Sciuromorpha ( 'squirrel-like') is a

rodent Rodents (from Latin , 'to gnaw') are mammals of the Order (biology), order Rodentia ( ), which are characterized by a single pair of continuously growing incisors in each of the upper and Mandible, lower jaws. About 40% of all mammal specie ...

suborder that includes several rodent families. It includes all members of the

Sciuridae Squirrels are members of the family Sciuridae (), a family that includes small or medium-sized rodents. The squirrel family includes tree squirrels, ground squirrels (including chipmunks and prairie dogs, among others), and flying squirrel ...

(the squirrel family) as well as the

mountain beaver The mountain beaver (''Aplodontia rufa'')Other names include boomer, mountain boomer, ground bear, giant mole, gehalis, sewellel, suwellel, showhurll, showtl, and showte, as well as a number of other Native American terms. "Mountain beaver" is a ...

species. Traditionally, the term has been defined on the basis of the shape of the infraorbital canal. A

sciuromorphous The zygomasseteric system (or zygomasseteric structure) refers to the anatomical arrangement of the masseter muscle and the zygomatic arch (cheek bone) in the skulls of rodents. This system plays a crucial role in the diverse chewing mechanics ...

zygomasseteric system The zygomasseteric system (or zygomasseteric structure) refers to the anatomical arrangement of the masseter muscle and the zygomatic arch (cheek bone) in the skulls of Rodent, rodents. This system plays a crucial role in the diverse chewing mechan ...

is characterized by attachment of the lateral masseter muscle along the side of the rostrum. Unlike

hystricomorphous The zygomasseteric system (or zygomasseteric structure) refers to the anatomical arrangement of the masseter muscle and the zygomatic arch (cheek bone) in the skulls of rodents. This system plays a crucial role in the diverse chewing mechanics ...

and

myomorphous The zygomasseteric system (or zygomasseteric structure) refers to the anatomical arrangement of the masseter muscle and the zygomatic arch (cheek bone) in the skulls of rodents. This system plays a crucial role in the diverse chewing mechanics ...

rodents, the medial masseter muscle does not pass through the infraorbital canal. Among extant rodents, only the families Sciuridae,

Castoridae Castoridae is a family of rodents that contains the two living species of beavers and their fossil relatives. A formerly diverse group, only a single genus is extant today, ''beaver, Castor.'' Two other genera of "giant beavers", ''Castoroides'' ...

, Heteromyidae, and Geomyidae are truly sciuromorphous. Some authorities would exclude the Geomyidae and Heteromyidae from that list due to the attachment of the medial masseter directly behind the zygomatic arch. Carleton and Musser (2005) redefined the rodent suborders on morphological and molecular grounds. They defined the Sciuromorpha as including three families, Sciuridae, Aplodontiidae, and Gliridae. Of these, only the Sciuridae are truly sciuromorphous. The Aplodontiidae are protrogomorphous and the Gliridae are myomorphous. The connection between Aplodontiidae and Sciuridae has been proposed numerous times in the past. The two families have been united into a common

infraorder Order () is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between Family_(biology), family and Class_(biology), class. In biological classification, the order is a taxonomic rank used in the classific ...

(Sciurida) or superfamily (Sciuroidea). It has long been suggested that

dormice A dormouse is a rodent of the family (biology), family Gliridae (this family is also variously called Myoxidae or Muscardinidae by different taxonomists). Dormice are nocturnal animals found in Africa, Asia, and Europe. They are named for their ...

(Gliridae) are not particularly related to the Myomorpha, and their zygomasseteric structure has been termed "pseudomyomorphy". The connection between squirrels and dormice has been almost exclusively suggested through genetic studies, and to a lesser degree via the

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

rodent Reithroparamys.

Current families

The suborder Sciuromorpha contains 307 living species in 61 genera and three families. At least three extinct families are also recognised. * † Allomyidae * Aplodontiidae – mountain beaver * † Mylagaulidae *

– squirrels, chipmunks, marmots, flying squirrels, etc. * † Reithroparamyidae * Gliridae – dormice

Historical families

– beavers * Geomyidae – pocket gophers * Heteromyidae – pocket mice, kangaroo rats, and kangaroo mice * Pedetidae – springhares * Anomaluridae – anomalures

References

Other Sources

* Carleton, M. D. and G. G. Musser (2005). "Order Rodentia". pp. 745–752 in ''Mammal Species of the World A Taxonomic and Geographic Reference'' (D. E. Wilson and D. M. Reeder eds.). Baltimore: Johns Hopkins University Press.

External links

* {{Taxonbar, from=Q724477 Rodent taxonomy Mammal suborders Extant Eocene first appearances Taxa named by Johann Friedrich von Brandt