Remember Tiktaalik (“Early tetrapod (“fishapod”) sheds light on transition to land—maybe ”), where post-hoopla, it turned out that other creatures’ tracks on land were found from 20 million years earlier?
The point was made that
The Polish trackways establish that Tiktaalik wasn’t anywhere near the first tetrapod, so the most important information about the transition to land doesn’t even include Tiktaalik at present. We need to find the creatures that made those tracks.
Some fish today routinely spend time out of the water, using a variety of mechanisms. But there is no particular reason to believe that they are on their way to becoming full time tetrapods or land dwellers. So we would need to be cautious about assuming that specific mechanisms that might be useful on land are definitive evidence of a definite, permanent move to full-time land dwelling.
A friend writes to point out a modern-day examples that illustrates this, the walking shark:
If this fish were found as a 500 mya fossil, it would be hailed as a transitional, but it is actually just occupying a niche from which it has no apparent intention of giving notice.
Of course there were transitionals, but the problem is, there are so many niches along the way that it’s going to take far more information than we have now to identify them with anything like the certainty that the popular science media affixes to any given find.
The Attenborough version simply assumes that Tiktaalik (tic-TALL-ik) is “the first” of a long line of something special.
Really? Maybe Tiktaalik was the last instance of a failed lineage. Maybe it was the duck-billed platypus of its time, a survivor but unique. Maybe it was doing something unusual, and that how it got fossilized when other life forms didn’t. This Atten-free version is messier and leaves us with lots more questions, but it is more like histories we are personally familiar with: messy and leaves us with lots more questions.
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