| Giant Beavers Temporal range: Late Pliocene - Late Pleistocene |
|
|---|---|
| Castoroides ohioensis | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Rodentia |
| Family: | Castoridae |
| Subfamily: | †Castoroidinae |
| Tribe: | †Castoroidini |
| Genus: | †Castoroides Foster, 1838 |
| Type species | |
| †Castoroides ohioensis |
|
| Species | |
Castoroides, or Giant Beaver, is an extinct genus of enormous beavers that lived in North America during the Pleistocene.
Contents |
There are two known species:
These two species of giant beaver (genus Castoroides) are not close relatives to modern beavers (genus Castor).[1]
This genus typifies the extinct subfamily Castoroidinae, which forms a North American lineage beginning with the Hemingfordian genus Monosaulax, followed by Eucastor, Dipoides, and Procastoroides, to finally culminate and go extinct with Castoroides.[2]
The giant beaver looked similar to modern beavers but, as the name implies, was considerably larger: it grew over 8 ft (2.4 m) in length — making it not only the largest rodent in North America during the last ice age but also the largest known beaver — and weighed roughly 60 to 100 kg (130 to 220 lb) — the size of a modern black bear.[1]
Its hind feet were much larger than in modern beavers, but, because soft tissues decay, it is not know whether its tail resembled the tails in modern beavers and, similarly, it can only be assumed that its feet were webbed like in modern species.[1]
The incisors were 15 cm (5.9 in) long, and had blunt, rounded tips, in contrast to the chisel-like tips found in modern beaver cutting teeth. The molars were well adapted to grinding and resembled those of capybaras with an S-shaped pattern on the grinding surfaces.[1]
The oldest know fossils (Castoroides leiseyorum) from Florida are 1.4 million years old, while the youngest (Castoroides ohioensis) from Toronto, Ontario, and the Old Crow Basin, Yukon, are 130,000 years old, but it is believed that the giant beaver died out about 10,000 years ago along with several other American species such as mammoths, mastodons, and ice-age horses. Giant beavers were most abundant south of the Great Lakes in present day Indiana and Illinois.[1]