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Eomyidae
Eomyidae
Heliscomyidae Florentiamyidae Geomyidae Heteromyidae
Heteromyidae

GEOMYOIDEA is a superfamily of rodent that contains the pocket gophers ( Geomyidae ), the kangaroo rats and mice ( Heteromyidae
Heteromyidae
), and their fossil relatives.

CONTENTS

* 1 Characteristics * 2 Relation to other rodents * 3 Taxonomy * 4 References

CHARACTERISTICS

Although dissimilar in overall appearance, gophers have been united with kangaroo rats into a common superfamily for a considerable time. The superfamily Geomyoidea
Geomyoidea
is among the few superfamilial relationships in rodents that is not subject to much controversy. Overall morphology , the fossil record, molecular analyses , and biogeography all support this relationship.

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 . Fossil
Fossil
taxa are known from throughout Laurasia
Laurasia
.

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 .

TAXONOMY

The family † Eomyidae
Eomyidae
is alternatively referred to as a member of the superfamily Geomyoidea
Geomyoidea
or as a separate superfamily (†Eomyoidea) within the shared infraorder GEOMORPHA. † Florentiamyidae and † Heliscomyidae are usually placed within the superfamily Geomyoidea regardless of if eomyids are treated as a separate superfamily or not (Korth et al., 1991). McKenna and Bell (1997) do not recognize heliscomyids as a distinct family, placing the one or two heliscomyid genera in Geomyoidea
Geomyoidea
incertae sedis. Sometimes the pocket gophers and heteromyids are placed as separate subfamilies within a single family (Geomyidae). These subfamilies are Geomyinae and Heteromyinae respectively.

* SUPERFAMILY GEOMYOIDEA

* Genus †Griphomys incertae sedis * Genus †Meliakrouniomys incertae sedis * Family † Eomyidae
Eomyidae
* Family † Heliscomyidae * Family † Florentiamyidae * Family Geomyidae - pocket gophers * Family Heteromyidae
Heteromyidae
- kangaroo rats and mice, pocket mice

Cladogram showing interrelationships among geomyoid families following Korth et al. (1991):

GEOMYOIDEA

Eomyidae
Eomyidae

Heliscomyidae

Florentiamyidae

Geomyidae (pocket gophers)

Heteromyidae
Heteromyidae
(kangaroo rats and mice, pocket mice)

REFERENCES

* 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

* Kingdom: Animalia * Phylum: Chordata * Class: Mammalia * Infraclass: Eutheria
Eutheria
* Superorder: Euarchontoglires

Sciuromorpha
Sciuromorpha
("Squirrel-like")

* Aplodontiidae (Mountain beaver) * Gliridae (Dormice) * Sciuridae (Squirrels, chipmunks, marmots, susliks and prairie dogs)

Castorimorpha
Castorimorpha
("Beaver-like") Castoroidea Castoridae (Beavers) Geomyoidea Geomyidae (Pocket gophers) Heteromyidae
Heteromyidae
(Kangaroo rats and mice, pocket mice)

Myomorpha ("Mouse-like") Dipodoidea
Dipodoidea
Dipodidae (Jerboas, jumping mice and birch mice) Muroidea Platacanthomyidae (Oriental dormice) Spalacidae (Zokors, bamboo rats, mole rats, blind mole rats) Calomyscidae (Mouse-like hamsters) Nesomyidae (Malagasy rats and relatives) Cricetidae (Hamsters and relatives) Muridae
Muridae
(House mouse and relatives)

Anomaluromorpha ("Anomalure-like")

* Anomaluridae (Anomalures) * Pedetidae (Springhares)

Hystricomorpha
Hystricomorpha
("Porcupine-like")

* Ctenodactylidae (Gundis) * Diatomyidae (Laotian rock rat) * Hystricidae (Old World porcupines)

Phiomorpha
Phiomorpha
Bathyergidae (Blesmols) Petromuridae (Dassie rat) Thryonomyidae (Cane rats) Caviomorpha
Caviomorpha
(New World hystricognaths) Erethizontidae (New World porcupines) Caviidae (Cavies) Cuniculidae (Pacas) Dasyproctidae (Agoutis and acouchis) Dinomyidae (Pacarana) Capromyidae (Hutias) Ctenomyidae (Tuco-tucos) Echimyidae (Spiny rats) Myocastoridae (Coypu, or nutria) Octodontidae
Octodontidae
(Degus and relatives) Abrocomidae (Chinchilla rats) Chinchillidae (Chinchillas and visca

.