Monotypic prehistoric rodent genera

REDIRECT Osborn's key mouse

REDIRECT Blunt-toothed giant hutia

Carletonomys cailoi is an extinct rodent from the Pleistocene (Ensenadan) of Buenos Aires Province, Argentina. Although known only from a single maxilla (upper jaw) with the first molar, its features are so distinctive that it is placed in its own genus, Carletonomys. Discovered in 1998 and formally described in 2008, it is part of a well-defined group of oryzomyine rodents that also includes Holochilus, Noronhomys, Lundomys, and Pseudoryzomys. This group is characterized by progressive semiaquatic specializations and a reduction in the complexity of molar morphology.

Spelaeomys florensis, also known as the Flores cave rat, is an extinct species of rat that was formerly endemic to the island of Flores, Indonesia. and Flemming assessed this species to be extinct in 1996, but believed it probably died out before 1500. This specimen is only known from subfossil remains, including at Liang Bua cave. It is the only member of the genus Spelaeomys. It was large sized species with a body mass of around . It is suggested to have been arboreal animal that lived in closed forests, and to have been herbivorous, consuming leaves and flowers.

Sivacanthion is an extinct genus of rodent from the Miocene of India. The build of Sivacanthion is very like that of a modern Old World porcupine, although details of the anatomy suggest that it is not a direct ancestor but a side branch of Hystricidae known in the Indian sub-continent.

REDIRECT Twisted-toothed mouse

Migmacastor is an extinct member of the beaver family, Castoridae, known from a single species, Migmacastor procumbodens. Only a single specimen has been reported, a skull from the late Oligocene or early Miocene of Nebraska. Features of the incisor teeth of Migmacastor indicate they were used to dig. Other extinct beavers, including the better-known Palaeocastor, were also fossorial (digging), but Migmacastor may have become a burrower independently.

REDIRECT Plate-toothed giant hutia

Reigomys primigenus is an extinct oryzomyine rodent known from Pleistocene deposits in Tarija Department, southeastern Bolivia. It is known from a number of isolated jaws and molars which show that its molars were almost identical to those of the living Lundomys. On the other hand, the animal possesses a number of derived traits of the palate which document a closer relationship to living Holochilus, the genus of South American marsh rats, and for this reason it was placed in the genus Holochilus when it was first described in 1996. The subsequent discoveries of Noronhomys and Carletonomys, wh

REDIRECT Lemke's hutia

REDIRECT Imposter hutia

Apeomyoides savagei is a fossil rodent from the Miocene of the United States, the only species in the genus Apeomyoides. It is known from fragmentary jaws and isolated teeth from a site in the early Barstovian, around 15–16 million years ago, of Nevada. Together with other species from scattered localities in the United States, Japan, and Europe, Apeomyoides is classified in the subfamily Apeomyinae of the extinct rodent family Eomyidae. Apeomyines are a rare but widespread group that may have been adapted to a relatively dry habitat.