One of the most misguided and silliest notions that some creationists have about the theory of evolution is that if it's true, we should find all kinds of chimeric animals that are a mishmash of parts of unrelated species. While the "crocoduck" is by far the most infamous example, creationists have ridiculed evolution with numerous others (such as a bird with a lizard's head or a buffalo with wings...)
They are, of course, attacking a straw man here. Something that the theory of evolution in no way predicts. (In fact, if such a chimeric animal were to be found, it would seriously question the theory of evolution and give more credence to the possibility of animals having been made as they are via some other, completely different mechanism.)
However, even a blind squirrel finds a nut once in a while, as the saying goes. One of those "ridiculous" chimera that some creationists have sometimes presented to mock the theory of evolution is a fish with legs. There are even some such pictures made where the legs are pretty short, resembling those of a small reptile.
Well, what do you know. In this particular instance this actually is something the current scientific understanding of the evolutionary history of life on Earth has predicted: Fish with some kind of proto-legs that could crawl on land. For once the creationists understood something about evolution correctly (even if it wasn't really the result of actually studying the subject.)
And what do you know, years after the first of those caricatures had been made, fossils of fish with proto-legs have been found. Morphological and anatomical analysis of these limbs strongly suggests that they were indeed used for crawling on land. They also are morphologically similar to modern tetrapod limbs (ie. with similar bone structure), giving strong evidence for the evolutionary history of land tetrapods from fish.
For once creationists got one of the "if evolution is right, then we should find one of these" claims right. And we have found them, thank you very much.