“Over 300 different body plans are found without any fossil transitions between them and single-cell organisms.”
“In the entire fossil record, there is not a single unequivocal transition form proving a causal relationship between any two species. From the billions of fossils we have discovered, there should be thousands of clear examples if they existed.”
“The lack of transitions between species in the fossil record is what would be expected if life was created.” – Institute for Creation Research, “Fossils Show Stasis and No Transitional Forms.”
We are all familiar with the creationist claim that there are no transitional fossils — it is ubiquitous and perhaps the smelliest red herring that they continually drag out in an attempt to overturn evolution. There are two very obvious objections to this tactic. (Actually there are three, but I will reveal the third one at the end of article three.) One is the logical fallacy of the false dichotomy — the idea that there are only two possible explanations for something, and therefore if you can destroy your opponent’s argument, yours must be correct. The truth is, you may both be wrong. The second is the simple fact that there are transitional fossils, which should be game, set, match: take that, creationists! Alas, it is not to be. But since they will continue to bring it up, we must continue to combat it, and we must be ready with examples which, while they have little chance of changing their minds, should at least alert the public that we know what we are talking about. You don’t have to change your opponent to win the argument, just win over the spectators.
The first celebrity on the transitional fossil scene was, without a doubt, Archaeopteryx. About 150 million years ago, during the Jurassic era, some of these animals died, which of course in itself is not really an event. But after being buried in fine silt which gradually became rock they caused quite a stir upon their rediscovery in a German quarry in the latter half of the nineteenth century. The theory of evolution was still new, and here was something that gave it a solid foundation that was almost unshakeable. In many respects it was much like any dinosaur, with claws, teeth, and a tail, but there was something else that was as metaphorically Earth-shattering as the literal cleavage in the rock that held the fossil — a fine set of feathers. Archaeopteryx has other anatomical features in common with birds, but there is still debate regarding whether it was in the true bird lineage or an offshoot pursuing its own path. Whatever, its value to science cannot be overstated.
Archaeopteryx was an accidental discovery, as many fossils are; but what if we could produce one that was found using one of the requirements of a true theory — something that was predicted by all the evidence and conclusions drawn from the theory? We can. And the discovery was made in Canada.
In 2004, a discovery was made that vindicated the scientific process and left no doubt about the predictive abilities of the theory of evolution. With typical scientific caution, the results of the study of the fossil were not announced until 2006, but when it was released it was very big news in the scientific community. In a search that had been proceeding for many years, a team of palaeontologists had narrowed their search, guided by a number of factors: the position of a significant gap in the fossil record, the sort of conditions would have produced an organism that would fill the gap, and how long ago that gap would have occurred. What it amounted to was an ancient freshwater environment that existed approximately 375 million years ago. So the hunt was on for just such an area.
This led them to an area of the Canadian arctic, specifically the southwestern part of Ellesmere Island at around latitude 77ºN. This is the domain of cold and polar bears, a barren landscape that has a major advantage over many others — there is little other than rocks exposed at the surface, ideal for finding fossils. Team leader Professor Neil Shubin from the University of Chicago, was accompanied by Dr. Ted Daeschler, Professor Farish Jenkins, Professor Stephen M. Gatesy, and the required small army of people it takes to organise and carry out such an expedition. They also had help from the local Inuit, people who have been surviving there for millennia.
So here we have what may seem to many like a fool’s errand: in a huge landscape littered with rocks, you’re looking for a specific rock. A needle in a haystack would be child’s play. You are up against elements that set a timeline — get in and look, and get out before you freeze or get eaten by a large white bear. Madness.
Fortunately there are people in this world who don’t mind appearing mad; in fact, they seem to revel in it. Dr. Shubin and his team are just such people. They carry in their hearts the drive of all their predecessors who have carried out expeditions all over this world, in space, and on the Moon, in order to advance scientific knowledge. If this is madness, then more people should be so afflicted.
To make a long story short*, in their second season in the field they found exactly what they were looking for. It was Stephen Gatesy who first recognised the required fossil material emerging from an outcropping of rock, and the painstaking process of excavation commenced. Even then the hard work was far from over. The fossils needed to be prepared for safe transit, slung under the belly of a helicopter, and taken back to the University of Chicago, where preparators were waiting to determine how to fit together a 375 million-year-old jigsaw puzzle. Once their work was done, the process of studying the entire animal could begin — its place in the fossil record could be established, and the news could be announced to the world.
To someone reading this account, the announcement may seem almost anti-climactic, but imagine the thrill of those who were able to break the word after all their hard work, and to those who were able to not only receive it, but fully understand the implications of it. If you’ve ever bragged to people about the birth of your first child, then you may have come close to feeling something similar.
Tiktaalik roseae is a sarcopterygian, which includes the lobe-finned group of fishes to which the well known coelacanth belongs, the lungfishes, and tetrapods, which includes us. But tiktaalik has gone further than a coelacanth, and appears to be part fish, part tetrapod. The tetrapods are those animals with the body plan shared by amphibians, reptiles, birds, and mammals. Tetrapods all have, or had, four legs, although over millions of years of evolution some have been highly modified. In the case of birds and bats they have become wings, in whales they have become front flippers, with the rear ones only existing as vestigial bones inside the body, and in snakes they have been lost altogether, but they did exist at one time. The neck of tiktaalik is articulated, meaning that it can turn its head, something that a fish cannot do independently of its body. The fins, while still very fish-like, are stout and strong, with a functioning wrist. Its ribs are more like a tetrapod than a fish, and it had lungs. The transition to land animal is well underway.
Tiktaalik is a wonderful representation of a moment in time when the first fish were beginning to explore the boundary between the water and the land, an area that their descendants would eventually leave entirely as they exploited the new territory before them. In the Inuit language tiktaalik means ‘big freshwater fish’, and Neil Shubin chose it to thank all the locals for their help during the expedition.
So did this discovery stand any chance of swaying the anti-science crowd? There was an interesting coincidence to this find. As the fossil was being chipped out from its resting place, a trial was taking place in Dover, Pennsylvania, in which the plaintiffs were seeking to insert intelligent design into the local school curriculum. The outcome was a victory for evolution and science, but overall the deniers are still active and vocal. Tiktaalik is powerful evidence of their obstinance, as much as it is a nail in their coffin.
*The long story is available in the book Your Inner Fish, by Neil Shubin, Vintage Books, ISBN 978-0-307-27745-9
In the next Critical Eye, part two of this series will discuss transitional forms, the steps we can see today.