The Info List - Castoridae

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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

Characteristics[edit] Main article: Beaver 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.[1] They have powerful incisors and the typical rodent dental formula:




Euhapsis barbouri fossil

The earliest castorids belong to the genus Agnotocastor, known from the late Eocene
and Oligocene
of North America
North America
and Asia.[2] Other early castorids included genera such as Steneofiber, from the Oligocene
and Miocene
of Europe, the earliest member of the subfamily Castorinae, which contains castorids closely related to living beavers.[3] Their teeth were not well suited to gnawing wood, suggesting this habit evolved at a later point, but they do appear adapted to semiaquatic living.[4] Later, such early species evolved into forms such as Palaeocastor
from the Miocene
of Nebraska. Palaeocastor
was about the size of a muskrat, and dug corkscrew-shaped burrows up to 2.5 m (8.2 ft) deep.

Eucastor tortus

Mounted skeleton of Castoroides

Giant forms evolved in the Pleistocene, including Trogontherium
in Europe, and Castoroides
in North America. The latter animal was as large as a black bear, yet had a brain only marginally larger than that of modern beavers. Its shape suggests it would have been a good swimmer, and it probably lived in swampy habitats.[5] Taxonomy[edit] McKenna and Bell[6] divided Castoridae
into two subfamilies, Castoroidinae and Castorinae. More recent studies [2][3] 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.[2] The Palaeocastorinae include beavers that are interpreted as fossorial (burrowing),[2] as are nothodipoidins and Migmacastor.[7] The following taxonomy is based on Korth[3][7][8] and Rybczynski,[2] with preference given to the latter where these differ.

Family Castoridae

†Migmacastor Subfamily †Agnotocastorinae (paraphyletic)

Tribe †Agnotocastorini

†Agnotocastor †Neatocastor

Tribe †Anchitheriomyini

†Anchitheriomys †Propalaeocastor †Oligotheriomys

Subfamily †Palaeocastorinae

†Palaeocastor †Capacikala †Pseudopalaeocastor Tribe †Euhapsini

†Euhapsis †Fossorcastor

Subfamily †Castoroidinae

†Priusaulax (placement in Castoroidinae questionable) Tribe †Nothodipoidini

†Eucastor †Microdipoides †Nothodipoides

Tribe †Castoroidini (paraphyletic)

†Monosaulax †Prodipoides †Dipoides †Castoroides †Procastoroides

Tribe †Trogontheriini

†Trogontherium †Boreofiber †Euroxenomys †Youngofiber †Asiacastor

Subfamily Castorinae

†Chalicomys (also incorrectly "Palaeomys") †Steneofiber †Zamolxifiber †Romanofiber †Schreuderia †Sinocastor †Hystricops Castor - modern beavers

North American beaver, Castor canadensis Eurasian beaver, Castor fiber †Castor californicus


^ Lancia, R.A.; Hodgdon, H.E. (1984). Macdonald, D., ed. The Encyclopedia of Mammals. New York: Facts on File. pp. 606–609. ISBN 0-87196-871-1.  ^ 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. Mammal
Evolution: an Illustrated Guide. Facts on File, New York, pp. 120–121 ISBN 0-8160-1194-X. ^ McKenna, Malcolm C., and Bell, Susan K. 1997. Classification of Mammals Above the Species Level. Columbia University Press, New York, 631 pp. ISBN 0-231-11013-8. ^ a b Korth W.W., 2007b. The skull of Nothodipoides (Castoridae, Rodentia) and the occurrence of fossorial adaptations in beavers Journal of Paleontology 81(6):1533-1537. ^ Korth W.W., 2007a. A new genus of beaver (Rodentia, Castoridae) from the Miocene
(Clarendonian) of North America
North America
and systematics of the Castoroidinae based on comparative cranial anatomy Annals of Carnegie Museum 76(2):117-134.

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Extant families in order Rodentia

Kingdom: Animalia Phylum: Chordata Class: Mammalia Infraclass: Eutheria Superorder: Euarchontoglires

Sciuromorpha ("Squirrel-like")

Aplodontiidae (Mountain beaver) Gliridae (Dormice) Sciuridae (Squirrels, chipmunks, marmots, susliks and prairie dogs)

Castorimorpha ("Beaver-like")

Castoroidea Castoridae

Geomyoidea Geomyidae (Pocket gophers) Heteromyidae
(Kangaroo rats and mice, pocket mice)

Myomorpha ("Mouse-like")

Dipodoidea Dipodidae
(Jerboas, jumping mice and birch mice)

Muroidea Platacanthomyidae
(Oriental dormice) Spalacidae
(Zokors, bamboo rats, mole rats, blind mole rats) Calomyscidae (Mouse-like hamsters) Nesomyidae
(Malagasy rats and relatives) Cricetidae
(Hamsters and relatives) Muridae
(House mouse and relatives)

Anomaluromorpha ("Anomalure-like")

Anomaluridae (Anomalures) Pedetidae

Hystricomorpha ("Porcupine-like")

Ctenodactylidae (Gundis) Diatomyidae
(Laotian rock rat) Hystricidae (Old World porcupines)

Phiomorpha Bathyergidae (Blesmols) Petromuridae (Dassie rat) Thryonomyidae (Cane rats)

(New World hystricognaths) Erethizontidae (New World porcupines) Caviidae
(Cavies) Cuniculidae (Pacas) Dasyproctidae
(Agoutis and acouchis) Dinomyidae
(Pacarana) Capromyidae (Hutias) Ctenomyidae (Tuco-tucos) Echimyidae
(Spiny rats and coypus) Octodontidae
(Degus and relatives) Abrocomidae (Chinchilla rats) Chinchillidae
(Chinchillas and viscachas)

Taxon identifiers

Wd: Q261363 ADW: Castoridae EoL: 8684 EPPO: 1KASTF Fauna Europaea: 12651 Fossilworks: 41534 GBIF: 5493 ITIS: 180210 MSW: 12600002 NCBI: 2


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