Trilobite: Eyewitness to Evolution

Natural history, deep-time may conjure up images of Stephen J. Gould's wondrous creatures of the early Cambrian (530 million years ago), dug out of the Burgess Shale in British Columbia. I realize that other paleontologists have had problems with some of his anatomical descriptions and theories of punctuated equilibrium ("Trilobite" spends a chapter defending Gould from some of his more vigorous critics), but the world that he created was strange, beautiful, and compelling. Fortey creates a similar vision of Earth as it existed for 300 million years, starting like Gould, in the Cambrian. No animal better exemplifies the drama of evolution and extinction than trilobites, except perhaps for the Johnny-come-lately dinosaurs. If you are interested in really deep time, you must travel back before the dinosaurs and peer with the author through the eyes of the trilobites. "'Look into my eyes,' the trilobite seems to say, 'and you will see the vestiges of your own history.'" And very strange eyes they are. In the chapter, "Crystal Eyes" the author plays an exuberant, complex riff on vision as it first evolved, and most specifically on the uniquely developed eyes of trilobites. I used to think of these creatures as mud-colored tripartite beetles that crawled around in warm, shallow Paleozoic seas--interesting basically because they lasted so long. But according to Fortey, their eyes were made of calcite crystals, which "makes them unique in the animal kingdom...Look into a crystal of Iceland spar and you can see the secret of the trilobyte's vision." The author then goes into quite a bit of detail as to why double vision was not a problem for these amazing arthropods, even though their eyes were made up of six-sided crystals. Since the trilobite's eyes were part of its exoskeleton and just as hard, it had to shed them with each molt. Trilobites ranged from dinner-platter-size down to bitty little bugs that were barely a millimeter long. Fortey describes them in loving detail and also defends the need to collect and study them. Lord Rutherford's remark that 'all science is either physics or stamp collecting' is vigorously repudiated (I think Rutherford's aphorism must have really stung, because it gets a good bashing in nearly every natural history book in my library). Just one of the reasons why trilobites are not like stamps is that their distribution helps us determine the outlines of continents and islands that predated not just the modern world, but the ancient supercontinent of Pangaea. Trilobites managed to squeeze through a couple of evolutionary bottlenecks, surviving and multiplying for over 300 million years. In his heart of hearts, the author admits to hoping that, like the ancient coelacanth, a remnant of this once-vast family of arthropods will be rediscovered, curled up on some unexplored sea bottom, or gazing through crystalline eyes at some newer denizen of the deep. After reading Fortey's fascinating account, I can only h

_Trilobite_ by Richard Fortey is a wonderful, witty, charming, very well-written, and very richly illustrated homage to the trilobite, an arthropod that teemed in the millions in the seas of the ancient earth for 300 million years before becoming extinct. Fortey is an enthusiastic expert on all things trilobite - having studied them for over 30 years - and did an excellent job in conveying his passion for these long extinct creatures in a very readable format with many dozens of excellent photographs and sketches. Early on Fortey introduced basic concepts of trilobite anatomy (he said eight technical names is all anyone needs to describe any species). With the help of a diagram of a representative species, we learn for instance that the head is properly termed the cephalon while the other end -the tail - is called the pygidium. Between the cephalon and the pygidium is the thorax, which is subdivided into segments (thoracic segments). A central convex portion or lobe running down the thorax and pygidium is called the axis, while to either side are the lateral or pleural parts. Reading about trilobite eyes was particular fascinating; they were made of calcite (the same substance that makes up the white cliffs of Dover and was popular in classical architecture), something unique in the entire animal kingdom. Fortey discussed the physics and chemistry of the crystal eyes of trilobites, how they enabled the animal to see, how the lenses on trilobite eyes were arranged and how they functioned, the unique optical properties of calcite, even experiments replicating the vision of individual trilobite species (in particular the experiments relating to the vision of _Phacops_ were extremely interesting; I never knew that physics had such a place in paleontology). We learn also that while whole trilobites are certainly found in the fossil record (or more accurately the carapace of the animal, as the soft and delicate parts such as the legs only rarely fossilize) much of what is found are only bits and pieces, often shed when molting. Thoracic segments, pygidium, and other parts litter the fossil record like puzzle pieces and it is often the job of the trilobite expert to reassemble them, much like a jigsaw puzzle. Some fossils sites - such as Beecher's Trilobite Bed, an Ordovician fossil site in New York - have preserved through unusual circumstances such delicate trilobite parts as their legs (long a mystery to researchers) and even antennae. The details about the life of the trilobite found there - genus _Triarthus_- was fascinating; apparently they lived in a very low oxygen, high sulfur seafloor environment and may have perished during a fatal drop of dissolved oxygen (and were thus preserved) but otherwise lived symbiotically with bacteria that derived energy from sulfur. Fortey introduced the reader to a wonderful parade of trilobite species, relating the history of the group from the Cambrian to its final days in the Permian (the true Age

This is a remarkable book that will introduce you to the process of science and a fascinating aspect of the emergence of life. Trilobites are among the best fossils for children to get to know because they are very distinct (the tri lobed shells) and very different from anything currently living (the horseshoe crab on American Atlantic beaches is comparable in unique appearance and attracts children with similar fascination).For those who want a better system of American science education, Fortey gives some powerful hints. Consider his language: "The fever of discovery was upon me.... I found a trilobite...the textbook came alive...this was my first discovery of the animals that would change my life (p.18)." He continues, "I knew, by some principle which I could not articulate, that the wider end was the head of the animal. And of course upon the head there were the eyes. Despite the unfamiliar conformation of the fossil I knew that eyes must always belong on heads. So despite the exoticism of the fossil there was already a common bond between me and the trilobite - we both had our heads screwed on the right way."(p.19) Again and again Fortey reminds us that scientists grow from discovery, mystery, romance, intrigue, while the memorization comes later. He reminds us that there is an enormous amount we still do not know and in the process introduces us to a world we have never considered: "I want to invest the trilobite with all the glamour of the dinosaur and twice its endurance. I want you to see the world through the eyes of trilobites, to help you make a journey back through hundreds of millions of years...this will be an unabashedly trilobite-centric view of the world,"(p.19).For anyone who wants to take a few hours to think different thoughts, to consider how brief our history has been and how successful other organisms have been, to contemplate the various catastrophic extinctions and their dramatic impact on life, to ask about life beyond the rush hour traffic and the monthly report, Fortey's work is a little gem of an introduction to a fascinating part of the world. I highly recommend it.

This is a wonderful book! Trilobite! Eyewitness to Evolution is a skillfully crafted narrative that displays Fortey's impeccable scientific credentials and his engaging and highly entertaining style of writing. Readers unfamiliar with these remarkable creatures and their 300 million year history will benefit from well organized chapters that explain the physiology, life habits, evolutionary patterns and geological time line with insight and clarity. Those readers with a better understanding of the class Trilobita, will enjoy the personal observations and anecdotes of a superb writer, who just happens to be a leading authority on the subject. Fortey even tackles the role of ombudsman in his attempt to soften the contentious battles between Simon Conway-Morris and Stephen J. Gould over those controversial early arthropods and other creatures of arguable affinity. I applaud his restraint and gentle hand in dealing with the emotional fervor of his contemporaries. If I have any criticism of this book, it would be to step on to the soapbox and point out that Fortey details the moment when he chipped out his first trilobite at age fourteen as an epiphany that determined his lifes work. He discusses Walcott and other self taught geologists and paleontologists who started as eager young fossil hunters. Sadly, in several places throughout the text, Fortey explains that these sites are now closed to collecting. Typically, these closures are to protect the area from the hammers of interested collectors (with special emphasis on those who might profit from the sale of their collections) in the misguided notion that invertebrate fossils are national treasures that must be protected for all through restrictions and the intervention of government agencies. I subscribe to the belief that a fossil left uncollected is a fossil that is lost. If common sense prevails, the search for specimens- even for profit- can benefit us all. Instead, we get over zealous regulation and permanent site closures. In the final pages of his book, Fortey marvels at the recently discovered trident Comura trilobite. (now Walliserops trifurcautus) I only wish he'd made it clear that this unique fossil discovery resulted from the activities of Moroccans digging the Devonian strata for a modest profit and that future fossil wonders, as well as future paleontologists, are much more likely to occur when people are allowed to freely explore the rocks, as Fortey was allowed to do in his youth.

The very best science book for laymen is the book that is written by an expert in a field about his favorite area of expertise. So it is a delight to read _Trilobite! Eyewitness to Evolution_ (Knopf) by Richard Fortey. Fortey is surely an expert; he is a senior paleontologist at the Natural History Museum in London, and has done extensive research in fossil fields all over the globe. His favorite specimens (he refers to them as "my animals") are trilobites, and reading his lucid, humorous, enthusiastic pages, one can certainly understand why.Fortey writes with humor about his adventures in the field. He has hunted trilobites everywhere on the globe, in desert as well as arctic wastes. But of course, most of Fortey's book is about the trilobite itself. The name comes from it's three lobes, not head, thorax, and tail, but the central body axis flanked by the left and right pleural regions. It was originally thought to be some sort of flatfish, but as more specimens were found, it became clear that it was an arthropod, with the nearest living relative the horseshoe crab (although they look more like the woodlice or roly-poly bugs, and some balled up like them). What is generally fossilized in trilobites is the outer upper shell. The underside, with the legs, is thin cuticle that decomposed before fossilization could take place. It was only when specimens were found from a certain field in New York state that details of limbs became plain. Because of a peculiarity in the minerals of the area, the thin cuticle had become gilded with pyrites, fool's gold. Every segment was shown to have a pair of branched legs, and the creature even showed antennae. Fortey's chapter on trilobite eyes, the only ones ever to use calcite prisms for lenses, is amazing.In Fortey's account, trilobites become interesting in themselves, but he clearly shows that they have larger importance. Trilobites were always marine, never freshwater, and they generally inhabited the coastal areas. Because of this, the outline of trilobites in what is now land shows where the coasts used to be. Trilobites help to track the movements of the continents as they split off and sailed to their current positions on the globe over millions of years. Fortey shows how tracking trilobites can sometimes top paleomagnetism as a way of documenting continental drift. In addition, trilobites serve as timekeepers. They are found all over the world and range through such times as Cambrian, Devonian, and Permian, and if you can confidently identify a trilobite, you can spot what range of times your rocks come from.Trilobites lived for over three hundred million years (humans have been around about a thousandth of that time), so they had, as the British say, a very good innings. They have been gone for over two hundred and fifty million years, and yet in this fascinating book, they live still and, with help from a superb reporter, they have news to tell us.