The

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 n ...

family Platacanthomyidae, or Oriental dormice, includes the spiny dormice and the Chinese pygmy dormice. In spite of their appearance, these animals are not true

dormice A dormouse is a rodent of the family Gliridae (this family is also variously called Myoxidae or Muscardinidae by different taxonomists). Dormice are nocturnal animals found in Africa, Asia, and Europe. They are named for their long, dormant hibe ...

, but are part of the large and complex

superfamily SUPERFAMILY is a database and search platform of structural and functional annotation for all proteins and genomes. It classifies amino acid sequences into known structural domains, especially into SCOP superfamilies. Domains are functional, str ...

Muroidea The Muroidea are a large superfamily of rodents, including mice, rats, voles, hamsters, lemmings, gerbils, and many other relatives. Although the Muroidea originated in Eurasia, they occupy a vast variety of habitats on every continent excep ...

. The platacanthomyids can be distinguished from the true dormice, because they have no

premolar The premolars, also called premolar teeth, or bicuspids, are transitional teeth located between the canine and molar teeth. In humans, there are two premolars per quadrant in the permanent set of teeth, making eight premolars total in the mouth ...

s, giving them three cheek teeth, like their relatives, the Muroidea. The evolutionary relationship of the Platacanthomyidae was uncertain until a molecular phylogenetic study found it to be the earliest extant lineage to branch within the superfamily

. They can be distinguished from both the family Spalacidae and the Eumuroida (all non-spalacid and non-platacanthomyid muroids), by the distinct shape of their

infraorbital canal The infraorbital canal is a canal found at the base of the orbit that opens on to the maxilla. It is continuous with the infraorbital groove and opens onto the maxilla at the infraorbital foramen. The infraorbital nerve and infraorbital arte ...

and by the presence of multiple openings in the

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 separ ...

of the skull. On the basis of these two characteristics, they have been considered to be distinct from all other muroids. More work is needed to determine the evolutionary position of this subfamily. The Platacanthomyidae contain three

genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...

– '' Neocometes'', ''

Platacanthomys The Malabar spiny dormouse (''Platacanthomys lasiurus'') is a species of muroid rodent endemic to the Western Ghats of India. It is the only extant species in the genus ''Platacanthomys'' and although resembling a dormouse, it is not closely r ...

'' (spiny dormice), and '' Typhlomys''Jansa, S.A., T.C. Giarla, and B.K. Lim. 2009. The Phylogenetic Position of the Rodent Genus Typhlomys and the Geographic Origin of Muroidea. "Journal of Mammalogy": October 2009, Vol. 90, No. 5, pp. 1083-1094. (pygmy dormice) – but only three extant

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriat ...

Taxonomy

*Family Platacanthomyidae **Genus †'' Neocometes'' ***†'' Neocometes brunonis'' ***†'' Neocometes orientalis'' ***†'' Neocometes similis'' **Genus ''

'' (spiny dormice) ***†''

Platacanthomys dianensis The Malabar spiny dormouse (''Platacanthomys lasiurus'') is a species of muroid rodent endemic to the Western Ghats of India. It is the only extant species in the genus ''Platacanthomys'' and although resembling a dormouse, it is not closely r ...

'' ***'' Platacanthomys lasiurus'' (spiny dormouse) **Genus '' Typhlomys'' (pygmy dormice) ***'' Typhlomys cinereus'' (Chinese pygmy dormouse) ***'' Typhlomys nanus'' ***†'' Typhlomys hipparionium'' ***†'' Typhlomys intermedius'' ***†'' Typhlomys macrourus'' ***†'' Typhlomys primitivus''

Taxonomy

References

Further reading