This was a discovery funded by the National Science Foundation, for whom work, I have the original hand drawn picture hanging in my office. Credit to Zina Deretsky
I learned in university that the first fish with 4 legs were fully aquatic. They developed them to walk on the ground of the ocean and later used them on land. That would make it a pre-adaptation. So the drawing has the evolutionary steps wrong. Would you agree on it? I'm just curious