information on mammals
Groups
Scientists do not yet agree on the exact number of mammal groups, but there is proven to be at least 21 different types of mammals. Some of the better known mammal groups include the primates, marsupials, bats, cetaceans, carnivores, rodents, elephants, and ungulates. Lesser known mammals include the hyraxes, monotremes, pangolins, tree shrews, and insectivores.
Species
There are between 4,500 and 5,000 species of mammals. Of all mammal groups, the most diverse are the rodents which includes over 1,700 species. Other diverse mammal groups include bats (977 species), primates (356 species), insectivores (365 species), and marsupials (292 species). Mammal groups with the fewest number of species include the aardvark (1 species), dugongs and manatees (4 species), and the flying lemurs (2 species).
Features
Mammals have four limbs, a characteristic that places them among the group of animals known as tetrapods. It should be noted that although some mammals such as whales, dugongs, and manatees have lost their hind limbs during the course of evolution, they are tetrapods by descent. Mammals all also have eyes, noses, ears and lungs as humans do. All female mammals give birth to their babies also as humans do. They do not lay eggs.
http://animals.about.com/od/mammals/a/tenfactsmammals.htm
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Muller's Gibbon. |