Quadrupedalism or pronograde posture is a form of terrestrial locomotion in animals using four limbs or legs. An animal or machine that usually moves in a quadrupedal manner is known as a quadruped, meaning "four feet" (from the Latin quattuor for "four" and pes for "foot"). The majority of quadrupeds are vertebrate animals, including mammals such as cattle, dogs and cats, and reptiles such as lizards.
Quadrupeds vs. tetrapods
Although the words quadruped and tetrapod are both derived from terms meaning "four-footed", they have distinct meanings. A tetrapod is any member of the taxonomic unit Tetrapoda (which is defined by descent from a specific four-limbed ancestor) whereas a quadruped actually uses four limbs for locomotion. Not all tetrapods are quadrupeds and not all quadrupeds are tetrapods.
The distinction between quadrupeds and tetrapods is important in evolutionary biology, particularly in the context of tetrapods whose limbs have adapted to other roles (e.g. hands in the case of humans, wings in the case of birds, and fins in the case of whales). All of these animals are tetrapods, but none is a quadruped. Even snakes, whose limbs have become vestigial or lost entirely, are nevertheless tetrapods.
Most quadrupedal animals are tetrapods but there are a few exceptions. For instance, among the insects, the praying mantis is a quadruped.
In July 2005, in rural Turkey, scientists discovered five Kurdish siblings who had learned to walk naturally on their hands and feet. Unlike chimpanzees, which ambulate on their knuckles, the Kurdish siblings walked on their palms, allowing them to preserve the dexterity of their fingers.
Many people, especially practitioners of Parkour and Freerunning and Georges Hébert's Natural Method, find benefit in quadrupedal movements to build full body strength. Kenichi Ito is a Japanese man famous for speed running on four limbs.
Also by NASA JPL, in collaboration with University of California, Santa Barbara Robotics Lab, is RoboSimian, with emphasis on stability and deliberation. It has been demonstrated at the DARPA Robotics Challenge.
- Naish, Darren (2008-12-03). "B. rex! – Tetrapod Zoology". Scienceblogs.com. Retrieved 2014-06-10.
- "Family Walks on All Fours, May Offer Evolution Insight, Experts Say". National Geographic. 8 March 2006.
- "Science May Finally Explain Why This Family Walks On All Fours". Huffingtonposts. 17 July 2014.
- "Time-warp family who walk on all fours". Daily Mail. 8 March 2006.
- Türkmen S, Demirhan O, Hoffmann K, et al. (May 2006). "Cerebellar hypoplasia and quadrupedal locomotion in humans as a recessive trait mapping to chromosome 17p". J. Med. Genet. 43 (5): 461–4. doi:10.1136/jmg.2005.040030. PMC . PMID 16371500.
- "MovNa t".
- Swatman, Rachel (12 November 2015). "Video: Watch Japan's Kenichi Ito scamper to GWR Day success with fastest 100 m running on all fours". Guinness World Records. Tokyo.
- "BigDog - The Most Advanced Rough-Terrain Robot on Earth". Boston Dynamics. Retrieved 2011-04-06.
- "DARPA Robotics Challenge, RoboSimian (Track A)". JPL Robotics. Retrieved 2016-03-07.