Sphenopalatine vacuities
Encyclopedia
In rodent
s, sphenopalatine vacuities are perforations of the roof of the mesopterygoid fossa, the open space behind the palate
, in between the parapterygoid fossae. They may perforate the presphenoid or basisphenoid bone. Their development and form are variable between and within species, and features of the sphenopalatine vacuities have been used as characters in cladistic
analyses.
Among Oryzomyini
, a mainly South American group, a recent study distinguished three character states—large, wide vacuities, as among others in Oligoryzomys
and Holochilus
; small, narrow vacuities, as among others in Lundomys and Nephelomys
; and no or vestigial vacuities, as among others in Mindomys and Oryzomys
. Phyllotini all have very large sphenopalatine vacuities, as does Sigmodon. The vacuities in Reithrodon
, formerly considered a phyllotine, are especially large. Nyctomys is special in having sphenopalatine vacuities restricted to the basisphenoid bone. Character polarity for the development of the vacuities in Cricetidae
is difficult to determine, but their absence may be primitive in the Neotominae
.
The development of sphenopalatine vacuities has also been used to distinguish among members of the Sciurini
group of squirrel
s.
Rodent
Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....
s, sphenopalatine vacuities are perforations of the roof of the mesopterygoid fossa, the open space behind the palate
Palate
The palate is the roof of the mouth in humans and other mammals. It separates the oral cavity from the nasal cavity. A similar structure is found in crocodilians, but, in most other tetrapods, the oral and nasal cavities are not truly separate. The palate is divided into two parts, the anterior...
, in between the parapterygoid fossae. They may perforate the presphenoid or basisphenoid bone. Their development and form are variable between and within species, and features of the sphenopalatine vacuities have been used as characters in cladistic
Cladistics
Cladistics is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants . For example, birds, dinosaurs, crocodiles, and all descendants of their most recent common ancestor form a clade...
analyses.
Among Oryzomyini
Oryzomyini
Oryzomyini is a tribe of rodents in the subfamily Sigmodontinae of family Cricetidae. It includes about 120 species in about thirty genera, distributed from the eastern United States to the southernmost parts of South America, including many offshore islands...
, a mainly South American group, a recent study distinguished three character states—large, wide vacuities, as among others in Oligoryzomys
Oligoryzomys
Oligoryzomys is a genus of rodents in the tribe Oryzomyini of family Cricetidae. Many species are known as pygmy rice rats or colilargos...
and Holochilus
Holochilus
Holochilus is a genus of semiaquatic rodents in the tribe Oryzomyini of family Cricetidae, sometimes called marsh rats. It contains three living species, Holochilus brasiliensis, Holochilus chacarius, and Holochilus sciureus, which are widely distributed in South America east of the Andes, and a...
; small, narrow vacuities, as among others in Lundomys and Nephelomys
Nephelomys
Nephelomys is a genus of South American oryzomyine rodents found in the Andes from Bolivia to Venezuela, with a westward extension into the mountains of Costa Rica...
; and no or vestigial vacuities, as among others in Mindomys and Oryzomys
Oryzomys
Oryzomys is a genus of semiaquatic rodents in the tribe Oryzomyini living in southern North America and far northern South America. It includes eight species, two of which—the marsh rice rat of the United States and O. couesi of Mexico and Central America—are widespread; the six others have...
. Phyllotini all have very large sphenopalatine vacuities, as does Sigmodon. The vacuities in Reithrodon
Reithrodon
Reithrodon is a genus of rodent in the family Cricetidae.It contains the following species:* Bunny Rat * Naked-soled Conyrat...
, formerly considered a phyllotine, are especially large. Nyctomys is special in having sphenopalatine vacuities restricted to the basisphenoid bone. Character polarity for the development of the vacuities in Cricetidae
Cricetidae
The Cricetidae are a family of rodents in the large and complex superfamily Muroidea. It includes true hamsters, voles, lemmings, and New World rats and mice...
is difficult to determine, but their absence may be primitive in the Neotominae
Neotominae
Neotominae is a subfamily of the family Cricetidae. It consists of four tribes, 16 genera, and many species of New World rats and mice, predominantly found in North America. Among them are the well-known deer mice, white-footed mice, packrats, and grasshopper mice.Neotomines are related to the...
.
The development of sphenopalatine vacuities has also been used to distinguish among members of the Sciurini
Sciurini
Sciurini is a tribe that includes about forty species of squirrels, mostly from the Americas. It includes five living genera—the American dwarf squirrels, Microsciurus; the Bornean Rheithrosciurus; the widespread American and Eurasian tree squirrels of the genus Sciurus, which includes some of the...
group of squirrel
Squirrel
Squirrels belong to a large family of small or medium-sized rodents called the Sciuridae. The family includes tree squirrels, ground squirrels, chipmunks, marmots , flying squirrels, and prairie dogs. Squirrels are indigenous to the Americas, Eurasia, and Africa and have been introduced to Australia...
s.
Literature cited
- Carleton, M.D. 1980. Phylogenetic relationships in neotomine-peromyscine rodents (Muroidea) and a reappraisal of the dichotomy within New World Cricetinae. Miscellaneous Publications, Museum of Zoology, University of Michigan 157:i–vii+1–146.
- Moore, J.C. 1959. Relationships among the living squirrels of the Sciurinae. Bulletin of the American Museum of Natural History 118:157–206.
- Steppan, S.J. 1995. Revision of the tribe Phyllotini (Rodentia: Sigmodontinae), with a phylogenetic hypothesis for the Sigmodontinae. Fieldiana Zoology 80:1–112.
- 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.