Dolphins have only lived in the water for 50m years or so, they still breathe air. They could re-adapt to the land in that kind of time frame easily.
Dolphins have only lived in the water for 50m years or so, they still breathe air. They could re-adapt to the land in that kind of time frame easily.
They'd still be dolphins in the same way that you are still a fish.
Also, I don't think you're right that they could do this easily. Their hind limbs have almost completely vanished, their pelvis too, and they have no chance of moving on land. To have a chance they would need to redevelop those things which they've lost, and I don't think there's a particularly plausible path where each step helps their survival at that step. In contrast, their four-limbed land adapted ancestors could swim much better than dolphins can walk.