Fossils in Paleobotany Study

This PPt has offered the bird's eye view of the fossils and their different issues in the study of Paleobotany.

1. Palaeobotany: Plant life through ages, Geological time table, Fossils -
definition, types, process of fossilization, factors for fossilization,
Importance.

3. Theword,‘Fossil’derivedfromtheLatinword,‘fodere’means‘todig’.Due
tosuddenchangesontheearthbymeansofthedifferentgeologicalprocesss
withthepassageofevolutionparalleltotheearth’sflora&fauna,plantsand
animalslieontherocksmillionsyearsbackandtheremnantoftheplantsand
animalsareexcavatedtreatedasfossil.Thus,itindicatesabouttheclimateand
environmentofthegeologicageexperiencedbytheearth.
Thescientificstudyofthefossilsoftheplantspreservedintherockare
generallytermedasPaleobotanyanditalsoaddressesthepreservedvestigesof
plantlifeinthegeologicalpast.Therefore,paleobotanicalstudiesrelyonthose
naturallypreservedmaterials,thefossilswhichareusuallyavailableinthe
differentrockstrata,especiallyonthesedimentaryrocksastherelicsofthe
ancientpastvegetation.
Paleontologyisabranchofbiologythatstudiesfossilsofallorganismssuchas
plants,animalsandmicrobes,whichexistedontheearth’ssurface,millions
andmillionsyearsago.
Thestudyofhowtheorganismsortheirpartsbecamefossilsarecalled
TaphonomyandtheTaphonomicpathwayscanestablishhowtheplantsand
animalsundergofossil.

5. Geologictimescale(GTS)isameansofmappinghistoryofearthsinceits
inceptionanditisanessentialtoolfortheunderstandingthegeological
historyoftheearthexperiencedwiththepassageoftime.
Soonafterthediscoveryofradioactivity,GTSwasfirstproposedbyArthur
Holmes(1890-1965)anditwascalculatedthe400millionyearsofold
earthexistence.
Stratigraphyoftheearthonthebasisofthesedimentaryrocksdeposited
layerafterlayeristreatedastheframeworkfortheconstructionoftheGTS
Generallydeepertherocks,olderthelayerwitholdfossilsalongwiththe
observationsoftheearth’smagneticfieldshowdifferentmagneticfieldsin
rocksfromthedifferentgeologicage.
Radioactivedatingtechniqueprovidesthedirectevidenceofthesequence
ofeventsontherock.
Theconstructionofgeologicaltimetableindicatesthesuccessivelayer
formation.

6. Radioactivedatingisamethodofdatingrocksandmineralsusing
radioactiveisotopes.Thismethodisusefulforigneousandmetamorphic
rocks,whichcannotbedatedbythestratigraphiccorrelationmethodused
forsedimentaryrocks.Over300naturally-occurringisotopesareknown.
Amongthebest-knowntechniquesareradiocarbondating,potassium–
argondatinganduranium–leaddating.Potassium-Argon(K-Ar)datingis
themostwidelyappliedtechniqueofradiometricdating.Potassiumisa
componentinmanycommonmineralsandcanbeusedtodeterminethe
agesofigneousandmetamorphicrocks.ThePotassium-Argondating
methodisthemeasurementoftheaccumulationofArgoninamineral.As
itsnameimplies,radioactivityistheactofemittingradiation
spontaneously.Thisisdonebyanatomicnucleusthat,forsomereason,is
unstable;it"wants"togiveupsomeenergyinordertoshifttoamore
stableconfiguration.Amaterial'sradioactivityismeasuredinBecquerel
(Bq,internationalunit)andcuries(Ci,U.S.unit).Thisisveryconvenient
onthebasiclawofradioactivitythatmeasurestheratioofproton:neutron
>1.5.

7. TheGTSiscomprisingofthefollowingunits:
Eon-TwoormoregeologicalerasformedEon,
Era-comprisingoftwoormoreperiods,
Periods-Basicpartofgeologicaltimeinwhichsingletypeofrocksystemis
formed,
Epoch-divisionofgeologicperiod,expandsmillionyears,
Age-Unitofgeologicaltimedistinguishedbysomefeatureslike‘Iceage’.
Eon→Era→Periods→Epoch→Era(descendingorder)
ThemodernGTScomprisingoffour“Eons”-Hadean(4.6-3.9Bya),
Archeozoin(3.9-2.5BYA),Proterozoiceon(2.5BYA-540MillionYears
age,MYA),Phanerozoiceon(540Myratotilldate).
HadeanEonissymbolofvolcanism&explosions,
ArcheozoicEon-Reducingfreeoxygenfirsttime,
ProterozoicEoncomprisesColonialalgae,softbodiesInvertebratescalled
ageofhiddenlife,
PhanerozoicEon-Paleozoic,Mesozoic&Cenozoic,eonofadvancedlife.

8. 1.ThePaleozoicEra(540-248Mya)-AncientageofEarth'slifelastedup
to292Mya,dividedintosevenperiods-
TheCambrian(540-500Mya)-theageofTrilobites
TheOrdovician(540-438Mya)-PrimitiveplantslikeBryophytesappeared
TheSilurian(438-408Mya)-Firstvascularplants&Arthropods
TheDevonian(408-360Mya)-Landplants,Fishes,Shark,Mollusksage
TheMississippian(360-325Mya)-
ThePennsylvanian(325-280Mya)
ThePermian(280-248Mya)
Accordingtorecentmodification,theMississippianandPennsylvanian
havebeentoCarboniferousperiod-coalage
ThePermianistheageofGymnosperms,amphibians,massivespreadof
conifers;endedwiththemassextinctionlargestmoss,Trilobiteswentinto
extinction,Seedfernsbecameextinct.

9. Mesozoic(252-66millionyearsago)means'middlelife'andthisisthe
timeofthedinosaurs.ThiseraincludestheTriassic,Jurassic,and
CretaceousPeriods,namesthatmaybefamiliar.Itisthemiddleageoflife
,oftentermedasageofreptiles,lastedforapproximately183Mya,divided
intothreeperiods-
Triassic-(248-208Mya),appearanceoffirstDinosaursandmammals,
abundanceofturtles,appearanceofCycads.
Jurassic(208-146Mya)-significantforreptiles,appearanceoffirstbird,
Arceopteris;manyferns,ginkgo,conifers&cycads.
Cretaceous(146-65Mya)-firstplacentalanimalswiththeprimitive
floweringplantslikeMagnolia,Ficusalongwiththedevelopmentofother
groupslikeFerns,horsetails,Cycads&ginkgoetc,agerofreptilescame
toanendandtheageofmammalsbeginduetotheclimatechange.

10. Ceno’means‘recent’and‘zoic’means‘life’;therecentagefrom65Mya
totoday.
Twoperiods-Tertiary&Quaternary
TERTIARY(65-1.8Mya)dividedintotwo-Paleogene&Neogene
Paleogenedividedintothreeepochscomprising-
A.Paleoceneepoch(65-54Mya)–evolvedfirstlargemammalsand
primitiveprimates,
B.Eocene(54-38Mya)-Appearedfirstrodentsandwhaleswithabundant
mammals,
C.Oligocene(38-24Mya)-Grassescommonwiththeappearanceofcats,
Deer,Rhinos
NEOGENE(24-1.8Mya)consiststwoepochs-
Miocene(24-5Mya)-appearanceofHorses,dogs,Bears,Modernbirds,
Monkeys,apes,
Pliocene(5-1.8Mya)-ModernwhalesandfirstHominidsappeared

11. Ii.QuaternaryPeriod(1.8-today)calledtheageofmancomprisingoftwo
epochs-PleistoceneEpoch(1.8Mya-.011Mya)&HoloceneEpoch
(11000Yrsago).
A.PleistoceneEpoch(1.8-.011Mya)calledGreatIceage,suddenfallof
temperature,thickmantleofsnowappearedinAmericaandpolarregions,
largenumberofmammals,manybirdsandplantsundergomassextinction,
Firsthuman,homosapiensevolvedandthelandsurfacewasdominated
withangiosperm.
B.HoloceneEpoch(11000yrsago)–Thisistheepochofthehuman
evolution,thelandmassesformedbytheretreatofsnowcover,subjected
toerosion,fertilelandturnedintobarrenlands,mandevelopedintellectual
establishmentwiththecontrolovertheanimalandplantkingdomby
meansofdomestication;humancivilizationestablished,flourishedand
continuedsincetoday;randomdevelopmentofconcretetechnologywith
thespredofthehumanpleasureofhappinessbytheinnovationand
technologicalpleasure.

12. Inpaleontology,afossilistheremainsortracesofaplantoranimalthat
livedinthepast.Fossilscantakemanydifferentforms,includingbones,
teeth,shells,andevenimpressionsofplantsoranimalsthathavebeen
preservedinrockorsediment.Theyareusuallyformedwhentheremains
ofanorganismareburiedinsediment,andovertimethesedimentturnsto
rock,preservingtheremainsintherock.Fossilsareanimportantsourceof
informationaboutthehistoryoflifeonEarthandcanhelpscientists
understandhowdifferentspeciesevolvedovertime.
There are many different types of fossils, depending on the type of
organism that was preserved and the way in which it was preserved. Some
common types of fossils include:
Body fossils: These are the actual remains of an organism, such as bones,
teeth, shells, and other hard parts.
Trace fossils: These are the marks or impressions left by an organism, such
as footprints, burrows, and other traces of its activity.

13. Moldandcastfossils:Theseareformedwhenanorganismisburiedin
sedimentandthesedimenthardensintorock,leavinganimpressionor
“mold”oftheorganism.Acastisformedwhenthemoldislaterfilledin
withsediment,creatingathree-dimensionalreplicaoftheoriginal
organism.
Permineralizedfossils:Theseareformedwhentheporesorotheropenings
inanorganism’shardpartsarefilledinwithminerals,preservingthe
structureoftheoriginaltissue.
Carbonizedfossils:Theseareformedwhentheorganicmatterinan
organismispreservedbybeingconvertedintoacarbonfilm.
Amberfossils:Theseareformedwhenanorganismispreservedinamber,
atypeoftreeresinthathardensovertime.
TheavailablePlantFossilsareofthefollowingtypes-
Compressions-2dimensionalwithorganiccontent,
Impressions-2dimensional,imprints,devoidoforganiccontent,
CastorMold-3dimensional,mayhavesurfaceoforganicmaterial

15. Permineralization-3dimensional,tissueinfilteredbymineralsshowing
internalpreservation,
Compaction-3dimensional,reducedvolume,flattened,whollyorganic,
Molecularfossils-Non-structural,preservesorganiccompoundslike
nucleicacidsandproteins,
Others-deadofpreservedfossilslikeindexfossil
Anindexfossilisafossilofaspeciesthatwaspresentforarelativelyshort
periodoftimeandhadawidegeographicdistribution,makingitusefulfor
determiningtheageofrocksandtherelativeagesofrocksindifferent
locations.Indexfossilsareoftenusedtocorrelatetheagesofrocksin
differentareas,astheycanhelptoestablishtherelativeagesofrocksthat
arefoundindifferentplaces.
Tobeagoodindexfossil,aspeciesmusthavelivedduringaspecifictime
period,beeasilyrecognizableandabundant,andhaveawidegeographic
distribution.Forexample,ammonites,whichareextinctmarineanimals
withacoiled,snail-likeshell,areoftenusedasindexfossilsbecausethey
werepresentduringaspecifictimeperiod(theMesozoicEra),areeasily
recognizable,andhadawidegeographicdistribution.

17. Fossilsareformedinnumerousways,andtheprocessiscalled
fossilization.
Mostofthefossilsareformedinseasandoceans.Whenalivingorganism
(suchasaplantoranimal)dies,itisquicklyburiedbysediment(suchas
mud,sandorvolcanicash)carriedinbybigrivers.
Decomposersdecomposethesoftpartsoftheseorganismsleavingonlythe
hardpartslikebones,scalesandshelletc.inanimalsandwoodorleafin
plants.
However,inspecialcircumstances,thesofttissuesoforganismscanalso
bepreserved.
Withtheadditionofmoresediments,volcanicashorlavaoverthetopof
theburiedorganism,allthelayerseventuallyhardenintosedimentaryrock
throughtheprocessofpetrificationorlithification.
Therocksarewornbackdownandwashedawaywiththecontinuous
processoferosionwhichrevealtheprehistoriclifeformswithintherocks
andstonesknownasfossils.
5commonwaysofformationoffossilsareasfollows:
Petrifaction,Impression,Amber,Tracefossilandsofttissues

18. Thecomplexfossilizationprocessinvolvesthedifferentlevelsof
organizationinthisrespectasfollows:
1.Cellularlevels-Chemicaldegradationisthefirststepsbutthickcuticle
surroundingthecellwall,lining,waxes,sporopolleninofpollengrains,
sporecoats,cystsofsomemarinealgaecanescapedfromdecomposition
duetotheirstablemolecularconformation.
2.Tissuelevel-Asthedecay-resistantmaterialsdistributedovertheplants
ingeneralandsclerenchymatissues,collenchymatoustissuesarexylem
canescapedfromdecompositionotherthanthesofttissuesoftheplants.
3.Organlevel-Duringtheburialprocess,thebrokenplantmaterials
undergotwoprocessofdeposition-
Autochthrounuswhereassemblageofplantfossilsarepreservedcloseto
theplacewheretheparentplantsgrow;Allocahthronuswherethe
assemblagetakesplaceinthedistantplaces.Althoughthedifferent
hydrodynamicprocessplayaverysignificantroleinthisregardandthe
organsassociatedwiththepreservationareidentifiedbyFormgenusand
organgenusinthisregard.

19. OrganismsLevel-Inacommunity,differentorganismshavedifferent
degreeoffossilizationlargewoodyplantswithresistanttissuesare
fossilizedbetterthantheherbsandpollenfossilsareverycommonthan
animals.Plantsadjacenttopreservationduetosedimentationthanthose
growfaraway.
EnvironmentLevel-Preservationbecomesmoreeasywhenitisclose
Organicmoleculesarecompletelyhydrolyzedandmoleculetomolecule
replacementtakesplacebymineralmoleculesavailableinthesurrounding
sediments.Afterthereplacement,itisreplacedbythesedimentaryrock.
InfiltrationTheory-Here,atomudinswamps,deltas,lakes,lowlandflood
plainsandvolcanicarea.
THEORIESOFFOSSIALIZATION
1.InfiltrationTheory-Herethebodyoftheorganismbecomes
disintegratedandreleasesfreecarbonintothesurroundingwater,asa
result,carbonatesofCa,Mg&Fetakeplace.Thesemoleculesalongwith
silicagraduallyinfilteredintothespaceandfossilisformed.

20. Moleculebymoleculereplacementtheory-Duringtheprocess,original
organicmoleculesbecomecompletelyhydrolyzedandthemoleculesto
moleculesreplacementoforganicmoleculestakeplacebythemineral
moleculesavailableinthevicinityinthesurroundingmudorsediments.
Afterthecompletereplacement,theorganismbecomespreservedinthe
sedimentaryrock.
FACTORSOFFOSSIALIZATION
Anoxicenvironment:lowoxygenconditionsrepelscavengerswhile
slowingtherateofbacterialdecay
Noscavengers:scavengersscatteranddestroyremains,stopping
fossilizationbeforeitstarts
Nobacteria:bacteriacancompletelydecomposeremains,leavingnothing
behindtofossilize
Highdepositionrate:thisallowstheorganismtobeburiedbefore
scavengers,bacteria,ortheenvironmentcantaketheirtoll,allowingthe
fossilizationprocesstobegin

21. Simpleskeleton:complex,articulatedskeletalpartstendtoseparate,
makingreconstructiondifficult
Highpopulationnumbers:themoreorganismsofaspeciesthatexist,the
greaterthechancesthatoneofthemwillbefossilized
Benthicinfaunallifestyle:thismeanstheorganismlivesinthesediment,
soit'salreadyburied.
Theidealconditionsfavoringpreservationsare-
Presenceofmoreamountofhardtissues,
Presenceofwaterandmoreamountoftoxicsubstances,
Lessdisturbancebythebioticandabioticagents,
Morequicklytheorganismgetburied,
Noorlesswind,
Otherinheritablefactorsalsoexpeditetheprocessofpreservationand
fossilization.

22. FossilsgiveusausefulinsightintothehistoryoflifeonEarth.Theycan
teachuswherelifeandhumanscamefrom,showushowtheEarthandour
environmenthavechangedthroughgeologicaltime,andhowcontinents,
nowwidelyseparated,wereonceconnected.Paleontologicalresources,or
fossils,areanyevidenceofpastlifepreservedingeologiccontext.They
areatangibleconnectiontolife,landscapes,andclimatesofthepast.They
showushowlife,landscapes,andclimatehavechangedovertimeandhow
livingthingsrespondedtothosechanges.Thoselessonsareparticularly
importantasmodernclimatecontinuestochange.
1.IdentificationanddistributionofFossilsintheGeologicalPast-To
reconstructthelifeofplantsandanimalsinthepassageofevolution,fossils
playcrucialrole,
2.GeologicconditionsofthePast-Fossilsprovideacompletepictiureof
variouschangesinthegeographicstructuresassociatedwithclimatic
conditionsoftheearththroughages.
3.Searchingfossilfuelsassourceofenergy
Evolutionofplantsandanimalsthroughagesandthepossiblechangesto
tracetheevolution.

25. 1. Google for images,
2. Different websites to enrich the domain,
3. Archegoniates-Biman Chandra Acharya,
4. A text Book of Botany-Bhattacharya, Hait, Ghosh
An Introduction to Paleobotany-Arnold
A Text book of Paleobotany –S.R. Mishra
Paleobotany & Evolution-Stewart
Disclaimer:
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students without any financial interest.