''Ivanantonia'' is the only

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

in the extinct

rodent Rodents (from Latin , 'to gnaw') are mammals of the Order (biology), order Rodentia ( ), which are characterized by a single pair of continuously growing incisors in each of the upper and Mandible, lower jaws. About 40% of all mammal specie ...

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Ivanantoniidae and is represented by a single species, ''Ivanantonia efremovi'', from the early Eocene of Mongolia. ''Ivanantonia'' is poorly known, with only the lower

dentition Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, it is the characteristic arrangement, kind, and number of teeth in a given species at a given age. That is, the number, type, and morpho-physiology ...

represented. The genus is unusual among early rodents in lacking all lower

premolar The premolars, also called premolar Tooth (human), teeth, or bicuspids, are transitional teeth located between the Canine tooth, canine and Molar (tooth), molar teeth. In humans, there are two premolars per dental terminology#Quadrant, quadrant in ...

s and in showing evidence of propalinal chewing. The relationships of ''Ivanantonia'' are unclear. It was described as a ctenodactyloid. Hartenberger et al. suggested a potential relationship to the

muroid 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 except ...

'' Nonomys'' but declined to assign Ivanantoniidae to a suborder within

Rodent Rodents (from Latin , 'to gnaw') are mammals of the Order (biology), order Rodentia ( ), which are characterized by a single pair of continuously growing incisors in each of the upper and Mandible, lower jaws. About 40% of all mammal specie ...

ia.

References

* *Shevyreva, N.S. 2007. 1989. New rodents (Ctenodactyloidea, Rodentia, Mammalia) from the Lower Eocene of Mongolia. Paleontological Journal, 3: 60–72.

References

Further reading