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The locomotion of the elephant (which is the largest terrestrial vertebrate) displays a similar loading distribution on its hind limbs and forelimbs. [10] The walking and running gaits of quadrupeds and bipeds show differences in the relative phase of the movements of their forelimbs and hind limbs, as well as of their right-side limbs versus ...
All vertebrate forelimbs are homologous, meaning that they all evolved from the same structures. For example, the flipper of a turtle or of a dolphin, the arm of a human, the foreleg of a horse, and the wings of both bats and birds are ultimately homologous, despite the large differences between them. [1]
The development of the basic limb plan is accompanied by the generation of local differences between the elements. For example, the radius and ulna of the forelimb, and the tibia and fibula of the hindlimb of the zeugopod are distinct from one another, as are the different fingers or toes in the autopod.
The cranial pair (i.e. closer to the head) of limbs are known as the forelimbs or front legs, and the caudal pair (i.e. closer to the tail or coccyx) are the hindlimbs or back legs. In animals with a more erect bipedal posture (mainly hominid primates, particularly humans), the forelimbs and hindlimbs are often called upper and lower limbs ...
One of these changes is having longer hindlimbs proportional to the forelimbs and their effects. As previously mentioned, longer hindlimbs assist in thermoregulation by reducing the total surface area exposed to direct sunlight while simultaneously allowing for more space for cooling winds. Additionally, having longer limbs is more energy ...
In mice, however, both hindlimbs and forelimbs can develop in the presence of either Tbx4 or Tbx5. [14] In fact, it is the Pitx1 and Pitx2 genes that appears to be necessary for specification of the developing hindlimb, whereas their absence results in forelimb development. [15] Tbx4 and Tbx5 appear to be important specifically for limb ...
There are structural differences between the limb anatomy of plantigrades, unguligrades, and digitigrades. Digitigrade and unguligrade animals have relatively long carpals and tarsals, and the bones which correspond to the human ankle are thus set much higher in the limb than in a human. In a digitigrade animal, this effectively lengthens the ...
These anatomical modifications may have been a result of selection to overcome the lack of buoyancy experienced on land. The hindlimbs were smaller than the forelimbs and unlikely to have borne full weight in an adult, while the broad, overlapping ribs would have inhibited side-to-side movements. [10]