Conversation so far:
What are mammals?
Mammals are vertebrate animals constituting the class Mammalia, and characterized by the presence of mammary glands which in females produce milk for feeding their young, a neocortex, fur or hair, and three middle ear bones.
What are mammals' key characteristics?
On the following slides, you'll learn about the eight main mammal characteristics, ranging from hair to four-chambered hearts.Hair and Fur. ...Mammary Glands. ...Single-Boned Lower Jaws. ...One-Time Tooth Replacement. ...Three Bones in the Middle Ear. ...Warm-Blooded Metabolisms. ...Diaphragms. ...Four-Chambered Hearts.

Question: How many legs do they have
Self-contained rewrite: How many legs do mammals have?