Scientists classify organisms in a hierarchical scheme. Each of these categories is called a taxon. The taxon to which mammals belong is the Class Mammalia, which is in the Phylum Chordata in the Kingdom Animalia. Placing mammals in one Class indicates that they are more closely related to one another than any mammal is to an animal in a different Class.
Mammals have many physical characteristics that make mammals distinct from other animals.
If you're interested in joining ASM, see our Membership in ASM section for details about the many benefits. ASM is also very proud of it's Mammal Image Library . It's an exhaustive collection of pictures of mammals which we make available to the public at very reasonable prices.