

Morphology

Protomarctus were short-faced, heavy-jawed canines usually massive in size. It would have shared its early existence with a variety of bear dog

Bear dog

Amphicyonidae is an extinct family of large terrestrial carnivores belonging to the suborder Caniformia and which inhabited North America, Europe, Asia, and Africa from the Middle Eocene subepoch to the Pleistocene epoch 46.2—1.8 Mya, existing for approximately .-Taxonomy:Amphicyonidae was named...

s like bone crushing canidae Aelurodontina, Tomarctus

Tomarctus

Tomarctus is a canine of the extinct subfamily Borophaginae which inhabited most of North America during the late Early Miocene to the Early Barstovian age of the Middle Miocene . Tomarctus existed for approximately ....

, Phlaocyonini

Phlaocyonini

Phlaocyonini † is a hypocarnivorous clade or tribe of Borophaginae. This is an extinct group of canids that were endemic to North America and which lived during the Oligocene epoch to the Miocene living ~33.3–5.3 Ma, existing for approximately . PhlaocyoniniThe clade includes Cynarctoides and...

, and Rhizocyon

Rhizocyon

Rhizocyon is an early member of the subfamily Borophaginae, an extinct subgroup of canids that were endemic to western North America during the Whitneyan and Arikareean stages) of the Oligocene epoch, living from ~33.3—20.6 Ma., existing for approximately .Rhizocyon was similar to a contemporary...

.

Body mass

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 (24.5 lb).

Sister genera

• Cormocyon
  Cormocyon
  Cormocyon is an extinct genus of the Borophaginae and a terrestrial canine which inhabited most of North America during the Geringian stage of the Paleogene through Harrisonian stage of the Oligocene epoch living 30.8—20.6 Mya, existing for about ....
  
  
• Desmocyon
  Desmocyon
  Desmocyon is an extinct genus of the Borophaginae and a terrestrial canine which inhabited most of North America during the Harrisonian stage of the Late Oligocene through Early Hemingfordian stage of the Early Miocene epoch living 24.8—16.3 Mya existing for approximately .-Fossil record:It is a...
  
  
• Euoplocyon
  Euoplocyon
  Euoplocyon is an extinct genus of the Borophaginae and a small terrestrial canine which inhabited most of North America during the Hemingfordian stage of the Early Miocene subepoch through the Barstovian stage of the Middle Miocene subepoch living 20.6—13.6 Mya, existing for about...
  
  
• Metatomarctus
  Metatomarctus
  Metatomarctus is an extinct genus of Borophaginae and a terrestrial canine which inhabited most of North America during the Early Hemingfordian stage of the Miocene epoch living 23.0—5.3 Mya, existing for approximately -Taxonomy:...
  
  
• Microtomarctus
  Microtomarctus
  Microtomarctus is an extinct genus of the Borophaginae and a small terrestrial canine which inhabited most of North America during the Whitneyan stage of the Early Miocene subepoch through the Barstovian stage of the Middle Miocene subepoch.Microtomarctus existed for approximately .Like other...
  
  
• Psalidocyon
  Psalidocyon
  Psalidocyon is an extinct genus of the Borophaginae and a small terrestrial canine which inhabited most of North America during the Hemingfordian stage of the Early Miocene subepoch through the Barstovian stage of the Middle Miocene subepoch 20.6—13.6 Ma, existing for about ..-Morphology:Fossil...
  
  
• Tephrocyon
  Tephrocyon
  Tephrocyon is an extinct genus of the Borophaginae and a small to medium sized terrestrial canine which inhabited most of North America during the Barstovian stage of the Middle Miocene 16.3—13.6 Ma, existing for approximately .-Morphology:...
  
  

Fossil range

Protomarctus specimens have been found in present day Nebraska, Colorado

Colorado

Colorado is a U.S. state that encompasses much of the Rocky Mountains as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains...

, as far west as California

California

California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

 and as far southwsest as New Mexico

New Mexico

New Mexico is a state located in the southwest and western regions of the United States. New Mexico is also usually considered one of the Mountain States. With a population density of 16 per square mile, New Mexico is the sixth-most sparsely inhabited U.S...

.

Further reading

• 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.