Zygomatic plate

The zygomatic plate serves to resist muscular tension resulting from the contraction of the incisors by the anterior deep masseter muscle; thus, rodents which pulverize hard food with the incisors tend to have broader zygomatic plates than those that rather use their molars for this purpose.Voss, 1988, pp. 408–410

The members of this large and diverse suborder have a narrow, low zygomatic plate.Ellerman, 1940, pp. 24–29, 33; Jenkins et al., 2005, p. 427

The suborder Sciuromorpha includes three families. Squirrels (family Sciuridae) tend to have broad zygomatic plate that extend above the infraorbital foramen.Ellerman, 1940, p. 30; Miller and Gidley, 1918, pp. 432–433 The mountain beaver (Aplodontia rufa), the only surviving member of its family, retains the primitive narrow and low plate.Ellerman, 1940, p. 29 The dormice (Gliridae) have broad, high zygomatic plates,Ellerman, 1940, p. 37 except for Graphiurus, which has a lower plate.Ellerman, 1940, p. 36

Members of the suborder Castorimorpha, which includes the beavers, pocket gophers, and pocket mice, tend to have broad zygomatic plate that extend above the infraorbital foramen.Ellerman, 1940, p. 31; Miller and Gidley, 1918, pp. 432–433

Anomaluromorpha is a small suborder, containing only two families. Anomaluridae have a low and narrow zygomatic plate.Ellerman, 1940, p. 32 Members of the subfamily Idiurinae are atypical in having the zygomatic plate extended forward nearly to the incisors.Ellerman, 1940, p. 33 The condition in the springhaas (Pedetes) is similar.

Myomorpha is the largest suborder of rodents.Carleton and Musser, 2005 In the most numerous subgroup, the Muroidea (including all living families except Dipodidae), the zygomatic plate is generally broad and tilted upwards.Ellerman, 1940, p. 35; Ellerman, 1941, pp. 1–2 Muroids may have the plate extending in front of the front (maxillary) root of the actual zygomatic arch, creating a zygomatic notch. In some, the plate extends at the front into a spinous process, the zygomatic spine.Steppan, 1995, p. 30; Weksler, 2006, fig. 17

Members of the family Dipodidae, which have hystricomorphous zygomasseteric morphology, have nearly horizontal, narrow zygomatic plates.Wood, 1935, p. 246; Ellerman, 1940, p. 34

Members of the small family Platacanthomyidae have a relatively narrow zygomatic plate.Miller and Gidley, 1918, p. 437; Ellerman, 1940, p. 37

The fossorially specialized family Spalacidae shows peculiarities in the condition of the zygomatic plate. In Tachyoryctes and the Rhizomyinae, it is tilted upward and fused to the sides of the snout (rostrum). In the Spalacinae and Myospalacinae, on the other hand, the plate is tilted downward into an almost horizontal position.Miller and Gidley, 1918, p. 438; Ellerman, 1940, p. 37

The mouse-like hamster (Calomyscus), the only member of its family, has a straight front margin on the zygomatic plate.Ellerman, 1941, p. 404

The family Nesomyidae is restricted to Africa.

Dendromus has a narrow zygomatic plate,Ellerman, 1941, p. 307 as do SteatomysEllerman, 1941, p. 311 and Prionomys.Ellerman, 1941, p. 315

Brachyuromys has an arvicoline-like high zygomatic plate. In Eliurus, the front border of the plate is straight.Ellerman, 1941, p. 76 Nesomys has a low zygomatic plate.Ellerman, 1941, p. 376 In Hypogeomys, it is broad, but rather low.Ellerman, 1941, p. 481

Muridae is the order's largest family, and contains several subfamilies.

Deomys, a member of the Deomyinae, has an unusually low zygomatic plate,Ellerman, 1941, p. 6 as does Lophuromys, a member of the same subfamily.

Most members of the subfamily Murinae, the Old World rats and mice, have a fairly broad zygomatic plate with a well-developed zygomatic notch.Tate, 1951, p. 210 A zygomatic spine is developed in some Australian genera, including Notomys and some Pseudomys. Except for Xeromys, Hydromys and related genera ("hydromyines") have a narrow plate, lacking the notch, as does Hyomys, Macruromys, Crunomys,Ellerman, 1941, p. 56 and Rhynchomys.Ellerman, 1941, p. 296 The Philippine Batomys, Carpomys, and Crateromys have well-developed zygomatic plates, reminiscent of those in Arvicolinae.Ellerman, 1941, p. 48 Phloeomys has a broad zygomatic plate.Ellerman, 1941, p. 292

The family Cricetidae is the order's second largest, containing several subfamilies and hundreds of species.Musser and Carleton, 2005

The subfamily Arvicolinae, the voles and lemmings, has the zygomatic plate tilted upwards very strongly.

In the subfamily Tylomyinae, Nyctomys has a narrow zygomatic plate.Ellerman, 1941, p. 375

Among members of the Neotominae, Baiomys, Reithrodontomys, Onychomys, and Peromyscus has a narrow zygomatic plate.Ellerman, 1941, pp. 378, 385, 401, 404

Members of the subfamily Sigmodontinae, which includes a number of tribes, usually have the antorbital bridge below the upper surface of the skull. Most have a zygomatic notch.Steppan, 1995, p. 30; Weksler, 2006, p. 32 The extent of the zygomatic plate at the back is also variable within Sigmodontinae, with some having the plate extending back to the level of the first upper molar and others having shorter plates.Weksler, 2006, p. 32

Members of the semiaquatic tribe Ichthyomyini are unique among the Sigmodontinae in lacking the zygomatic notch.Voss, 1988, p. 284 In ichthyomyines, the development of the zygomatic plate is correlated with the development of the teeth: those species with large molars and small incisors, including species of Anotomys and Rheomys, have slender plates that do not extend back to the first molars, whereas those with larger incisors and smaller molars, including some Ichthyomys and Neusticomys, have broader zygomatic plates that do reach the level of the first molars.Voss, 1988, pp. 289–290

The genus Sigmodon, which is classified in its own tribe, has a broad zygomatic plate and a zygomatic spine.Voss, 1992, p. 13 Relative width of the zygomatic plate can distinguish some species of Sigmodon.Voss, 1992, p. 35

Most members of the tribe Phyllotini have the antorbital bridge located higher than is usual in Sigmodontinae (Calomys and Andalgalomys show the normal sigmodontine condition). A similar condition characterizes Euneomys, Neotomys, Reithrodon, which are no longer considered phyllotines, but to an even larger extent than in most actual phyllotines; in Euneomys, the antorbital bridge is inserted on the upper surface of the skull.Steppan, 1995, pp. 28–29; D'Elía et al., 2007, pp. 191–192 Most phyllotines have zygomatic spines, but the structure is more well-developed in Reithrodon. The zygomatic plate not extending backwards to the first molars is a diagnostic character of phyllotines.Steppan, 1995, p. 72

Most thomasomyines lack a well-developed zygomatic notch.Steppan, 1995, p. 30 The genus Rhipidomys has a narrow zygomatic plate, no zygomatic spine and only a narrow notch.Patton et al., 2000, p. 162 Thomasomys shares a narrow zygomatic plate.Ellerman, 1941, p. 367

In the Akodontini, Oxymycterus and Lenoxus have a low zygomatic plate, similar to that of Lophuromys.Ellerman, 1941, p. 330 Scapteromys shares a low plate.Ellerman, 1941, p. 426 In Akodon, the plate is narrow,Ellerman, 1941, p. 407 as in many others akodontine; this is extremely so in Blarinomys.Ellerman, 1941, p. 422

The tribe Abrotrichini is characterized by a narrow zygomatic plate, without an extension at the upper border.D'Elía et al., 2007, p. 188

In the tribe Oryzomyini, the configuration of the zygomatic plate is variable. Most have a well-developed zygomatic notch. In the three related genera Holochilus, Pseudoryzomys, and Lundomys, this extension has further developed into a zygomatic spine. In contrast, Microryzomys, Oreoryzomys, Oecomys, Scolomys, and Sigmodontomys aphrastus lack a well-defined notch and do not have the plate extending appreciably in front of the root of the zygomatic arch.Weksler, 2006, pp. 31–32, fig. 17; Weksler et al., 2006, for nomenclature The zygomatic plate extending back to the level of the upper first molar is a putative synapomorphy of Clade C within Oryzomyini.Weksler, 2006, p. 128

The sigmodontine Juliomys pictipes has an almost vertical zygomatic plate.Osgood, 1933, p. 12; Musser and Carleton, 2005, p. 1121

{{reflist|colwidth=30em}}

{{Refbegin|30em}}

• {{Cite book

| last1 = Carleton | first1 = M.D.

| last2 = Musser | first2 = G.G.

| chapter = Order Rodentia | pages = 745–752

| editor1-last = Wilson | editor1-first = D.E.

| editor2-last = Reeder | editor2-first = D.M.

| title = Mammal Species of the World: a taxonomic and geographic reference

| year = 2005 | edition = 3rd | location = Baltimore

| publisher = The Johns Hopkins University Press

| chapter-url = http://www.bucknell.edu/msw3

| isbn = 978-0-8018-8221-0}} 2 vols., 2142 pp.

• {{Cite journal

| last1 = D'Elía | first1 = G.

| last2 = Pardiñas | first2 = U.F.J.

| last3 = Teta | first3 = P.

| last4 = Patton | first4 = J.L

| title = Definition and diagnosis of a new tribe of sigmodontine rodents (Cricetidae: Sigmodontinae), and a revised classification of the subfamily

| journal = Gayana | year = 2007 | volume = 71 | issue = 2 | pages = 187–194 | doi=10.4067/s0717-65382007000200007| doi-access = free }}

• {{Cite book

| last = Ellerman | first = J.R

| title = The families and genera of living rodents. Volume I. Rodents other than Muridae

| year = 1940 | location = London | publisher = Printed by order of the Trustees of the British Museum

| url = https://archive.org/stream/familiesgeneraof01elle#page/36/mode/2up/

}} 689 pp.

• {{Cite book

| last = Ellerman | first = J.R.

| title = The families and genera of living rodents. Volume II. Family Muridae

| year = 1941 | location = London | publisher = Printed by order of the Trustees of the British Museum

| url = https://archive.org/stream/familiesgeneraof02elle#page/2/mode/2up/search/Lophiomyidae

}} 690 pp.

• {{Cite journal

| last1 = Jenkins | first1 = P.D.

| last2 = Kilpatrick | first2 = C.W.

| last3 = Robinson | first3 = M.F

| last4 = Timmins | first4 = R.J.

| title = Morphological and molecular investigations of a new family, genus and species of rodent (Mammalia: Rodentia: Hystricognatha) from Lao PDR

| journal = Systematics and Biodiversity | year = 2005 | volume = 2 | issue = 4 | pages = 419–454 | doi=10.1017/S1477200004001549| s2cid = 86411689

}}

• {{Cite journal

| last1 = Miller | first1 = G.S. Jr.

| last2 = Gidley | first2 = J.W.

| title = Synopsis of the supergeneric groups of rodents

| journal = Journal of the Washington Academy of Sciences | year = 1918 | volume = 8 | pages = 431–448| doi = 10.5962/bhl.part.6490

| url = https://www.biodiversitylibrary.org/part/6490

}}

• {{Cite book

| last1 = Musser | first1 = G.G.

| last2 = Carleton | first2 = M.D.

| chapter = Superfamily Muroidea | pages = 894–1531

| editor1-last = Wilson | editor1-first = D.E.

| editor2-last = Reeder | editor2-first = D.M.

| title = Mammal Species of the World: a taxonomic and geographic reference

| year = 2005 | edition = 3rd

| chapter-url = http://www.bucknell.edu/msw3

| location = Baltimore | publisher = The Johns Hopkins University Press

| isbn = 978-0-8018-8221-0}} 2 vols., 2142 pp.

• {{Cite journal

| last = Osgood | first = W.H.

| title = Two new rodents from Argentina

| journal = Fieldiana Zoology | year = 1933 | volume = 20 | issue = 3 | pages = 11–14

| url = https://www.biodiversitylibrary.org/bibliography/3096}}

• {{Cite book

| last = Patterson | first = B.

| title = Trachytherus, a typotherid from the Deseado beds of Patagonia

| publisher = Field Museum of Natural History | year = 1934 | series = Geological Series | volume = 6 | pages = 91–111}}

• {{Cite journal

| last1 = Patton | first1 = J.L.

| last2 = da Silva | first2 = M.N.F.

| last3 = Malcolm | first3 = J.R.

| title = Mammals of the Rio Juruá and the evolutionary and ecological diversification of Amazonia

| journal = Bulletin of the American Museum of Natural History | year = 2000 | volume = 244 | pages = 1–306 | doi=10.1206/0003-0090(2000)244<0001:motrja>2.0.co;2| hdl = 2246/1593

| s2cid = 85577629

| url = https://zenodo.org/record/5347311

| hdl-access = free }}

• {{Cite journal

| last1 = Reguero | first1 = M.A.

| last2 = Dozo | first2 = M.T.

| last3 = Cerdeño | first3 = E.

| title = A poorly known rodentlike mammal (Pachyrukhinae, Hegetotheriidae, Notoungulata) from the Deseadan (Late Oligocene) of Argentina. Paleoecology, biogeography, and radiation of the rodentlike ungulates in South America

| journal = Journal of Paleontology | year = 2007 | volume = 81 | issue = 6 | pages = 1301–1307 | doi=10.1666/05-100.1| s2cid = 55259241

| url = http://naturalis.fcnym.unlp.edu.ar/repositorio/_documentos/sipcyt/bfa004875.pdf

}}

• {{Cite journal

| last = Steppan | first = S.J.

| title = Revision of the tribe Phyllotini (Rodentia: Sigmodontinae), with a phylogenetic hypothesis for the Sigmodontinae

| journal = Fieldiana Zoology | year = 1995 | volume = 80 | pages = 1–112 | doi=10.5962/bhl.title.3336| doi-access = free }}

• {{Cite journal

| last = Tate | first = G.H.H.

| title = The rodents of Australia and New Guinea

| journal = Bulletin of the American Museum of Natural History | year = 1951 | volume = 97 | pages = 187–430

| hdl = 2246/1060

| hdl-access = free}}

• {{Cite journal

| last = Voss | first = R.S.

| title = Systematics and ecology of ichthyomyine rodents (Muroidea): patterns of morphological evolution in a small adaptive radiation

| journal = Bulletin of the American Museum of Natural History | year = 1988 | volume = 188 | pages = 259–493}}

• {{Cite journal

| last = Voss | first = R.S.

| title = A revision of the South American species of Sigmodon (Mammalia: Muridae) with notes on their natural history and biogeography

| journal = American Museum Novitates | year = 1992 | issue = 3050 | pages = 1–56}}

• {{Cite journal

| last = Weksler | first = M.

| title = Phylogenetic relationships of oryzomyine rodents (Muroidea: Sigmodontinae): separate and combined analyses of morphological and molecular data

| journal = Bulletin of the American Museum of Natural History | year = 2006 | volume = 296 | pages = 1–149

| doi=10.1206/0003-0090(2006)296[0001:PROORM]2.0.CO;2| hdl = 2246/5777

| s2cid = 86057173

}}

• {{Cite journal

| last1 = Weksler | first1 = M.

| last2 = Percequillo | first2 = A.R.

| last3 = Voss | first3 = R.S.

| title = Ten new genera of oryzomyine rodents (Cricetidae: Sigmodontinae)

| journal = American Museum Novitates | year = 2006 | issue = 3537 | pages = 1–29

| doi=10.1206/0003-0082(2006)3537[1:TNGOOR]2.0.CO;2| hdl = 2246/5815

| s2cid = 84088556

| url = https://zenodo.org/record/5385275

}}

• {{Cite journal

| last = Wood | first = A.E.

| title = Evolution and relationships of the heteromyid rodents with new forms from the Tertiary of western North America

| journal = Annals of Carnegie Museum | year = 1935 | volume = 24 | pages = 73–262| doi = 10.5962/p.215194

| s2cid = 251511528

| doi-access = free}}

{{Refend}}

Category:Mammal anatomy

Category:Rodent anatomy