Rodent
| Rodents | ||||||||
|---|---|---|---|---|---|---|---|---|
Capybara, the largest living rodent | ||||||||
| Scientific classification | ||||||||
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| Families | ||||||||
| Many: see text |
Most rodents are small. The tiny African Pygmy Mouse is only 6 cm in length and 7 grams in weight. On the other hand, the Capybara can weigh up to 45 kg (100 pounds) and the extinct Phoberomys pattersoni is believed to have weighed 700 kg.
Rodents have two incisors in the upper as well as in the lower jaw which grow continuously and must be kept worn down by gnawing; this is the origin of the name, from the Latin rodere, to gnaw. These teeth are used for cutting wood, biting through the skin of fruit, or for defence. Nearly all rodents feed on plants, seeds in particular, but there are a few exceptions which eat insects or even fish.
The order Rodentia may be divided into suborders, superfamilies and families. This is a common classification scheme:
Classification
Recent work has suggested that the rodents may actually be biologically polyphyletic (i.e. have evolved more than once), specifically the Myomorpha may constitute a distinct and separate lineage, in which case the order would have to be revised.