EARTH HISTORY AND EVOLUTION

The Big Bang Theory

Many scientists believe that the Earth was formed at the same time as many other planetsAbout 4.6 billion years ago

After a massive explosion, rock, dust, and ice began being pulled together by gravity forming the Earth

EARLY EARTHThis artist’s illustration shows Earth shortly after the moon formed. Notice the rocky objects striking Earth from space, and the molten rock overflowing the surface.

Earth Origins Feature Early Earth Later Pre-Cambrian

Atmosphere Helium and Hydrogen N, CO2, water vapor

Continents None (Earth was molten)

Less dense material began to cool and form land masses known as continents

Oceans None (too hot) As the surface cooled, water vapor began to condense to form rain. Gradually, rain water began to accumulate and form oceans

Atmosphere

The Beginning of Life

Scientists have found fossils of single-celled organismsBelieved to have formed about 3.5 billion

years agoProbably similar to present-day bacteria

Scientists hypothesize that all other forms of life on Earth arose from these simple organismsEarly organisms lived only in water

Life Moves on Land

About 2.5 billion years ago, many organisms began using energy from the sun to make their own foodProcesses in the atmosphere changed

some of this O2 into a form called ozone (O3) The atmosphere developed a layer rich in

ozone that blocked out the deadly UV raysThis allowed organisms to survive on land

Earth’s Timeline

LAB!!!

Earth History Timeline

See NJ ASK Coach Book for timeline….copy into notebook!!!

Know major ERAS and PERIODS of Earth’s history!

FOSSILS

Key Ideas and Vocabulary How do fossils form? What are the different kinds of fossils? What does the fossil record tell about organisms and environments of

the past?

Terms fossil sedimentary rock mold cast petrified fossil carbon film trace fossil paleontologist scientific theory evolution extinct

Fossil-the preserved

remains or traces of

living things

Fossils

Fossils found in rock include: molds and casts petrified fossils carbon filmsand trace fossils

Other fossils form when the remains of organisms are preserved in substances such as tar, amber, or ice.

Fossils

Fossils are usually found in sedimentary rock

They provide clues to the past sedimentary rock- type of rock that is

made of hardened sedimentExamples: sandstone, coal, limestone

Scientific Theory- well-tested concept that explains a wide range of observations

Evolution- the process by which all the different kinds of living things have changed over time

http://www.brainpop.com/science/ecologyandbehavior/humanevolution/preview.weml

DARWIN’S THEORY OF EVOLUTION

Who was Charles Darwin?

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Darwin’s Journey

December 1831 at 22 years old, Darwin set sail on the British ship HMS BeagleBecame the ship’s naturalistStudied plants, animals, and everything

about the natural world Darwin’s most important observations:

Diversity of living thingsRemains of ancient organismsCharcteristsics of organisms on the

Galapagoes Islands

Darwin’s Journey

Making Connections

On his journey, Darwin observed that there were similarities between the organisms on South American and the Galapagos IslandsHowever, there were important

differences…

Mainland vs. Island

Mainland Iguanas Galapagos Iguanas

Comparisons between the islands

ADAPTATIONS

READ ONLY SLIDEEvolution

Darwin reasoned that plants or animals that arrived on the Galápagos Islands faced conditions that were different from those on the mainland. Perhaps, Darwin hypothesized, the species gradually changed over many generations and became better adapted to the new conditions. The gradual change in a species over time is called evolution.

Evolution

Evolution- The gradual change in a species over timeNow that Darwin had a theory, he needed to

find out how evolution worked A main component to his theory was

natural selection

Natural Selection

The process by which individuals that are better adapted to their environment are more likely to survive and reproduce than other members of the same species

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Overproduction and Variation

Natural Selection

Competition and Selection

Other factors tht contribute to evolution include:EnvironmentGenetic factors

○ Science was not far enough along for Darwin to be able to explain variations in genes in relation to evolution

Evidence for Evolution

Evidence of Evolution

Fossils Patterns of early development Similar body structures

All provide evidence that organisms have changed over time

Early Development Similarities

Similarities in Body Structure

Look at the drawing below of the bones in a crocodile’s leg. Compare this drawing to the previous slide.

Do you think that crocodiles sahare a common ancestor with birds, dolphins, and dogs? Support your answer with evidence.