CHINCHILLIDAE

Chinchillas y viscachas

PHYLUM: Chordata	CLASS: Mammalia	SUBCLASS:	ORDER: RODENTIA	SUBORDER:	FAMILY: CHINCHILLIDAE
Genera: Lagidium	Biology	Lagidium viscacia	References
Specie: viscacia	Biology
	Six species in 3 genera make up this family, which is found along the central and southern Andes and throughout most of Patagonia in southern South America. Members of this family are medium (500 gms) to large-sized rodents (8kg) with thick, soft fur; well-developed hind limbs, which are longer than the forelimbs; large eyes; and moderately large ears. Their tails are bushy and range from short up to about 1/3 the length of the body; in the species with the longest tail (Lagostomus), however, the tail is easily broken and often partly lost. Fleshy pads called pallipes are found on the feet of all chinchillids. The soles are not furry. The forefeet have four toes, which are easily manueverable and used for grasping. The number of toes on the hind feet is reduced to 4 in Lagidium and Chinchilla (both of which have weakly developed hind claws) and 3 in Lagostomus (strong hind claws), which are powerful diggers. Plains viscachas (Lagostomus) have a striking black and white facial pattern, lacking in the other species; the bodies of all are grey or grey-brown dorsally and paler on the venters. The crania of chinchillids are hystricognathous, but the condition is not as strongly developed in this group as in most of the South American Hystricognathi, probably due to secondary loss. They are, however, strongly hystricomorphous, with a much-enlarged infraorbital foramen and reduced zygomatic plate. The mandibles have no masseteric crest. Lacrimals are large, and the lacrimal canal opens on the side of the rostrum. The auditory bullae range from moderately large to extremely inflated (chinchillas), and the paroccipital processes can be either long or short. Cheek teeth (dental formula 1/1, 0/0, 1/1, 3/3 = 20) are hypsodont and evergrowing (rootless). Their occlusal surfaces are composed of 2 or 3 closely packed lamellar plates. All chinchillids have fairly delicate incisors. Members of this family often jump bipedally, but mostly they move on all four limbs. Chinchillas and mountain viscachas (Lagidium) live in mountainous, rocky areas, where they move adeptly over and through the rocks. They are not strong diggers. Plains viscachas live in the great plains areas of Argentina, from the Chaco in the north to Patagonia in the south. They are excellent diggers and construct extensive burrow systems. This habit that has not endeared them to ranchers, whose livestock sometimes break legs when they step into viscacha holes. Chinchillas, mountain viscachas, and plains viscachas are all colonial, living in groups that range from a few individuals to hundreds. Mountain and especially plains viscachas have fairly large repertoires of vocalizations used in social interactions. Unfortunately, chinchillas are nearly extinct in the wild, so little is known of their behavior under natural conditions. Viscachas, once abundant, are now seriously threatened and uncommon. Mountain viscachas are uncommon and live in remote areas. As a result, none of the species in this family have been thoroughly studied under natural conditions. All are primarily vegetarian. It is said that 10 plains viscachas eat as much as one sheep, another aspect of their biology that has earned them the wrath of agriculturalists.
	Lagidium viscacia
	Mountain viscacha
	Lagidium is found in the extreme southern portion of Peru, Western and Central Bolivia, Northern and Central Chile, and in Western Argentina. Biology: mass: 3 kg: Like all members of this family, viscachas have thick, soft pelage, except on their tails where it is coarse. They have pale yellow or grey upper parts, and a black tail tip. Overall, viscachas look like rabbits. They have long, fur covered ears, edged with a fringe of white fur. All feet have four digits. The enamal of the incisors is not colored. Mountain viscachas are reputed to eat just about any plant they encounter. Their diet is principally composed of grasses, mosses and lichens. These animals are diurnal and most active near sunrise and sunset. They spend the day on perches, grooming and sunning themselves. They are adept at moving over rocky surfaces. They do not hibernate. Mating occurs from October through December. After a gestation of 120-140 days, a female gives birth to a single, precocious young. The young are born fully furred, with their eyes open, and are able to eat solid food on their first day of life. Nursing continues for eight weeks. Females are remarkable for the large number of ova they ovulate (around 300) during each estrus period. Viscachas inhabit rugged, rocky mountanous country with sparse vegetation
	References

	All the above information was adapted from: The animal diversity web: http://www.oit.itd.umich.edu/bio108/ 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. 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.

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