Dear aspirant,

Homologous structure refers to those organs or body part which appear to be very similar but they differ in their function. The homologous structure supports the idea that different animal descents belong to common ancestor and serve as an evidence of Evolution.

For example.

Bird's wing , cat's leg and human's arm are considered as homologous structure demonstrating that these creatures have common ancestors.

Tailbone in human beings is also homologous structure.

There is equal number of neck bones(7) in giraffe as in giant whale and tiny human.

Human beings , dogs and cats have similar pelvises.

The homology was later on explained by Charles Darwin in his theory 'Theory of evolution'