Tiktaalik has dominated a lot of the media discussion about evolution in the last few years.  For those who don't know, Tiktaalik is a fossil "fish-o-pod" found in Canada, that is claimed to be an "intermediate form" between fish and early tetrapods (tetrapods are four-limbed creatures).  In addition, it was claimed that it was in the evolutionary-correct position in the fossil record for the fish-tetrapod transition (late Devonian). 

Now, the basic problem in Tiktaalik is that it isn't "transitional" so much as mosaic - that is, it has features of "earlier" and "later" creatures, but no features that might be considered "in transition".  Each feature that it has, it has fully. This indicates that, if it did "evolve", it did so non-Darwinistically - that is, the information seems to have already been in the gene pool, and was merely activated.  On the other hand, in absense of a mechanism of macroevolution, there is no reason to think that it evolved at all.  And from a flood geology perspective it gets even more interesting, but I'll leave that for the moment.

In addition to all this, there is a certain kind of criticism that emerges from lay people that you don't tend to find among experts.  That criticism is of the form of "is this really all the information there is?  Does it really add up the way you say it does?  Is it not possible that there is other evidence out there that you just haven't found yet - perhaps because you weren't looking for it?"

Now, this kind of criticism is usually just ignored by experts, but I personally think that it is epistemologically valid, and an important part of public discourse.  The fact is, every discipline needs to be confident in its own ability to find truth.  However, equally important, is that the public should not grant each discipline the same amount of credulity that it grants for itself.  A discipline can't go anywhere if it has to spend all its days proving its assumptions.  On the other hand, if you can't prove your assumptions fully, then your findings are not binding on others.  If someone has a larger worldview, then different aspects may be in competition.  Why should a person give up belief X which is important to them and which they believe they hold validly, when they don't agree with the assumptions of contradictory belief Y, especially if it is relatively unimportant to their daily lives?

The reason I say all of this is that, in the case of Tiktaalik, it is the lay criticism that wound up being correct.  Let's look at a new article that came out in Nature.  For those of you who are not nature subscribers, here is a short news article on the subject.

What they found is, according to evolutionary timescales, a full-fledged tetrapod existed about 20 MILLION years prior to Tiktaalik.  While Tiktaalik was a transitional, this thing was fully-tetrapod. So, this blows any story about Tiktaalik and evolution completely out of the water.  Tiktaalik has nothing to do with the evolution of tetrapods, because, if evolution is correct, full-blown tetrapods predated the transitional species by about 20 million years.

It's dangerous to put your faith in circumstantial evidence, because the facts can change that quickly.  Yesterday it was an open-and-shut case for Tiktaalik being found right where it was supposed to be in evolutionary transition.  Today, it is more than 20 million years out-of-date.  I say "more than" because, according to evolutionary theory, the tetrapods would have still required time to evolve before this creature existed.

So here's where it gets really interesting - the new find is footprints.  Here's a few things that don't usually get a large mention in introductory textbooks:

1. There are large gaps (sometimes a hundred million years) in the fossil record where a given species must have existed but did not leave any fossils.  Two examples are the Wollemi pine and the Coelacanth.  These were last seen in the fossil record 150 and 65 million years ago, respectively, yet they still live today.
2. Many measures of the fossil record show that it is relatively complete
3. Most creatures are first known from trace fossils (i.e. footprints or other types of trackways) long before we ever see their body fossils.

The interesting implication of #1 is that there is NO WAY AT ALL to infer from the fossil record how long something has been in existence.  If we can verify that the fossil record can be off 100 million years in one direction, if we assume that the same thing can happen in the other direction, then that means that you have a possible margin of error of about half of the phanerozoic era (the phanerozoic is the complete fossil-bearing section of the fossil record).  How can you possibly have a detailed evolutionary progression when you can have this kind of discrepancy between fossil evidence and reality?  If the best you can do is establish which half of the geologic column they existed in, how good is your data, and how are you going to derive evolutionary expectations from it?

Let's look at the second idea - that the fossil record actually seems complete.  There are many ways of measuring completeness.  The interesting thing is that most of them point to the fossil record being essentially complete, at least to the biological "family" level.  That doesn't mean that we won't find anything new, just that we've probably found more than we haven't.  So, this makes an interesting corrective to the preceding paragraph.  Maybe the completeness of the fossil record gives us confidence that most of the extents of organisms are well-represented in the fossil record, and these two (and some others) are merely anomalies.  That could almost work, except...

Why on earth do trace fossils precede body fossils?  As the Nature article on Tiktaalik points out:

Trace fossils — footprints, trackways or trails — are fascinating but often frustrating sources of information. Body fossils of the track makers almost never occur in the same rock beds, so complicating interpretation.

It is much harder to preserve a trackway than a bone.  So why do we know most organisms by trace fossils before we know them as body fossils, and why are the two rarely found in the same rock beds?

The answer, perhaps, is contained in an old Creation-oriented paper titled Stratigraphic Distribution of Vertebrate Fossil Footprints Compared with Body Fossils

In this paper, Brand and Florence argue that the reason for this is that it evidences fleeing behavior.  The flood didn't happen all at once.  It waxed and waned until it covered the earth, which didn't happen until day 150.  Until then, the increasing floods would still have had tides from the moon, and gone in and out over increasing landmasses.  Therefore, if there is a footprint, it is probably of a living creature, not a drowning one.  If there is a body fossil, it is probably a drowned creature.  So if the waters had temporarily receded, new trackways could be lain.  When the waters come back and deposit a new layer, they are killing off organisms into a different rock bed.

Also, as Kurt Wise has pointed out recently, if the fossil record is of a global flood, we should expect much more completeness than the evolutionists.

In any case, this is getting to be rambling.  My main point is that this new fossil find has very interesting implications for both creationists and evolutionists, and tends to validate thought-patterns of lay critics of evolution.

UPDATE:

I wrote this last night but forgot to publish it.   In the meantime, several other people have chimed in on the new tracks:

• Todd Wood points to another recent article by Kurt Wise in Answers Magazine which visits the ground as Brand and Florence.
• David Coppedge gives nice pull-quotes from several news sources, and points out that the researchers noted that many tracks in even older sediments may have been misinterpreted, and may be tetrapods as well. One thing that is interesting to note is that these older tracks have been with us the whole time, and the reason they were not interpreted as tetrapods is that tetrapods weren't expected to have been alive at that time.  It is always fascinating the ways that our minds work - in many cases only by believing in the credibility of something beforehand are we able to find the evidence that supports that.
• Finally, Casey Luskin points out that Neil Shubin has made a whole lot of hoopla about Tiktaalik being in just the right place at just the right time.  This blows Neil's whole theory out of the water, completely.  This whole incident reminds me of a line out of Ocean's 11.  Right after Rusty reveals that Benedict's video surveillance of his own vault is rigged, and he is actually in the middle of being robbed, he says "In this town, your luck can change just that quickly."