The following tags are used to highlight each species' conservation status as assessed by the IUCN:
|EX||Extinct||No reasonable doubt that the last individual has died.|
|EW||Extinct in the wild||Known only to survive in captivity or as a naturalized populations well outside its previous range.|
|CR||Critically Endangered||The species is in imminent risk of extinction in the wild.|
|EN||Endangered||The species is facing an extremely high risk of extinction in the wild.|
|VU||Vulnerable||The species is facing a high risk of extinction in the wild.|
|NT||Near Threatened||The species does not meet any of the criteria that would categorise it as risking extinction but it is likely to do so in the future.|
|LC||Least Concern||There are no current identifiable risks to the species.|
|DD||Data Deficient||There is inadequate information to make an assessment of the risks to this species.|
Some species were assessed using an earlier set of criteria. Species assessed using this system have the following instead of Near Threatened and Least Concern categories:
|LR/cd||Lower Risk/conservation dependent||Species which were the focus of conservation programmes and may have moved into a higher risk category if that programme was discontinued.|
|LR/nt||Lower Risk/near threatened||Species which are close to being classified as Vulnerable but are not the subject of conservation programmes.|
|LR/lc||Lower Risk/least concern||Species for which there are no identifiable risks.|
Rodents make up the largest order of mammals, with over 40 percent of mammalian species. They have two incisors in the upper and lower jaw which grow continually and must be keep short by gnawing. Most rodents are small though the capybara can weigh up to 45 kg (100 lb).
The bats' most distinguishing feature is that their forelimbs are developed as wings, making them the only mammals in the world naturally capable of flight. Bat species account for about 20% of all mammals.
The order Cetacea includes whales, dolphins and porpoises. They are the mammals most fully adapted to aquatic life with a spindle-shaped nearly hairless body, protected by a thick layer of blubber, and forelimbs and tail modified to provide propulsion underwater.
The carnivores include over 260 species, the majority of which eat meat as their primary dietary item. Carnivores have a characteristic skull shape and dentition.
The even-toed ungulates are ungulates whose weight is borne about equally by the third and fourth toes, rather than mostly or entirely by the third as in perissodactyls. There are about 220 artiodactyl species, including many that are of great economic importance to humans.
Didelphimorphia is the order of common opossums of the Western Hemisphere. Opossums probably diverged from the basic South American marsupials in the late Cretaceous or early Paleocene.They are small to medium-sized marsupials, about the size of a large house cat, with a long snout and prehensile tail.