The Hystricognathi are an
infraorder of
rodent
Rodents (from Latin , 'to gnaw') are mammals of the Order (biology), order Rodentia ( ), which are characterized by a single pair of continuously growing incisors in each of the upper and Mandible, lower jaws. About 40% of all mammal specie ...
s, distinguished from other rodents by the
bone
A bone is a rigid organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red and white blood cells, store minerals, provide structure and support for the body, ...
structure of their
skulls. The
masseter medialis (a jaw muscle) passes partially through a hole below each eye socket (called the
infraorbital foramen) and connects to the bone on the opposite side. This, together with their lack of an
infraorbital plate and the relative size of the
infraorbital foramen, distinguishes hystricognaths from other rodent groups.
The 18
families within the Hystricognathi are divided into two
parvorders, the
Phiomorpha and the
Caviomorpha. The Caviomorpha are mostly native to
South America
South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...
, with a few species in the
Caribbean
The Caribbean ( , ; ; ; ) is a region in the middle of the Americas centered around the Caribbean Sea in the Atlantic Ocean, North Atlantic Ocean, mostly overlapping with the West Indies. Bordered by North America to the north, Central America ...
and
North America
North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...
, while the Phiomorpha occur in the
Old World.
Behavior
Play behavior has been observed in seven hystricognath families. The caviomorphs chase each other, play-wrestle, and gallop. The longer-legged species chase more often than the shorter-legged species. They also rotate their heads and body muscles as a form of play.
[Fagen, Robert. ''Animal Play Behavior''. Oxford University Press, 1981.]
Phiomorphan hystricognath families
*
Bathyergidae (African mole rats)
*
Heterocephalidae (naked mole rats,
monotypic
In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...
taxon)
*
Hystricidae (Old World porcupines)
*
Petromuridae (dassie rat,
monotypic
In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...
taxon)
*
Thryonomyidae (cane rats)
Caviomorphan hystricognath families
*
Abrocomidae (chinchilla rats)
*
Capromyidae (hutias)
*
Caviidae (guinea pigs, wild cavies, and capybaras)
*
Chinchillidae (chinchillas and viscachas)
*
Ctenomyidae (tuco-tucos)
*
Cuniculidae (pacas)
*
Dasyproctidae (agoutis and acouchis)
*
Dinomyidae (pacaranas and their fossil relatives, including some of
megafaunal size)
*
Echimyidae (spiny rats)
*
Erethizontidae (New World porcupines)
*
Myocastoridae (coypu)
*
Octodontidae (13 species including the
degus)
See also
*
Sciurognathi
*
Hystricomorpha
References
Citations
Sources
* Alfred L. Gardner Curator of North American mammals and Chief of Mammal Section, National Biological Service, Smithsonian Institution, National Museum of Natural History, Washington, DC, USA
* Charles A. Woods Florida Museum of Natural History, University of Florida, Gainesville, FL 32611-2035
*
McKenna, Malcolm C. and Susan K. Bell 1997 ''Classification of mammals above the species level'' 631 Columbia University Press New York, New York, USA
* Wilson, Don E., and DeeAnn M. Reeder, eds. 1993 ''Mammal Species of the World: A Taxonomic and Geographic Reference'', 2nd ed., 3rd printing xviii + 1207 Smithsonian Institution Press Washington, DC, USA Corrections were made to text at 3rd printing
External links
* https://web.archive.org/web/20061130080256/http://animaldiversity.ummz.umich.edu/site/topics/mammal_anatomy/rodent_jaws.html
{{Taxonbar, from=Q1063601
Hystricomorpha
Rodent taxonomy
Mammal infraorders
Extant Eocene first appearances