Looking at Mammals
Mammals are vertebrates (ver-ta-brits), meaning they have a backbone and are warm-blooded. Humans are mammals, one of the newest species of mammal on the planet. Mammals can be found nearly everywhere on earth, both on land and in water (and even in the air, because bats are mammals, too!). Mammals are the only animals with hair, like the hair covering an otter's body or like the hair on your head. Some mammals walk around on two legs, like people, while others walk around on four legs, like dogs and cats.
Another thing that sets mammals apart is a layer of tissue the wraps around the outside of the brain. This part of the brain is called the neocortex ("neo" means "new," which refers to the more recent development in history of that part of the brain). Mammals are some of the most diverse types of animals on the planet. Sloths, polar bears, bats, humans, elephants, goats, and many others all belong to this group.
