the rise and progress of palaeontology-第2章

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to　palaeontology　was　Nicolas　Steno；　professor　of　anatomy　in

Florence；　though　a　Dane　by　birth。　Collectors　of　fossils　at　that

day　were　familiar　with　certain　bodies　termed　〃glossopetrae；〃　and

speculation　was　rife　as　to　their　nature。　In　the　first　half　of

the　seventeenth　century；　Fabio　Colonna　had　tried　to　convince　his

colleagues　of　the　famous　Accademia　dei　Lincei　that　the

glossopetrae　were　merely　fossil　sharks'　teeth；　but　his　arguments

made　no　impression。　Fifty　years　later；　Steno　re…opened　the

question；　and；　by　dissecting　the　head　of　a　shark　and　pointing

out　the　very　exact　correspondence　of　its　teeth　with　the

glossopetrae；　left　no　rational　doubt　as　to　the　origin　of　the

latter。　Thus　far；　the　work　of　Steno　went　little　further　than

that　of　Colonna；　but　it　fortunately　occurred　to　him　to　think　out

the　whole　subject　of　the　interpretation　of　fossils；　and　the

result　of　his　meditations　was　the　publication；　in　1669；　of　a

little　treatise　with　the　very　quaint　title　of　〃De　Solido　intra

Solidum　naturaliter　contento。〃　The　general　course　of　Steno's

argument　may　be　stated　in　a　few　words。　Fossils　are　solid　bodies

which；　by　some　natural　process；　have　come　to　be　contained　within

other　solid　bodies；　namely；　the　rocks　in　which　they　are

embedded；　and　the　fundamental　problem　of　palaeontology；　stated

generally；　is　this：　〃Given　a　body　endowed　with　a　certain　shape

and　produced　in　accordance　with　natural　laws；　to　find　in　that

body　itself　the　evidence　of　the　place　and　manner　of　its

production。〃　The　only　way　of　solving　this　problem　is　by　the

application　of　the　axiom　that　〃like　effects　imply　like　causes；〃

or　as　Steno　puts　it；　in　reference　to　this　particular　case；　that

〃bodies　which　are　altogether　similar　have　been　produced　in　the

same　way。〃　Hence；　since　the　glossopetrae　are　altogether

similar　to　sharks'　teeth；　they　must　have　been　produced　by

sharklike　fishes；　and　since　many　fossil　shells　correspond；　down

to　the　minutest　details　of　structure；　with　the　shells　of

existing　marine　or　freshwater　animals；　they　must　have　been

produced　by　similar　animals；　and　the　like　reasoning　is　applied

by　Steno　to　the　fossil　bones　of　vertebrated　animals；　whether

aquatic　or　terrestrial。　To　the　obvious　objection　that　many

fossils　are　not　altogether　similar　to　their　living　analogues；

differing　in　substance　while　agreeing　in　form；　or　being　mere

hollows　or　impressions；　the　surfaces　of　which　are　figured　in　the

same　way　as　those　of　animal　or　vegetable　organisms；　Steno

replies　by　pointing　out　the　changes　which　take　place　in　organic

remains　embedded　in　the　earth；　and　how　their　solid　substance　may

be　dissolved　away　entirely；　or　replaced　by　mineral　matter；　until

nothing　is　left　of　the　original　but　a　cast；　an　impression；　or　a

mere　trace　of　its　contours。　The　principles　of　investigation　thus

excellently　stated　and　illustrated　by　Steno　in　1669；　are　those

which　have；　consciously　or　unconsciously；　guided　the　researches

of　palaeontologists　ever　since。　Even　that　feat　of　palaeontology

which　has　so　powerfully　impressed　the　popular　imagination；　the

reconstruction　of　an　extinct　animal　from　a　tooth　or　a　bone；　is

based　upon　the　simplest　imaginable　application　of　the　logic　of

Steno。　A　moment's　consideration　will　show；　in　fact；　that　Steno's

conclusion　that　the　glossopetrae　are　sharks'　teeth　implies　the

reconstruction　of　an　animal　from　its　tooth。　It　is　equivalent　to

the　assertion　that　the　animal　of　which　the　glossopetrae　are

relics　had　the　form　and　organisation　of　a　shark；　that　it　had　a

skull；　a　vertebral　column；　and　limbs　similar　to　those　which　are

characteristic　of　this　group　of　fishes；　that　its　heart；　gills；

and　intestines　presented　the　peculiarities　which　those　of　all

sharks　exhibit；　nay；　even　that　any　hard　parts　which　its

integument　contained　were　of　a　totally　different　character　from

the　scales　of　ordinary　fishes。　These　conclusions　are　as　certain

as　any　based　upon　probable　reasonings　can　be。　And　they　are　so；

simply　because　a　very　large　experience　justifies　us　in　believing

that　teeth　of　this　particular　form　and　structure　are　invariably

associated　with　the　peculiar　organisation　of　sharks；　and　are

never　found　in　connection　with　other　organisms。　Why　this　should

be　we　are　not　at　present　in　a　position　even　to　imagine；　we　must

take　the　fact　as　an　empirical　law　of　animal　morphology；　the

reason　of　which　may　possibly　be　one　day　found　in　the　history　of

the　evolution　of　the　shark　tribe；　but　for　which　it　is　hopeless

to　seek　for　an　explanation　in　ordinary　physiological　reasonings。

Every　one　practically　acquainted　with　palaeontology　is　aware

that　it　is　not　every　tooth；　nor　every　bone；　which　enables　us　to

form　a　judgment　of　the　character　of　the　animal　to　which　it

belonged；　and　that　it　is　possible　to　possess　many　teeth；　and

even　a　large　portion　of　the　skeleton　of　an　extinct　animal；　and

yet　be　unable　to　reconstruct　its　skull　or　its　limbs。　It　is　only

when　the　tooth　or　bone　presents　peculiarities；　which　we　know　by

previous　experience　to　be　characteristic　of　a　certain　group；

that　we　can　safely　predict　that　the　fossil　belonged　to　an　animal

of　the　same　group。　Any　one　who　finds　a　cow's　grinder　may　be

perfectly　sure　that　it　belonged　to　an　animal　which　had　two

complete　toes　on　each　foot　and　ruminated；　any　one　who　finds　a

horse's　grinder　may　be　as　sure　that　it　had　one　complete　toe　on

each　foot　and　did　not　ruminate；　but　if　ruminants　and　horses　were

extinct　animals　of　which　nothing　but　the　grinders　had　ever　been

discovered；　no　amount　of　physiological　reasoning　could　have

enabled　us　to　reconstruct　either　animal；　still　less　to　have

divined　the　wide　differences　between　the　two。　Cuvier；　in　the

〃Discours　sur　les　Revolutions　de　la　Surface　du　Globe；〃　strangely

credits　himself；　and　has　ever　since　been　credited　by　others；

with　the　invention　of　a　new　method　of　palaeontological　research。

But　if　you　will　turn　to　the　〃Recherches　sur　les　Ossemens

Fossiles〃　and　watch　Cuvier；　not　speculating；　but　working；　you

will　find　that　his　method　is　neither　more　nor　less　than　that　of

Steno。　If　he　was　able　to　make　his　famous　prophecy　from　the　jaw

which　lay　upon　the　surface　of　a　block　of　stone　to　the　pelvis　of

the　same　animal　which　lay　hidden　in　it；　it　was　not　because

either　he；　or　any　one　else；　knew；　or　knows；　why　a　certain　form

of　jaw　is；　as　a　rule；　constantly　accompanied　by　the　presence　of

marsupial　bones；　but　simply　because　experience　has　shown　that

these　two　structures　are　co…ordinated。　





The　settlement　of　the　nature　of　fossils　led　at　once　to　the　next

advance　of　palaeontology；　viz。　its　application　to　the

deciphering　of　the　history　of　the　earth。　When　it　was　admitted

that　fossils　are　remains　of　animals　and　plants；　it　followed

that；　in　so　far　as　they　resemble　terrestrial；　or　freshwater；

animals　and　plants；　they　are　evidences　of　the　existence　of　land；

or　fresh　water；　and；　in　so　far　as　they　resemble　marine

organisms；　they　are　evidences　of　the　existence　of　the　sea　at　the

time　at　which　they　were　parts　of　actually　living　animals　and

plants。　Moreover；　in　the　absence　of　evidence　to　the　contrary；　it

must　be　admitted　that　the　terrestrial　or　the　marine　organisms

implied　the　existence　of　land　or　sea　at　the　place　in　which　they

were　found　while　they　were　yet　living。　In　fact；　such　conclusions

were　immediately　drawn　by　everybody；　from　the　time　of　Xenophanes

downwards；　who　believed　that　fossils　were　really　organic

remains。　Steno　discusses　their　value　as　evidence　of　repeated

alteration　of　marine　and　terrestrial　conditions　upon　the　soil　of

Tuscany　in　a　manner　worthy　of　a　modern　geologist。

The　speculations　of　De　Maillet　in　the　beginning　of　the

eighteenth　century　turn　upon　fossils；　and　Buffon　follows　him

very　closely　in　those　two　remarkable　works；　the　〃Theorie　de　la

Terre〃　and　the　〃Epoques　de　la　Nature〃　with　which　he　commenced

and　ended　his　career　as　a　naturalist。



The　opening　sentences　of　the　〃Epoques　de　la　Nature〃　show　us　how

fully　Buffon　recognised　the　analogy　of　geological　with

archaeological