Answer: Rodents

The mammal family tree is vast, but there are no creatures in the tree more numerous in both the number of species and the sheer number of individual creatures than the Rodentia order, which is comprised of all of Earth’s numerous rodents.

There you’ll find mice, rats, hamsters, gerbils, squirrels, beavers, chinchillas, capybaras, and prairie dogs, among other rodents, and the numerous variations of each. Rodents are naturally found on every continent except Antarctica and, barring there, New Zealand and a handful of islands.

All told, rodents comprise a little over 40 percent of the entire mammalian family tree and significantly outnumber their nearest prolific cousins, the bats and Soricomorpha (shrews and allies).