''Dipoides'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

of beaver-grouped

rodent Rodents (from Latin , 'to gnaw') are mammals of the order Rodentia (), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are n ...

s. ''Dipoides'' were about two thirds the size of modern

Canadian beaver The North American beaver (''Castor canadensis'') is one of two extant beaver species, along with the Eurasian beaver (''Castor fiber''). It is native to North America and introduced in South America (Patagonia) and Europe (primarily Finland ...

s. Where modern beavers have square chisel shaped teeth, ''Dipoides'' teeth were rounded. However an excavation of a site that was once a marsh, in Ellesmere Island, showed signs that they dined on bark and young trees, like modern beavers. The excavation seemed to show that, like modern beavers, ''Dipoides'' dammed streams. Other research suggests that the building of dams by ''Dipoides'' started as a side effect to the consumption of wood and bark, and was a specialization that evolved for cold weather survival due to the earth's cooling during the late Neogene period.

Natalia Rybczynski Natalia Rybczynski is a Canadian paleobiologist, professor and researcher. She is a research scientist with the Canadian Museum of Nature and holds a professorship at Carleton University in Ottawa, Ontario. Her doctorate was obtained at Duke Uni ...

, of the Canadian Museum of Nature, analyzed the teeth, and wood chips, of modern beavers, and ''Dipoides''. She concluded that they all used just one of their teeth at a time, when cutting down trees. She concluded that modern beavers' square teeth required half as many bites as ''Dipoides less evolved round teeth. Rybczynski argues that eating bark and building dams are unlikely to have evolved twice, so modern beavers and Dipoides shared a wood eating common ancestor, 24 million years ago.

References

External links

Dipoides Jaeger 1835
on: Encyclopedia of Life, National Museum of Natural History, Smithsonian Prehistoric beavers Prehistoric rodent genera Ringold Formation Miocene Fauna {{paleo-rodent-stub