On evolutionnews.org, lawyer Casey Luskin, ‘argues’ that Tiktaalik as an evolutionary icon is poor, in a retrospective confession of ignorance. Let’s see how he reached such a ‘conclusion’.
Casey Luskin wrote:
The Rise and Fall of Tiktaalik? Darwinists Admit “Quality” of Evolutionary Icon is “Poor” in Retroactive Confession of Ignorance
How did Luskin reach this ‘conclusion’? Because he read an interview with the lead-researcher who made the following claim:
Previous data from another ancient fish called Tiktaalik showed distal radials as well – although the quality of that specimen was poor. And the orientation of the radials did not seem to match the way modern fingers and toes radiate from a joint, parallel to each other.
A logical conclusion would be to accept the observation that the quality of the specimen was ‘poor’ regarding the details of ‘distal radials’, but instead Luskin decided to mine the statement to mean that the quality of Tiktaalik was poor.
Casey Luskin wrote:
The “quality” of Tiktaalik as a fossil specimen was “poor”? When did we see Darwinists admit this previously? Never. They wouldn’t dare make such admissions until they thought they had something better.
But in fact, the ‘Darwinists’ had already admitted that the fossil specimen for Tiktaalik poorly resolved the distal radials.
Anyone interested in the issue would have done a search of Tiktaalik to determine the nature of the fossil and quickly come to realize that, contrary to Luskin’s statements, science already had admitted that the well preserved fossil did in fact poorly resolve the nature of distal radials while also preserving details of important features such as the neck, shoulder and front fins..
From the University of Chicago Tiktaalik website we learn for instance that “Tiktaalik’s head, shoulders, front fins and body are very well preserved for a 375 million year old body”
and from the article which described Tiktaalik we learn
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
Source: New technologies show Panderichthys and Tiktaalik on the way to living on land Non Discovery blog
In other words, Tiktaalik lacked complete distal radials and in case of Panderichthys, the fossil hard to separate from its surroundings
Using a CT scan, the authors, Boisvert et al, allowed a reinterpretation of the Panderichtys and the formation of digits. In fact, even though Tiktaalik lacked a complete set of distal radials, they already looked ‘digit like’.
Our reinterpretation of the distal fin endoskeleton of Panderichthys removes the final piece of evidence supporting the formerly popular hypothesis that tetrapod digits are wholly new structures without homologues in [lobe-finned] fish fins. This hypothesis … has already been called into question by the discovery of digit-like radials in Tiktaalik and the fact that Hox gene expression patterns closely resembling those associated with digit formation in tetrapods occur in the distal fin skeletons of paddlefish & Australian lungfish.
Now I understand that Luskin has do deny any evolutionary role for Tiktaalik and more recent fossils, but the mental gymnastics that caused Luskin to reach his conclusions seem to me a bit pathetic
Yet, what else is an Intelligent Design proponent but to do than reject scientific knowledge, since his own position is one of ignorance.
In the mean time, science progresses to unravel these minor mysteries
“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.”
Now that is science for you. Ask yourself, what has ID done to contribute to our knowledge of science, other than to attempt to trivialize it?
Boisvert et al. The pectoral fin of Panderichthys and the origin of digits, Nature advance online publication 21 September 2008
Now ask yourself, is this the kind of ‘controversy’ you want your children to be exposed to in schools? As a father of two children, I am incredibly concerned about the lack of scientific content in “Intelligent Design”, as a Christian I am even more concerned about its flawed theology.
As such I have to agree with Philip “Godfather of Intelligent Design” Johnson who observed
Philip Johnson wrote:
I also don’t think that there is really a theory of intelligent design at the present time to propose as a comparable alternative to the Darwinian theory, which is, whatever errors it might contain, a fully worked out scheme. There is no intelligent design theory that’s comparable. Working out a positive theory is the job of the scientific people that we have affiliated with the movement. Some of them are quite convinced that it’s doable, but that’s for them to prove…No product is ready for competition in the educational world.
Source: Michelangelo D’Agostino, In the matter of Berkeley v. Berkeley, Berkeley Science Reviews, (10), Spring 2006
But in addition to a lack of positive contributions, Intelligent Design also relies on maintaining a status of ignorance amongst its followers, since knowledge would undermine Intelligent Design.
Protect our children from such ignorance I say.
Postscript: Per Ahlberg describes in more detail his statement that “finger development took a step backward with Tiktaalik”
In Acanthostega (d below), which is a very primitive tetrapod, the radius is still longer than the ulna but all the other characteristics seem to be there.
Now, in Panderichthys, we find that the ulnare is much shorter than the ulna and really looks like a wrist bone. Furthermore, the ulnare is the last axial element, and beyond it the distal radials are arranged in something of a fan shape. But in Tiktaalik the ulna and ulnare are equal in size, there are two more axial elements beyond the ulnare, and the distal radials are arranged bipinnately (i.e. like the leaflets of a palm leaf) on either side of this distal axis. In all these respects Tiktaalik’s fin skeleton (c) is less limb-like than that of Panderichthys (b) and compares more closely with lobe-finned fishes (e.g. Eusthenopteron, a):
The interesting question is whether this means that:
The detailed similarities between Panderichthys and tetrapods are convergent, or -
The seemingly more primitive fin skeleton of Tiktaalik represents an evolutionary reversal, or -
The current phylogenetic hypothesis is wrong and Panderichthys is actually more closely related to tetrapods than Tiktaalik.
One of these three explanations must be correct, but it is not yet possible to tell which one.
Sadly, we don’t have any data at all on the limb structure of Ventastega. A reasonable guess is that they resembled those of Acanthostega, because the limb girdles are similar, but no limb bones have been found.
Others seem to point out yet another possibility
Michael Coates, an evolutionary biologist at the University of Chicago, called the new findings “intriguing” but is not convinced that the digit-like structures in Panderichthys’s fin are the equivalent of our fingers.
For one thing, they seem unusually flat for radial bones, Coates said.
“Radials are generally cylindrical. When you look at [a] cross-section [of the digit], they’re dumbbell-shaped.”
The structures are so peculiar, they might just be fragments of damaged bone, he added.