A forelimb is an anterior limb (arm, leg, or similar appendage) on a terrestrial vertebrate's body. For quadrupeds, the term foreleg is often used instead. (A forearm however is the part of the arm or forelimb between the elbow and the wrist.)
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[a] are ultimately analogous, despite the large differences between them.
- de Beer, Gavin (1956). Vertebrate zoology: an introduction to the comparative anatomy, embryology, and evolution of chordate animals. Sidgwick and Jackson.
- Bat wings are however composed largely of a thin membrane of skin supported on the five fingers, whereas bird wings are composed largely of feathers supported on much reduced fingers, with finger 2 supporting the alula and finger 4 the primary feathers of the wing; there are only distant homologies between birds and bats, with much closer homologies between any pair of bird species, or any pair of bat species.
- "Image Gallery: Homo Sapiens. homology: homologies of the forelimb among vertebrates". Encyclopædia Britannica. Retrieved January 27, 2013.
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