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Fossils and Evolution

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Fossils and Evolution What is Evolution? (YouTube Video) http://www.youtube.com/watch?v=GhHOjC4oxh8 Earth formed about 4.5 billion years ago. In that time, life has ... – PowerPoint PPT presentation

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Title: Fossils and Evolution


1
Fossils and Evolution
  • What is Evolution? (YouTube Video)
  • http//www.youtube.com/watch?vGhHOjC4oxh8

2
  • Earth formed about 4.5 billion years ago.
  • In that time, life has evolved from a few simple
    single-celled organisms to many different
    single-celled and multi-celled organisms.

3
  • The fossil record shows that Earths living
    things have evolved.
  • Fossils provide evidence of past life forms.
  • Fossils are preserved imprints or remains of
    once-living organisms.

4
  • Most fossils form in sedimentary rock.
  • Sedimentary rock forms gradually as layers of
    sediment are compacted or pressed and cemented
    together.

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  • Body fossils are the preserved remains of an
    organism (actual body, bones etc.).
  • Trace fossils are imprints left behind by
    organisms (tracks, nests, etc.)

8
  • Scientist can tell when organisms lived by
    comparing them to other fossils of a known
    certain age called index fossils.
  • Scientists can also use the positions of fossils
    in rock layers to determine which organisms came
    first.

9
Relative Dating
  • The older a fossil is the deeper it will be
    buried in sedimentary rock compared to other
    fossils.

10
  • The oldest fossils known were from single-celled
    organisms nearly 3 billion years ago.
  • For 2 billion years all life on Earth was
    comprised of only single-celled organisms.

11
  • By comparing fossils with each other and
    creatures today, scientists can determine how
    organisms are related and how evolution has
    occurred to produce the organisms we see today.

12
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