Dispatches from the Culture Wars

The ID folks are relying on the ignorance of their followers, hoping that they will conflate "missing link" and "transitional form", which do not mean the same thing at all. First of all, the whole notion of a "missing link" is nonsense. No one fossil is going to be the one fossil that proves ancestry. What matters is the pattern of appearance that we find all over the place in the fossil record. So they look at one specific fossil, Archaeopteryx for example, and say, "There are some feathered dinosaurs that existed before this one, so it can't be the missing link.

But paleontologists don't care about "missing links", they care about patterns. Yes, there are many feathered dinosaurs in the fossil record now. Do we know which exact species gave rise to birds? Nope. And we never will. What we do know, based on the patterns found in a whole range of paleo-species, is that the traits that define birds first developed in theropod dinosaurs. The fact that we have so many feathered theropods now means we can't be sure which exact species split off from which; it also means that the case that birds evolved from one of them is considerably stronger.

In the case of Tiktaalik, it's not one single missing link that shows the transition, it's a whole series of fossils showing the gradual development of all of the key diagnostic traits of amphibians from rhipidistian fish. Through a series of fossils from Panderichthys to the true amphibians (Amniator, Crassigyrinus, Colosteidae, etc), we can see the development of tetrapods from fish. We can basically "watch" the bones in the fins, the brain case, the nasal passages, and many other traits become gradually more adapted to life on land with each new species to appear - and they appear in precisely the right anatomical and temporal order that would be predicted by evolution. Indeed, that is why they were able to predict exactly the type and age of the deposits that Tiktaalik would be found in.

There simply is no rational explanation for this pattern other than common descent, regardless of whether we can define precise species-to-species ancestral relationships. Whether Elginerpeton split off specifically from Sauripterus or from another closely related species, it is the pattern of appearance that compels common descent as an explanation. But creationists want their followers to think that if we can't prove beyond a shadow of a doubt that species B came from species A, then there's no evidence for evolution. This is utter nonsense, and they know it's nonsense.

And what makes it all the more ridiculous is that the ID folks scream constantly that they're not creationists, that unlike creationists they can accept evolution as long as it's not purely materialistic. Yet they mimic the creationist arguments against common descent constantly. They just don't have a coherent argument on this at all.