Download The evolution of Life in the History of Earth

The evolution of Life in the
History of Earth
Lars Holmer
[email protected]
Introduction
Principles
p of Geology
gy &
Palaeontology

Gould: 2222-35
Introduction
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Palaeontology - the study of the history
of life on Earth, stretching over a period of
almost 4 billion years
y
Historical geology - the study of Earth's
‘archive of time’, as represented by the
sedimentary record
Life on a Changing Earth
Life is a continuum - from the earliest
organisms to the great variety of species
that exist today
• Geological events change the course of
biological evolution
• Conversely, life changes the planet that it
inhabits

Biosphere - five
kingdoms
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1. Prokaryotes
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2.
3.
4.
5.
bacteria
Protists
Fungi
Plants
Animals
Geologic time
When was the Earth formed?
When did life on Earth originate?
When did life invade the land?
What is the rate of biological, chemical, and
climatic change?
Measuring geologic time

Relative dating
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Absolute dating
Absolute dating
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1654 James Ussher,
Archbishop, Irland - 4004
BC
9.00 (GMT??), 23 October
(Sir John Lightfoot)
Absolute dating
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James Hutton (1726(17261797) – The Earth is
ancient
" ...no vestige of a
beginning, no
prospect of an end."
During the 18th
Century absolute
dating was impossible
Georges-Louis Leclerc
Comte de Buffon (17071788)
William Thomson, 1st Baron Kelvin
(1824-1907)
Absolut dating – exact numerical value
 Radiometic
dating
• 1896 - Henri
Becquerel
• 1902 - Ernest
Rutherford
• radioactive
elements decay at
constant rates to
stable daughter
products, e.g.
Potassium--Argon.
Potassium
Relative dating -- the sequence in
which the geological events occurred
Nicholaus Steno 16381638-1686
Niels Stensen
geologist, bishop
- & saint!
Steno´
Steno
´s laws
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Law of superposition oldest sediments at the
bottom
Law of original
horizontality - sediments
were originally flat lying
Law of fossil succession
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Fossils occur in the
same succession over
the world –
EVOLUION!!
Correlation between
the sequences
Relative Dating: using fossils
William ’strata’ Smith
(1769--1839)
(1769
The father of
biostatigraphy
The ”map that changed the world” (1815)
Geologic time scale

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Based mainly on the
“Law of fossil
succession”
Eon, Era, Period,
Epoch
Developed without
knowledge of
absolute dating
Geological time scale
All of the names are based on
biostratigraphy!
Roderick Impey
Murchison
1792-1871
Di t G
Director
Generall
Geological Survey of
Great Britain
1855-1871
Marloes Sand, Wales
Visby
The Earth´
Earth´s dynamic system
How does it work now?
How did it work in the past?
Uniformitarianism
James Hutton (1726
(1726--1797)

Theory of the Earth
1795: ”the past
history of our globe
must be explained
b what
by
h can b
be seen
to be happening
now””
now
The present is
the Key to the
Past”
”
Hutton’s unconformity
100 million years later!
425 million years ago
1. Horizontal deposition of strata
1. Horizontal deposition of strata
2. Tectonic tilting of strata
(this takes millions of years)
1. Horizontal deposition of strata
2. Tectonic tilting of strata
(this takes millions of years)
3. New horizontal deposition on top
Uniformitarianism - gradualism
Principles of Geology 1830
1830--33
Charles Lyell (1797(1797•1875)
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Catastrophism
Baron Georges Cuvier 17691769-1832

The history of Life and
Earth is mainly shaped
by catastrophes
WSU, Pullman, A sunny Sunday 18th May 1980,
12:00
500,000 km3
Today, extinctions are a palaeontological fact of life.
The K/T event marks
the end of the dinosaurs
K T
The structure of the Earth
Oceanic crust - heavier and thinner.
Continental crust - lighter and thicker
(up to 70 km underneath mountains)
1 = continental crust
2 = oceanic crust
3,4 = upper & lower mantle
5,6 = outer & inner core
Distribution of earthquakes
along plate boundaries!
•Bridge across the Álfagjá rift valley
•Eurasian and North American tectonic plates.
http://www.ig.utexas.edu/research/projects/plates/teaching_ideas.htm
Rifting
Rocks & minerals
 Mineral
- A naturally occurring inorganic solid
with a crystalline structure and a specific chemical
composition
 Rock
- A compact and consolidated mass of
mineral matter

Three types of rock are recognized: igneous
igneous,,
sedimentary,, and metamorphic
sedimentary
metamorphic..
Gneiss, a metamorphic rock
Igneous rocks
Basalt (volcanic)
Gabbro (plutonic)
Both of these rocks formed from the same type of magma. But while
basalt cooled quickly after a volcanic eruption, gabbro cooled slowly at
several kilometers depth
The Phanerozoic of
Sweden
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Only 20%
C b i -Silurian
CambrianCambrian
Sil i
Mesozoic only in
Scania
Sedimentary rocks &
environments
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Sediment refers to any loose
unconsolidated material, such as sand,
clay etc.
Sedimentary rock – forms through
compaction, cementation)
lithification (e.g. compaction,
Sedimentary rocks cover approximately
75% of the Earth’s surface (Sweden being
an exception)
Sedimentary environments include:

Terrestrial (deserts, rivers etc)
Sedimentary environments include:

Shallow marine
Sea level
Sea rising 8.000 m?
The Recent biosphere
approx. 13.6 million species
•Insects (8,000,000)
•Insects
•Fungi (1,500,000 )
•Baccteria (1,000,000)
•Ba
•Spiders
•Spi
ders (750,000)
•Virus (400,000)
•Algae
•Alg
ae (400,000)
•Nematodess (400,000)
•Nematode
•Plants (320,000)
•Protists (200,000)
•Molluscs (200,000)
•Crayfish (150,000)
•Vertebrates (50,000)
•Other (250,000)
Fossils
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Latin, fossilis - originally
anything that was dug
up
Now - remains or traces
of any recognizable
organic structure
preserved from pre
pre-historic times
Taphonomy
Taphonomy
Taphonomy
Usually ends with complete
destruction
Occasionally the process of
decay is partially stopped
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Special preservation
- Lagerstätten
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Uniquely preserved
fossils including soft
body anatomy
Rapid burial, lack of
oxygen etc.
E.g. Solnhofen
(Jurassic),
Special preservation
- Lagerstätten
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Amber (fossil
(fossil resin;
Baltic mostly
Oligocene pine tree)
Deep freezing
(Siberian fauna from
the tundra, including
mammoths)
Special preservation
- Lagerstätten
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Mummification
Tar p
pits ((open
p ‘oil
wells’ like those at La
Brea, Los Angeles)
Peat bogs (the 2000
years old ‘bog people’
from Denmark),
Modes of fossilisation
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Mineralization - cavities in
skeleton filled with mineral
Replacement - original
skeleton dissolved and replaced
by another mineral (silicification)
Natural moulds - original
skeleton dissolved, but not
replaced
Carbonisation - removal of the
‘light’ constituents leaving coalcoallike film of carbon
Trace fossils
Hard parts – shells and skeletons
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Calcium
carbonate
Calcium
phosphate
p osp a e
Silica
Organic
Summary
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Gaia, Historical Geology, Palaeontology
Geologic time
Geologic time scale
Earths structure/dynamic system
Rocks, minerals
Sedimentary rocks
Fossils & taphonomy