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Temporal range: Miocene
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Family: Canidae
Subfamily: Borophaginae
Tribe: Borophagini
Genus: Microtomarctus
Wang, 1999
Type species
Microtomarctus conferta
Wang, 1999

Microtomarctus is an extinct genus of the subfamily Borophaginae and a small terrestrial canine which inhabited most of North America during the Whitneyan stage (20.6 Mya) of the Early Miocene subepoch through the Barstovian stage (13.6 Mya) of the Middle Miocene subepoch.[1] Microtomarctus existed for approximately 7 million years.

Like other Borophaginae it had powerful, bone crushing jaws and teeth.


Fossil specimens of two individuals' body mass were examined by Legendre and Roth. The first specimen was estimated to weigh 7.06 kg (15.5 lbs). The second specimen was estimated to weigh 6.80 kg (14.9 lbs).[2]


M. conferta (synonymous with Tomarctus paulus) was named by Matthew in 1918. In 1924, Matthew recombined it and named it Tomarctus confertus. It again was verified by Matthew in 1924, Green (1948), Hough (1948) and Downs in 1956. X. Wang restudied the specimens and recombined it as Microtomarctus conferta.[3]

Sister genera[edit]

Otarocyon, Oxetocyon and Rhizocyon.

Fossil distribution[edit]

Fossil specimens were found in Nebraska, coastal southeast Texas, California, New Mexico, Nevada and Colorado.


  1. ^ PaleoBiology Database: Microtomarctus 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: Microtomarctus conferta Species