Hystricognathi

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Hystricognaths
Fossil range: Late Eocene - Recent
Capromys pilorides
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Rodentia
Suborder: Hystricomorpha
Infraorder: Hystricognathi
Tullberg, 1899
Families

Hystricidae
Bathyergidae
Petromuridae
Thryonomyidae
Abrocomidae
Agoutidae
Capromyidae
Caviidae
Chinchillidae
Ctenomyidae
Dasyproctidae
Dinomyidae
Echimyidae
Erethizontidae
Myocastoridae
Octodontidae


Contents

[edit] Anatomy

Hystricognathi is an infraorder of rodents. Hystricognaths are distinguished from other rodents by the bone structure of their skulls. The masseter medialis (jaw muscle) passes partially through 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.

There are 18 families within the Hystricognathi, divided into two infraorders, the Phiomorpha and the Caviomorpha. The Caviomorpha are mostly native to South America, with a few species in North America, while the Phiomorpha occur in the Old World.

Skull of a Nutria demonstrating the hystricognathous lower jaw and hystricomorphous zygomasseteric system
Skull of a Nutria demonstrating the hystricognathous lower jaw and hystricomorphous zygomasseteric system


[edit] 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 1981).


[edit] Phiomorphan hystricognath familiæ

[edit] Caviomorphan hystricognath familiæ

[edit] External links

http://animaldiversity.ummz.umich.edu/site/topics/mammal_anatomy/rodent_jaws.html

[edit] References

Fagen, Robert. Animal Play Behavior. Oxford University Press, 1981.

[edit] See also

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