Paleontology, types & uses of fossils

Main Topic of Paleontology (Study of Fossils or remains of living organisms), Fossils and Types of Fossils & Significance of Fossils

1. PALEONTOLOGY
FOSSILS & TYPES
USES OF FOSSILS
LECTURE NO. 1
05 DECEMBER 2020
By
KASHIF MANZOOR (PH.D SCHOLAR)
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2. INTRODUCTION TO PALEONTOLOGY
Thesciencewhichdealswiththestudyofthefossilizedremainsofplantsand
animalsfoundinearth’scrustORthestudyoffossilsiscalledPaleontology.
(Greekwordspailos=ancient+onta=existing+logos=knowledge).
A.PALEOBOTANY :isthestudyoffossilplants.
B.PALEOZOOLOGY :isthestudyoffossilanimals.
i.INVERTEBRATE PALEONTOLOGY :isthestudyoffossilanimalswithout
backbones.
ii.VERTEBRATE PALEONTOLOGY :isthestudyoffossilanimalswith
backbonesorvertebralcolumn.
iii.MICROPALEONTOLOGY :isthestudyoffossilthataresosmallthatthey
canbestudiedundermicroscopeonly.
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3. 3
PALEOZOOLOGY

4. 4
MICROPALEONTOLOGY PALEOBOTANY

5. FOSSILS
ThewordfossilisderivedfromLatinword“fossilis”,meaning“dug-up”.
Formanyyearsanycuriousobjectthatwasdugoutofthegroundwas
consideredtobeafossil.
Todaywedefinefossilas“theremainsorrelicsofanyorganismthat
livedpriortoRecenttimes”.
Fossilsarefoundinmanyformsdependinguponthe
a)originalcharacteroftheorganism,
b)thetypeofmaterialinwhichitwasburied,and
c)thechemicalactiontowhichitwassubjectedafterburial.
Fossilsmaybearrangedintofourgroupsaccordingtotheirmethodof
preservation.
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6. 6

7. TYPES
OF
FOSSILS
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8. a). ORIGINAL SOFT PARTS OF ORGANISMS
Usuallyonlythehardpartsoforganismsarefossilizedbut,underexceptionally
favorableconditions,eventhesoftpartsarealsopreserved.Organismsmaybe
preservedintactinamediumthatprotectsthemfromdecaybybacterialaction.
Examplesofsuchspecialmediaareice,oilsaturatedsoil,andAmber.
ThebestknownexamplesoffossilspreservediniceorfrozensoilareWooly
mammothsofSiberiaandAlaska.Thesehugeelephantlikemammals(with
curvedtusks)apparentlydiedduetoheavyglaciationandwereburiedin
permafrost(frozensoil)manythousandyearsago.Thefirstsuchfindwasreported
fromSiberiain1799,morethanfiftyadditionalspecimenshavebeen
discoveredsincethen.
Theicepreservationissoperfectthatskin,hairs,blood,fleshandotherparts
ofthebodyareintact.
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TYPES OF FOSSILS

9. 9
Amberisfossilizedtreeresinthathasbeenappreciatedforits
colorandnaturalbeautysinceNeolithictimes.Muchvalued
fromantiquitytothepresentasagemstone,amberismade
intoavarietyofdecorativeobjects.Amberisusedinjewelry.
Ithasalsobeenusedasahealingagentinfolkmedicine.

10. 10
MAMMOTHS

11. a). ORIGINAL SOFT PARTS OF ORGANISMS
TheremainsofanextinctRhinoceroshasbeenobtainedfromoilsaturatedsoil
inEasternPoland.Thisisratheruncommonmediumofpreservationbutithas
resultedinwellpreservedskinandflesh.
Anotherinterestingmediumofpreservationisamber.Prehistoricinsectsbecame
entrappedinastickygumlikeresinthatexudesoutfromthetrunkoftrees.This
yellowishcolouredresiniscalledAmber.Asitdriedandsolidified,theinsects
remainembeddedintheresinasremarkablywellpreservedfossilwhichshow
evenhistologicaldetailslikethefreshlypreservedspecimens.
Desertformsmaybedriedoutbythehot,dry,desertwindsandthenburiedin
shiftingsandsresultingintowellpreservedskinandbone.
Thetotalnumberoffossilsofsoftpartsofanimalsis,however,verysmall
comparedtothatofothermethodsoffossilization.
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TYPES OF FOSSILS

12. 12
RHINOCEROS

13. b). ORIGINAL HARD PARTS OF ORGANISMS
Mostanimalsandplantshavesomehardpartsintheirbodieswhicharecapableof
fossilization.Thesemaybeinthefollowingforms.
I.CALCITICREMAINS:e.g.shellsofforaminifers,corals,testofechinoderms
andbrachiopods(commonconstituentofthesehardpartsismineralcalcite).
II.ARAGONITICREMAINS:shellsofgastropods,pelycepodsandcephalopods
(anunstableformofcalcite).
III.PHOSPHATICREMAINS:Bonesofvertebrates.
IV.SILICEOUSREMAINS:e.g.Radiolarianshellsandskeletonofsome
sponges.
V.CHITINOUSREMAINS:exoskeletonofarthropods.
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TYPES OF FOSSILS

14. c). ALTERED HARD PARTS OF ORGANISM
Theoriginalhardstructureofmanyorganismsmayundergoconsiderablevariation
withthepassageoftime.Thesechangesmaycomeoutinmanydifferentways,
dependingonthebodymaterialoftheorganisms,theenvironmentalconditions
inwhichorganismslivedandtheconditionsunderwhichtheremainsof
organismsdeposited.
1.CARBONIZATION ORDISTILLATION:Softorganicmaterialmaybe
preservedbycarbonizationordistillation,aprocessinwhich,astimepassed,
nitrogen,oxygenandhydrogenarelostandonlyathinfilmofcarbonaceous
materialremains.Thiscarbonresidemayretainmanyofthecharacteristicsofthe
formoforiginalorganism.Ifthefilmofcarbonislostfromfossilpreservedinfine
grainedsediment,areplicaofthesurface,calledasimpression,maystillshow
considerabledetail.Jellyfish,fishandpartsoftreeshavebeenfossilizedinthis
manner.
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TYPES OF FOSSILS

15. c). ALTERED HARD PARTS OF ORGANISM
II.PERMINERALIZATION ORPETRIFICATION:Oftenfossilsbecome
petrified(literallyturnedintostones),meaningthatthesmallinternalcavities
orporesoftheoriginalstructurearefilledwithprecipitatedmineral
matter.Thehardpartsofmanyorganismshavebeenpreservedbythismethod
andsuchfossilsareheavyandstonelike.Petrifiedwoodisthemostcommon
exampleofthistypeofpreservation.
III.REPLACEMENT ORMINERALIZATION :Thistypeofpreservation
occurswhencirculatingwaterdissolveschemicalsfrombonesorshellsand
leavesthemlightandspongy.Moreoftenaschemicalsaredissolvedtheyare
replacedbyothers(i.e.thegapsarefilledbythedepositionofothermineral
bearingsolution).Thereplacingmineralsareofmorethanfiftytypes.Most
commonaresilica,lime,quartz,pyritesetc.
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TYPES OF FOSSILS

16. d). TRACES OF ORGANISMS
Inadditiontothefossilsalreadymentioned,therearenumerousothertypes,many
ofthemonlytracesorimpressionsofprehistoriclife.Examplesofsuchindirect
evidenceincludes;
I.MOLD:Amoldistheimpressionofanorganisminthesurrounding
material.Forexample,whenashellorboneorotherstructureisburiedin
sedimentandthendissolvedbygroundwater,leavingacavity,amoldiscreated.
Themoldreflectsonlytheshapeandsurfacemarkingsoftheorganisms,butdoes
notrevealanyinformationconcerningitsinternalstructure.Moldsofthinforms,
suchasleavesofplants,arecalledIMPRINTS.
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TYPES OF FOSSILS

17. d). TRACES OF ORGANISMS
II.CAST:Ifthehollowcavityormoldissubsequentlyfilledwithsomemineralmatter,
anaturalcastisformed.Thisdiffersfrompetrificationinthatitretainsonlytheform(or
shape)oforganismbutnotitsstructure.Anartificialcastisproducedwhenthemoldis
filledwithliquidrubber,dentalwaxorplasterofparis.
III.TRACESANDTRAILS:Tracksortracesarefootprintsmadebyanimalsasthey
walkoverground.Thesetracksaremorelikelytobepreservedinaridandsemi-aridareas.
Footprints,occurringinseries,however,mayindicatethesizeandshapeoffoot,length
oflimbs,postureandtypesofgait.Footprintsofdinosaurshavebeenfoundinexcellent
shapeintheredstoneoftheConnecticutValley,U.S.A.
Trailsareimpressionsmadebythebodiesoforganismsastheycrawlovertheground.
Boringsorburrowsofwormsandmolluscshavealsobeenpreservedasfossils.
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TYPES OF FOSSILS

18. d). TRACES OF ORGANISMS
IV.GASTROLITHS:Gastrolithsaresmoothroundedstonesfoundintherib
cagesofdinosaurs.Thesestonesprobablyhelpedthedinosaursindigestionjustas
pigeonshavegravelintheirgizzardstocrushgrains.Gastrolithsarefoundin
dinosaursonly.
V.COPROLITES:Fossilfaecalpelletsorcastingofanimalsdroppingsare
calledcoprolites.Coprolitesareusuallyfoundinassociationwiththeanimalsthat
madethem,andastudyoffossilexcreteamayprovidevaluableinformation
pertainingtothefoodhabitsoftheseorganisms.
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TYPES OF FOSSILS

19. USES OF FOSSILS
Fossilsareusefulinnumberofways.Prehistoricmanutilizedfossilsinan
attempttowardoffevilspirits,whilemedicinemenofcertainprimitive
cultureoftodayusefossilbonesinthebeliefthattheypossesssome
mysteriouspowerofhealingwounds.
Thescientists,however,usefossilstorecreatethegeologicalhistoryofearth.
Perhapstheimportanceoffossilisinthetracingofthedevelopmentofplants
andanimals.Someoftheimportantusesare;
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USES OF FOSSILS

20. USES OF FOSSILS
I.ASSTRATIGRAPHIC INDICATOR:Fossilsareoneofthemostvaluabletools
ofthestratigrapherandcanprovideimportantcluestotheageofrocks
containingthem.Itispossibletousefossilsforthispurposebecauseithaslong
beenknownthatthereisadefiniterelationshipbetweenfossilcontentsoftherocks
andpositionoftheserocksingeologicalcolumn.
AccordingtotheLAWOFSUPERPOSITION,weknowthatinanormal
sequenceofsedimentaryrocks,youngerstrataarelaiddownonthetopofthe
olderstrata.Henceitfollowsthatoldestfossilswillnormallybefoundatthe
bottomofarocksequencewithyoungerfossilsneartopofthesequence.In
somecases,however,therockshavebeendisturbedbycrustaldeformation.Inthese
regions,thebedsmayhavebeenoverturnedorolderrocksthrustontopofthe
youngerones.Ifthestrataintheareasarefossiliferousandifthegeologistknows
theorderinwhichthefossilsnormallyoccurinthesection,hecanthenworkout
theproperstratigraphicsequence.
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USES OF FOSSILS

21. USES OF FOSSILS
II).ASCLIMATICINDICATOR:Fossilshavebeensuccessfullyusedto
demonstratetheexistenceofdifferentclimaticconditionsinthegeologicalpast.
Ifwefindremainsoftropicalplantsoranimalsinaregionthathastemperateor
coldclimatetodayweassumethatatropicalclimateprevailedinthatareaatone
time.Forexample,
a).FossilfernsfromGreenlandindicate,amuchwarmerclimateforthese
areasinothertime,
b).RemainsofthereefbuildingcoralshavebeenfoundinSiberia.Sincethese
animalshavealwayslivedinwarmerseas,theirfossilsindicatethattheclimatewas
tropicalatleastduringSilurianperiod,
c).FossilsofreindeerfromFrance,indicateonceitsclimatewasextremelycold.
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USES OF FOSSILS

22. USES OF FOSSILS
III).ASEVIDENCEOFCHANGINGGEOGRAPHIC PATTERN:Fossilshave
beenprovideduswithmuchinformationaboutthedistributionoftheseasand
landmassesofthepast.Certainanimalssuchas,corals,echinodermsand
brachiopodshavealwayslivedinthesea.
Thepresenceoftheseanimalsindicatemarinedepositionfortherockscontaining
them.Similarly,occurrenceoflandplantsorfossilsofterrestrialanimalswill
indicatethepresenceoflandmassesinthatparticulararea.
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USES OF FOSSILS

23. USES OF FOSSILS
IV).ASRECORDOFPREHISTORICLIFE:Thestudyoffossilshasprovided
usmuchinformationabouttheoriginandevolutionoforganismslivingtoday.
Theknowledgeispossiblebecauseallmodernanimalshavedescendedfromtheir
primitiveancestorswhichpopulatedtheearthintimespast.Bystudyingtherecord
ofthechangesthatorganismshaveundergone,thepaleontologistisabletowork
outthefamilytreeorevolutionarypatternofformostthepresentdaylife.Itis
thuspossibletodeterminetherelationshipbetweendifferentgroupsofplants
andanimalsandtoseehowlifeslowly,butcontinuously,becomeprogressively
morecomplex.
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USES OF FOSSILS

24. USES OF FOSSILS
IV).ASECONOMIC TOOLS:Fossilsnotonlyareofvalueinconducting
scientificstudiesbuthavepracticalapplicationsaswell.
Sincemanyofourmoreimportantresourcesareassociatedwithsedimentaryrocks,
fossils,whenpresent,maybeofhelpinlocatingmineralores,coal,oilandgas
deposits.Forexample,mininggeologistusesfossilstodatethestrataaboveand
belowtherocksthatcontainvaluableminerals.Fossilplantsarecommonly
associatedwithcoaldeposits.Foraminifera(importantgroupofprotozoanfossils)
areimportantinlocatingfields.
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USES OF FOSSILS

25. THE END
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