Hystricognathi is an infraorder of rodents. 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.

Phiomorphan hystricognath familiæ

• Bathyergidae
• Hystricidae
• Petromuridae
• Thryonomyidae

Caviomorphan hystricognath familiæ

• Abrocomidae
• Agoutidae
• Capromyidae
• Caviidae
• Chinchillidae
• Ctenomyidae
• Dasyproctidae
• Dinomyidae
• Echimyidae
• Erethizontidae
• Hydrochaeridae
• Myocastoridae
• Octodontidae

See also

• Sciurognathi
• Hystricomorpha

Rodents | Hystricognath rodents

Stachelschweinverwandte | Hystricognatha | Hystricognathi | Piikkisianleukaiset jyrsijät