* 1 Characteristics * 2 Relation to other rodents * 3 Taxonomy * 4 References
Although dissimilar in overall appearance, gophers have been united
with kangaroo rats into a common superfamily for a considerable time.
Geomyoids are most noticeably characterized by the position of the infraorbital canal . Unlike all other rodents who have the opening of the infraorbital canal facing forward , geomyoids have an infraorbital canal that faces to the side. Instead of passing through the zygoma , the infraorbital canal of geomyoids has moved to the side of the snout . This condition is so pronounced and the snout so narrow in heteromyids that the infraorbital canals from either side connect. Essentially, if the skull of a heteromyid is viewed from the side, the viewer can see directly through it.
Modern geomyoids are mostly restricted to North America, but some
representatives have extended their range into South America since the
Great American Interchange .
RELATION TO OTHER RODENTS
Geomyoids have been considered to be either sciuromorphous or myomorphous depending on the authority. The masseter muscle does not pass through the infraorbital canal; it cannot due to the position of the canal. Some authorities consider the geomyoids related to squirrels , beavers , and mountain beavers on this basis.
The masseter muscle does attach directly behind the zygomatic arch in a manner very different from sciuromorphs. Some authorities consider geomyoids myomorphs based on this feature. This suggests they may be related to mice , jerboas , and perhaps dormice .
The family †
* SUPERFAMILY GEOMYOIDEA
* Genus †Griphomys incertae sedis
* Genus †Meliakrouniomys incertae sedis
* Family †
Cladogram showing interrelationships among geomyoid families following Korth et al. (1991):
Geomyidae (pocket gophers)
* Korth, W.W., J.H. Wahlert, and R.J. Emry, 1991. A new species of Heliscomys and recognition of the family Heliscomyidae (Geomyoidea: Rodentia) Journal of Vertebrate Paleontology 11(2):247-256. * McKenna, Malcolm C., and Bell, Susan K. 1997. Classification of Mammals Above the Species Level. Columbia University Press, New York, 631 pp. ISBN 0-231-11013-8
* v * t * e
Extant families in order Rodentia
* Aplodontiidae (Mountain beaver) * Gliridae (Dormice) * Sciuridae (Squirrels, chipmunks, marmots, susliks and prairie dogs)
* Anomaluridae (Anomalures) * Pedetidae (Springhares)
* Ctenodactylidae (Gundis) * Diatomyidae (Laotian rock rat) * Hystricidae (Old World porcupines)