Dolphins are mammals, breath air, give birth and nurse their young ones. The ancestors of dolphins were animals that once lived on land but turned to the sea about 50 million years ago and never returned to land hence the dolphin’s ancestor had to slowly adapt to its new environment. Its front legs became flippers and its tail became flukes that it uses for swimming and steering respectively. The same bone structure is shared by bats, flying mammals in the order Chiroptera. While the trait for them was inherited from a common ancestor, the bones that form flippers in dolphins form a bat’s wings (homologous trait, example of divergent evolution) Its back legs diminished completely into the body. They have a layer of blubber beneath their