Mass Extinction!
“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
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
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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 #
1
2
3
# of flips
158
14
# pos.
74
2
# neg.
84
12
192
91
101
4
5
$5
24
432
7
211
12
221
1
2
147
23
71
9
76
14
3
15
5
10
4
5
241
45
118
20
123
25
GAMBLER’S RUIN Results
$10 Trial 2
$10 Trial 4
$10 Trial 5
GAMBLER’S RUIN Results
$5 Trial 2
$5 Trial 3
$5 Trial 4
Survivorship Curve
Proposed Physical Causes of
Extinction
Mass Extinctions
Background extinction
• Global climate change
• Regional climate change
• Global sea level change • Regional sea level
change
• Change is salinity of
ocean
• Anoxia
• Volcanism
• Extraterrestrial Impact
Geochemical Toolbox
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Carbon isotopes
Oxygen isotopes
Strontium isotopes
Iridium and platinum
group elements
Carbon isotopes
• Typically reported as 𝜹13C where:
𝜹13C=
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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 midocean 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
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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
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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
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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
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Cephalopods
Bivalves
Gastropods
Brachiopods
• Continental realm
– Plants less affected than marine
– Tetrapod turnover
Geochemical Signals
Causes of End-Permian Mass Extinction
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Climate Change
Volcanism ?
Bolide Impact
Sea level Change
Anoxia
Cretaceous-Paleogene Mass Extinction
What went extinct?
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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
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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
EndOrdovician
X (Fall)
X (Cool)
EndDevonian
Global
Ocean
Anoxia
Brackish
Ocean
Bolide
Impact
X (cool or
warm?)
X
X
?
X
X
?
X
?
X?
X
X
End-Permian
X (Fall)
X (cool)
End-Triassic
X (Fall)
X (cool or
warm?)
EndCretaceous
X (Fall)
X
Volcanism
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.