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 ([email protected])

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 # 1 2 3 # of flips 158 14 192 # pos.

74 2 91 # neg.

84 12 101 2 3 4 5 4 5 $5 1 24 432 147 23 15 241 45 7 211 71 9 5 118 20 12 221 76 14 10 123 25

GAMBLER’S RUIN Results

$10 Trial 2 $10 Trial 4 $10 Trial 5

GAMBLER’S RUIN Results

$5 Trial 2 $5 Trial 4 $5 Trial 3

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 𝜹 13 C where: 𝜹 13 C= • Marine biomass 𝜹 13 C= 25 ‰ • Oceanic carbonates 𝜹 13 C= 0.5 to 1‰ • Increase organic matter burial, 𝜹 13 C carb • Decrease organic matter burial, 𝜹 13 C carb goes up goes down • Ocean anoxic event= + change in 𝜹 13 C carb

Oxygen isotopes

• Typically reported as 𝜹 18 O where: 𝜹 18 O = • Positive 𝜹 18 O carb • Negative 𝜹 18 O carb climate values indicate colder climate values indicate warmer

Strontium isotopes

• Ratio of 87 Sr to 86 Sr 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 End Ordovician End Devonian Sea Level Rise/Fall X (Fall) End-Permian X (Fall) Climate Change X (Cool) X (cool or warm?) X (cool) Global Ocean Anoxia Brackish Ocean Bolide Impact Volcanism X X X X ?

?

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

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.