Index Fossils andIndex Fossils andInternational International StratotypesStratotypes

Biostratigraphy and Global Biostratigraphy and Global PoliticsPolitics

Systems, Series, Systems, Series, StagesStages Devonian SystemDevonian System

– Upper Devonian SeriesUpper Devonian Series FamennianFamennian FrasnianFrasnian

– Middle Devonian SeriesMiddle Devonian Series GivetianGivetian EifelianEifelian

– Lower DevonianLower Devonian EmsianEmsian PragianPragian LochkovianLochkovian

Silurian SystemSilurian System– Upper Silurian SeriesUpper Silurian Series

PPřířídoldolíí Stage Stage

Units DefinedUnits Definedby Index Fossilsby Index Fossils What is an Index Fossil?What is an Index Fossil? Limited Stratigraphic RangeLimited Stratigraphic Range Widespread Geographic Widespread Geographic

DistributionDistribution Commonly PelagicCommonly Pelagic Or, tolerant of a wide variety of Or, tolerant of a wide variety of

environments (found in many environments (found in many facies)facies)

Index FossilsIndex Fossilsand the S-D Boundaryand the S-D Boundary

Graptolites *Graptolites * Conodonts *Conodonts * Chitinozoans *Chitinozoans * TrilobitesTrilobites BrachiopodsBrachiopods CephalopodsCephalopods

Definition ofDefinition ofthe S-D Boundarythe S-D Boundary

GSSP: Global Stratotype Sequence and PointGSSP: Global Stratotype Sequence and Point Point chosen as first appearance of the Point chosen as first appearance of the

graptolite graptolite Monograptus uniformis uniformisMonograptus uniformis uniformis Auxiliary index species – the conodont Auxiliary index species – the conodont Icriodus Icriodus

woschmidti woschmidtiwoschmidti woschmidti Stratotype: Klonk, near Suchomasty, Czech Stratotype: Klonk, near Suchomasty, Czech

RepublicRepublic Auxiliary Stratotype: BudAuxiliary Stratotype: Budňňanskanskáá Sk Skáála/Karlla/Karlšštejn tejn

Definition ofDefinition ofthe S-D Boundarythe S-D Boundary

Stratotype: Stratotype: Klonk, near Klonk, near Suchomasty, Suchomasty, Czech RepublicCzech Republic

S-D GSSPS-D GSSP

First appearance First appearance of of Monograptus Monograptus uniformis uniformis uniformisuniformis

Bed 20Bed 20 Klonk, CzechiaKlonk, Czechia

Preserving the GSSPPreserving the GSSP

Dr. Ivo Chlupáč

Auxiliary Stratotype: Auxiliary Stratotype: BudBudňňanskanskáá SkSkáála/Karlla/Karlšštejntejn

PPřířídoldolí Stratotype: í Stratotype: PožáryPožáry

Pragian Stratotype:Pragian Stratotype:VelkVelká Chuchleá Chuchle

Why does it matter?Why does it matter?

Precise correlationsPrecise correlations Precise timing for inter-regional Precise timing for inter-regional

comparisonscomparisons Time frame for discerning global Time frame for discerning global

eventsevents

Ranges of ConodontsRanges of Conodontsnear the S-D Boundarynear the S-D Boundary