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Bio Ch17 – History of Life on Earth How long has life been on Earth? What are the relationships between organisms as time moved forward? 1
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Fossil Records 2
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3 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, half- amphibian that all but confirmed paleontologists' theories about how land- dwelling 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. Lets examine five important cases. 4
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Fossil Formation Lucy 10
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Age-determining Techniques Biological – tree rings Geologic – sedimentary layers Geochemical – Sea salt concentration Geophysical – Relative cooling of earths crust Chemical – Weathering Relative dating – Fossil relations Radioactive dating – Comparative amount of elements 11
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Relative Dating 12
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Radioactive dating 14
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Radioactive decay in everyday life 15
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Geologic Time Scale Evidence used to construct timeline of development of life on Earth Fossil records Relative Dating Radioactive dating LEADS TO 17
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Early Earth Atmosphere Hydrogen Cyanide Carbon Dioxide Carbon Monoxide Nitrogen Hydrogen Sulfide Water 20
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Patterns of Evolution (Macroevolution) Extinction Adaptive Radiation Convergent Evolution Coevolution Punctuated Equilibrium Changes in developmental genes 21
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Extinction Mass extinctions –Causes –Impact on life 22
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Adaptive Radiation 23
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Convergent Evolution Similar torpedo-shape body & fluke/tail. Mammals were initially land-based with four walking limbs. 24
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Coevolution Evolution of separate species in response to each other (not abiotic response) 25
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Punctuated Equilibrium 26
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Changes in Developmental Genes Genetic change can produce major evolutionary transformation 27
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