Rodent wiki:
all>Fossil Range: Paleocene - Recent See Classification Section The order Rodentia is the most numerous of all the branches on the mammal family tree. Currently there are, depending on the authority consulted, between 2000 and 3000 species of rodentâroughly half of all mammal species. Rodents are found in vast numbers on all continents except Antarctica (they are the only placental order other than bats (Chiroptera) to reach Australia without human introduction), most islands, and in all habitats bar the oceans.
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