"walking" dolphin???

Once again, I'm a few days late in talking about "current events", but have you seen this story about the dolphin with an additional set of hind fins? Evolutionists are jumping all over this as an "unprecedented discovery". I'm definitely no scientist, but can't we use a little common sense here? Why is this mutation (a rare exception to the rule of typical dolphin anatomy) hailed as a monumental evolutionary discovery and "evidence" that dolphins used to walk on land? What about an extremely rare case where a human is born with no arms? Is that evidence that millions of year ago our bodies were more streamlined like dolphins and proof that humans once lived in the ocean? Come on. Boooo scientists grasping for straws. Hooray lucky dolphin with extra fins!