Superregnum: Eukaryota
Cladus: Unikonta
Cladus: Opisthokonta
Cladus: Holozoa
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Superphylum: Deuterostomia
Phylum: Chordata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Megaclassis: Osteichthyes
Cladus: Sarcopterygii
Cladus: Rhipidistia
Cladus: Tetrapodomorpha
Cladus: Eotetrapodiformes
Cladus: Elpistostegalia
Superclassis: Tetrapoda
Cladus: Reptiliomorpha
Cladus: Amniota
Cladus: Synapsida
Cladus: Eupelycosauria
Cladus: Sphenacodontia
Cladus: Sphenacodontoidea
Cladus: Therapsida
Cladus: Theriodontia
Subordo: Cynodontia
Infraordo: Eucynodontia
Cladus: Probainognathia
Cladus: Prozostrodontia
Cladus: Mammaliaformes
Classis: Mammalia
Subclassis: Trechnotheria
Infraclassis: Zatheria
Supercohors: Theria
Cohors: Eutheria
Infraclassis: Placentalia
Cladus: Boreoeutheria
Superordo: Euarchontoglires
Ordo: Rodentia
Subordo: Sciurognathi
Infraordines: Geomorpha - Myodonta - Sciurida
Sciurognathi is a suborder of rodents that includes squirrels, chipmunks, beavers, and many types of mice. The group is characterized by a specific shape to the lower jaw. In sciurognaths, the angular process of the jaw is in the same plane as the root of the incisors. This is in contrast to the suborder Hystricognathi where the angular process is outside the plane formed at the root of the incisor due to the presence of a shelf for muscle attachment.[1]
The sciurognathous condition is considered to be the primitive condition in rodents, and is therefore not a good character for cladistic analysis. Although hystricognaths are almost universally accepted as representing a real evolutionary grouping, most researchers do not consider Sciurognathi as an equally valid group. In particular, gundis are thought to be more closely related to the hystricognathous rodents than to other sciurognaths. In spite of this, most texts continue to use these two suborders due primarily to a lack of a viable alternative.
Alternatively, some texts group rodents into three suborders on the basis of the shape of the infraorbital canal. According to this taxonomy the rodents are divided into the suborders Sciuromorpha, Hystricomorpha, and Myomorpha.
See also
Castorimorpha
Anomaluromorpha
References
Hautier, Lionel; Lebrun, Renaud; Saksiri, Soonchan; Michaux, Jacques; Vianey-Liaud, Monique; Marivaux, Laurent (2011-04-07). Goswami, Anjali (ed.). "Hystricognathy vs Sciurognathy in the Rodent Jaw: A New Morphometric Assessment of Hystricognathy Applied to the Living Fossil Laonastes (Diatomyidae)". PLOS ONE. 6 (4): e18698. Bibcode:2011PLoSO...618698H. doi:10.1371/journal.pone.0018698. ISSN 1932-6203. PMC 3072414. PMID 21490933.
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