Transcript Bio History of Life on Earth

Bio Ch17 –
History of Life on Earth
How long has life been on Earth?
What are the relationships between
organisms as time moved forward?
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Fossil Records
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Fossil Records
Petrified tree sap = “amber”
(Basis for Jurassic Park movies)
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Fossil Evidence
In 2004, scientists digging in the Canadian
Arctic unearthed fossils of a half-fish, halfamphibian that all but confirmed
paleontologists' theories about how landdwelling tetrapods–four-limbed animals,
including us–evolved from fish.
It is a classic example of a transitional form,
one that bridges a so-called evolutionary gap
between different types of animal.
Let’s examine five important cases.
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Fossil Formation
“Lucy”
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Age-determining Techniques
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Biological – tree rings
Geologic – sedimentary layers
Geochemical – Sea salt concentration
Geophysical – Relative cooling of earth’s crust
Chemical – Weathering
Relative dating – Fossil relations
Radioactive dating – Comparative amount of
elements
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Relative Dating
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Radioactive dating
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Radioactive decay
in everyday life
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Evidence used to construct “timeline” of
development of life on Earth
• Fossil records
• Relative Dating
• Radioactive dating
LEADS TO
Geologic Time Scale
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Early Earth Atmosphere
•Hydrogen
Cyanide
•Carbon
Dioxide
•Carbon
Monoxide
•Nitrogen
•Hydrogen
Sulfide
•Water
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Patterns of Evolution
(Macroevolution)
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Extinction
Adaptive Radiation
Convergent Evolution
Coevolution
Punctuated Equilibrium
Changes in developmental genes
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Extinction
• Mass extinctions
– Causes
– Impact on life
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Adaptive Radiation
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Convergent Evolution
Similar torpedo-shape body & fluke/tail.
Mammals were initially land-based with four walking limbs.
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Coevolution
• Evolution of separate species in response to
each other (not abiotic response)
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Punctuated Equilibrium
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Changes in Developmental Genes
• Genetic change can
produce major
evolutionary
transformation
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