- The largest living land mammal is the African bush elephant.
- The smallest living land mammal is the Etruscan shrew.
- Humans are the only mammal capable of learning language.
- Mammals are the only animals that produce milk.
- Mammals are the only known animals that regulate heat internally.
- The mammal brain is more developed than the brain of any other animal, and is responsible for a range of complex behaviors.
- Mammals have a diaphragm, a sheet of muscle that separates the thoracic cavity from the abdominal cavity.
- The mammalian heart has four chambers, two atria and two ventricles, separated by valves.
- Mammals are the only animals that have hair.
- The skin and furs of mammals come in many colors and patterns, which can be used for camouflage, social signaling, and temperature regulation.
- The teeth of mammals are adapted for the specific diet of each species, with some mammals having sharp teeth for tearing meat and others having flat teeth for grinding plants.
- Mammals have a well-developed sense of hearing and smell, which allows them to navigate and avoid danger.
- The skeletal structure of mammals is diverse and adapted for many different environments and modes of locomotion.
- Mammals are the most widely distributed group of animals, with some species found on all seven continents.