bípedo

Bípedo is the term used in several Romance languages to describe an animal that walks on two legs. In English, the corresponding term is biped. A bípedo may refer to an organism that uses two legs for locomotion as its normal mode (habitual biped) or to an individual that can walk on two legs in certain contexts (facultative biped). This concept is a key distinction in locomotion biology and body-plan classification, separating two-legged gait from quadrupedal and other forms of movement.

Habitual bipeds consistently rely on two limbs for standing and walking, often with an upright posture. Birds are a prominent biological example: their locomotion typically involves two legs, with forelimbs adapted as wings. Humans are another well-known habitual biped, with a pelvis, limb arrangement, and foot mechanics specialized for upright walking. Some extinct animals, notably many theropod dinosaurs, are interpreted as habitual bipeds, and birds evolved from such theropods, inheriting their bipedal gait.

Facultative bipeds can alternate between two- and four-legged locomotion. Among living mammals, this is seen in certain primates and other species that adopt a two-legged stance briefly, usually for reaching or carrying objects, before returning to a quadrupedal gait. Kangaroos represent another form of obligate bipedal locomotion, moving primarily on two hind limbs.

Locomotion as a bípedo involves biomechanical adaptations in the spine, pelvis, leg joints, and feet. Advantages of bipedalism include forelimb freedom and an elevated view, while challenges include energy costs on uneven terrain and balance maintenance.