Dinomyidae was once a very speciose group of South America

South America

South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...

n hystricognath rodent

Rodent

Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....

, but now contains only a single living species, the Pacarana

Pacarana

The Pacarana is a rare and slow-moving nocturnal rodent found only in tropical forests of the western Amazon River basin and adjacent foothills of the Andes Mountains from northwestern Venezuela and Colombia to western Bolivia, including the yungas. One place that it is common is Cotapata National...

. The Dinomyidae included among its ranks the largest rodents known to date, the bison

Bison

Members of the genus Bison are large, even-toed ungulates within the subfamily Bovinae. Two extant and four extinct species are recognized...

-sized Josephoartigasia monesi

Josephoartigasia monesi

Josephoartigasia monesi, an extinct species of South American caviomorph rodent, is the largest rodent known, and lived approximately 4 to 2 million years ago during the Pliocene to early Pleistocene. The species may have weighed , considerably larger than its closest living relative, the pacarana...

and the smaller Josephoartigasia magna

Josephoartigasia magna

Josephoartigasia magna is an extinct species of giant rodent. J. magna is known form Pliocene age fossil teeth found in the San Jose Formation, Playa Kiyu, Chapadmalalan, Uruguay. The species was described in 1966 by J. C. Francis and A. Mones and was placed in the genus Artigasia. After restudy, A...

. It is thought that the dinomyids were able to occupy ecological niche

Ecological niche

In ecology, a niche is a term describing the relational position of a species or population in its ecosystem to each other; e.g. a dolphin could potentially be in another ecological niche from one that travels in a different pod if the members of these pods utilize significantly different food...

s associated with large grazing mammals due to the lack of true ungulate

Ungulate

Ungulates are several groups of mammals, most of which use the tips of their toes, usually hoofed, to sustain their whole body weight while moving. They make up several orders of mammals, of which six to eight survive...

s in South America until its later connection

Great American Interchange

The Great American Interchange was an important paleozoogeographic event in which land and freshwater fauna migrated from North America via Central America to South America and vice versa, as the volcanic Isthmus of Panama rose up from the sea floor and bridged the formerly separated continents...

 to 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...

. The modern pacarana is only modest sized, considerably smaller than the capybara

Capybara

The capybara , also known as capivara in Portuguese, and capibara, chigüire in Venezuela, Colombia, and Ecuador ronsoco in Peru, chigüiro, and carpincho in Spanish, is the largest living rodent in the world. Its closest relatives are agouti, chinchillas, coyphillas, and guinea pigs...

.

The Neoepiblemidae

Neoepiblemidae

The Neoepiblemidae are an extinct family of hystricognath rodents from South America. The genus Dabbenea, formerly placed here, is now included in Phoberomys...

, an entirely extinct family, may actually be part of the Dinomyidae; they are certainly closely related.

Genera

• Family Dinomyidae
  • †Pseudodiodomus incertae sedis
    Incertae sedis
    , is a term used to define a taxonomic group where its broader relationships are unknown or undefined. Uncertainty at specific taxonomic levels is attributed by , , and similar terms.-Examples:*The fossil plant Paradinandra suecica could not be assigned to any...
    
    
  • †Agnomys incertae sedis
  • Subfamily Eumegamyinae
    • †Doellomys
    • †Gyriabrus
    • †Briaromys
    • †Tetrastylus
    • †Phoberomys
    • †Colpostemma
    • †Orthomys
    • †Eumegamys
      Eumegamys
      Eumegamys is an extinct genus of dinomyid rodent from the late Miocene and Pliocene of South America.-Sources:*McKenna, Malcolm C., and Bell, Susan K. 1997. Classification of Mammals Above the Species Level. Columbia University Press, New York, 631 pp. ISBN 0-231-11013-8...
      
      
    • †Pseudosigmomys
    • †Pentastylodon
    • †Eumegamysops
    • †Telicomys
      Telicomys
      Telicomys is an extinct genus of rodent from South America.With a length of more than in T. gigantissimus, it contains two or three of the largest rodents that ever lived, along with Phoberomys, Josephoartigasia, and the giant beaver...
      
      
    • †Perumys
    • †Josephoartigasia
      Josephoartigasia
      Josephoartigasia is an extinct genus of rodent from the Early to Late Pliocene that is related to the living pacarana. The genus includes the largest known rodent, Josephoartigasia monesi. It resembles a modern capybara....
      
      

• • Subfamily Potamarchinae
    • †Scleromys
    • †Olenopsis
    • †Simplimus
    • †Eusigmomys
    • †Potamarchus
  • Subfamily Dinomyinae
    • Dinomys - the Pacarana
      Pacarana
      The Pacarana is a rare and slow-moving nocturnal rodent found only in tropical forests of the western Amazon River basin and adjacent foothills of the Andes Mountains from northwestern Venezuela and Colombia to western Bolivia, including the yungas. One place that it is common is Cotapata National...
      
      
    • †Telodontomys