It appears that adaptations in fish started to appear well before fish started to navigate dry land:-http://www.livescience.com/42525-early-fish-evolved-rear-legs.html?cmpid=556392-Earlier theories proposed that the limbs developed as the fish attempted to use dry land. This would make the current discovery an exaptation, which I define as an evolutionary event producing a change of no current usefulness, but a preparation for a future development, i.e., in this case walking on land. This is the type of finding that suggests guided evolution, and such events are all through evolutionary fossils.