The 
                  order Rodentia, the "gnawing" mammals, contains over 
                  40% of all species in the class Mammalia. A consistent diagnostic 
                  character for all rodents is an upper and lower pair of arc-shaped 
                  chisel-edged incisors. Rodents have adapted to most habitats 
                  and include terrestrial, fossorial, saltatorial, arboreal, gliding, 
                  and semiaquatic forms. They range in size from the smallest 
                  mice, weighing only a few grams, up to the largest living rodent, 
                  the capybara, weighing up to 50 kilograms. Most rodents are 
                  primarily omnivorous, feeding on bark, grass, seeds, other vegetation, 
                  insects and other animal matter. With a few exceptions, an external 
                  tail is present, but its form and length vary greatly. Rodents 
                  are well haired over most of their body. Most are quadrupedal, 
                  but some arid-land species have greatly enlarged hind limbs, 
                  and are capable of ricochetal locomotion. The distribution of 
                  rodents is almost worldwide. They are native to most land areas 
                  except some Arctic and oceanic islands, New Zealand and Antarctica.
                 
                  
                
                SUBORDER 
                  SCIUROMORPHA  
                  Family Aplodontiidae
                   
                
                Family 
                  Sciuridae
                  Subfamily Sciurinae
                  Tribe Sciurini  
                
                Tribe 
                  Pteromyini