Biogeography. Lecture 5

Alexey Shipunov

Minot State University

January 25, 2016

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Outline

PalaeogeographyPlate tectonics

Most important eras and periodsCryogenian period (850–635 Mya) and Snowball EarthEdiacarian period: 635–550 MyaCambrian periodOrdovician, Silurian and Devonian: three ages of fishes

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Outline

PalaeogeographyPlate tectonics

Most important eras and periodsCryogenian period (850–635 Mya) and Snowball EarthEdiacarian period: 635–550 MyaCambrian periodOrdovician, Silurian and Devonian: three ages of fishes

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Palaeogeography Plate tectonics

PalaeogeographyPlate tectonics

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Palaeogeography Plate tectonics

Mantle convection

I The driving force of floating continents is a mantle convectionI In ocean ridges, new ocean cortex is constantly forming and

expandingI In ocean trenches and continental ridges, different plates are

colliding and often forming mountains

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Palaeogeography Plate tectonics

Mantle convection

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Palaeogeography Plate tectonics

Mantle convection

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Palaeogeography Plate tectonics

The result of mantle convection

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Palaeogeography Plate tectonics

What is going on now

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Palaeogeography Plate tectonics

Two living examples of continental drift on U.S. territory

I Yellowstone hotspotI Hawaiian hotspot

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Palaeogeography Plate tectonics

Yellowstone hotspot

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Palaeogeography Plate tectonics

Hawaiian hotspot

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Most important eras and periods Cryogenian period (850–635 Mya) and Snowball Earth

Most important eras andperiods

Cryogenian period (850–635 Mya)and Snowball Earth

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Most important eras and periods Cryogenian period (850–635 Mya) and Snowball Earth

Rodinia—the first super-continent

I Tectonic plates formed (and will form) one continent several timesI 650 Mya this continent—Rodinia was formed right over the South

Pole

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Most important eras and periods Cryogenian period (850–635 Mya) and Snowball Earth

Cryogenian continents which formed Rodinia

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Most important eras and periods Cryogenian period (850–635 Mya) and Snowball Earth

Rodinia: view from South Pole

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Most important eras and periods Cryogenian period (850–635 Mya) and Snowball Earth

Marionan glaciation: Snowball Earth

I First global glaciation was started because ice started toconcentrate over the pole and increase Earth albedo (this is thepositive feedback)

I And because the configuration of continents blocked theequatorial warm current

I And because concentration of oxygen was high but greenhousegases (like CO2)—small

I As a result, from time to time Earth was completely covered withice sheet 1 km tall!

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Most important eras and periods Cryogenian period (850–635 Mya) and Snowball Earth

Star Wars Hoth—ice planet

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Most important eras and periods Cryogenian period (850–635 Mya) and Snowball Earth

Snowball Earth

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Most important eras and periods Ediacarian period: 635–550 Mya

Most important eras andperiods

Ediacarian period: 635–550 Mya

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Most important eras and periods Ediacarian period: 635–550 Mya

Rodinia breaks

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Most important eras and periods Ediacarian period: 635–550 Mya

Ediacarian continents

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Most important eras and periods Ediacarian period: 635–550 Mya

Life in Cryogenian and Ediacarian

I Before: prokaryotes, included photosynthetic (cyanobacteria),then unicellular eukaryotes

I Cryogenian: multicellular eukaryotes, e.g. algaeI Ediacarian: first animals

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Most important eras and periods Ediacarian period: 635–550 Mya

Ediacarian life

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Most important eras and periods Cambrian period

Most important eras andperiods

Cambrian period

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Most important eras and periods Cambrian period

Cambrian map

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Most important eras and periods Cambrian period

Cambrian climate and life

I Gradually changed from colder to warmerI Cambrian explosion: appearance of most of animal phyla with

skeletonI Little or no terrestrial lifeI The main driver of animal evolution during Cryogenian–Cambrian

was probably oxygenation of waterI One theory states that pre-Cambrian ocean water was muddy and

rich of organic compounds, animal filtration changed this condition

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Most important eras and periods Cambrian period

Cambrian life

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Most important eras and periods Ordovician, Silurian and Devonian: three ages of fishes

Most important eras andperiods

Ordovician, Silurian and Devonian:three ages of fishes

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Most important eras and periods Ordovician, Silurian and Devonian: three ages of fishes

Ordovician period

I Climate changed from hot to glaciated (Gondwana hits the South Pole)

I Marine fauna spread out, especially cephalopods, conodonts andgraptolites

I In the end, the first great extinction: 85% of marine species extinct

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Most important eras and periods Ordovician, Silurian and Devonian: three ages of fishes

Silurian period

I Fluctuating climate

I Prospering of marine fauna again

I Land colonization started from plants and arthropods!

I South Pole still in the Gondwana

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Most important eras and periods Ordovician, Silurian and Devonian: three ages of fishes

Silurian sea

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Most important eras and periods Ordovician, Silurian and Devonian: three ages of fishes

Devonian period

I Moderate climate becoming warmer

I Exceptionally high sea level

I Greatest diversity of marine fauna in Paleozoic (especially fishes)

I Terrestrial vertebrates: tetrapods appeared!

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Most important eras and periods Ordovician, Silurian and Devonian: three ages of fishes

Summary

I Continents of Earth are constantly changing their position due tothe mantle convection (“plate tectonics”)

I From Cryogenian to Ordovician, super-continent Rodinia brokeand climate on Earth became milder

I Most of water-inhabiting animal groups appeared by Ordovician

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Most important eras and periods Ordovician, Silurian and Devonian: three ages of fishes

For Further Reading

A. Shipunov.Biogeography [Electronic resource].2014—onwards.Mode of access:http://ashipunov.info/shipunov/school/biol_330

Plate tectonics.http://en.wikipedia.org/wiki/Plate_tectonics

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