50；000 species of creature in the fossil record； thatreduces the proportion to just one in 120；000。 either way； what we possess is the merestsampling of all the life that earth has spawned。
moreover； the record we do have is hopelessly skewed。 most land animals； of course； don鈥檛die in sediments。 they drop in the open and are eaten or left to rot or weather down tonothing。 the fossil record consequently is almost absurdly biased in favor of marine creatures。
about 95 percent of all the fossils we possess are of animals that once lived under water；mostly in shallow seas。
i mention all this to explain why on a gray day in february i went to the natural historymuseum in london to meet a cheerful； vaguely rumpled； very likeable paleontologist namedrichard fortey。
fortey knows an awful lot about an awful lot。 he is the author of a wry； splendid bookcalled life： an unauthorised biography； which covers the whole pageant of animate creation。
but his first love is a type of marine creature called trilobites that once teemed in ordovicianseas but haven鈥檛 existed for a long time except in fossilized form。 all shared a basic body planof three parts； or lobes鈥攈ead； tail； thorax鈥攆rom which es the name。 fortey found hisfirst when he was a boy clambering over rocks at st。 david鈥檚 bay in wales。 he was hookedfor life。
he took me to a gallery of tall metal cupboards。 each cupboard was filled with shallowdrawers； and each drawer was filled with stony trilobites鈥攖wenty thousand specimens in all。
鈥渋t seems like a big number；鈥潯e agreed； 鈥渂ut you have to remember that millions uponmillions of trilobites lived for millions upon millions of years in ancient seas； so twentythousand isn鈥檛 a huge number。 and most of these are only partial specimens。 finding aplete trilobite fossil is still a big moment for a paleontologist。鈥�
trilobites first appeared鈥攆ully formed； seemingly from nowhere鈥攁bout 540 million yearsago； near the start of the great outburst of plex life popularly known as the cambrianexplosion； and then vanished； along with a great deal else； in the great and still mysteriouspermian extinction 300；000 or so centuries later。 as with all extinct creatures； there is anatural temptation to regard them as failures； but in fact they were among the most successfulanimals ever to live。 their reign ran for 300 million years鈥攖wice the span of dinosaurs；which were themselves one of history鈥檚 great survivors。 humans； fortey points out； havesurvived so far for one…half of 1 percent as long。
with so much time at their disposal； the trilobites proliferated prodigiously。 most remainedsmall； about the size of modern beetles； but some grew to be as big as platters。 altogetherthey formed at least five thousand genera and sixty thousand species鈥攖hough more turn upall the time。 fortey had recently been at a conference in south america where he wasapproached by an academic from a small provincial university in argentina。 鈥渟he had a boxthat was full of interesting things鈥攖rilobites that had never been seen before in southamerica； or indeed anywhere； and a great deal else。 she had no research facilities to studythem and no funds to look for more。 huge parts of the world are still unexplored。鈥�
鈥渋n terms of trilobites？鈥�
鈥渘o； in terms of everything。鈥�
throughout the nineteenth century； trilobites were almost the only known forms of earlyplex life； and for that reason were assiduously collected and studied。 the big mysteryabout them was their sudden appearance。 even now； as fortey says； it can be startling to go tothe right formation of rocks and to work your way upward through the eons finding no visiblelife at all； and then suddenly 鈥渁 whole profallotaspis or elenellus as big as a crab will popinto your waiting hands。鈥潯hese were creatures with limbs； gills； nervous systems； probingantennae； 鈥渁 brain of sorts；鈥潯n fortey鈥檚 words； and the strangest eyes ever seen。 made of calcite rods； the same stuff that forms limestone； they constituted the earliest visual systemsknown。 more than this； the earliest trilobites didn鈥檛 consist of just one venturesome speciesbut dozens； and didn鈥檛 appear in one or two locations but all over。 many thinking people inthe nineteenth century saw this as proof of god鈥檚 handiwork and refutation of darwin鈥檚evolutionary ideals。 if evolution proceeded slowly； they asked； then how did he account forthis sudden appearance of plex； fully formed creatures？ the fact is； he couldn鈥檛。
and so matters seemed destined to remain forever until one day in 1909； three months shyof the fiftieth anniversary of the publication of darwin鈥檚 on the origin of species ； when apaleontologist named charles doolittle walcott made an extraordinary find in the canadianrockies。
walcott was born in 1850 and grew up near utica； new york； in a family of modest means；which became more modest still with the sudden death of his father when walcott was aninfant。 as a boy walcott discovered that he had a knack for finding fossils； particularlytrilobites； and built up a collection of sufficient distinction that it was bought by louisagassiz for his museum at harvard for a small fortune鈥攁bout 70；000 in today鈥檚 money。
although he had barely a high school education and was self taught in the sciences； walcottbecame a leading authority on trilobites and was the first person to establish that trilobiteswere arthropods； the group that includes modern insects and crustaceans。
in 1879 he took a job as a field researcher with the newly formed united states geologicalsurvey and served with such distinction that within fifteen years he had risen to be its head。 in1907 he was appointed secretary of the smithsonian institution； where he remained until hisdeath in 1927。 despite his administrative obligations； he continued to do fieldwork and towrite prolifically。 鈥渉is books fill a library shelf；鈥潯ccording to fortey。 not incidentally； hewas also a founding director of the national advisory mittee for aeronautics； whicheventually became the national aeronautics and space agency； or nasa； and thus canrightly be considered the grandfather of the space age。
but what he is remembered for now is an astute but lucky find in british columbia； highabove the little town of field； in the late summer of 1909。 the customary version of the storyis that walcott； acpanied by his wife； was riding on horseback on a mountain trail beneaththe spot called the burgess ridge when his wife鈥檚 horse slipped on loose stones。 dismountingto assist her； walcott discovered that the horse had turned a slab of shale that contained fossilcrustaceans of an especially ancient and unusual type。 snow was falling鈥攚inter es earlyto the canadian rockies鈥攕o they didn鈥檛 linger； but the next year at the first opportunitywalcott returned to the spot。 tracing the presumed route of the rocks鈥櫋lide； he climbed 750feet to near the mountain鈥檚 summit。 there； 8；000 feet above sea level； he found a shaleoutcrop； about the length of a city block； containing an unrivaled array of fossils from soonafter the moment when plex life burst forth in dazzling profusion鈥攖he famous cambrianexplosion。 walcott had found； in effect； the holy grail of paleontology。 the outcrop becameknown as the burgess shale； and for a long time it provided 鈥渙ur sole vista upon the inceptionof modern life in all its fullness；鈥潯s the late stephen jay gould recorded in his popular bookwonderful life 。
gould； ever scrupulous； discovered from reading walcott鈥檚 diaries that the story of theburgess shale鈥檚 discovery appears to have been somewhat embroidered鈥攚alcott makes nomention of a slipping horse or falling snow鈥攂ut there is no disputing that it was anextraordinary find。
it is almost impossible for us whose time on earth is limited to a breezy few decades toappreciate how remote in time from us the cambrian outburst was。 if you could fly backwardsinto the past at the rate of one year per second； it would take you about half an hour to reachthe time of christ； and a little over three weeks to get back to the beginnings of human life。
but it would take you twenty years to reach the dawn of the cambrian period。 it was； in otherwords； an extremely long time ago； and the world was a very different place。
for one thing； 500…million…plus years ago when the burgess shale was formed it wasn鈥檛 atthe top of a mountain but at the foot of one。 specifically it was a shallow ocean basin at thebottom of a steep cliff。 the seas of that time teemed with life； but normally the animals left norecord because they were soft…bodied and decayed upon dying。 but at burgess the cliffcollapsed； and the creatures below； entombed in a mudslide； were pressed like flowers in abook； their features preserved in wondrous detail。
in annual summer trips from 1910 to 1925 （by which time he was seventy…five years old）；walcott excavated tens of thousands of specimens （gould says 80；000； the normallyunimpeachable fact checkers of national georgraphic say 60；000）； which he brought back towashington for further study。 in both sheer numbers and diversity the collection wasunparalleled。 some of the burgess fossils had shells； many others did not。 some were sighted；others blind。 the variety was enormous； consisting of 140 species by one count。 鈥渢he burgessshale included a range of disparity in anatomical designs never again equaled； and notmatched today by all the creatures in the world鈥檚 oceans；鈥潯ould wrote。
unfortunately； according to gould； walcott failed to discern the significance of what hehad found。 鈥渟natching defeat from the jaws of victory；鈥潯ould wrote in another work； eightlittle piggies； 鈥渨alcott then proceeded to misinterpret these magnificent fossils in the deepestpossible way。鈥潯e placed them into modern groups； making them ancestral to today鈥檚 worms；jellyfish； and other creatures； and thus failed to appreciate their distinctness。 鈥渦nder such aninterpretation；鈥潯ould sighed； 鈥渓ife began in primordial simplicity and moved inexorably；predictably onward to more and better。鈥�
walcott died in 1927 and the burgess fossils were largely forgotten。 for nearly half acentury they stayed shut away in drawers in the american museum of natural his