Rodents

Rodents are mammals of the order Rodentia, characterized by two pairs of continuously growing incisors, one pair in the upper and one in the lower jaw. About forty percent of all mammal species are rodents, and they are found in vast numbers on all continents except Antarctica. They are the most diversified mammalian order, including mice,rats, squirrels, prairie dogs, porcupines,beavers, guinea pigs, and hamsters, and can be found in a variety of habitats, including manmade environments. There are arboreal,burrowing, and semi-aquatic species. While the largest species, the capybara, can weigh as much as 66 kg (146 lb), many rodents weigh less than 100 g (3.5 oz) and have robust bodies, short limbs and long tails. They use their sharp incisors to gnaw food, defend themselves, and shape their habitat. Most eat seeds or other plant material. Many species live in societies with complex forms of communication. Rodents can bemonogamous, polygynous, or promiscuous. The rodent fossil record dates back to thePaleocene on the supercontinent ofLaurasia.