In
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
Incisors (from Latin ''incidere'', "to cut") are the front teeth present in most mammals. They are located in the premaxilla above and on the mandible below. Humans have a total of eight (two on each side, top and bottom). Opossums have 18, whe ...
, 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'' 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'', 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
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 ...
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'', ''
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
''Scolomys melanops'', also known as the short-nosed scolomys, South American spiny mouse, Ecuadorian spiny mouse, or gray spiny mouse, is a species of rodent in the genus ''Scolomys'' of family Cricetidae. It is a forest mouse and was thought to ...
'', and ''
Sigmodontomys aphrastus'' 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