Today

1
Todays Agenda3/7

• Bellringer Hidden Frogs Questions
• Discuss yesterdays Hidden Frogs activity and
  questions
• Notes on Fossils and the Geologic Time Scale
• Homework Name That Period Worksheet

2
Looking Into the Past

• Fossils and Geologic Time
• Study Pack 4

3
Todays Targets

• I understand what fossils and the fossil record
  are.
• I can describe the usefulness of the fossil
  record.
• I understand that fossils provide evidence of
  biological change.

4
Types of Fossils

• Most of the evidence for evolution comes from
  fossils
• A fossil is the remains, imprint, or a trace of a
  once living organisms

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Types of Fossils

• Page 344 Figure 9
• Cast fossils
• Minerals fill in cracks to create a cast
• Example Animal tracks become filled in
• Fossils in amber
• Sticky material from trees harden and trap
  insects

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Types of Fossils

• Mineralized fossils
• Minerals replace wood or bone
• Petrified wood
• Frozen fossils
• Fossils are normally found in sedimentary rock
• Layers of sand, silt, clay or mud are compacted
  and cemented together with fossils inside

7
Determining a Fossils Age

• Relative Dating
• Younger rock layers are on top of older rock
  layers
• Provides an estimate of a fossils age
• Compare fossils to the layers of rock to
  determine their age

8
Determining a Fossils Age
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Determining a Fossils Age

• Radiometric or absolute dating
• More accurate
• Use the amount of radioactive elements in the
  rock where the fossil is found to determine its
  age

10
The Fossil Record

• The fossil record provides us with clues that
  organisms have changed over time
• Organisms have gone from simple to more complex
• Fossils tell us
• What the organisms looked like
• How it behaved
• What types of food it ate
• What type of environment it lived in

11
Geologic Time Scale

• Using absolute dating scientists have calculated
  the ages of many different fossils and rocks
• From this information scientists have created a
  calendar of Earths history that spans more
  than 4.6 billion years

12
Geologic Time Scale

• Scientists divide Earths history into smaller
  units called eras
• Eras are divided into units called periods
• Each era and period contains certain events and
  the presence of certain prehistoric creatures
• For example Dinosaurs in the Mesozoic Era

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Which time period?

• Name the time period in which the following
  events occurred! ?

14
Which time period?

• Do we currently live in?
• Quaternary Period

15
Which time period?

• Did amphibians evolve in?
• Devonian Period

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Which time period?

• Did the first dinosaurs evolve in?
• Triassic Period

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Which time period?

• Did humans evolve in?
• Quaternary Period

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Which time period?

• Did the earliest fishes evolve in?
• Ordovician Period

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Which time period?

• Consists of the beginning of Earths history?
• Precambrian

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Which time period?

• Did the earliest reptiles appear in?
• Carboniferous Period

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Which time period?

• Did land plants and animals evolve in?
• Silurian Period

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Which time period?

• Did plants that reproduce with seeds appear in?
• Permian Period

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Which time period?

• Did the first birds appear in?
• Jurassic Period

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Which time period?

• Did sponges, clams, snails, and worms evolve in?
• Cambrian Period

25
Which time period?

• Did flowering plants become the most common type
  of plant in?
• Tertiary Period

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Which time period?

• Dinosaurs become extinct in?
• Cretaceous Period

27
Which time period?

• Did insects and spiders resembling those of today
  appear in?
• Silurian period

28
Which time period?

• Did the shark appear in?
• Devonian period

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Homework

• Geological Time Scale Worksheet