Lecture 8 - Mass extinctions

What are the five main mass extinction events?

1. End-Ordovician.

2. Late Devonian.

3. End-Permian.

4. End-Triassic.

5. Cretaceous-Paleogene.

When was the End-Ordovician extinction?

445-443 MYA.

What was the impact of the End-Ordovician extinction?

Loss of 85% of marine species.

What was the stream of events in the End-Ordovician extinction?

EARLY HIRNANTIAN - first pulse saw glaciation destroy shallow and deep habitats.

LATE HIRNANTIAN - second pulse saw rising sea levels and anoxia cause extinction in all habitats.

When was the Late Devonian extinction?

372-359 MYA.

What was the impact of the Late Devonian extinction?

Multiple extinction events within a close time frame.

What was the stream of events in the Late Devonian extinction?

KELLWASSER EVENT (372 MYA) and HANGENBERG EVENT (359 MYA).

Major changes to the environment with the loss of 70-80% of marine species, all placoderms, 99% of reefs, 90% of ammonites.

When was the End-Permian extinction?

251 MYA.

What was the impact of the End-Permian extinction?

The Great Dying!

Nearly saw all multi-cellular life go extinct.

What was the stream of events in the End-Permian extinction?

Most likely caused by the Siberian Traps (world's larges LIP formation), magma passed over coal which increased CO2 emissions.

Ocean temp changes (10-20), global warming, anoxia, acidification of oceans.

90% marine species, 75-80% terrestrial fauna.

Diapsids radiation.

When was the End-Triassic extinction?

201 MYA.

What was the impact of the End-Triassic extinction?

Start of dinosaur dominance!

What was the stream of events in the End-Triassic extinction?

Tectonic plate movement separated Pangea and opened volcanic rift causing explosions = ocean acidification and climate change.

When was the Cretaceous-Paleogene extinction?

66 MYA.

What was the impact of the Cretaceous-Paleogene extinction?

End of the dinosaurs :(

75% of marine species.

What was the stream of events in the Cretaceous-Paleogene extinction?

K-Pg event massive asteroid impact released sulphuric acid (acidified oceans), IR radiation (firestorms), dust clouds (no photosynthesis).

Deccan Traps eruptions reduced the extent of extinction.

What are some methods to trace the past events?

Fossil series.

Shale colours.

Plate tectonics.

Flood basalts (LIPs).

Stable isotope ratios.

Modelling of past climates.