The Stories Fossils Tell

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The Stories Fossils Tell
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Can you name the 4 types of Fossils ?
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Name the 4 types of Fossils

• Mold
• Trace
• Casts
• True form

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Describe how Mold Fossils are formed.
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Mold Fossils-are usually formed in
sediment-organisms like shells, leaves or bones,
are covered with mud-over time mud
hardens-water enters mold and dissolves dead
organism-mold fossils are HOLLOW on the inside
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Describe how Casts Fossils are formed.
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Casts fossils-need a mold fossil first-after
organism dissolves and leaves an empty space-the
empty space fills with minerals -as time passes
it hardens to form a cast fossil
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Describe how Trace Fossils are formed.
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Trace Fossils-are markings left by
animals-examples include leaf prints,
footprints, eggs and nests-Trace fossils are
good for scientists to use to understand animals
BEHAVIORS
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Fossil footprints have yielded
information about Speed and length of stride
whether they walked on two or four legs the
bone structure of the foot stalking behavior (a
carnivore hunting a herd of herbivores) the
existence of dinosaur herds and stampedes how
the tail is carried (few tail tracks have been
found, so tails were probably held above the
ground)
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Describe how True Form Fossils are formed.
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True Form FossilsTrue Form fossils are
formed when the animals soft tissues or hard
parts did not decay over the years because they
are trapped in sap that hardens to become
amber.This evidence gives scientists the BEST
observation of past plants and animals.
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Fossils start out as living things.
The organism can be either a plant or an animal.
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When the organism dies . . .

• The soft parts that are exposed to air decompose
  quickly.
• Hard parts like bones, shells, or wood, dont
  decompose as quickly. They have the greatest
  chance of becoming a fossil.

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The organism may be buried in layers deep in the
earth. These layers might be composed of mud,
lava or water.
Sediments
Basalt
Fossil layer
Sandstone
Basalt
Coal
Sedimentary Rock
Basalt
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Scientists sometimes dig in the Earth looking for
fossils.
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How do fossils help us learn about the past?
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Thinking like a paleontologist
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Lets practice making inferences about living
things.
Would the tree live in this environment?
Look at these pictures of things that come from a
tree. Make a prediction about the environment
where you would find this tree.
or, would the tree live in this environment?
This is more difficult isnt it? Why? What would
help you decide on the correct environment?
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Can you be a paleontologist?
This is the environment where you are looking for
fossils.
Here in an example of the kinds of fossil your
team has found. What do you think the
environment might have been like in the past?
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Lets try another example!
You just found the plant fossils, on the left, in
an area where it is now hot and dry like the
picture on the right. What predictions can you
make about what the environment might have been
like in the past?
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Once Upon a Time is not just for fairy tales.
Asian Elephant
Wooly Mammoth
How are these two animals the same? How are
they different?
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The wooly mammoth is the ancestor of the modern
Asian elephant.
Asian Elephant
Wooly Mammoth
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Once Upon a Time A Look at the Horse
Horse B
Horse A
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Change Over Time A Horses Foot

• Note how the distance of the wrist bones from the
  ground changes. What else has changed?

wrist
Adapted from Florida Museum of Natural History.
For more information visit their website at
http//www.flmnh.ufl.edu/natsci/vertpaleo/fhc/rela
tives1.htm
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How have the bones in horse feet changed over
time? Why might this have happened?
Lets Look More Closely
Adapted from Florida Museum of Natural History.
For more information visit their website at
http//www.flmnh.ufl.edu/natsci/vertpaleo/fhc/rela
tives1.htm
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Wrap-Up

• Fossils are formed under very special conditions.
• They give us clues about what life was like long
  ago.
• Fossils also give us clues about the environment
  from a long time ago.
• They help us understand that plant and animal
  species change over time.

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Group 1, group 3, group 4, group 2Group 2 is the
youngest.
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• Rivers deposited the shells
• The region was once under an ocean environment
• Early Native American left them there.

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b.The region was once under an ocean environment
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