So another missing link has been found. It's indeed a refutation of the intelligent designists' complaint that there are no transitional fossils, but don't expect them to admit that. They have the benefit of Zeno's wisdom, even if they don't realize it.
Zeno lived in Greece, Elea to be specific, about 450 bce. He showed how you can never get here from there, by means of a story about Achilles and a tortoise. Tiktaalik isn't quite a tortoise, with a head that looks like a particularly ugly catfish-crocodile, but the principle holds in evolution as well as in walking across a room.
To get from there to here, you have to first cover half the distance. Then you have to cover half that distance, and so on. There is always a distance to cover, and you have to cover half of it before the other half. So you can't ever cover the whole distance. The link I've provided gives the mathematical proof that you can get from there to here. I'll just say that at some point, that distance is less than you can cover in one stride, so you do it.
In the same way, the intelligent designists will stroke their beards, fiddle with their pipes, and declare that the truly transitional species, the real missing link, hasn't been found. We need a fossil whose fin/paw bones are a little more like fins or a little more like paws, splitting that distance in either direction.
Like Zeno, they'll always have a halfway that hasn't been found. So they'll always believe they're right. But Tiktaalik is one of the great mothers of us all. The distance has been bridged because we are here. Tiktaalik has her place in the evolutionary chain. The intelligent designists can't call on Zeno for help.
12 April: Welcome to those visiting from Tangled Bank!