Scientists used evolutionary theory to figure out where
to find the bones of this fishibian.
Lately I have been reading Jerry Coyne’s Why Evolution is True. And so far it is a fascinating read.
What is so great about this book for a scientist is that it gives the big picture on evolution. This sort of thing can be hard to get sometimes because we scientists are so specialized. As I like to tell people, I worked on a single amino acid of a single human protein for my postdoctoral project. For three years.
Coyne’s book synthesizes genetics, anatomy, biogeography, physiology, paleontology, geology, and lots of other “ologies” to show how strong the case is for evolution. This is great for me because, of course, I tend to focus on genetics and molecular biology and spend less time on the other fields. Which means I miss important, subtle nuances to some big findings.
For example, I had heard about the fossil of Tiktaalik roseae that was found in 2004 that linked fish to amphibians. This was a huge deal because the animal that the bones came from had characteristics of both fish and amphibians. And it appeared in the fossil record at the right time to be a transitional animal between the two.
What I hadn’t fully appreciated was that the scientists decided to look where they did based on how old they thought the fossil should be. In other words, they were able to use the theory of evolution to predict where to find the fossil they were looking for.
They knew from previous fossil finds that something like Tiktaalik roseae would have appeared between 360 and 390 million years ago. The scientists also knew from previous research that the beast would have been in freshwater. So they got out a geological map and looked for places that met these criteria. They settled on Ellesmere Island in Canada and after five years, they found this marvelous fossil.
This is important for a lot of reasons. One is that it obviously tells us a lot about how vertebrates emerged onto dry land. Another is that it provides further validation of geological dating methods. They had to rely on these methods to know where to look for the fossil and the methods worked.
This find is also important because it is based on a prediction made by evolutionary theory. Around 390 million years ago, the only vertebrates were fish. By 360 million years ago, there were four-footed vertebrates on land. So the scientists looked in a place that was 375 million years old.
Scientists used evolution to make a testable prediction that turned out to be true. And evolution came through with flying colors like any good scientific theory should.