Flippers of Penguins and Dolphins are examples of

The anatomically different structures evolved towards the same function due to adaptations to similar needs or similar habitats. This is called the convergent evolution because anatomically dissimilar and origin-wise different structures converge towards the common function. Hence, analogous structures are the result of convergent evolution.

Flippers of Penguins and Dolphins: Penguin (a bird) and Dolphin (a mammal), both have flippers that serve the common function of swimming although have different internal structures and origins.