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 n ...
s, the alisphenoid strut is an extension of the
alisphenoid bone that separates two
in the skull, the
masticatory–buccinator foramen and the
foramen ovale accessorium. The presence or absence of this strut is variable between species, but also within them; some
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 ...
even have a strut on one side of the skull but lack it on the other side.
[Weksler, 2006, p. 38]
References
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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