Skull of a beaver
The family CASTORIDAE contains the two living species of beavers and their fossil relatives. This was once a highly diverse group of rodents , but is now restricted to a single genus, Castor .
* 1 Characteristics * 2 Evolution * 3 Taxonomy * 4 References
Castorids are medium-sized mammals, although large compared with most other rodents. They are semiaquatic , with sleek bodies and webbed hind feet, and are more agile in the water than on land. Their tails are flattened and scaly, adaptations that help them manoeuvre in the water. Castorids live in small family groups that each occupy a specific territory, based around a lodge and dam constructed from sticks and mud. They are herbivores, feeding on leaves and grasses in the summer, and woody plants such as willow in the winter. They have powerful incisors and the typical rodent dental formula :
Euhapsis barbouri fossil
The earliest castorids belong to the genus
Agnotocastor , known from
Giant forms evolved in the
McKenna and Bell divided Castoridae into two subfamilies, Castoroidinae and Castorinae. More recent studies have recognized two additional subfamilies of basal castorids, Agnotocastorinae and Palaeocastorinae, which is followed here. Within the family, Castorinae and Castoroidinae are sister taxa; they share a more recent common ancestor with each other than with members of the other two subfamilies. Both subfamilies include semiaquatic species capable of constructing dams. The Palaeocastorinae include beavers that are interpreted as fossorial (burrowing), as are nothodipoidins and Migmacastor . The following taxonomy is based on Korth and Rybczynski, with preference given to the latter where these differ.
* FAMILY CASTORIDAE
* † Migmacastor
* Subfamily †Agnotocastorinae (paraphyletic )
* Tribe †Agnotocastorini
* † Agnotocastor * †Neatocastor
* Tribe †Anchitheriomyini
* Subfamily †Palaeocastorinae
* † Palaeocastor * †Capacikala * †Pseudopalaeocastor
* Tribe †Euhapsini
* †Euhapsis * †Fossorcastor
* Subfamily † Castoroidinae
* †Priusaulax (placement in Castoroidinae questionable)
* Tribe †Nothodipoidini
* † Eucastor * †Microdipoides * †Nothodipoides
* Tribe †Castoroidini (paraphyletic)
* Tribe †Trogontheriini
* Subfamily Castorinae
* †Chalicomys (also incorrectly "Palaeomys")
* Castor - modern beavers
* ^ Lancia, R.A.; Hodgdon, H.E. (1984). Macdonald, D., ed. The
Encyclopedia of Mammals. New York: Facts on File. pp. 606–609. ISBN
* ^ A B C D E Rybczynski N., 2007. Castorid phylogenetics:
implications for the evolution of swimming and tree-exploitation in
beavers Journal of Mammalian Evolution 14(1):1-35.
* ^ A B C Korth W.W., 2002. Comments on the systematics and
classification of the beavers (Rodentia, Castoridae) Journal of
Mammalian Evolution 8(4):279-296.
* ^ Palmer, D., ed. (1999). The Marshall Illustrated Encyclopedia
of Dinosaurs and Prehistoric Animals. London: Marshall Editions. p.
284. ISBN 1-84028-152-9 .
* ^ Savage, R.J.G., and Long, M.R. 1986.
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* v * t * e
Extant families in order Rodentia
* Aplodontiidae (Mountain beaver) * Gliridae (Dormice) * Sciuridae (Squirrels, chipmunks, marmots, susliks and prairie dogs)
* Anomaluridae (Anomalures) * Pedetidae (Springhares)
* Ctenodactylidae (Gundis) * Diatomyidae (Laotian rock rat) * Hystricidae (Old World porcupines)