Ivanantonia
Encyclopedia
Ivanantonia is the only genus
in the extinct rodent
family
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
represented. The genus is unusual among early rodents in lacking all lower premolar
s and in showing evidence of propalinal chewing (Hartenberger et al., 1997). The relationships of Ivanantonia are unclear. It was described as a ctenodactyloid (Shevyreva, 1989). Hartenberger et al. (1997) suggested a potential relationship to the muroid
Nonomys but declined to assign Ivanantoniidae to a suborder within Rodent
ia.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
in the extinct rodent
Rodent
Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....
family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
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
Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, the characteristic arrangement, kind, and number of teeth in a given species at a given age...
represented. The genus is unusual among early rodents in lacking all lower premolar
Premolar
The premolar teeth or bicuspids are transitional teeth located between the canine and molar teeth. In humans, there are two premolars per quadrant, making eight premolars total in the mouth. They have at least two cusps. Premolars can be considered as a 'transitional tooth' during chewing, or...
s and in showing evidence of propalinal chewing (Hartenberger et al., 1997). The relationships of Ivanantonia are unclear. It was described as a ctenodactyloid (Shevyreva, 1989). Hartenberger et al. (1997) suggested a potential relationship to the muroid
Muroidea
Muroidea is a large superfamily of rodents. It includes hamsters, gerbils, true mice and rats, and many other relatives. They occupy a vast variety of habitats on every continent except Antarctica. Some authorities have placed all members of this group into a single family, Muridae, due to...
Nonomys but declined to assign Ivanantoniidae to a suborder within Rodent
Rodent
Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....
ia.