Hystricognath Rodents

Hystricognath Rodents

Hystricidae
†Bathyergoididae
Bathyergidae
†Myophiomyidae
†Diamantomyidae
†Phiomyidae
†Kenyamyidae
Petromuridae
Thryonomyidae
Erethizontidae
Chinchillidae
†Neoepiblemidae
Dinomyidae
†Cephalomyidae
†Eocardiidae
Caviidae
Dasyproctidae
Cuniculidae
Ctenomyidae
Octodontidae
Abrocomidae
Echimyidae
Myocastoridae
Capromyidae
†Heptaxodontidae

Hystricognathi is an infraorder of rodents. Hystricognaths are distinguished from other rodents by the bone structure of their skulls. The masseter medialis (a 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.