FOSSILS

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FOSSILS
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I. What is a fossil?

• A fossil is any evidence of past life preserved
  by natural processes.

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II. There are many different types of fossils
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1. Fossilized footprints, casts and imprints
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Example 1 Human-like footprints

• Footprints of human ancestors in Laetoli, Africa.
  The footprints were formed 3.5 million years ago
  when at least two individuals walked over wet
  volcanic ash. The wet ash hardened like cement
  and was then covered by more ash.

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• The footprints also show that the individuals had
  perfect, two-footed strides. They reveal that one
  hominid was larger than the other. And because
  the footprints fall next to each other, they
  indicate that the two hominids were walking
  side-by-side and close enough to each other to be
  touching.

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Example 2

• Fossilized worm from the early Cambrian period -
  around 500 million years ago.

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2. Mineralized hard tissue

• When hard tissues such as bone, wood or shells
  are covered by sediments, the tissue is partially
  or totally replaced by minerals over time(like
  petrified wood).

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Example 1
No longer made of pure bone, this skull consists
at least partially of minerals (rock). Very old
specimens consist entirely of rock.

• Cave Bear fossil from the Pleistocene period (1.8
  MYA - 10,000 YA) The Cave Bear stood over 9 feet
  tall on its hind legs.

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Example 2 Megalodon tooth

• At up to 100 feet in length the Megalodon is
  believed to be the largest predator to ever exist.

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Example 3Fossilized T-Rex skeleton found in 66
million year old Hell Creek deposits in Montana
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3. Fossils preserved in amber or ice
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Example 1

• A praying Mantis fossilized in Amber

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• There are 300 insect specimens in this large
  fossilized amber sample.

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Example 2Otzi the iceman found frozen in the
Italian Alps in 1991 is over 5,000 years old!
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Example 3 La Doncella is the Inca girl who was
almost perfectly preserved in ice on top of a
volcano after being sacrificed 500 years ago.
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III. Fossil formation is an extremely rare event

• We see evidence for only a small percentage of
  the life that existed in the past.
• http//www.bbc.co.uk/sn/prehistoric_life/dinosaurs
  /burying_bodies/