chapter 15 evolution evidence & theory. 15-1 the fossil record

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Chapter 15

Evolution

Evidence & Theory

15-1 The Fossil Record

Nature of Fossils

• Fossil– Trace of long dead organism

• Where Found– Sedimentary rock

• How Created– Dust, sand, mud deposited by wind/water

over dead organisms• Develop From

– Shell, bone, teeth, stem

Types of Fossils

• Mold– Imprint on rock such as limestone– Shape of organism

• Cast– Mold filled with hard minerals

• Amber– Fossilized tree sap

Robert Hooke

• In 1668– Concluded fossils are remains of once living

plants and animals– What else did he do? Remember way back

when…

– Hmmm?

Distribution of Fossils• Age

– Relative• Steno 1670 Law of Superposition• Determined by fossils position in strata/rock• Oldest fossils = deepest youngest = surface

– Absolute• Radioactive dating• Radioactive isotopes

– Carbon-14; Carbon-12– Ratio of decay of carbon-14 to

stable carbon-12

Succession of Forms

• Extinct– Species no longer exists

• Mass Extinction– Period in which large number of species

disappear• Biogeography

– Study of geographical distribution of fossils & living organisms

– Ex of biogeography

Geological History of Earth

• Table 15-1

• Era Period Epoch

• Interactive geologic time

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