| Group | Number of described species | Examples |
|---|
| PROTOTHERIANS | | |
| Monotremes (Monotremata) | 5 | Echidnas, duck-billed platypus |
| THERIANS | | |
| Marsupials | | |
| Diprotodonts (Diprotodontia) | 146 | Kangaroos, wallabies, possums, koala, wombats |
| New World opossums (Didelphimorphia) | 93 | Opossums |
| Carnivorous marsupials (Dasyuromorphia) | 75 | Quolls, dunnarts, numbat, Tasmanian devil |
| Omnivorous marsupials (Peramelemorphia) | 24 | Bandicoots and bilbies |
| Shrew opossums (Paucituberculata) | 7 | Andean rat opossums |
| Marsupial moles (Notoryctemorphia) | 2 | Southern and northern marsupial moles |
| Microbiothere (Microbiotherea) | 1 | Monito del monte |
| Eutherians | | |
| Rodents (Rodentia) | 2,337 | Rats, mice, squirrels, woodchucks, ground squirrels, beaver, capybara |
| Bats (Chiroptera) | 1,171 | Fruit bats, echo-locating bats |
| Even-toed hoofed mammals and cetaceans (Cetartiodactyla) | 469 | Deer, sheep, goats, cattle, antelopes, giraffes, camels, swine, hippopotamus, whales, dolphins |
| Shrews, moles, and relatives (Soricomorpha) | 428 | Shrews, moles, solenodons |
| Primates (Primates) | 396 | Lemurs, monkeys, apes, humans |
| Carnivores (Carnivora) | 284 | Wolves, dogs, bears, cats, weasels, pinnipeds (seals, sea lions, walruses) |
| Rabbits and relatives (Lagomorpha) | 92 | Rabbits, hares, pikas |
| African insectivores (Afrosoricida) | 50 | Tenrecs, golden moles |
| Hedgehogs (Erinaceomorpha) | 24 | European hedgehog |
| Armadillos (Cingulata) | 21 | Giant armadillo, nine-banded armadillo |
| Tree shrews (Scandentia) | 20 | Pygmy tree shrew, pen-tailed tree shrew |
| Odd-toed hoofed mammals (Perissodactyla) | 16 | Horses, zebras, tapirs, rhinoceroses |
| Elephant shrews (Macroscelidea) | 15 | Elephant shrews, jumping shrews, sengis |
| Anteaters, sloths (Pilosa) | 10 | Anteaters, tamanduas, two- and three-toed sloths |
| Pangolins (Pholidota) | 8 | Asian and African pangolins |
| Hyraxes and relatives (Hyracoidea) | 5 | Hyraxes, dassies |
| Sirenians (Sirenia) | 4 | Manatees, dugongs |
| Elephants (Proboscidea) | 3 | African and Indian elephants |
| Colugos (Dermoptera) | 2 | Flying lemurs |
| Aardvark (Tubulidentata) | 1 | Aardvark |