Insect wings may have begun to evolve as lateral extensions of the body that were used as heat dissipaters for thermoregulation. When they had become sufficiently large, these extensions became useful for gliding through the air. Additional selection refined them as flight- producing wings. If this hypothesis is correct, modern insect wings would be an example of .

Exaptation

Explanation:

In this example, the lateral extensions that developed were meant for thermoregulation.

But these became sufficiently large to support gliding through the air and later on were used for flight.

Thus the structure assumed a function for which it was not meant and its original function shifted to a completely different dimension giving rise to modern insect wings. So we can say that this is an example of Exaptation.