Toe walker

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Skeleton specimen of a house cat in a natural position. Note the raised proximal elements of the anatomical hand or foot, which function as part of the arm or leg.
Sole of the right hand of a domestic dog . Hairless and horny are only the weight-bearing fingers and the area of ​​the wrist (carpal ball, E). The ball of the finger (B) cushions the distal phalanx and the ball of the hand (C) cushions the proximal phalanx and the transition to the metacarpal.

Toe walkers are terrestrial vertebrates that only touch the ground when moving via the acropodium ( fingers or toes ). This type of locomotion is also called digitigrad e gait (from the Latin digitus "finger", gradi "walking") or digitigradie .

It is realized by the more or less elongated metapodium (metapodium or metatarsus) acting as an extension of the arm or leg and the wrist or ankle taking on the role of a second elbow or knee joint, or in other words: the proximal joint Elements of the anatomical hand or the anatomical foot are the distal elements of the functional arm or functional leg . Well-known examples of toe walkers are dogs , cats , birds and the extinct non-avian theropods (see also →  Arctometatarsus ). In contrast to mammals, the digitigrady of theropods and birds is limited to the hind extremities due to their obligate bipedia .

Animals with a digitized gait are usually good and fast runners, not least because the length of the stride is relatively large due to the lengthening of the functional arm or leg, so that a relatively long distance can be covered with each step. With the cheetah , the toe walkers are the fastest land vertebrate on earth.

Unlike toes goers touched during peak goers only the last finger or toe element in sole-goers the whole hand or the whole walk the floor.

literature

  • Christopher McGowan: The Raptor and the Lamb - Predators and Prey in the Living World , Penguin Books, London 1998, ISBN 0-14-027264-X
  • P. David Polly: Limbs in mammalian evolution. Pp. 245-268 in: Brian K. Hall (Ed.): Fins into Limbs: Evolution, Development, and Transformation. University of Chicago Press, Chicago 2007, ISBN 978-0-226-31336-8
  • Wilfried Westheide, Reinhard Rieger (Hrsg.): Special zoology. Part 2: vertebrates or skulls. 2nd Edition. Spectrum Academic Publishing House, Berlin / Heidelberg 2010, ISBN 978-3-8274-2039-8