万物简史英文版_比尔·布莱森-第61章

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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�he　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�these　were　creatures　with　limbs；　gills；　nervous　systems；　probingantennae；　鈥渁　brain　of　sorts；鈥潯�in　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�according　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�slide；　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�as　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�gould　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�gould　wrote　in　another　work；　eightlittle　piggies；　鈥渨alcott　then　proceeded　to　misinterpret　these　magnificent　fossils　in　the　deepestpossible　way。鈥潯�he　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�gould　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　history　inwashington；　seldom　consulted　and　never　questioned。　then　in　1973　a　graduate　student　fromcambridge　university　named　simon　conway　morris　paid　a　visit　to　the　collection。　he　wasastonished　by　what　he　found。　the　fossils　were　far　more　varied　and　magnificent　than　walcotthad　indicated　in　his　writings。　in　taxonomy　the　category　that　describes　the　basic　body　plans　ofall　organisms　is　the　phylum；　and　here；　conway　morris　concluded；　were　drawer　after　drawer　ofsuch　anatomical　singularities鈥攁ll　amazingly　and　unaccountably　unrecognized　by　the　manwho　had　found　them。

with　his　supervisor；　harry　whittington；　and　fellow　graduate　student　derek　briggs；　conwaymorris　spent　the　next　several　years　making　a　systematic　revision　of　the　entire　collection；　andcranking　out　one　exciting　monograph　after　another　as　discovery　piled　upon　discovery。　manyof　the　creatures　employed　body　plans　that　were　not　simply　unlike　anything　seen　before　orsince；　but　were　bizarrely　different。　one；　opabinia；　had　five　eyes　and　a　nozzle…like　snout　withclaws　o