What is the Largest group of Mammals on Earth and how many are there?

Rodents make up the largest order of mammals, with the most number of species in their group.

There are over 2,277 species of rodents, or about 40 percent of mammal species belonging to the order. Their small size, a varied diet, and short breeding cycle have attributed to this success.

About half of all mammal species are in the order Rodentia, which includes such familiar animals as mice, rats, squirrels, chipmunks, moles, lemmings, and beavers.

Bats, another large group of mammals, come in second, with about 900 different species. Compare that with a pathetic 180 different species of primates.

Rats and bats are laughing at the lowly little primates while they steal our food and drink.