Ch.17 Survey - The history of life

» Fossil Record» Earth’s Early History» Evolution of Multicellular Life» Patterns of Evolution

Kevin

Fossil RecordFossil record can be used as evidence of Earth’s long history and the change of organisms as time passes. Mostly found in sedimentary rock.Shows that certain species have become extinct.Relative dating compares its placement with those of others in other layers of rock.Radioactive dating works by paleontologists’ measuring the amounts of certain isotopes that fossil contains. Both technique above help to determine the age of fossils.

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Earth’s Early History

Six components of Earth’s early atmosphere: hydrogen cyanide, carbon dioxide, carbon monoxide, nitrogen, hydrogen sulfide, and water.

Contain little or no oxygen.

Rising Oxygen drove some lives to extinction while new organisms generated by it.

Ocean didn’t exist.

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<Formation of the Earth><Formation of the Earth>

Organic molecules

Photosynthetic oxygen

Water

Atmospheric oxygen

Eukaryotes

Sexual reproduction

Multicellular organisms Kevin

Evolution of Multicellular life

Precambrian Time: Unicellular life started to change.Paleozoic Era: Many types of marine life were altered into new forms of life. Cambrian Period: Evolvement of animals with hard outer bone occurred.Ordovician and Silurian Periods: Fishes having no jaw and land plants appeared as the first time.

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Precambrian Time -Unicellular life evolves.Precambrian Time -Unicellular life evolves.

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Evolution of Multicellular life

Devonian Period: Animals began to move to the land.

Carboniferous and Permian Periods: Forests and winged insects evolved.

Mesozoic Era: Flower appeared.

Cenzoic Era: Mammals flourished everywhere.

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Patterns of Evolution

Examples of patterns of Macroevolution : Mass extinction, Adaptive radiation, Coevolution, Punctuated equilibrium, and changes in developmental genes.Through Mass extinction, a lot of species disappear very quickly. By adaptive radiation, some species evolve into different forms.During coevolution, the pattern of macroevolution reacts to the changes in each other overtime.

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Hox genes are the basis for major evolutionary changes.

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