In some

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

s, the subsquamosal fenestra is an opening between two parts of the

squamosal bone The squamosal is a skull bone found in most reptiles, amphibians, and birds. In fishes, it is also called the pterotic bone. In most tetrapods, the squamosal and quadratojugal bones form the cheek series of the skull. The bone forms an ancestral co ...

, at the back of the

skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, the ...

. It can be seen in lateral view. Most

Oryzomyini Oryzomyini is a tribe of rodents in the subfamily Sigmodontinae of the family Cricetidae. It includes about 120 species in about thirty genera,Weksler et al., 2006, table 1 distributed from the eastern United States to the southernmost parts of S ...

have the fenestra, but some species, including those in the genera ''

Nectomys ''Nectomys'' is a genus of rodent in the tribe Oryzomyini of family Cricetidae. Musser and Carleton, 2005. It is closely related to ''Amphinectomys'' and was formerly considered congeneric with ''Sigmodontomys''. It consists of five species, which ...

'', ''

Sigmodontomys ''Sigmodontomys'' is a genus of rodent in the tribe Oryzomyini of family Cricetidae. It is related to ''Nectomys'' and ''Melanomys'' and used to be included in ''Nectomys''. It includes two species, ''Sigmodontomys alfari'' and the much rarer ''S ...

'', and ''

Melanomys ''Melanomys'' is a genus of rodent in the tribe Oryzomyini of family Cricetidae, which is distributed in northern South America and adjacent Central America. It contains three species, two of which—'' Melanomys robustulus'' and '' Melanomys ...

'' among others, lack it.Weksler, 2006, pp. 38–39

References

{{reflist

Literature cited

*Weksler, M. 2006
Phylogenetic relationships of oryzomyine rodents (Muroidea: Sigmodontinae): separate and combined analyses of morphological and molecular data
Bulletin of the American Museum of Natural History 296:1–149. Rodent anatomy