Gy 112 earth history
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GY 112: Earth History. Proterozoic Fossils. Agenda. Key Events of the Proterozoic Proterozoic Plate Tectonics Proterozoic Glaciation Background Proterozoic Life Forms Evidence of Proterozoic Life Factors Affecting Development of Proterozoic Life Implications of Proterozoic Info.

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GY 112: Earth History

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GY 112: Earth History

Proterozoic Fossils


Agenda

Key Events of the Proterozoic

Proterozoic Plate Tectonics

Proterozoic Glaciation

Background

Proterozoic Life Forms

Evidence of Proterozoic Life

Factors Affecting Development of Proterozoic Life

Implications of Proterozoic Info


Key Events of the Proterozoic


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f03_01_pg29


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Key Events

  • 2 Supercontinent Episodes

  • 3 Glacial Episodes (Snowball Earth)

  • Change from O2 Poor to O2 Rich

  • 2 Major Meteor Impacts

  • BIFs (Major Source of Iron)

  • Major Copper Deposits

  • Evolution of Life from One Cell to Multi-Cell


Proterozoic Super Continent Episodes


Plate Tectonics

  • Wilson Cycle (3 Parts)

    • Opening of an Ocean Basin

    • Sedimentation

    • Closing of an Ocean Basin

  • Supercontinent Episodes

    • Rodinia: 1.6 to 1.0 bya

    • Columbia (Laurentia): 2.5 to 1.6 bya

  • Orogenic Episodes

    • Wopmay (Laurentia)

    • Keeweenewan (Laurentia)

    • Greenville (Rodinia)


Proterozoic Glaciation


Glaciation

Snowball Earth (635 – 750 MA)

  • Marinoan (635 – 700 MA)

  • Sturtian (700 – 750 MA)

  • Huronian (2.5 – 1.6 GA)


PROTEROZOIC DETAILS


Background Info

Proterozoic is the largest Eon of the 4 Eons

(542 MA to 2.5 GA: ~ 2 Billion years old)

  • Consists of 3 Eras - Each is as large or larger than the entire Phanerozoic Eon.

    • Neoproterozoic (542 MA to 1.0 GA)

    • Mesoproterozoic (1.0 GA to 1.6 GA)

    • Paleoproterozoic (1.6 GA to 2.5 GA)


Proterozoic Era Highlights

Paleoproterozoic (2.5 GA to 1.6 GA )

  • Evolution of Cyanobacteria (O2 Producers)

  • O2 Catastrophy

  • BIFs (Banded Iron Formations)

  • Huronian Glaciation

  • 2 Largest Impact Events in Earth’s History

    • South Africa – Vredefort

    • Ontario Canada – Sudbury Basin

  • Earth’s Atmosphere Changed to an O2 Environment

  • Columbia Supercontinent Formed


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Proterozoic Era Highlights

Mesoproterozoic (1.6 GA to 1.0 GA)

  • Red Algae

    • First Sexual Reproduction

    • Earliest Complex Multicellular Organism

  • Columbia Supercontinent Broken up

  • Rodinia Supercontinent Formed


f09_10_pg10

f09_10_pg10


Proterozoic Era Highlights

Neoproterozoic (1.0 GA to 542 MA)

  • Extreme Glaciation (Snowball Earth)

  • Earliest Multicellular Organisms (Ediacaren)

  • Break-up of Rodinia Supercontinent


Oxygen Catastrophy(1.6 – 2.5 bya)

  • Oxygen created from photosynthesis

  • Oxygen toxic to anaerobic organisms

  • Initial lag of 300 million years for free oxygen in the atmosphere

  • Oxygen initially combined with free iron in the oceans to form magnetite.


Snowball Earth(630 – 850 mya)

  • Glacial Periods: Startian & Marinoan/Varanger

  • Causes

    • Reflective surface of continents

    • Removal of CO2 from atmosphere

    • Change in ocean circulation patterns

    • Intro of pure oxygen which converted methane into CO2

    • Reduction in Organic Activity

  • Subsequent melting caused by emission of CO2 from volcanic activity


ICE THICKNESSES


Proterozoic Life Forms


Proterozoic Life Forms


Proterozoic Life Forms

  • Life Forms

    • Acritiarchs (Single Celled)

    • Ediacarens (Multi-Celled)

  • Evolutionary Development

    • From Prokaryotic to Eukaryotic

    • Onset of Sexual Reproduction

    • From Single Cell to Multi-Cell

    • Soft-Bodied to Shell Covering


Proterozoic Life Forms

  • During the Archean, we saw the rise of the prokaryotes:

  • Small

  • No nucleus

  • DNA spread throughout the cell

  • Asexual reproduction

  • Could only be single-celled


Proterozoic Life Forms

  • During the Proterozoic, something wonderful happens:

  • the rise of the eukaryotes:

  • Larger (>0.06 mm)

  • A nucleus and organelles

  • DNA contained within the nucleus

  • Sexual reproduction

  • Could be multi-celled (metazoans)


Proterozoic Life Forms

The first eukaryotes appeared around 2 GA. Archritarchs were small, single celled silica beasties that floated in the oceans (pelagic). They peaked in abundance at 750 MA and then went away…

0.1mm


Proterozoic Life Forms

… or did they? They might in fact be ancestors to equally small single celled organisms that are around today called dinoflaggelates.

0.1mm


Proterozoic Life Forms

Another big change in the Proterozoic was the appearance of the first Metazoans

5 cm


Proterozoic Life Forms

They are known as the Ediacarin Fauna

http://www.snowballearth.org/end.html

http://www.cartage.org.lb/en/themes/Sciences


Proterozoic Life Forms

They are known as the Ediacarin Fauna

And they are found around the world

http://www.snowballearth.org/end.html

http://www.cartage.org.lb/en/themes/Sciences


Proterozoic Life Forms

What were the Ediacarins?

Three major “forms”

http://www.cartage.org.lb/en/themes/Sciences


Proterozoic Life Forms

What happened to them?


Proterozoic Life Forms

What happened to them?

1) a now extinct line of beasties


Proterozoic Life Forms

What happened to them?

1) a now extinct line of beasties

2) ancestors to living phyla

Kimberella sp.

http://www.ucmp.berkeley.edu/vendian/kimberella.jpg


Proterozoic Life Forms

What were the Ediacarins?

1) a now extinct line of beasties

2) ancestors to living phyla

Dickinsonia sp.


Proterozoic Life Forms

Whatever they were, they “exploded” onto the scene immediately after the last Snowball Earth.

http://pharyngula.org/index/science/2004/08/


Evidence of Proterozoic Life


Evidence of Proterozoic Life

Direct Evidence

Fossils

Trace Fossils


Evidence of Proterozoic Life

Indirect Evidence

BIFs (Banded Iron Formation)


Factors Affecting Development of Proterozoic Life


Proterozoic Fossils

Severe environmental changes drives evolutionary adaptation.

http://www.snowballearth.org/end.html


Proterozoic Fossils

Severe environmental changes drives evolutionary adaptation.

We need bad things to happen in order to evolve.

http://www.snowballearth.org/end.html


Factors Affecting Development of Proterozoic Life

Terrestrial

Atmospheric Changes

Climate

Geography


Factors Affecting Development of Proterozoic Life

“Atmospheric Changes”


Factors Affecting Development of Proterozoic Life

“Atmospheric Changes”


Factors Affecting Development of Proterozoic Life

“Climatic Changes”

We now recognize three major Earth phases

1) Greenhouse Earth

(no continental glaciers present)

2) Icehouse Earth

(continental glaciers present)

3) Snowball Earth

(Frozen oceans at equator)

http://www.snowballearth.org/end.html


Factors Affecting Development of Proterozoic Life

Extra-Terrestrial

Solar Radiation

Impact Events


Implications of Proterozoic Info


Implications of Proterozoic Info

Ediacarin Evolutionary Development

Diversity of Life

Present Day Global Warming


THE END


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