Tripedalism (from the Latin tri = three + ped = foot) is locomotion by the use of three limbs. Real-world tripedalism is rare, in contrast to the common bipedalism of two-legged animals and quadrupedalism of four-legged animals. The code for bilateral symmetry seems to have become entrenched very early in evolution, appearing even before appendages like legs, fins or flippers had evolved; with that template came a built-in bias toward even-numbered limb configurations.[2]
- ^ Melody W. Young, Edwin Dickinson, Nicholas D. Flaim and Michael C. Granatosky (2022). Overcoming a ‘forbidden phenotype’: the parrot’s head supports, propels and powers tripedal locomotion, Proceedings of the Royal Society B: Biological Sciences, 20220245, https://doi.org/10.1098/rspb.2022.0245
- ^ Tracy J. Thomson (2019) Three‐Legged Locomotion and the Constraints on Limb Number: Why Tripeds Don’t Have a Leg to Stand On, BioEssays 41 (10): 1900061 https://doi.org/10.1002/bies.201900061