lecture 2-6-06 history of life

lecture 2-6-06 history of life - Chapter 26 History of Life...

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Chapter 26 - History of Life on Earth Learning objectives Describe the major events in Earth’s history from the time of its origin, noting when the Earth first formed, when life first evolved, and what forms of life existed Explain how index fossils can be used to determine the relative age of fossil-bearing rock strata; how radiometric dating can be used to determine the absolute age of rock strata. Describe the mass extinctions of the Permian and Cretaceous periods and hypotheses that accounts for each Know how the snowball-Earth hypothesis explains why multicellular eukaryotes were so limited in size, diversity, and distribution until the late Proterozoic Describe the timing and significance of the evolution of oxygenic photosynthesis. Describe the key evolutionary adaptations that arose as life colonized land.
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Earth’s History: Some “benchmark” dates (estimated) 4.5 bya 4-3.5 2.7 ~2.0 1.2 0.5 0.05 2/6/06 Earth formed prokaryotes oxygen atmosphere eukaryotes multicellular land colonization primates you ! (?) photosynthesis
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Index fossils Are similar fossils found in the same strata in different locations Allow strata at one location to be correlated with strata at another location Figure 26.6
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How Rocks and Fossils Are Dated Sedimentary strata Reveal the relative ages of fossils (‘before/after’) The absolute ages of fossils (approximate age in years) Can be determined by radiometric dating
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Figure 26.7 1 2 3 4 Accumulating “daughter” isotope Ratio of parent isotope to daughter isotope Remaining “parent” isotope 1 1 1 1 Time (half-lives) 2 4 8 16
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remains in a fossil at the time of analysis? A) one
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This note was uploaded on 03/19/2008 for the course BIO 311D taught by Professor Reichler during the Spring '08 term at University of Texas.

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lecture 2-6-06 history of life - Chapter 26 History of Life...

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