Tiktaalik has turned out to be an epic fail for evolution.
After Tiktaalik was found fossil footprints were found that predated it in the Zachelmie Quarry. This shows that the data on which the prediction was based was wrong and hence the finding of Tiktaalik was simply fortuitous, and destroys the claim of predictive capacity.
Not really, no. They went looking for rocks in a time window of about 20 million years that they expected to find the tetrapodal transitional forms. And they ended up finding those forms in that time window . That early tetrapodal forms were also found 10-20 million years earlier than this does not break the prediction that tetrapodal transitionals should be found in the twenty million year window just before full tetrapods were found. It turns out they are found in a 40 million window before that. Nobody predicted this. But then it isn't like failing to predict one thing means you failed to predict another. That would be like saying 'I predicted Trump would win the Presidency' is undermined by failing to predict it would only last 6 months.
The prediction was that early tetrapodal forms would appear between the earliest known Rhipidistia (410million years ago) and creatures such as Ichthyostega (360 million years ago). So the full window of opportunity is actually 50 million years - the prediction was that basically in the middle of these two periods was the best place to find the transitionals, but mostly anywhere in there would be fine as far as natural history is concerned - but there'd likely be some gap after Rhipidistia to allow for evolution to actually occur! It turns out that it was on the early side of things, meaning there wasn't as big a gap between Rhipidistia and early tetrapodal forms as had been expected - but it didn't break an prediction.
The palaeontologist David Raup wrote
That phyletic gradualism isn't what we find, which he regards as Darwin's notion of evolution - although Darwin never committed to it and even suggested wasn't the case. His final argument was that evolution obviously happened, and Darwin's theory explains
some of the how but is insufficient to explain the whole thing. But you know, that's a pretty well established concept at this point. We don't slavishly follow Darwin. He isn't Pope Darwin the Infallible of Evolution.
Similarly whale evolution is looking very problematic since (a)Pakicetus was shown to be fully terrestial instead of the otter like creature originally postulated
Using evidence to better update our understanding of natural history from speculative drawings on the cover of magazines is not a problem for evolution. But exploring your 'problems' with natural history takes us wildly off topic regarding the definition of evolution.
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