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MARGINALIA

Missing Links and Found Links

In and out of the water, transitional forms from the fossil record illuminate the nuts and bolts of evolution

Pat Shipman

Grasping the Brass Link

Finding a missing link is a life's ambition for many paleontologists, often taking years of hard work, travel to remote regions and more than a generous dollop of luck. The aftermath of finding a missing link is more subtle than might be supposed. The paleontological record will always be sparse compared to the total number of creatures that ever lived, because fossilization is a very rare event. Millions of animals are born and die every day, but only a few of their bodies find habitats suitable for fossilization and preservation. Of those few creatures that die in the right place at the right time, many are preserved in places so thinly inhabited by human beings that no one who could recognize the fossil for what it is will ever see it. Not only does an organism have to be fossilized, but it must be found and recognized by a trained eye to add to the sum of scientific knowledge.

Although the discovery of a missing link is cause for celebration, it is also cause for more and deeper studies. Ironically, even as one link is found, two new missing links are "created"—one the immediate ancestor and one the immediate descendent of the newly found creature. But slowly, as discoveries proceed, paleontologists are able to compile an ever-clearer record of the evolution of life on Earth.

Ellesmere IslandClick to Enlarge Image

The discovery of Tiktaalik will encourage paleontologists to continue their intrepid searches in far-flung areas. With luck, its existence may spark others to rethink their position, too. Intelligent design advocates and creationists claim that too many links are missing for evolution to be credible; they see only the abrupt appearance of new forms created by an Intelligent Designer. Stephen Meyer, director of the Center for Science and Culture of the Discovery Institute, asserts that "the transitional life forms that ostensibly occupy the nodes of Darwin's branching tree of life are unobservable...."

The highly observable Tiktaalik is exactly the sort of transitional form that Meyer maintains does not exist. The fossils are real and solid evidence that you can hold in your hand. If you are willing to take the time to study their anatomy, you can see for yourself the evolutionary adaptations that were made over time. This ancient fish mutely tells a story of mosaic changes, of piecemeal adaptation to a new ecological niche. It joins myriad other "found links" that document transitions from one type of creature to another or from one habitat to another. Together these found links form a stony edifice in support of evolutionary theory.








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