TRIVIAL PURSUITS: What Is the Largest Group of Mammals?

The class Mammalia has approximately 4,660 species.

What is the largest group of mammals?


Rodents are the largest group of mammals, constituting almost half of the class Mammalia’s species.


Rodents, (order Rodentia), consist of any of more than 2,050 living species of mammals characterized by upper and lower pairs of ever-growing rootless incisor teeth.


According to the Encyclopedia Britannica, they are indigenous to every land area except Antarctica, New Zealand, and a few Arctic and other oceanic islands, although some species have been introduced even to those places through their association with humans. This huge order of animals encompasses 27 separate families, including not only the “true” rats and mice but also such diverse groups as porcupines, beavers, squirrels and chipmunks.