Fossils

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Fossils

• Inside the Restless Earth
• Chapter 3 Section 4

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What are fossils?

• A fossil of a preserved remains of once living
  organisms.
• Fossils give clues about organisms that lived
  long ago. They help to show that evolution has
  occurred.
• They also provide evidence about how Earths
  surface has changed over time.
• Fossils help scientists understand what past
  environments may have been like.

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QWhat fossils are in rocks?

• AFossils are the remains of organisms that are
  preserved.
• Hard parts (bones, shells) get buried in sediment
• Soft parts of the organism decays

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QWhat is petrifaction?

• APetrifaction is the process in which minerals
  replace an organisms tissues.
• Replacement-organisms tissues are completely
  replaced by minerals
• Permineralization-minerals fill spaces

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What is petrifaction?
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Q How do fossils get preserved in amber?

• A An organism gets stuck in soft, sticky tree
  sap and then gets covered in more sap. The sap
  then hardens.
• Hardened tree sap is called amber.
• Insects, frogs, lizards have been found in amber.
• Organism land on sap
• Gets stuck
• Gets covered in more sap
• Sap hardens

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Q How do fossils get preserved in amber?
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Q What are frozen fossils?

• A Frozen fossils are the remains of organisms
  that have been preserved in ice. Usually during
  the ice age.
• Cold temperatures slow down decay
• Organism falls-freezes
• Makes good fossils

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Q What are frozen fossils?
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Q How do fossils end up in tar/asphalt?

• A Fossils are in asphalt because organisms got
  stuck in the thick, sticky substance.
• La Brea asphalt/tar pits in California are over
  38,000 years old.
• Scientists learned a lot about the past
  environment in California.

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Q How do fossils end up in tar/asphalt?

• La Brea Tar Pits

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QWhat are trace fossils?

• A These form when animal footprints, burrow, or
  coprolite are filled in with sediment and are
  preserved in rock.
• Tell how big the animal was
• How fast the animal moved
• Borrows that animals made are an example
• Coprolite is preserved animal dung

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What are trace fossils?
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What are trace fossils?
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Q What are casts and molds?

• A A mold is a cavity (hole-space) where a plant
  or animal was buried.
• A A cast is an object created when sediment
  fills a mold and becomes a rock.
• Mold-impression in ground or rock
• Castsediment filled mold

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What are molds?

• Internal and External mold

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What are casts?
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Q What information do scientists obtain from the
fossil record.

• A The fossil record provides evidence about the
  past.
• We know more about organisms with hard parts (ex.
  Shells)
• The fossil record is incomplete.
• Many organisms never become fossils
• Many fossil havent been discovered

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QHow does the environment affect fossils?

• A Fossil records provide evidence of changes in
  the environment.
• Marine fossils were found on a mountain top. This
  suggests that the mountain top was once the ocean
  floor.
• Fossils show evidence of climate

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Q How do fossils show the history of the way
organisms changed?

• A Fossils show how organisms have changed over
  time. Scientists study the relationship between
  fossils.
• Fossils in different rock layers suggest that
  fossils can be younger or older depending on the
  layer they are found in.
• Only a fraction of organisms in history have been
  fossilized incomplete fossil record

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Q How are fossils used to date rocks?

• A Fossils are used to date rocks because certain
  types of fossils can be used to estimate the
  absolute (exact) age of the sedimentary rock they
  are found in.
• An index fossil is a fossil used to estimate the
  absolute age of rock layers.
• An index fossil lived for a short period of time.
• Ammonites and Trilobites (index fossils)

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Q What is mummification?

• AMummification is the preservation of a body,
  either animal or human.
• Some mummies are preserved wet, some are frozen,
  and some are dried.
• It can be a natural process or it may be
  deliberately achieved.
• Eliminate moisture