lecture 3: the fossil record and patterns of evolution (17-1 ......fossils and ancient life the...

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Copyright Pearson Prentice Hall

Lecture 3: The Fossil Record and Patterns of

Evolution (17-1 and 17-4)

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17-1 The Fossil Record


Fossils and Ancient Life

The fossil record…

1. provides evidence about the history of life on Earth (but it is incomplete)

a) 99% of all species on Earth extinct

2. shows how organisms have changed over time

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How Fossils Form

Fossil Formation

Water carries small rock particles to lakes and seas.

Dead organisms are buried by layers of sediment, which forms new rock.

The preserved remains may be later discovered and studied.

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Interpreting Fossil Evidence


The age of fossils are determined by using

(1)Relative dating

(2)Radioactive dating

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1. Relative Dating: Age is determined by comparing its placement with that of fossils in other layers of rock.

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2. Radioactive Dating: the absolute age of a fossil is calculated based on the amount of remaining radioactive isotopes it contains.

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Half-life:-the time it takes for half of the radioactive

isotope to decay.


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Extinction

Patterns of Evolution

1. Mass Extinctions

• provide ecological opportunities for organisms that survived

• result in bursts of evolution that produced many new species

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Adaptive Radiation

2. Adaptive Radiation

process by which a single species or a small group of species evolves into several different forms that live in different ways

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Convergent Evolution

3. Convergent EvolutionThe process by which unrelated organisms come to resemble one another

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Convergent Evolution

4. Analogous structuresStructures that look and function similarly but are made up of parts that do not share a common evolutionary history

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Coevolution

5. CoevolutionThe process by which two species evolve in response to changes in each other over time

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Punctuated Equilibrium

6. Punctuated equilibrium: periods are interrupted by brief periods of more rapid change.

Gradualism: slow and steady change over time

lecture 3: the fossil record and patterns of evolution (17-1 ......fossils and ancient life the...

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