Bipedalism is locomotion on two legs. Among living forms, birds and humans are exclusively bipedal.

Keywords: locomotion; birds; dinosaurs; hominids; adaptation

Figure 1.

Biomechanics of bipedalism. Top: elements of the stride cycle. Middle: inverted pendulum model of walking. Bottom: spring‐like model of running. CM refers to the body's centre of mass.

Figure 2.

Evolution of bipedalism in archosaurs. Key features are plotted on the phylogeny to reconstruct when they originated. Illustrated skeletons are modified from Carroll RC (1988) Vertebrate Paleontology and Evolution. New York: WH Freeman; following Gatesy (1990).

Figure 3.

Evolution of bipedalism in hominids. Key features are plotted on the phylogeny to reconstruct when they originated. It is unclear when the most derived features of human bipedalism evolved, but they were clearly present in Homo erectus and later hominids. Illustrated skeletons are modified from Norman D (1994) Prehistoric Life. New York: Macmillan.


Further Reading

Alexander RMcN (1989) The Dynamics of Dinosaurs and Other Extinct Giants. New York: Columbia University Press.

Coppens Y and Senut B (eds) (1991) Origine(s) de la Bipédie Chex les Hominidés (Cahiers de Paléoanthropologie). Paris: Editions du CNRS.

Gatesy SM (1990) Caudofemoral musculature and the evolution of theropod locomotion. Paleobiology 16: 170–186.

Gatesy SM and Biewener AA (1991) Bipedal locomotion: effects of speed, size and limb posture in birds and humans. Journal of Zoology 224: 127–147.

Hutchinson JR and Gatesy SM (2000) Adductors, abductors, and the evolution of archosaur locomotion. Paleobiology 26: (in press).

Leakey M and Hay RL (1979) Pliocene footprints in the Laetoli beds at Laetoli, north Tanzania. Nature 278: 317–323.

Lovejoy CO (1988) Evolution of human walking. Scientific American 259(5): 118–125.

Rose J and Gamble JG (eds) (1994) Human Walking. Baltimore, MD: Williams & Wilkins.

Sereno PC (1991) Basal archosaurs: phylogenetic relationships and functional implications. Journal of Vertebrate Paleontology 11 (4 supplement): 1–53.

Tuttle RH (1975) Primate Functional Morphology and Evolution. Paris: Mouton & Co.

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How to Cite close
Hutchinson, John R, and Gatesy, Stephen M(Apr 2001) Bipedalism. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1038/npg.els.0001869]