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PRI's Environmental News Magazine

Trilobites

Air Date: Week of February 23, 2001

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Transcript

CURWOOD: Think of fossils and you'll likely think of dinosaurs, unless you're a kindred spirit of Richard Fortey. Richard Fortey's passion is the trilobite. These comparatively small fossilized animals offer a more complete panorama of the prehistoric world than the mega-beasts and go back even further in time. Richard Fortey is a senior paleontologist at the Natural History Museum in London. And in homage to the creature he's devoted his life's work to, he's written a book called Trilobite: Eyewitness to Evolution. Mr. Fortey says trilobites were prehistoric beetles, and compared to the beetles of today they were large.

FORTEY: Well, you'd notice something that was probably about as big as the palm of your hand, with a hard shell. And it would be divided along its length into three lobes, hence its name. And as you looked at it, it would probably be crawling along, because underneath the carapace, which is the part you usually get preserved as fossils, there are lots of little legs. And those legs are jointed like the legs of a crab or a lobster. You would look at it, and it would look back at you because rather prominently on its head there would be two eyes. And the trilobites are remarkable, because they have the first really well-preserved eyes in the fossil record. So, this was a complex animal, in spite of the fact that they go back hundreds of millions of years.

CURWOOD: Now, I have to ask you, Richard Fortey, how is it that you first became interested in these strange creatures?

FORTEY: Well, I suppose you could say it was a case of love at first sight. I was on holiday as a child in a part of west Wales, and posted on the wall in the hotel was a geological map. And on the geological map there was some writing that said trilobites can be found here. And it sounded mysterious and exciting to me, and I spent most of that holiday breaking up rock with a coal hammer. And eventually I was lucky.

CURWOOD: I'm wondering if you could read an excerpt from your book that describes when you first discovered a trilobite.

FORTEY: Yes, I'd be pleased to. (Reads) The rock simply parted around the animal like some sort of revelation. The truth is that the fossil itself had rendered the rock weaker. It was predisposed to reveal itself, almost as if it desired disclosure. I was left holding two pieces of rock. In my left hand, the positive impression of the creature itself. In my right hand, the negative mold, which had once comprised its other half. The two together snuggled up to survive the vicissitudes of millions of years of entombment. There was a brownish stain on the fossil, but to me it was no disfigurement. Surely, what I held was the textbook come alive. Drawings and photographs could not compare with the joy of actually touching a find which seemed, in the egotistical glow of boyhood, dedicated to yourself alone. This was my first discovery of the animals that would change my life. The long, thin eyes of the trilobite regarded me, and I returned the gaze. More compelling than any pair of blue eyes, there was a shiver of recognition across 500 million years.

CURWOOD: Now, why did you pick trilobites? Paleontologists get a lot of press and interest from dinosaurs and big things like that. This kind of looks like a bug, a beetle.

FORTEY: I don't know. I mean, the child's usual attraction is towards the dinosaur, isn't it? Simply because they were enormous and fierce and spectacular. But I wanted to redress the balance in a way, from the rule of the dinosaurs, to show you how real paleontologists infer things about the past, using these smaller and you might say humbler animals. But of course, when you look at them, you see that there's much more beauty and variety than you would have at first thought. You know, these were fantastically varied creatures. Some of them are as prickly as porcupines. Some of them had enormous goggly eyes. Wrapped up in that single word trilobite, there is a metaphor for the variety of life throughout geological time.

CURWOOD: Now, how did a trilobite make its living as a creature?

FORTEY: The first thing to say is, they were exclusively marine. But within the seas, they did almost everything that crustaceans -- crabs, lobsters, and their allies -- do today. I mean, some of them were ocean swimmers. They swam freely in the open ocean, rather like krill. There were others that crawled on the sea floor, more or less eating mud, about the lowliest existence you can have as a marine animal. But there were others, again, including some monsters, trilobite standard, of course, perhaps three feet long, which were predators. And then there were others that were filter feeders. So they exploited a wide variety of ecological niches. In fact, had you been around, let's say, in the Cambrian period 500 million years ago, you would have encountered trilobites everywhere from the shallow shore to the deep sea. The world would have been swarming with them.

CURWOOD: Now, I understand that the horseshoe crab is just about the closest living relative of the trilobite. You write that maybe it's a second cousin. You also wrote that you had done some informal research on this crab. What was that about?

FORTEY: Well, I was doing field work in Thailand, and at the end of the day, you know, we always retreated to a rather nice restaurant. And one evening, looking in the fish tank -- you know, where they have the live fish that can be brought to your table --

CURWOOD: Oh, yes.

FORTEY: I was astonished to see a close relative of Limulus wandering about in the bottom of the tank. So I thought to myself, this is my only chance to find out what a trilobite actually tasted like. Well, I discovered when it was brought to my table that the horseshoe crab has, at this time of year, only -- so I was very lucky -- a brood of extremely yolky eggs. And that was the edible bit of the horseshoe crab. I have to say it tasted rather like rancid fish. The curious thing is, this is an example of how imagination or luck suggests things in your scientific life, I'd been puzzled why certain trilobites had a great balloon on the front of their heads. There seemed to be no functional explanation for it. After I'd finished eating my horseshoe crab eggs, I suddenly realized that the place that the horseshoe crabs carried their yolky eggs was, well, analogous certainly and probably homologous with where these trilobite bulbs were. So, it occurred to me that maybe these were, after all, brood pouches that carried the eggs in just the same way as the horseshoe crab. It's an appealing idea.

CURWOOD: Even if it's not an appealing meal.

FORTEY: Even if it's not an appealing meal, yes.

CURWOOD: Richard Fortey, how do you do describe what you do to others?

FORTEY: With some difficulty. (Curwood laughs) I think I've only ever received one rude remark by somebody who said, and this was not from the man in the street, this was a rather well-paid barrister, who said, "And does the taxpayer subsidize this work you do?" And when I explained that he did, he said, "How tremendously arcane." But apart from that, most people seem to find it a rather thrilling way to spend your life.

CURWOOD: What's an average day in the field like for you when you go looking for trilobites?

FORTEY: Well, you have to find the right rock section to hit, first of all. Then really it is a matter of hard labor. You know, in the old days, criminals used to be, I believe, sentenced to breaking up stones. Well, that's what I have to do for a living when I'm in the field. And one of the joys of paleontology, of course, is that there is this strong element of serendipity. You never know what the next hammer blow is going to bring. So, quite often it's frustrating, you didn't find much, and then maybe suddenly you will open a page on history that has never been seen before. I can recall occasions, for example, where I found within the space of half an hour perhaps half a dozen animals previously, as they used to say, unknown to science. And that's quite a thrill.

CURWOOD: Is there something that separates the study of trilobites from the rest of paleontology?

FORTEY: No. No. The kind of things I explain in my book apply to other kinds of fossils as well. What I wanted to show was, you know, by studying something apparently arcane, you can actually open windows on things which everybody can understand is important. By studying trilobites, you can actually reconstruct the vanished geographies of ancient worlds.

CURWOOD: In your book you compare the extinction of the trilobites with Franz Joseph Haydn's "Farewell Symphony." How's that?

FORTEY: Well, you know, the symphony begins with a lot of bustle, the orchestra all playing together. And now I think it was a protest that Haydn made on the behalf of the poor pay of his orchestra.

(Music up and under: Haydn's "Farewell Symphony")

FORTEY: He got progressive members of the orchestra to pack up and leave the stage, until only, I think it was the first violin alone remained fiddling. Well, so it is with the decline of the trilobites. There was a glorious variety of them in the Ordovician Period, and indeed in the Silurian Period. And then gradually, gradually, the variety dwindled, until at the end of their history there were just a few left. And then of course the rest is silence.

(Haydn up and under)

CURWOOD: Richard Fortey is senior paleontologist at the Natural History Museum in London and author of the book Trilobite: Eyewitness to Evolution. Mr. Fortey, thanks for joining us.

FORTEY: It's been my pleasure.

(Music up and under: Haydn's "Farewell Symphony")

 

 

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