Tiktaalik Blown "Out of the Water" by Earlier Tetrapod Fossil Footprints
[Editor's Note: Further commentary on this fossil discovery, including responses to criticisms, can be found here.]
When Tiktaalik was reported in 2006, the media went Darwin-happy over the discovery of an alleged transitional fossil. BBC News announced, "Fossil animals found in Arctic Canada provide a snapshot of fish evolving into land animals." At MSNBC, Tiktaalik co-discoverer Ted Daeschler was quoted boasting that, "If one considers adaptation as a process of collecting tools to live in a new environment, the new finding offers 'a snapshot of the toolkit at this particular point in this evolutionary transition." The article even postured Tiktaalik as an actual ancestor of tetrapods, stating: "Scientists have caught a fossil fish in the act of adapting toward a life on land, a discovery that sheds new light on one of the greatest transformations in the history of animals." But this week Tiktaalik's status as an actual transitional fossil between fish and tetrapods has been called into question by the discovery of unambiguous footprints (with digits) of a full-tetrapod that were made about 20 million years before Tiktaalik. An article in Nature explains the havoc wreaked by these footprints:
The fish--tetrapod transition was thus seemingly quite well documented. There was a consensus that the divergence between some elpistostegalians (such as Tiktaalik or Panderichthys) and tetrapods might have occurred during the Givetian, 391--385 Myr ago. Coeval with the earliest fossil tetrapods, trackways dating to the Late Devonian were evidence for their ability to walk or crawl on shores.The fossil tetrapod footprints indicate Tiktaalik came over 10 million years after the existence of the first known true tetrapod. Tiktaalik, of course, is not a tetrapod but a fish, and these footprints make it very difficult to presently argue that Tiktaalik is a transitional link between fish and tetrapods. It's not a "snapshot of fish evolving into land animals," because if this transition ever took place it seems to have occurred millions of years before Tiktaalik.
Now, however, NiedÅºwiedzki et al. lob a grenade into that picture. They report the stunning discovery of tetrapod trackways with distinct digit imprints from Zachemie, Poland, that are unambiguously dated to the lowermost Eifelian (397 Myr ago). This site (an old quarry) has yielded a dozen trackways made by several individuals that ranged from about 0.5 to 2.5 metres in total length, and numerous isolated footprints found on fragments of scree. The tracks predate the oldest tetrapod skeletal remains by 18 Myr and, more surprisingly, the earliest elpistostegalian fishes by about 10 Myr.
(Philippe Janvier & GaÃ«l ClÃ©ment, "Muddy tetrapod origins," Nature Vol. 463:40-41 (January 7, 2010).)
Tiktaalik's Place in the Fossil Record: A
Confirmed Failed Prediction of Evolution
Some, such as Tiktaalik co-discoverer Neil Shubin, have turned Tiktaalik's place in the fossil record into an argument for neo-Darwinism. As Shubin said in PBS's Judgment Day: Intelligent Design on Trial:
What evolution enables us to do is to make specific predictions about what we should find in the fossil record. The prediction in this case is clear-cut. That is, if we go to rocks of the right age, and the rocks of the right type, we should find transitions between two great forms of life, between fish and amphibian. ...What we see when we look at the fossil record, at rocks of just the right age, is a creature like Tiktaalik.The New York Times presaged Shubin's argument, first reporting on Tiktaalik that "the scientists concluded that Tiktaalik was an intermediate between the fishes Eusthenopteron and Panderichthys, which lived 385 million years ago, and early tetrapods. The known early tetrapods are Acanthostega and Ichthyostega, about 365 million years ago." But would neo-Darwinism have predicted true tetrapods from 397 million years ago? Definitely not: Janvier and ClÃ©ment said it best: these tracks are "anachronistic." Tetrapod paleontologist Jenny Clack said the track discovery " blows the whole story out of the water." Or as a Nature news story put it, these tetrapod tracks are "more than 18 million years before tetrapods were thought to have evolved."
So where are the fish that turned into tetrapods? According to Nature, they must exist in the "'ghost range' -- that is, a period of time during which members of the groups should have been present but for which no body fossils have yet been found." Shubin's arguments that these fossils confirm a "specific prediction" of evolution appear to have been wrong. (But don't expect a correction from PBS anytime soon.)
Lessons to be Learned
In 2007, Stan Guthrie discussed in Christianity Today about whether media hype on transitional forms should be believed. Saying he's always "secretly identified with the apostle Thomas," Guthrie wrote:
Last year, however, came word of Tiktaalik roseae, which looks discomfitingly like those offensive "Darwin fishes" on the cars of smug college professors. Giddy evolutionists immediately hailed the 375-million-year-old fossil as a "missing link" between fish and land animals. "It's a really amazing, remarkable intermediate fossil," scientist Neil H. Shubin told The New York Times. "It's like, holy cow."These are good words; unfortunately, Guthrie then goes on to quote and endorse theistic evolutionists such as Francis Collins who basically fully capitulate to the claims of neo-Darwinists without much sign of a willingness to doubt. Guthrie quotes Collins saying, "The evidence mounts every day to support the concept that we and all other organisms on this planet are descended from a common ancestor," and that "the theory of evolution is really no longer a theory in the sense of being untested. It is a theory in the sense of gravity. It is a fact." But yet we see the "facts" of neo-Darwinism constantly being revised. Last year alone:
So what's a Doubting Thomas to do? First, we need to remember that scientists have hailed "missing links" before, only to be embarrassed when further evidence came out. The Discovery Institute, which supports Intelligent Design, noted that enthusiasm over this latest find is a backhanded admission by paleontologists that the fossil record has not been kind to Darwin's theory.
Archaeopteryx was challenged as an intermediate between dinosaurs and birds Theropod dinosaurs were challenged as the ancestors of birds
Ardi was hyped as human ancestor based upon questionable evidence
Ida was the "link" that went bust
2010 is only a few days old and already one of the newest icons of neo-Darwinism -- Tiktaalik -- is coming under heavy fire. Perhaps when it comes to neo-Darwinism, Collins and those who follow him would do better to insist on taking the approach of Doubting Thomas after all.