Final answer:
Bipedalism is the term for creatures that walk on two legs. This form of locomotion has prompted significant anatomical changes to balance on one leg at a time.
Step-by-step explanation:
The term used to describe a creature that walks on two legs is bipedalism. Bipedal locomotion involves one leg, the stance leg, supporting the body while it is on the ground, and the other, the step leg, moving through the air. For most of the time, bipedal organisms such as humans manage to balance themselves on just the stance leg. This form of locomotion has led to many anatomical adaptations since the earliest hominin ancestors to avoid falling while on a single leg. Creatures that walk on two legs can range from terrestrial to aerial, and include humans, birds, and some dinosaurs from the past. A creature that walks on two legs is commonly referred to as a biped. Bipedal locomotion is the ability to move using only two legs, with one leg on the ground while the other leg is in motion.