“There are millions of different species of animals and plants on earth—possibly as many as forty million. But somewhere between five and fifty billion species have existed at one time or another. Thus, only about one in a thousand species is still alive—a truly lousy survival record: 99.9% failure!”~David Raup

Mass Extinction!

Presented by: Livia Montone (montone@marine.rutgers.edu)

How do you define “Mass Extinction”?• Any substantial increase in the amount of

extinction (ie. lineage termination) suffered by more than one geographically widespread higher taxon during a relatively short interval of geologic time, resulting in at least temporary decline of standing diversity. (from Sepkoski, 1986)

How do you define “Mass Extinction”?• Any substantial increase in the amount of

extinction (ie. lineage termination) suffered by more than one geographically widespread higher taxon during a relatively short interval of geologic time, resulting in at least temporary decline of standing diversity. (from Sepkoski, 1986)

• An extinction of a significant portion of the world’s biota in a geologically insignificant period of time. (from Hallam and Wignall, 2000)

Outline

• Geologic Time Scale

• Background and mass extinctions

• Phases of extinction

• Biological causes of extinction

• Physical causes of extinction

• Geochemical Toolbox

• The Big Five

A side note about time units vs. rock units…

Time Units (ie. periods of time)

• Eon• Era• Period• Epoch • Age

• Rock Units (ie. sequence of rocks)

• Eonothem• Erathem• System• Series• Stage

Phases of Mass Extinction

Biological Causes of Extinction

• Minimum Viable Population and the Problems of small populations– Demographic Stochastity– Genetic Deterioration– Social Dysfunction– Extrinsic Forces

GAMBLER’S RUIN!

GAMBLER’S RUIN Results$10

Trial # # of flips # pos. # neg.

1 158 74 84

2 14 2 12

3 192 91 101

4 24 7 12

5 432 211 221

$5

1 147 71 76

2 23 9 14

3 15 5 10

4 241 118 123

5 45 20 25

GAMBLER’S RUIN Results

$10 Trial 2 $10 Trial 4

$10 Trial 5

GAMBLER’S RUIN Results

$5 Trial 3$5 Trial 2

$5 Trial 4

Survivorship Curve

Proposed Physical Causes of Extinction

Mass Extinctions• Global climate change• Global sea level change• Change is salinity of

ocean• Anoxia• Volcanism• Extraterrestrial Impact

Background extinction• Regional climate change• Regional sea level

change

Geochemical Toolbox

• Carbon isotopes• Oxygen isotopes• Strontium isotopes• Iridium and platinum

group elements

Carbon isotopes

• Typically reported as 𝜹13C where: 𝜹13C=• Marine biomass 𝜹13C= -25 ‰• Oceanic carbonates 𝜹13C= -0.5 to 1‰

• Increase organic matter burial, 𝜹13Ccarb goes up• Decrease organic matter burial, 𝜹13Ccarb goes down• Ocean anoxic event= + change in 𝜹13Ccarb

Oxygen isotopes

• Typically reported as 𝜹18O where: 𝜹18O =

• Positive 𝜹18Ocarb values indicate colder climate

• Negative 𝜹18Ocarb values indicate warmer climate

Strontium isotopes

• Ratio of 87Sr to 86Sr is the result of:– Continental weathering processes– Interaction of seawater with basalt at mid-

ocean ridges• Marine carbonates correspond to seawater

values

Iridium and Platinum Group Elements

• Increased Iridium (several ppb) as an indicator of bolide impact

• Increased Ir with appropriate ratios to Platinum, Gold, and Asmium

The Big Five

• Paleogeography

• Pre-extinction Taxa

• Big Losers

• Geologic and Fossil Record

• Possible Causes

• Geochemical Reconstructions

Ordovician Mass Extinction

Ordovician Mass Extinction

Ordovician Invertebrate Fossils

Ordovician Mass Extinction

Ordovician Mass Extinction

What went extinct in the Ordovician?• 57% of genera; >25% of families

• Graptolites, conodonts, nautiloids, plankton, brachiopods, trilobites, ostracods, bryozoans, echinoderms, bivalves, rugose and tabulate corals, stromatoporoids…

Ordovician Mass Extinction

Ordovician Mass Extinction

O-S GSSP Location- Dob’s Linn, Scotland

• Other well-studied locations on Anticosti Island, Quebec

Ordovician Mass Extinction

Causes of Ordovician Mass Extinction

• Glacial episode beginning in Mid-O

• Sea level regression

• Global cooling

Ordovician Mass Extinction

Stable Isotope Data

Ordovician Mass Extinction

The End-Devonian Mass Extinction

Devonian Mass Extinction

Devonian Mass Extinction

Devonian Mass Extinction

Selectivity of End-Devonian Mass Extinction

• Kellwasser (Frasnian-Famennian)– Preferential loss of warm-water taxa– Loss of shallow-water taxa– Loses among some pelagic groups

• Hangenberg (Devonian-Carboniferous)– Most severe extinction in water column – Less in benthos

Devonian Mass Extinction

Geochemical Signals

• Carbon-isotopes– Ambiguous records

• Oxygen-isotopes– Equally as confusing

• Ir and trace metals – Enriched in Ni and V

Devonian Mass Extinction

Causes of End-Devonian Mass Extinction

• Bolide impact

• Anoxia

• Cooling?

• Warming?

• Brackish oceans

Devonian Mass Extinction

Paleozoic “nemesis”The End-Permian Mass Extinction

Permian Mass Extinction

Geochemical Signals

Causes of End-Permian Mass Extinction

• Cosmic Radiation

• Brackish Oceans

• Regression

• Bolide Impact

• Cooling? Warming?

• Hypercania

• Volcanic Winter

• Global Marine Anoxia

End-Triassic Mass Extinction

• Not well-studied• In marine realm- 48% extinction of invertebrate

genera– Cephalopods– Bivalves– Gastropods– Brachiopods

• Continental realm– Plants less affected than marine– Tetrapod turnover

Geochemical Signals

Causes of End-Permian Mass Extinction

• Climate Change

• Volcanism ?

• Bolide Impact

• Sea level Change

• Anoxia

Cretaceous-Paleogene Mass Extinction

What went extinct?

• Planktonic foraminifera

• Benthic foraminifera

• Calcareous Nanoplankton

• Organic-walled Nanoplankton

• Rudist bivalves, ammonites, and belemnites

• Mosasaurs, ichthosaurs, and plesiosaurs

• Plants

Geochemical Signals

Causes of K-P Mass Extinction

• Bolide Impact

• Volcanism

• Climate Change

• Marine Regression

• Anoxia

Summary of Possible Causes of the Mass Extinctions

Mass Extinction/

Cause

Sea Level Rise/Fall

Climate Change

Global Ocean Anoxia

Brackish Ocean

Bolide Impact

Volcanism

End-Ordovician

X (Fall) X (Cool)

End-Devonian

X (cool or warm?)

X X ?

End-Permian X (Fall) X (cool) X X ? X

End-Triassic X (Fall) X (cool or warm?)

? X?

End-Cretaceous

X (Fall) X X X

References(in order of importance)

• Hallam, A. and P.B. Wignall (2000), Mass extinctions and their aftermath. Oxford University Press. (Chapters 1,3,4,6, and 9).

• Raup, D. M. (1991), Extinction: bad genes or bad luck? W.W. Norton and Company, New York.

• Stanley, S.M. (2005), Earth System History. W.H. Freeman and Company, New York.

• Prothero, D.R. (2004)., Bringing Fossils to Life. McGraw Hill, New York.