Q&A Session with Neil Shubin
The following questions were posed to Neil Shubin in April 2006, after the unveiling of the discovery of Tiktaalik roseae. Video clips accompany each answer - just click on the image thumbnails to the left of each answer to play the videos.
- Where did you discover Tiktaalik?
- What drew you to conduct research in this region?
- What is your most significant discovery at this site?
- Were you hoping to find this type of fish, or was this an accidental discovery?
- How did you decide on a name for the new species?
- Why is Tiktaalik of particular importance?
- Would you describe the unique physical characteristics of Tiktaalik?
- What do Tiktaalik's anatomical structures tell us about how it lived?
- Have there been other comparable discoveries of complete fossils demonstrating the vertebrate transition from water to land?
- How are your expeditions supported?
- Now that you've found Tiktaalik, what's next?
Q: Where did you discover Tiktaalik?
A: The discovery of the new fossil came from the Canadian Arctic, up near the North Pole, about 600 miles south of the North Pole. It is an Arctic landscape. It is daylight 24-hours of the day in the summer. There are polar bears and musk ox running around. But for us, it is absolutely perfect for finding fossils, because in the Arctic there are no trees, no soil, no dirt, there are no buildings. Whatever rock is there in the Arctic is actually exposed to the surface, which allows us to find lots of fossils.
Q: What drew you to conduct research in this region?
A: The story behind us beginning to work in the Arctic, or discovering this area to work on, is actually interesting. We discovered these areas looking through an undergraduate geology textbook. I was having an argument with one of my colleagues, and we went through my undergraduate geology text and there is a figure in there. It shows where rocks from the age of 380 to 360 million years ago are exposed on the Earth. And there were three sites: one was in Eastern North America, which is where this person and I made lots of discoveries before; another was in Greenland, which is very famous for producing some of the earliest creatures to live on land; and there was a third. The third was in the Canadian Arctic, stretching from what is now Ellesmere Island all the way to the West, about 1500 km. It turned out that no one ever worked there before, except the geologists that mapped it. So after seeing that image in the textbook, we went out and tried to raise money, get the permits, and then ran a series of expeditions up there to find just the kind of creature we ended up discovering six years later. There were other paleontologists who had worked in this region in the past. Explorers, a Norwegian team around the turn of the century in the early 1900s worked up there. There were people interested in fossil plants who worked up there for a period of time. No one had gone up there to look for fossils of vertebrates, of fish and amphibians. We were the first team that I know of.
Q: What is your most significant discovery at this site?
A: The most significant discovery at this site is a special kind of fish. It is a fish that blurs the distinction between a fish and a land-living animal. It looks like a fish, in that it has scales and fins. But when you look inside the skeleton you see how really special it is. It has, inside its fins, a wrist and finger-like structures like a limbed-animal. It has a flat head, like a limbed-animal, an amphibian. It has a neck--for the first time in the fossil record--like a limbed-animal. In fact, it is a mosaic of half limbed-animal and half fish. And that really tells us how fish evolved to walk on land, how they evolved to inhabit terrestrial ecosystems, and so forth. It is really remarkable, and has lots of surprises for us. It tells us things we didn't fully expect before. The first is, it has ribs --big ribs that attach to one another-- of a kind that we see only in animals that need to support themselves in gravity. What's a fish doing with this kind of thing? Obviously, that tells us a lot about how fish developed to walk on land.
Q: Were you hoping to find this type of fish, or was this an accidental discovery?
A: Our team has been looking for this fish for past six years. We made four trips up to the Arctic to find this particular kind of fish. The first year we struck out almost completely. The second year we found bits and pieces of some things that suggested that something might be there. The third year we found a locality and larger bits of fish that suggested we might be on to something important. And it wasn't until the fourth year, July 2004, when we discovered whole skeletons of this creature.
Q: How did you decide on a name for the new species?
A: One of the great joys of finding a new species is that that you get to name it. In this case, once we knew we had something new, we asked a council of elders in the Nunavut territory of Canada to offer suggestions for the name. And they came up with a name, “Tiktaalik,” which in the Inuktitut language means "large, freshwater fish." How perfect!
Q: Why is Tiktaalik of particular importance?
A: One of the special things about this fossil is that it has a fin, but inside the fin are many of our own arm bones: it has an upper arm bone, it has a lower arm bone, it has forearm bones, it has a wrist, it has finger-like things. It is a fin that is able to support the animal. That goes together with other features that the animal has. It has a neck that suggests its head can move independent of the body. It has ribs that can support the body in gravity. So when you take the whole skeleton together, what is this thing telling us? It is telling us that this is a fish that can live in the shallows and even make short excursions on to land.
Q: Would you describe the unique physical characteristics of Tiktaalik?
A: When we look at this creature what we see is a mosaic of fish features and those we find in land living animals. Let's look at the fish parts first. There are scales like a fish; you can see they look like chain mail here. There are even scales on the fin. But the other thing that is very fish-like is that it has a fin. There is the fin. See these little bones here; those are fin-rays that you even see in fishes like salmon and trout and so forth. So it has scales and fins like a fish. Now, like land-living animals, it has a few things that are quite different. A flat head with eyes on top. It has a neck. Fish have a situation where the head is actually physically attached to the shoulder. What we have in this creature, and you can see it in the skeleton, is that you have a head that is actually separate from the shoulder, meaning that it has a neck that can move the head around. Other interesting features are that here's the fin, and you can see that the low part of the fin is what is really interesting. That is, if you look inside here what you would see are equivalents to pretty much all the bones in our arms and hands. So, you have a shoulder. You have a fish with an elbow. And there is even a little wrist out here. So it is a fish with shoulder, elbow, and wrist. It is a fish with a head much like a crocodile. It is a fish with a neck. In fact, when you look at the cast of the skeleton here, you even have, when you flip it over, you even have little rods here, and those are ribs, unknown in any other fish.
Q: What do Tiktaalik's anatomical structures tell us about how it lived?
A: When you take all these features together--from a fin with a shoulder, an elbow, and a wrist, to a neck, to ribs--what you have is an animal that can prop up and support itself in gravity. It has a very strong arm-like fin. It has a head that can move independently of the body. It has eyes that are on top, not on the side, so that it is able to look up. You have an animal that is able to support itself in gravity, either in the shallow waters, or on land.
Q: Have there been other comparable discoveries of complete fossils demonstrating the vertebrate transition from water to land?
A: This discovery is unique in that it is fully intact; there are several specimens of a whole size range, a variation of arguably one of the most important creatures in the transition to land. There is nothing else like it. What we usually use are bits and pieces of skeletons and put them together to try to make a reconstruction. Here we are privileged to be able to make a reconstruction from virtually the entire skeleton preserved in articulation.
Q: How are your expeditions supported?
A: You can imagine that working up in the Arctic is very expensive... It is arguably some of the most expensive paleontology you can do. So we have had to cobble together support from a variety of sources. We have in-house support from the Biological Sciences Division (of The University of Chicago), for instance, has supported us very well. We've also had support from the National Geographic Society, National Science Foundation, The Academy of Natural Sciences in Philadelphia, Harvard University. It is really a mosaic of support put together that helps us work up there. Helicopters cost $1700 per hour up there. And it takes many, many hours of time to get to our sites, to get the fossils out of our sites, so the meter is running. We've been fortunate to have a variety of different places supporting us in our research.
Q: Now that you've found Tiktaalik, what's next?
A: What this discovery does is that it gives us a new search image: a place, a time, a type of rock to look at that is highly likely to preserve more things like this. So what we can do, this summer for instance I am going to be returning in July to these sites, what we can do is go to different parts of the Canadian Arctic to look for more things like this--different kinds of them, maybe different species of them. The other important thing we can do is to go higher in the section, that is, to look at rocks that are younger. Maybe we can find more limbed-animals, creatures more on the amphibian end of things--the other side of the transition, which is clearly something we'd else like to discover in the coming years working there.