New technologies show Panderichthys and Tiktaalik on the way to living on land

In a recent paper in Nature, Catherine A. Boisvert, Elga Mark-Kurik, and Per E. Ahlberg show how a prehistoric fish, Panderichthys who lived 385 million years ago, had bone structure that resembles animal digits instead of typical fin architecture. It appears that there is some debate among paleontologists as to the when “fingers” first arose and this paper pushed the date back. It had previously been hypothesized that digits arose from an extrapolation of prehistoric fin structure. However, fossil evidence of Panderichthys and similar fish had indicated that they do not have any such digit bones. However, more advanced technology used in this paper has revealed that Panderichthys_BWat Panderichthys does in fact have these features.

The authors used CT scanning and analyzed a largely undisturbed fin (except when it got smashed upon excavation!) to be able to see inside the fossil. Previously, imperfect fossils and the remains of the fish’s scales did not allow researches to see these bones.

These early fish having these fingerlike digits is not wholly unexpected. In fact, the presence of these bones in the closely related lobe-finned fish Tiktaalik pointed in this direction. Furthermore, the presence of certain developmental genes (hox genes) that are involved in digit development in related present day fish nearly predicted it.

Changes in the details of our knowledge of evolution are what makes science the best way to understand the world. The scientists here resolved some contradictory evidence of where early digits arose evolutionary. At the same time, they proved other scientists wrong. There is nothing wrong with this and it shows the strength of the scientific approach.

The Discovery Institute does not see it that way. They believe that scientists are now backpedalling to try fix some imaginary mistake that they say scientists made. Take for instance, Casey Luskin’s blog post from September 26, 2008 entitled: The Rise and Fall of Tiktaalik? Darwinists Admit “Quality” of Evolutionary Icon is “Poor” in Retroactive Confession of Ignorance.

The first point I want to make is that scientists are not at all one cohesive group with the same exact goals. In fact, scientists working on similar subjects are actually competitors. They compete for money, resources, talent, and recognition. In many respects and unfortunately, it benefits one group for a competitor to be proven wrong. So when Luskin takes a quote from one scientist that contradicts what another said, it does not mean that scientists are engaging in “Retroactive confessions of ignorance.”

Besides, when the article published in 2006 describing Tiktaalik as an example of a transitional fossil, they plainly stated that they do not know the state of Panderichthys’ limb structure.  From the article:

Unfortunately, the distal region of the best-known pectoral fin of the elpistostegid Panderichthys is covered by lepidotrichia and the complete distal endoskeleton is unknown

Perhaps Luskin should have actually read the article that he is referring to when making such claims.  The paleontologists were upfront and honest with their ignorance at the time.

So what is the big problem with “Retroactive confessions of ignorance” anyway?  Are scientists supposed to know everything from the beginning? New technologies or even new insights can tell us what we thought we knew was wrong. It can also tell us that there are things that we didn’t know we didn’t know.  Unlike intelligent design/ creation proponents, scientists are willing to change their minds when new facts and ideas emerge.

Getting back to Luskin’s post, he states:

My main observation is this: if Panderichthys is dethroning Tiktaalik as the icon of the fish-to-tetrapod transition, what does that say about all the hype we’ve seen surrounding Tiktaalik? It says that “poor” and “primitive” Tiktaalik was never all it was hyped up to be.

Tiktaalik is still a good example of a transitional fossil, but so is Panderichthys. Tiktaalik has other tetrapod features that tiktaalik_f from NSFPanderichthys lacks (including changes in skull and rib structures) pointing to it being closer to a tetrapod.  However, Panderichthys shows that fish may have evolved digit-like structures earlier than we previously thought.  Both a re important for our understanding and there was no “dethroning.”

Luskin did something semi-unethical in the post with his figure that compares Panderichthys with a “real tetrapod”. I can’t show the figures from the research article here because of copyright issues, but Luskin took two separate figures and put them together to show a comparison. However, the authors already had made a similar figure that compared not only Panderichthys to a “real tetrapod,” but includes a comparison to Tiktaalik and a more fishlike ancestor. I can only think that he did this to highlight differences to the untrained eyes, because the original figure is much more compelling. What makes his argument even more egregious is that Luskin does not show the very similar drawing from the original Tiktaalik paper that showed the fin bones of Panderichthys as large flat pieces.  Of course that would have disproved the whole “retroactive confession of ignorance.”

Of course, as is often the case with Luskin, that was not the only instance of questionable writing in his post.  His post was filled with the usual quote mining.  For example, he quotes Catherine A. Boisvert from a New Scientist article:

it is now completely proven that fingers have evolved from distal radials already present in fish that gave rise to the tetrapod.” Boisvert also praised her findings, stating: “The disposition of distal radials in Panderichthys are much more tetrapod-like than in Tiktaalik

Luskin makes it sound like Boisvert is ignoring the evidence brought to light by the discovery and analysis of Tiktaalik. Is this what she meant by her statement?  Lets see the original quote (emphasis is mine):

“The disposition of distal radials in Panderichthys are much more tetrapod-like than in Tiktaalik,” Boisvert wrote. “Combined with fossil evidence from Tiktaalik and genetic evidence from sharks, paddlefish and the Australian lungfish, it is now completely proven that fingers have evolved from distal radials already present in fish that gave rise to the tetrapod.”

Rather than bore you with more examples of quote mining, I will just finish with a couple questions:  Are there tetrapods located present at this time in history? Do Intelligent Design proponents have a better theory for the presence of these transitional fossils?

hat tip: JLT

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3 Responses

  1. The first part of your post was fascinating. You know, there’s lots of times when talking about creationist hacks is amusing, but when real science shows up, why mention irrelevent crackpot criticism and ideas?

    I think this is a fascinating development, and the only development that happened here is humanity knowing about natural history than it did before. This is not a victory for ignorance, it’s a crushing defeat.

  2. The original post said,

    –Besides, when the article published in 2006 describing Tiktaalik as an example of a transitional fossil, they plainly stated that they do not know the state of Panderichthys’ limb structure. From the article: “Unfortunately, the distal region of the best-known pectoral fin of the elpistostegid Panderichthys is covered by lepidotrichia and the complete distal endoskeleton is unknown”–

    Now I am really confused — what does Panderichthys’ distal limb structure got to do with Tiktaalik’s quality as an example of a transitional fossil? And how well-preserved are Tiktaalik’s limb structures? That’s what counts.

    I agree that Casey Luskin did some quote-mining but I think that he is partly right. Casey Luskin repeatedly implies that Tiktaalik is “poor” in general as fossil evidence of an evolutionary transition from fish to tetrapods. However, it appears that the Darwinists are not admitting that Tiktaalik is “poor” in general as such fossil evidence but are only admitting that Tiktaalik is poor as evidence of an evolutionary transition from fishes’ radial fin bones to tetrapods’ digital bones. Tiktaalik still has a lot of tetrapod-like features: a flat, crocodile-like head; a neck that can bend; a rib cage; and ear notches — see http://tiktaalik.uchicago.edu/meetTik.html That admission by Darwinists is certainly a big deal if they are making it for the first time, but Luskin should be clear as to exactly what they are admitting.

  3. “Wikipedia is biased against Christianity and conservative ideals.”

    This is because the truth is biased against Christianity and conservative ideals.

    You might like to send creationists here when then pipe up, It’s a tl;dr on the fossil issue: http://www.transitional-fossil.com.

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