Bipedalism is a form of terrestrial locomotion where an organism moves by means of its two rear limbs, or legs. An animal or machine that usually moves in a bipedal manner is known as a biped ( /ˈbaɪpɛd/), meaning "two feet" (from the Latin bi for "two" and ped for "foot"). Types of bipedal movement include walking, running, or hopping, on two appendages (typically legs).

Relatively few modern species are habitual bipeds whose normal method of locomotion is two-legged. Within mammals, habitual bipedalism has evolved multiple times, with the macropods, kangaroo mice, dipodids, springhare, hopping mice, pangolins and homininan apes, as well as various other extinct groups evolving the trait independently. In the Triassic period some groups of archosaurs (a group that includes the ancestors of crocodiles) developed bipedalism; among their descendants the dinosaurs, all the early forms and many later groups were habitual or exclusive bipeds; the birds descended from one group of exclusively bipedal dinosaurs.

A larger number of modern species utilise bipedal movement for a short time. Several non-archosaurian lizard species move bipedally when running, usually to escape from threats. Many primate and bear species will adopt a bipedal gait in order to reach food or explore their environment. Several arboreal primate species, such as Gibbons and Indriids, exclusively utilise bipedal locomotion during the brief periods they spend on the ground. Many animals rear up on their hind legs whilst fighting or copulating. A few animals commonly stand on their hind legs, in order to reach food, to keep watch, to threaten a competitor or predator, or to pose in courtship, but do not move bipedally.

Read more about Bipedalism:  Definition, Movement, Bipedal Animals, Evolution, Physiology, Bipedal Robots

Other articles related to "bipedalism":

... public, providing convincing evidence of bipedalism in Pliocene hominids based on analysis of the impressions ... Dated to 3.6 million years ago they were also the oldest known evidence of bipedalism at the time they were found, although now older evidence has been found such as the Ardipithecus ramidus fossils ... excavated at Laetoli showed clear evidence that bipedalism preceded enlarged brains in hominids ...
Henry Mc Henry - Efficient Walker Theory
... to explain the evolutionary advent of bipedalism among hominids, McHenry and Peter Rodman have advanced the Efficient Walker theory, based on energetic analysis ... They concluded bipedalism was selected simply because it allowed for a further range of travel for hominids ... hominids were forced into the savannas, the scientists reason, bipedalism enabled greater access to resources ...
Laetoli - Interpretation and Significance
... in the evolutionary time line a larger brain or bipedalism ... to grassland environments has a strong correlation with upright posture and bipedalism in humans ... This could have initiated the evolution to bipedalism of the hominids found at Laetoli ...
Homininae - Evolution - Evolution of Bipedalism
... See also Human skeletal changes due to bipedalism Recent studies of Ardipithecus ramidus (4.4 million years old) and Orrorin tugenensis (6 million years old) suggest some degree of bipedalism ... ramidus may have possessed an arboreal type of bipedalism ...