Evolutionists claim that fish evolved to walk on land. And that also some animals on land went back into the water to become whales. Here is a video showing what evolutionists like to use as evidence for this, which is the lung fish.
The next video is an animation of how evolutionists believe whales evolved.
And the next video shows the problems involved with this kind of idea that evolutionists refuse to address.
Claiming that their theory is now a true proven fact with mountains of empirical evidence makes them feel smug enough so that they do not think they need to answer such questions. Basically implying the evolution has become an absolute.