A quadruped is any animal that walks on four legs. The word comes from Latin roots meaning “four feet.”

Dogs, cats, horses, elephants, and deer are all quadrupeds. So are mice, lions, and rhinoceroses. When you watch a squirrel scamper across your yard or see a cow grazing in a field, you're watching quadrupeds in action. Most mammals are quadrupeds, using all four legs to walk, run, climb, or gallop.

Humans are not quadrupeds because we walk upright on two legs, making us bipeds instead. Birds are also bipeds, walking on two legs while their wings serve a different purpose. Insects have six legs, so they're not quadrupeds either.

Scientists who study animal movement notice that quadrupeds can run faster and more steadily than bipeds. A horse's four-legged stance gives it better balance and power.

When a human baby crawls on hands and knees, people sometimes joke that the baby is being a quadruped, even though technically the baby is using hands, not four feet.