Mice, rats, gerbils, and relatives is the largest, most diverse, and most widespread group of rodents in the world. With more than 1500 species, it also represents about 38% of all mammal species in the world! This is an exceptionally diverse group, with all kinds of lifestyles, body sizes, and habitats represented. Members of this group are found throughout the world, except for Antarctica, New Zealand, and some small oceanic islands. Most members of this group are small mice and rats.
Tanya Dewey (author), Animal Diversity Web.