Finding Tiktaalik

Neil Shubin talks about his famous discovery

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From fins to limbs...

Professor Neil Shubin talks about the discovery of Tiktaalik and one of the greatest evolutionary events in Earth’s history: when the very first fish ventured out onto land.

Widely known as the "fishapod", Tiktaalik roseae is a 375 million year old fossil fish discovered by a team of six palaeontologists in the Canadian Arctic in 2004.

Tiktaalik looks like a cross between the primitive fish it lived amongst and the first four-legged animals, a group called "tetrapods". Derived from "tetra-", meaning four, and"-pod", meaning foot, all animals that descended from these pioneer amphibians, including us, can be called tetrapods. 

Tiktaalik lived about 12 million years before the first tetrapods (which are approximately 363 million years old). With the earliest appearance in the fossil record of tetrapod features in a fish, the discovery has become a key piece of evidence in the transition from life in water to life on land.

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Natural World

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Type:
Interview
People:
Professor Neil Shubin
Location:
Royal Institution, London
Filmed in:
The Theatre
Published:
2013
Filmed:
2013
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The Royal Institution

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cc_by-nc-sa License: Creative Commons

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Transcript

My name is Neil Shubin. I'm from the University of Chicago where I'm a professor in the faculty of the anatomy department there. I also hold an appointment at the Field Museum of Natural History, also in Chicago.

So you have to understand the setting. The setting of the day we found it was, this was our last expedition to the Canadian Arctic. We were running out of money, and I'm not saying this for drama. It's really expensive to work there. We had worked there for a number of years already with very little success. We had not much to show for ourselves. We decided to sort of spend the lot and have one last season working at that layer.

So Steve's cracking rocks. Steve is up about seven feet from me and he says, hey Neil, what's this? And I remember looking at the thing and saying, OK, we have a flat-headed fish. I looked at Ted and Farish who were the co-leaders of the expedition. We were like, oh, my god. I mean, there were two feelings, one was just incredible joy, but the other was incredible relief. This was our last chance at this. And as soon as I saw what this object was, I knew we had found what we had spent six years and I'd spent 20 years before looking for.

Well, since I was a graduate student, I was interested in one of the great evolutionary events in earth history, which is the transition from life in water to life on land. And you think about that. It's a remarkable transition, because so much in the animals have to change.

So I got interested early on in this transition and my goal was to find new evidence to tell us about how it happened. So what I did starting in the early '90s was to try to find rocks in the world that had the right properties to hold the fossils that would tell us about this transition, from a fish that has like a conical head and fins to a land-living animal of the time, in the Devonian, which has a flat head with limbs.

So we looked around the world and it eventually became clear through a moment of serendipity that one of the best places and most unexplored places to look for such a fossil was in the Canadian Arctic. We discovered it from a geological textbook, not the scientific literature. It was completely accidental. But it turns out these were the perfect rocks of the right age and exposed to the surface to produce such an intermediate.

And what it looks like is you have a flat head with eyes on top, and then you essentially have the body of what looks like a fish, a stubby fish, because it has scales and stubby fins. Now, what's great about Tiktaalik it's a great melange of characteristics of fish and land-living creature. The shape of the head, the proportions of the head, the bones, and so forth are very much like a land-living animal and then other parts are fish-like.

What's remarkable about the fin is when you take out the fin webbing, it has bones that correspond to the upper arm, a humerus, forearm, a radius ulna, and even portions of the risk, the so-called proximal carpel, so a real remarkable transitional creature. It had both lungs and gills. And what's exceptional about this is just how ordinary it is in the sense that it's exactly the intermediate that you would likely predict.

So what this does, is it tells us a lot about the shift from water to land along with the other creatures that's up there, hundreds of other fossils that colleagues around the world have found. It tells us a lot about how this great transition happened.

When Tiktaalik was announced in the pages of Nature, we had two articles which was nice because it gives us a chance to do a lot of basic description of the creature. Well, it hit a lot of news headlines in April of 2006 when it came out. So much so I was dropping my son of at school the day it was announced, and his teacher said, hey, bring in the fish. So I brought the cast of fossil, which we made at that point.

I remember showing if the kids, and I said, hey, guys, what do you think it is? One kid said, oh, it looks like a crocodile. And you can see why he said it's like a crocodile because it has flat eyes on top and you can even see teeth on the side. Another kid corrected him and said, no, no, it's a fish. It's got scales, and it has fins.

And I said, hey, you're both right, because they got the concept right immediately. And so you know, if only adults in Louisiana would get what kids got really quickly in preschool.

What inspires me is this transition from life in water to life on land is not just some esoteric twig on the evolutionary tree. It's very important for us. It's very important because this event is part of our own evolutionary history when our common ancestor was a fish. So that this proto wrist we see for the first time in Tiktaalik and its evolution cousins, it's something that became our own wrists.

This neck that we see for the first time in Tiktaalik and its evolutionary cousins is something that was to become our own necks. Inside our organs, inside our genes, inside our cells carry artefacts of the history of life, carry events like this of which is one of countless events in the last three billion years.

The basis for the name, we had a naming project with the Inuit elders. And we have all the pieces together. It takes the right geological conditions. It takes the right geological conditions to find it, and then it takes almost the right geological conditions--

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