Temporal range: late Oligocene or early Miocene
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Rodentia
Suborder: Castorimorpha
Family: Castoridae
Subfamily: incertae sedis
Genus: Migmacastor
Korth & Rybczynski, 2003
Species: M. procumbodens
Binomial name
Migmacastor procumbodens
Korth & Rybczynski, 2003

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 (Korth & Rybczynski 2003, p. 667). Features of the incisor teeth of Migmacastor indicate that they were used to dig. Other extinct beavers including the better-known Palaeocastor were also fossorial (digging), but Korth & Rybczynski (2003, p. 674) suggested that 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