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The History of Life on Earth

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Petrified tree at Mammoth Hot Springs in Yellowstone National Park ... 4 bya: Earth's surface was cool enough for water to exist as a liquid ... – PowerPoint PPT presentation

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Title: The History of Life on Earth


1
The History of Life on Earth
2
  • Rocks provide clues to the earths history

3
3 Main types of rock
  • Igneous Rocks that form from the cooling and
    solidification of magma
  • Sedimentary Rocks that form from accumulation
    of sediment, usually in water
  • Metamorphic Rocks that are changed by heat
    and/or pressure

4
Lava lake in Surtsey Crater in Iceland.
5
  • Formation of sedimentary rock

6
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7
Gniess Example of metamorphic rock
8
Fossils
  • Preserved remains of ancient organisms or some
    trace of their presence
  • Many found in sedimentary rock

9
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10
Index fossils
Can be used to compare relative ages of fossils
11
Carbonaceous films
12
Impressions imprints left by an organism
contain no organic matter
Dinosaur Ridge
13
  • Noahs Raven
  • Footprints found by 12-year old Pliny Moody in
    Massachussetts in 1802
  • People thought the prints must have been made by
    giant ravens released by Noah from the Ark

14
Petrified tree at Mammoth Hot Springs in
Yellowstone National Park
15
Mold of a lower Cambrian trilobite
16
Cast of a Pompeii citizen killed by the 79 AD
eruption of Mt. Vesuvius.
17
Cast of a dog produced by 79 AD eruption of Mt.
Vesuvius.
18
Radioactive Dating
  • Uses radioactive decay of elements in rocks to
    determine absolute age of rocks
  • Based on half-life of a radioactive element
  • Half-life length of time required for half of
    the radioactive atoms in a sample to decay
  • C14 has half life of 5730 years
  • K40 has half life of 1.3 billion years

19
Formation of the Earth
  • Pieces of cosmic debris accumulated over 100
    million years
  • Collisions of early planet with other objects
    caused repeated melting of entire globe
  • Densest elements formed earth core lighter
    elements formed a crust
  • H, He, other light elements became atmosphere

20
Formation of the Earth---early atmosphere
  • Hydrogen cyanide
  • Carbon dioxide
  • Carbon monoxide
  • Nitrogen
  • Hydrogen sulfide
  • Water

21
The first organic molecules
  • 4 bya Earths surface was cool enough for water
    to exist as a liquid
  • Primitive oceans covered the earth----an abiotic
    stew of inorganic matter
  • Chemical reactions caused synthesis of first
    organic molecules
  • 3.8 bya first life forms appeared---single
    celled prokaryotes

22
  • Stanley Miller

23
Miller-Urey Experiment
N2 CH4 H2 NH3
Mixture of gases simulating atmospheres of early
Earth
Spark simulating lightning storms
Cold water cools chamber, causing droplets to form
Condensation chamber
Wter vapor
Liquid containing amino acids and other organic
compounds
Amino acids Fatty acids Other hydrocarbons (no
purines, pyrimidines, sugars, nucleic acids)
Go to Section
24
First signs of life
  • Proteinoid microspheres
  • Bubbles of organic compounds
  • Membranes
  • Store and release energy
  • Acquired additional characteristics of life
  • Evolution of DNA and RNA
  • Small sequences of RNA formed and replicated
  • DNA-directed protein synthesis

25
Evolution of Life
Early Earth was hot atmosphere contained
poisonous gases.
Earth cooled and oceans condensed.
Simple organic molecules may have formed in the
oceans..
Small sequences of RNA may have formed and
replicated.
First prokaryotes may have formed when RNA or DNA
was enclosed in microspheres.
Later prokaryotes were photosynthetic and
produced oxygen.
An oxygenated atmosphere capped by the ozone
layer protected Earth.
First eukaryotes may have been communities of
prokaryotes.
Multicellular eukaryotes evolved.
Sexual reproduction increased genetic
variability, hastening evolution.
Go to Section
26
Geologic Time Scale with Key Events
(millions of years ago)
Key Events
Era
Period
Time
Glaciations mammals increased humans Mammals
diversified grasses Aquatic reptiles
diversified flowering plants mass
extinction Dinosaurs diversified
birds Dinosaurs small mammals cone-bearing
plants Reptiles diversified seed plants mass
extinction Reptiles winged insects diversified
coal swamps Fishes diversified land vertebrates
(primitive amphibians) Land plants land animals
(arthropods) Aquatic arthropods mollusks
vertebrates (jawless fishes) Marine invertebrates
diversified most animal phyla evolved Anaerobic,
then photosynthetic prokaryotes eukaryotes, then
multicellular life
Cenozoic Mesozoic Paleozoic Precambrian Ti
me
Quaternary Tertiary Cretaceous Jurassic Triassic P
ermian Carboniferous Devonian Silurian Ordovician
Cambrian
1.8present 651.8 14565 208145 245208 290245
363290 410363 440410 505440 544505 650544
27

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29
First forms of life 3.5 bya
  • Cyanobacteria
  • Fossil colonies
  • called stromatolites
  • are 3.5 billion years
  • old
  • Created atmospheric O2 as byproduct of
    photosynthesis

30
  • Sexual reproduction increases the chance of
    evolutionary change due to natural selection
  • Appearance of multicellular organisms increased
    diversity of life

31
Vendotaenid algae from Namibia (2.5 245
mya) One of the first eukaryotes, first
multicellular organisms
32
Origin of Eukaryotic Cells
Endosymbiotic Theory
Chloroplast
Plants and plantlike protists
Aerobic bacteria
Ancient Prokaryotes
Photosynthetic bacteria
Nuclear envelope evolving
Mitochondrion
Primitive Aerobic Eukaryote
Animals, fungi, and non-plantlike protists
Ancient Anaerobic Prokaryote
Go to Section
33
Lynn Margulis
34
Cambrian Period, 540-500 mya
35
Ordovician Period
36
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37
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38
Silurian Period 425-408 MYA
39
Devonian The age of Fishes -- 390 mya
Map of the world during the Devonian period
40
Devonian Period, 408-362 MYA
2nd mass extinction 360 mya
41
Carboniferous Period, 362-290 MYA
42
Permian Period, 290-245 MYA 3rd mass extinction
245 mya
43
Triassic Period, 245-208 MYA
4th mass extinction 210 mya
44
Jurassic Period, 208-145 MYA
45
Jurassic Period, 208-145 MYA
46
Cretaceous Period, 145-65 MYA
5th mass extinction 65 mya
47
Tertiary Period, 65-1.64 MYA
48
Tertiary Period, 65-1.64 MYA --- Hominids in
Africa
49
Quaternary Period, 1.64 MYA - present
50
1.64 mya - present Homo sapiens
Quaternary Period, Neanderthals

51
Radiometric Dating Problems
  • C-14 has a half life of 5770 years. (This means
    that it takes 5770 years for half of the
    radioactive C-14 in a sample to decay into other
    substances)
  • If a fossil is 11540 years old, then how many
    half lives have passed?
  • K-40 has a half life of 1.3 billion years (1300
    million years).
  • If a fossil is found having ½ of the initial
    amount of K-40, how many half lives have passed?
  • How old is the fossil?
  • If a fossil is found having 1/16 of the initial
    amount of K-40, how many half lives have passed?

52
Radiometric Dating Problems
  • C-14 has a half life of 5770 years. (This
    means that it takes 5770 years for half of the
    radioactive C-14 in a sample to decay into other
    substances)
  • If a fossil is 11540 years old, then how many
    half lives have passed?
  • 11570/5770 2 2
    half lives
  • K-40 has a half life of 1.3 billion years
    (1300 million years).
  • If a fossil is found having ½ of the initial
    amount of K-40, how many half lives have passed?
  • Since half of the K40 has
    decayed, this means 1 half life has passed
  • 3. How old is the fossil?
  • Since the half life of K40 is
    1.3BY, this fossil is 1.3 billion years old
  • 4. If a fossil is found having 1/16 of the
    initial amount of K-40, how many half lives have
    passed?

53
Radiometric Dating Problems
  • 4. If a fossil is found having 1/16 of the
    initial amount of K-40, how many half lives
    have passed?
  • after 1 half life..1/2 is left
  • after 2 half lives..1/4 is left
  • after 3 half lives..1/8 is left
  • after 4 half lives..1/16 is left
  • after 5 half lives..1/32 is left
  • So, 4 half lives have passed for this
    fossil

54
THE END
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