''Migmacastor'' is an extinct member of the

beaver Beavers are large, semiaquatic rodents in the genus ''Castor'' native to the temperate Northern Hemisphere. There are two extant species: the North American beaver (''Castor canadensis'') and the Eurasian beaver (''C. fiber''). Beavers ar ...

family, Castoridae, known from a single species, ''Migmacastor procumbodens''. Only a single specimen has been reported, a skull from the late

Oligocene The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the ...

or early Miocene of Nebraska. Features of the incisor teeth of ''Migmacastor'' indicate they were used to dig. Other

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

beavers, including the better-known '' Palaeocastor'', were also

fossorial A fossorial () animal is one adapted to digging which lives primarily, but not solely, underground. Some examples are badgers, naked mole-rats, clams, meerkats, and mole salamanders, as well as many beetles, wasps, and bees. Prehistoric eviden ...

(digging), but ''Migmacastor'' may have become a burrower independently.Korth, William W.; Rybczynski, Natalia (2003), "A new, unusual castorid (Rodentia) from the earliest Miocene of Nebraska", Journal of Vertebrate Paleontology 23 (3): 667–675, doi:10.1671/2371

References

Prehistoric beavers Oligocene rodents Miocene rodents Cenozoic mammals of North America Prehistoric monotypic mammal genera Prehistoric rodent genera {{paleo-rodent-stub