What are homologous structures ?


What are homologous structures ? Give an example. Is it necessary that homologous structures always have a common ancestor ?


Homologous structures or organs are those structures which have similar origin, similar development, similar internal structure and similar basic plan

but show different external form and function, e.g., forelimbs of amphibians, reptiles, mammals and birds. Homologous structures are always have

a common ancestry because otherwise there cannot be any similarity in basic plan, internal structure, development or origin. Modifications have

occurred in them due to varied adaptations.

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