Download Paleontology and Life, part 3

FOSSILSandFOSSILIZATION
part3–LifeForms:Eukarya(Pro@stsandPlants)
AlessandroGrippo,Ph.D.
PaleozoicCrinoids,photographed(withpermission)inafossilsandrocksstore,LasVegas,Nevada
©AlessandroGrippo
LifeForms:aSummary
LifeonEarthisdividedinthreeDomains
•  Archaea
–  Prokaryotes
•  Bacteria
–  Prokaryotes
•  Eukarya
–  Eukaryotes
•  AlllifeformsareformedbycellscontainingDNA
•  ProkaryoGccellslackinternalorganizaGon
•  EukaryoGccellspresentinternalstructuring
DomainEukarya
•  Eukaryainclude:
1. 
2. 
3. 
4. 
ProGsts
Plants
Fungi(mushrooms)
Animals
1.Pro@sts
•  Includemanykindsofsingle-celledorganisms
andafewkindsofsimplemulGcellularorganisms
•  Plant-likeproGsts(algae)arephotosyntehGc
–  dinoflagellates,diatoms,coccolithophores
•  alltheseareveryimportantinthefossilrecord
•  Animal-likeproGsts(orprotozoans)
–  amoebas,zooflagellates,ciliates
•  radiolariansandforaminiferaareamoeba-likeproGststhat
arealsoveryimportantinthefossilrecord
ClockwisefromupperleQ:liveDiatoms;Coccolithophores;liveForaminifer;liveRadiolarian
Nekton,Benthos,Plankton
•  Organismsthatliveintheoceancanbeclassifiedas:
–  Nekton:swimmers
–  example:dolphins,octopuses,squids,whales
–  Benthos:boXomdwellers
•  sessile(standinginoneplace,likeatreeonland)
–  example:sealilies
•  mobile(onthesurface–epifauna;diggingintothe
substrate–infauna)
–  example:crabsandlobsters
–  Plankton:floaters
ImportantPlanktonicPro@stsinthefossilrecord
•  Phytoplankton(plant-like)
–  DiatomsandCoccolithophores
•  Zooplankton(animal-like)
–  RadiolariansandForaminifera
•  Theseorganismssecretea
skeleton(alsocalleda“test”,or
ashell)
•  Whentheydie,theseskeletons
sinktotheboXomoftheocean
andformarock
Alltheseorganismsaremicroscopic:
theycanonlybeobservedundera
microscope.
Coccolithophoresaresosmallthat
theycanonlybeimagedwithaSEM
(ScanningElectronMicroscope)
CaCO3shell
Phytoplankton
Zooplankton
Coccoliths
SiO2shell
Coccoliths
Diatoms
Foraminifera
Radiolarians
(disksfromCoccolithophores)
Foraminifer
Diatom
Radiolarian
ChemicalSedimentaryRocks
formedfromPro@sts’skeletons
•  Calcareousoozes
–  Chalk
–  Micrite
•  Siliceousoozes
–  DiatomaceousEarthandRadiolarite
–  Chert
Chalk
Micrite
Chert
2.Plants
•  Allplantsevolvedfromalgaethatdevelopeda
condiGoncalledendosymbiosis
•  Symbiosisoccurswhentwokindsoforganisms
livetogetherinamannerthatbenefitsthem
•  “Endo”means“inside”
endosymbiosis
•  DuringthePrecambrian,a
photosyntheGcbacterial
cellwas“eaten”byanon
photosyntheGcone
•  Thesecondcouldnot
digestthefirst
•  Theeatencellbecamea
chloroplast,theorganelle
insideaplantcellwhere
photosynthesisoccurs
Plants:GreenAlgae
•  MostscienGstsclassifyGreenAlgaeasPlants
•  SomemulGcellularalgaeareadriQintheocean,
whilesomeothersareanchoredtotheboXom
•  MostaresoQ,fleshyorganisms,butsomesecrete
askeletonofcalciumcarbonate(CaCO3)
•  Fragmentsofsuchskeletonsaremajor
consGtuentsofmarinelimestones
Halimedaincrassata(Ellis,1768)onshallow,aragoni@csandyseafloor
Halimedaisacalcareousgreenalgaecontainingchipsofcalciumcarbonate(inthiscase,aragonite).AQerthealgaedieandthe
soQpartsdecayaway,thearagoniGcchipsbecomesand-sizedseafloorsediments.ThesesedimentswillinGmeturntolimestone.
©JamesSt.Johnonflickr:hXps://www.flickr.com/photos/jsjgeology/16027635766
Plants:landplants
•  Landplantsaredifferentbecausetheirbodiesare
dividedinto@ssues
–  Tissuesareconnectedgroupsofsimilarcellsthatperform
aparGcularfuncGon
•  Also,theyaredifferentfromalgaebecauseof
reproduc@on
–  Algaeshedeggsandspermintowater:ferGlizaGonis
externalandoffspringdevelopindependently
–  InLandPlants,eggsareferGlizedwithintheparentplant,
andtheembryoremainsprotectedwithintheirparents’
bodyforaGme
LandPlants
•  Problemswithlivingonland:
–  lackofsupportfromwater
•  developmentofrigidstructures(roots,stems,trunks)
forsupport
–  drycondiGons
•  rootscanabsorbwaterfromsoil
•  developmentofvessels(vascularplants)forwaterand
nutrienttransport
•  Allplantsareeithernon-vascularorvascular
NonvascularPlants
• 
• 
• 
• 
• 
Liverworts,mosses,hornworts
LackconducGngvessels
Relyondiffusionfortransportcelltocell
Haveascantfossilrecord
HavenotchangedmuchingeologicGmesince
LowerPaleozoic
VascularPlants
•  VascularplantshavespecialGssuesandcanalstotransport
moistureandnutrientsfromthesoiltothechlorophyllbearingleaves,wherephotosynthesisisaccomplished
•  VascularplantsalsohavefeaturesthatpreventdesiccaGon,
supporttheweightoftheplant,andfacilitatereproducGon
onland
•  Therearethreemajorgroupsofvascularplants:
–  Seedlessvascularplants
–  Vascularplantswithnakedseeds(Gymnosperms)
–  Vascularplantswithprotectedseedsandflowers(Angiosperms)
SeedlessVascularPlants
•  Firstplantstoinvadelandwerespore-bearing,seedlessvascular
plants
•  PossiblyfromOrdovician
• 
• 
• 
• 
• 
Adultplantsproducespores
SporesdonotrequireferGlizaGon
Sporesfalltomoistgroundanddevelopintoagametophyte
Agametophyteproduceseggsandsperm
Thatwoulddevelopanewspore-generaGngplant
•  Twomaingroups
–  Lycophytes
–  Monilophytes
Lycophytes
Muchsmalleranduncommontoday
VeryimportantandbiginsizeduringthePaleozoic
LeavesleQdiamond-shapedscarsontrunks:“scaletrees”
HugeforestsduringtheLatePaleozoicdiedandformed
peat
•  Peatturnedintocoal(Carboniferous:Mississippianand
Pennsylvanian)
• 
• 
• 
• 
–  Curiosity:arrivaloftheseplantsonlandcausedanenormous
absorpGonofCO2fromatmosphereandreleaseofO2,thus
creaGngacoolingeffect
Fernleaveswithspores
Monilophytes
•  Ferns
•  Horsetails
•  Psilotum
Right:
Horsetails
(Equisetum)
LeQ:
Psilotum
fromSporestoSeeds
•  Seedplantsincludemostspeciesoflargelandplantstoday
•  Seedsaredurablestructuresthatdispersetheoffspringsofthese
plants
•  EvoluGonofseedsduringPaleozoictriggeredagreatecological
expansionoflandplants:noneedformoistenvironmentslikefor
spores
•  Seeddisperseindifferentways:
– 
– 
– 
– 
blowninthewind
aXachedthroughbarbstomobileanimals
surroundedbyfruitseatenbyanimals
animalsmovearoundandexpelseedsinfeces,whichareusedas
ferGlizers
NakedSeedsPlants(Gymnosperms)
•  “Naked”becauseattheGmeofpollinaGonthe
seedsarenotcompletelyenclosedbytheGssues
oftheparents
•  Include:
–  Seedferns(exGnctduringtheCretaceous)
–  Glossopteris(seeninWegener’sconGnentaldriQ)
–  Conifers
–  Cycads
–  Gynkgoes
Glossopteris
Conifers
• 
Pines,spruces,firs,redwoods,cedars
• 
DisGncGve,smallermalecones
producepollengrainscontaining
sperm
• 
Biggerfemaleconescontainovules
whereeggsdevelop
• 
FerGlizedseedsdevelopontopof
scalesthatformacone
• 
AppearedduringLateCarboniferous
Maleandfemalecones(strobili)fromapinetree
Conifers:pineconesandnuts
Pinenuts(inshells)fromfemalecones
Unshelledandshelledpinenuts
CycadsandGinkgoes
•  Cycadswerecommoninthe
Mesozoicbutmanyspeciesare
nowexGnct
•  Thosesurvivingtodayare
knownas“sagopalms”
•  Ginkgoesarecharacterizedby
bilobedfan-shapedleaves
•  AppearedduringPermian,
boomedinTriassicandJurassic
•  Today,onlyGinkgobiloba
survives
ProtectedSeedsandFlowersPlants
(Angiosperms)
•  StartedintheCretaceousandboomedright
aQer
•  OneofmostdramaGceventsinplant
evoluGon
•  Mostplantsalivetodayareangiosperms
(“seedswithinavessel”)
ferGlizaGoninAngiosperms
•  Seedsdevelopinachamberoftheflowercalledovule,or
ovary
•  Pollenisproducedonstamens,thentransferredtopisGls
•  ApollentubedevelopswhenpollenrestsontoapisGl,through
whichspermmovesandferGlizestheeggintheovary
ferGlizaGoninAngiosperms
fromflowertofruit
•  ferGlizaGonoftheeggproducesafruitwithseeds
•  enclosedseedsallowformaGonofediblefruits
•  ediblefruitsenhancedispersalofseedsby
animalsthateatthem
ferGlizaGoninAngiosperms
•  coloredpetalsaXract
birdandinsect
pollinators
•  thereisadirect
relaGonshipbetween
angiospermandinsect
evoluGon
AngiospermsthroughGme
•  AngiospermsdiversifiedrapidlyaQertheir
Cretaceousearlystart
•  BytheendoftheCretaceous,allthemajor
groupsoftodayhadappeared
•  Manyofthoseplantsareverysimilartotheones
oftoday
•  Grassesfinallyappearedbythemid-Cenozoic
similaritybetweenEarlyCenozoicandtoday’sAngiosperms
•  LeQ:Angiospermsand
Gymnospermsfossils(leaves,
cones,berries)fromFlorissant,
Colorado(about35myago)
•  BoXom:Angiospermsleaves
fromFossilBuXe,Wyoming
(about50myago)
Palynology
•  OQen,sporesandpollensfromplantsare
muchmoreabundantinthefossilrecordthan
plantsthemselves
•  Theycanbetransportedtogreatdistancesby
watercurrentsandwinds
•  Theirstudyiscalledpalynology
FossilsandFossiliza@on
LifeForms:Pro@stsandPlants
endofpart3