Castoridae

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Castoridae
Temporal range: Late Eocene–Recent
Beaver.jpg
North American beaver, Castor canadensis
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Rodentia
Superfamily: Castoroidea
Family: Castoridae
Hemprich, 1820
Type genus
Castor
Linnaeus, 1758
Genera

See text

Skull of a beaver Biberschaedel-drawing.jpg
Skull of a beaver

Castoridae is a family of rodents that cointains the two living species of beavers and their fossil relatives. A formerly diverse group, only a single genus is extant today, Castor. Two other genera of "giant beavers", Castoroides and Trogontherium, became extinct in the Late Pleistocene.

Contents

Characteristics

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:

Dentition
1.0.1-2.3
1.0.1.3

Evolution

Euhapsis barbouri fossil Euhapsis barbouri v2.JPG
Euhapsis barbouri fossil

The earliest castorids belong to the genus Agnotocastor , known from the late Eocene and Oligocene of 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 Eucastor tortus.jpg
Eucastor tortus
Mounted skeleton of Castoroides ohioensis Skeleton of Castoroides ohioensis.jpg
Mounted skeleton of Castoroides ohioensis

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

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.

Related Research Articles

<span class="mw-page-title-main">Beaver</span> Genus of semiaquatic rodents that build dams and lodges

Beavers are large, semiaquatic rodents of the Northern Hemisphere. There are two existing species: the North American beaver and the Eurasian beaver. Beavers are the second-largest living rodents, after capybaras, weighing up to 50 kg (110 lb). They have stout bodies with large heads, long chisel-like incisors, brown or gray fur, hand-like front feet, webbed back feet, and tails that are flat and scaly. The two species differ in skull and tail shape and fur color. Beavers can be found in a number of freshwater habitats, such as rivers, streams, lakes and ponds. They are herbivorous, consuming tree bark, aquatic plants, grasses and sedges.

<span class="mw-page-title-main">Spalacidae</span> Family of rodents

The Spalacidae, or spalacids, are a family of rodents in the large and complex superfamily Muroidea. They are native to eastern Asia, the Horn of Africa, the Middle East, and southeastern Europe. It includes the blind mole-rats, bamboo rats, mole-rats, and zokors. This family represents the oldest split in the muroid superfamily, and comprises animals adapted to a subterranean way of life. These rodents were thought to have evolved adaptations to living underground independently until recent genetic studies demonstrated they form a monophyletic group. Members of the Spalacidae are often placed in the family Muridae along with all other members of the Muroidea.

<span class="mw-page-title-main">Aplodontiidae</span> Family of rodents

The family Aplodontiidae also known as Aplodontidae, Haplodontiidae or Haploodontini is traditionally classified as the sole extant family of the suborder Protrogomorpha. It may be the sister family of the Sciuridae. There are fossils from the Oligocene until Miocene in Asia, from Oligocene in Europe and from the Oligocene until the present in North America, where there is the only living species: the mountain beaver.

<i>Castoroides</i> Extinct genus of beaver

Castoroides, or giant beaver, is an extinct genus of enormous, bear-sized beavers that lived in North America during the Pleistocene. Two species are currently recognized, C. dilophidus in the Southeastern US and C. ohioensis in the rest of its range. C. leiseyorum was previously described from the Irvingtonian of Florida, but is now regarded as an invalid name. All specimens previously described as C. leiseyorum are considered to belong to C. dilophidus.

<span class="mw-page-title-main">Geomyoidea</span> Superfamily of rodents

Geomyoidea is a superfamily of rodent that contains the pocket gophers (Geomyidae), the kangaroo rats and mice (Heteromyidae), and their fossil relatives.

<i>Palaeocastor</i> Extinct genus of rodents

Palaeocastor is an extinct genus of beavers that lived in the North American Badlands during the late Oligocene period to early Miocene. Palaeocastor was much smaller than modern beavers. There are several species including Palaeocastor fossor, Palaeocastor magnus,Palaeocastor wahlerti, and Palaeocastor peninsulatus.

<i>Steneofiber</i> Extinct genus of rodents

Steneofiber is an extinct genus of beavers from the Miocene. They contain several species of beavers. Amongst them are S.barbouri, S.complexus, S.depereti, S.fossor, S.gradatus, and S.hesperus. Their various species are found all the way from the eastern end of the Iberian peninsula to southern Japan. S.depereti has been found in northwest Germany.

<span class="mw-page-title-main">Eomyidae</span> Extinct family of rodents

Eomyidae is a family of extinct rodents from North America and Eurasia related to modern day pocket gophers and kangaroo rats. They are known from the Middle Eocene to the Late Miocene in North America and from the Late Eocene to the Pleistocene in Eurasia. Eomyids were generally small, but occasionally large, and tended to be squirrel-like in form and habits. The family includes the earliest known gliding rodent, Eomys quercyi.

<span class="mw-page-title-main">Heliscomyidae</span> Extinct family of rodents

Heliscomyidae is a family of extinct rodents from the mid-Tertiary of North America related to pocket gophers and kangaroo rats and their relatives. The family contains four genera, Apletotomeus, Heliscomys, Passaliscomys, and Tylionomys. McKenna and Bell (1997) placed the first two genera in synonymy, with Heliscomys as the senior synonym.

<span class="mw-page-title-main">Sciurini</span> Tribe of rodents

Sciurini is a tribe that includes about forty species of squirrels, mostly from the Americas. It includes five living genera—the American dwarf squirrels, Microsciurus; the Bornean Rheithrosciurus; the widespread American and Eurasian tree squirrels of the genus Sciurus, which includes some of the best known squirrel species; the Central American Syntheosciurus; and the American pine squirrels, Tamiasciurus. Like other arboreal squirrels, they are sometimes referred to as tree squirrels.

<span class="mw-page-title-main">Mylagaulidae</span> Extinct family of rodents

The Mylagaulidae or mylagaulids are an extinct clade of sciuromorph rodents nested within the family Aplodontiidae. They are known from the Neogene of North America and China. The oldest member is the Late Oligocene Trilaccogaulus montanensis that lived some 29 million years ago (Mya), and the youngest was Ceratogaulus hatcheri—formerly in the invalid genus "Epigaulus" —which was found barely into the Pliocene, some 5 Mya.

<i>Castor californicus</i> Species of mammal (fossil)

Castor californicus is an extinct species of beaver that lived in western North America from the end of the Miocene to the early Pleistocene. Castor californicus was first discovered in Kettleman Hills in California, United States. The species was similar to but larger than the extant North American beaver, C. canadensis.

<i>Anchitheriomys</i> Extinct genus of rodents

Anchitheriomys is an extinct member of the beaver family, Castoridae. It inhabited North America and Eurasia during the middle Miocene. The name of the genus comes from Anchitherium, an extinct genus of horses, and the Greek word for mouse, μῦς (mys), thus meaning "Anchitherium's mouse", because the fossils of both genera usually co-occur.

<span class="mw-page-title-main">Mesotheriidae</span> Extinct family of mammals

Mesotheriidae is an extinct family of notoungulate mammals known from the Oligocene through the Pleistocene of South America. Mesotheriids were small to medium-sized herbivorous mammals adapted for digging.

Propalaeocastor is a poorly known extinct genus of beavers from the early Oligocene of Europe and Asia. Recently described material of a new species of Propalaeocastor, P. irtyshensis, indicates the genus is probably the earliest known member of the subfamily Castorinae, which includes all castorids more closely related to living beavers than to the extinct giant beaver. Previously, Propalaeocastor had been allied with more basal beavers such as Agnotocastor and Anchitheriomys. According to Wu and coauthors, Propalaeocastor, specifically P. butselensis, is the likely ancestor of the better-known Eurasian castorine Steneofiber.

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.

<i>Trogontherium</i> Extinct genus of giant beaver

Trogontherium is an extinct genus of Eurasian giant beavers that lived from the Late Pliocene to the Late Pleistocene. Fossils of Trogontherium have been found across northern Eurasia, from Western Europe to China and Siberia.

<span class="mw-page-title-main">Echimyidae</span> Family of rodents

Echimyidae is the family of neotropical spiny rats and their fossil relatives. This is the most species-rich family of hystricognath rodents. It is probably also the most ecologically diverse, with members ranging from fully arboreal to terrestrial to fossorial to semiaquatic habits. They presently exist mainly in South America; three members of the family also range into Central America, and the hutias are found in the Greater Antilles in the Caribbean. Species of the extinct subfamily Heteropsomyinae formerly lived on Cuba, Hispaniola, and Puerto Rico in the Antilles, probably until the arrival of Europeans.

<i>Apeomyoides</i> Extinct genus of rodents

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.

This paleomammalogy list records new fossil mammal taxa that were described during the year 2011, as well as notes other significant paleomammalogy discoveries and events which occurred during that year.

References

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  2. 1 2 3 4 5 Rybczynski, N. (27 December 2006). "Castorid phylogenetics: implications for the evolution of swimming and tree-exploitation in beavers". Journal of Mammalian Evolution. 14 (1): 1–35. doi:10.1007/s10914-006-9017-3. S2CID   33659669.
  3. 1 2 3 Korth, W.W. (December 2001). "Comments on the systematics and classification of the beavers (Rodentia, Castoridae)". Journal of Mammalian Evolution. 8 (4): 279–296. doi:10.1023/A:1014468732231. S2CID   27935955.
  4. Palmer, D., ed. (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. p. 284. ISBN   1-84028-152-9.
  5. 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.
  6. 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.
  7. 1 2 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.
  8. Korth W.W., 2007a. A new genus of beaver (Rodentia, Castoridae) from the Miocene (Clarendonian) of North America and systematics of the Castoroidinae based on comparative cranial anatomy Annals of Carnegie Museum 76(2):117-134.