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By Phil Myers
This family contains 3 species placed in a single genus. Chinchilla rats are found in the Andes of South America from southern Peru to northern Chile. They occur in rocky areas and thickets to around 5000 m elevation.
Chinchilla rats are medium-sized (head-body length 150-250 mm), and have a rat-like body with a long pointed nose, large rounded ears, and large eyes. Their legs are unremarkable. The forefeet have 4 digits and the hindfeet 5. Stiff hairs project beyond the nails of the middle hind digits and probably serve as a comb; similar hairs are found in the families Chinchillidae, Ctenomyidae, and Octodontidae. The nails are weakly built. The tail is shorter than the head and body, cylindrical, and well-furred.
The common name of these rats is probably due to their long, dense, and soft fur, which is sometimes sold in fur markets, although it is not as desirably as that of true chinchillas (Chinchillidae).
The 
skulls of chinchilla rats have long and narrow rostra, a rounded braincase, enlarged bullae, and delicate zygomatic arches. Incisive foramina are especially long and narrow. The lacrimal canal opens on the rostrum. Chinchilla rats are hystricomorphous and hystricognathous, but hystricognathy is not well developed in this group (the angular process of the dentary arises close to the alveolus of the incisor). There is no separate canal or groove for the passage of nerves and blood vessels through the infraorbital canal. Paroccipital processes are short and pressed against the bullae. The dental formula is 1/1, 0/0, 1/1, 3/3 = 30, and the molars, which are unrooted, have high, flat crowns.
These rodents may be colonial. They are probably herbivorous, but their diets, like most other aspects of their biology, are poorly known.
References and literature cited
Feldhamer, G. A., L. C. Drickamer, S. H. Vessey, and J. F. Merritt. 1999. Mammalogy. Adaptation, Diversity, and Ecology. WCB McGraw-Hill, Boston. xii+563pp.
Lawlor, Timothy. 1979. Handbook to the orders and families of living mammals. Mad River Press, Eureka, California.
Macdonald, David. 1984. The encyclopedia of mammals. Facts on File Publications, New York.
Nowak, Ronald M. and John L. Paradiso. 1983. Walker's mammals of the world. The Johns Hopkins University Press, Baltimore and London, pp 803-810.
Vaughan, T. A. 1986. Mammalogy. Third Edition. Saunders College Publishing, Fort Worth. vii+576 pp.
Vaughan, T. A., J. M. Ryan, N. J. Czaplewski. 2000. Mammalogy. Fourth Edition. Saunders College Publishing, Philadelphia. vii+565pp.
Wilson, Don E. and DeeAnn M. Reeder (eds.). 1993. Mammal species of the world: A taxonomic and geographic reference, 2nd ed.. Smithsonian Institution Press, Washington and London.
Woods, C. A. 1984. Hystricognath rodents. Pp. 389-446 in Anderson, Sydney and J. Know Jones, Jr. (eds.). Orders and familes of mammals of the world. John Wiley and Sons, New York.
Contributors
Phil Myers (author), Museum of Zoology, University of Michigan.
