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, incisor procumbency refers to the orientation of the upper incisor, defined by the position of the cutting edge of the incisor relative to the vertical plane of the incisors. Proodont incisors have the cutting edge in front of the vertical plane, orthodont teeth have it perpendicular to the plane, opisthodont incisors have it behind the plane, and hyper-opisthodont teeth have the cutting edge even behind the back of the

alveolus Alveolus (; pl. alveoli, adj. alveolar) is a general anatomical term for a concave cavity or pit. Uses in anatomy and zoology * Pulmonary alveolus, an air sac in the lungs ** Alveolar cell or pneumocyte ** Alveolar duct ** Alveolar macrophage * Mam ...

of the incisor. Phyllotini are mostly opisthodont, but ''

Auliscomys ''Auliscomys'' is a genus of rodent in the family Cricetidae. It contains the following species: * Bolivian big-eared mouse (''Auliscomys boliviensis'') * Painted big-eared mouse (''Auliscomys pictus'') * Andean big-eared mouse (''Auliscomys subl ...

'' and '' Galenomys'' are orthodont and have sometimes even been described as proodont, and ''

Eligmodontia The genus ''Eligmodontia'' consists of five or six species of South American sigmodontine mice restricted to Bolivia, Chile, and Argentina. Species of ''Eligmodontia'' occur along the eastern side of the Andes Mountains, in Patagonia, and in ...

'', ''

Loxodontomys ''Loxodontomys'' is a genus of South American rodents in the tribe Phyllotini of family Cricetidae. Two species are known, found in Argentina and Chile Chile, officially the Republic of Chile, is a country in the western part of South Am ...

'', and some species of ''

Calomys Vesper mice are rodents belonging to a genus ''Calomys''. They are widely distributed in South America. Some species are notable as the vectors of Argentinian hemorrhagic fever and Bolivian hemorrhagic fever. The genus was originally named ''He ...

'' are hyper-opisthodont. ''

Irenomys ''Irenomys tarsalis'', also known as the Chilean climbing mouse, Chilean tree mouse, or long-footed irenomys,Musser and Carleton, 2005, p. 1121 is a rodent found in Chile, from about 36° to 46°S, and in adjacent Argentina, mainly in forests. It ...

'', ''

Reithrodon ''Reithrodon'' is a genus of rodent in the family Cricetidae. It contains the following living species: * Bunny rat (''Reithrodon auritus'') * Naked-soled conyrat (''Reithrodon typicus'') The scientific name translates as "channel tooth" and r ...

'', and '' Neotomys'', formerly classified as phyllotines, are also hyper-opisthodont.Steppan, 1995, p. 18 Oryzomyini are also mostly opisthodont, but ''

Amphinectomys savamis ''Amphinectomys savamis'', also known as the Ucayali water ratMusser and Carleton, 2005 or amphibious rat,Duff and Lawson, 2004 is a rodent from the Peruvian Amazon. It is placed as the only member of genus ''Amphinectomys'' in the tribe Oryzomyin ...

'', ''

Handleyomys fuscatus ''Handleyomys fuscatus'', also known as the dusky-footed Handley's mouseMusser, G. G. and M. D. Carleton. 2005. Superfamily Muroidea. pp. 894–1531 ''in'' Mammal Species of the World a Taxonomic and Geographic Reference. D. E. Wilson and D. ...

'', ''

Melanomys caliginosus ''Melanomys caliginosus'', also known as the dusky melanomysMusser and Carleton, 2005 or dusky rice rat, is a species of rodent in the genus '' Melanomys'' of family Cricetidae. It is found from Central America, in Honduras, Nicaragua, Costa Rica ...

'', ''

Mindomys hammondi ''Mindomys'' is a genus of sigmodontine rodents in the family Cricetidae. It includes two species known only from Ecuador, Hammond's rice rat ''Mindomys hammondi'', also known as Hammond's rice rat or Hammond's oryzomys,Musser and Carleton, ...

'', '' Scolomys melanops'', and ''

Sigmodontomys aphrastus ''Tanyuromys aphrastus'', known as the long-tailed sigmodontomys, Harris's rice water rat, or the long-tailed rice rat, is a species of rodent in the family Cricetidae. It is known from Costa Rica, Panama, and Ecuador. In 2012, it was reassigned ...

'' are orthodont.Weksler, 2006, p. 43

References

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Literature cited

*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. Rodent anatomy