Hystricognathi


Hystricognaths
Fossil Range: Late Eocene - Recent
Image:Laonastes aenigmamus.jpg
Laotian Rock Rat drawing by R.J. Timmins
Scientific classification
Kingdom:Animalia
Phylum:Chordata
Class:Mammalia
Order:Rodentia
Suborder:Hystricognathi
Families

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

Hystricognathi is a suborder of the Rodentia, or rodent, branch of the mammal tree.

Hystricognaths are distinguished from other rodents by the bone structure of their skulls. They exhibit a partial passage of the masseter medialis through the infraorbital foramen as the masseter maxillomandibularis, which being transmitted axially by the rostral surface of the maxilla distinguishes them from the Myomorpha and the Protrogomorpha. The lack of infraorbital plate to which to anchor the masseter lateralis and the relative size of the infraorbital foramen distinguishes hystricognathi from the Sciuromorpha.

There are 18 families within the Hystricognathi, divisible into a dual classification of 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.

Image:Nutriaschädel.jpg
Skull of a Nutria demonstrating the hystricognathous lower jaw and hystricomorphous zygomasseteric system

Phiomorphan hystricognath familiæ

Caviomorphan hystricognath familiæ

See also


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