|It has been suggested that Castoroides ohioensis and Castoroides leiseyorum be merged into this article or section. (Discuss) Proposed since April 2010.|
There are two known species:
- Castoroides leiseyorum (found in Florida only)
- Castoroides ohioensis, synonym Castoroides nebrascensis (found throughout continental United States and Canada)
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.
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.
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.
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.
The oldest know fossils (Castoroides leiseyorum) from Florida are 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., while the youngest (Castoroides ohioensis) from Toronto, Ontario, and the
|Wikimedia Commons has media related to: Castoroides|