Tiktaalik Is Back, This Time With a Hip Twist
Discoverer of a putative ancestor of tetrapods thinks it came with rear-wheel drive.
Neil Shubin of Your Inner Fish fame (1/16/08) did some more digging, and found the rear fins of his iconic fish-a-pod that made headlines in 2006 (see 04/06/2006, 05/03/2006, 10/20/2006). Publishing the new findings in PNAS, he says that the rear hip bones of the creature he named Tiktaalik roseae provide insight into the great transition from swimming to walking:
At first glance, the origin of tetrapods (limbed vertebrates) from finned precursors seems an almost insurmountable transition between life in water and life on land. If the basis of comparison were living taxa alone, then the anatomical and behavioral differences among finned and limbed vertebrates could appear vast: for example, fin structure and function differ dramatically from those of limbs. Fossil evidence, in particular vertebrates from the middle and late part of the Devonian period (393–359 Mya), offers intermediate conditions that bridge this gap.
Shubin and team compared the hip bones of swimmers he feels were ancestral, like Eusthenopteron, and later landlubbers, like Acanthostega, to show evolutionary progress toward tetrapodhood. The story, however, is not one of simple progression. For one, Tiktaalik appears to be a “mosaic” of “derived” (evolved) and “plesiomorphic” (primitive) features.
Although the size and general robusticity of the pelvis is derived relative to other finned forms, aspects of the general architecture of the girdle are plesiomorphic ….
Plesiomorphic features of Tiktaalik can be interpreted as highlighting a functional difference with limbed forms ….
Another complication from the new findings is a falsification of the “front-wheel drive” theory of the transition. Here’s what previous work expected to find:
However, the best comparisons available from these data strongly supported the hypothesis that the closest finned relatives of tetrapods were “front wheel drive animals,” possessing enlarged pectoral fins, robust pectoral girdles, and relatively small pelvic appendages that were incapable of providing extensive degrees of body support and propulsion.
Unexpectedly, the pelvis of Tiktaalik is large and robust compared to the front limbs, looking different from both the putative ancestor and descendant. “The pelvis is greatly enlarged relative to other finned tetrapodomorphs,” Shubin says, even though he claims it retains certain “primitive features such as the lack of both an attachment for the sacral rib and an ischium.” The remains, though, are open to interpretation, as they appear fragmented in the photograph. Additionally, there is no clear line of descent between the fossil specimens reputed to be evolving into tetrapods (12/04/08). That makes it speculative to consider this creature the thing that gave humans legs and hiccups (12/16/08).
Shubin did not mention the finding from 2010 that potentially dethrones his iconic fish as ancestor of tetrapods: trackways in Poland 18 million years older than Tiktaalik (1/06/10). Neither did the news media, who were all too eager to display the new artwork of the fish-a-pod that was ready on cue to greet the publication. Each reporter exalted Tiktaalik as our walking pioneer with glamorous headlines:
- Our Fishy Ancestors Had Fins Made for Walking (National Geographic)
- Discovery of New Tiktaalik Roseae Fossils Reveals Key Link in Evolution of Hind Limbs (Science Daily)
- …it provides insight into life’s evolutionary move from water into the terrestrial environment (BBC News)
All these articles presented Tiktaalik as a transitional form in one of evolution’s great transformations. No skeptics were interviewed . Live Science gave a smiling Shubin a ten-photo slide show about the find. Science Daily mentioned that Shubin will be hosting a three-part TV series on PBS featuring his book and the fossil.
Update 1/16/14: An interview with Shubin appeared in PNAS the next day. Shubin did not add much new information, except to clarify that the sheer size of Tiktaalik’s pelvis was a “big surprise” that implies it must have evolved earlier, in fish, before tetrapods began to evolve. He admitted he did not know how the pelvic architecture arose, how it changed, the sequence of changes, and the timing of onset of attachment of the pelvic girdle to the vertebral column. Interviewer Prashant Nair was hardly objective, claiming Tiktaalik may have “crossed an evolutionary Rubicon,” has “come to represent an intermediate link between fish and amphibian,” and “paved the way for the first four-limbed vertebrates that ventured onto land.” He treated the new paper as a “long-awaited sequel” to this “saga of evolution,” indicating he was unlikely to ask any hard questions. Indeed, he did not.
What a racket this is. Neil Shubin, like other evolutionists before him, e.g., Donald Johanson (Lucy), Sidney Fox (microspheres), Eugene Dubois (Java Man) and other Darwin flimflam artists, makes a name for himself by conjuring up some iconic evolutionary landmark out of artifacts that provide no necessary or sufficient support for their stories. You could weave an evolutionary tale with the tools in your garage, the utensils in your kitchen drawer, or the Legos in your kid’s bedroom, building blocks of life and all. There’s far more design than mutation in Tiktaalik, far more more gap than link in the fossil record, and far more horizontal diversification than vertical progression in the data. But if you are convinced that the screwdriver evolved into the wrench in a grand transformation, you can imagine transitional forms in the chisels and crowbars, failing to see the real story: design.
Like his predecessors, Shubin will become rich and famous for a myth that will eventually be discarded on the trash heap of irrelevant or falsified stories. Tiktaalik was not seeking to become a tetrapod. It was a well-designed creature that was doing just fine in its habitat, swimming around in shallow water, not trying to become something else. How could this creature happen upon a radius, ulna, digits, and the muscles and nerves attached to them, to say nothing of a brain able to operate them, just because the land was there, waiting to be conquered? Can miracles happen without design? It can only in the imagination of evolutionists who wave the magic wand of time in mythical worlds of their own making.
Nobody mentions that we have fish alive today, mudskippers (7/01/11, 7/11/13) and leaping blennies (1/21/12), joyfully flopping up on the land or crawling around on front fins, not evolving legs and toes. Remember that Coelacanth was thought to be a transitional form till it was found alive, still unevolved, and not using its bony fins for walking. The diversity of fish is so broad, one could take any number of unusual forms and make evolutionary icons out of them. Learn a few jargon words and measurement techniques and you might become rich and famous, too. Maybe you could write a book, Your Inner Toad, to explain why people croak, or Your Inner Sponge, to explain why people expect entitlements. If Shubin and his toadies in the press had not sworn an oath to protect Charles Darwin, this storytelling would be seen for what it is: a modern-day form of divination by shamans seeking fame and respect from the peasants (1/16/08). Where are the skeptics? Where are the investigative reporters asking hard questions, demanding rigorous support for claims, exploring alternative explanations, including non-evolutionary ones? What a racket this is.
The cure is to laugh. Shubin and the other charlatans will back off red-faced in shame when we don’t by their product, but erupt in hearty guffaws at the silliness. “Front wheel drive? Your inner fish? Yee-haw!” Tell Shubin about his inner serpent, his inner croc, or, especially, his inner DODO. Get the crowd singing like the fishies sing, Under the Sea (12/16/08). Don’t take this stuff so seriously. Fight silliness with silliness.