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The wings of pterosaurs (1), bats (2) and birds (3) are analogous: they serve the same function and are similar in structure, but each evolved independently.

Two structures in biology are said to be analogous if they perform the same or similar function by a similar mechanism but evolved separately. Similar structures may have evolved through different pathways, a process known as convergent evolution, or may be homologous.

The concept of analogy is contrasted with that of homology, which refers to two structures that share a common ancestor and share basic structure. Homologous structures may retain the function they served in the common ancestor or they may evolve to fulfill different functions for example, the wings of birds versus the forelimbs of mammals.

[edit] See also

Evolutionary biology portal

[edit] References

[edit] External links

• Pictures of analogous and homologous structures (Archived 2009-10-31) at MSN Encarta

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