Fossil Talk

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Fossil Talk
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What is a fossil?

• Remains or traces of a prehistoric plant or
  animal found in earth or rock.

Dinosaur footprint
Dinosaur bones
Petrified trees
Leaf impressions
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What are not fossils?
Arrowhead
Caribou skull
Amethyst crystal
Geode
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How old are fossils?
2.5 Billion Years Old!!!
Bacteria and Algae from the sea.
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How old are fossils?
The first common fossils come from the Cambrian
period over 600 million years ago! Phacobs, a
common Trilobite fossil dates from 400 million
years ago!!
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How old are fossils?
Most dinosaur fossils come the Mesozoic period
over 230 million years. Stegosaurus, from the
Jurassic period, 195 million years ago.
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How old are fossils?
Tyrannosaurus Rex and Triceratops of the
Cretaceous period date from 140 million years
ago.
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Fish fossils at Fossil Butte date from 50 million
years ago.
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Just the right conditions are needed to make a
fossil.
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Types of Fossils
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Unaltered Remains
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Petrified Remains

• When something petrifies it turns to stone. A
  fossil must be buried for a very long time.
  Water dissolves the original material, and
  replaces it with minerals. Slowly, the fossil
  turns to stone. Dinosaur bones are petrified.

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Coprolites
Believe it, or not, these are petrified animal
droppings. They have turned to solid rock.
Cant tell exactly what animal left them!!
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Molds and Casts
Sometimes, what looks like a fossil shell really
isnt a shell at all, but a mold or cast, an
exact copy or the original.
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Molds and Casts

• The animal dies and is buried.
• It is buried under layers of sand that turns to
  rock.
• The hard part slowly dissolves, leaving a space
  shaped like the original hard part. This is
  called the mold.
• Dissolved chemicals fill the mold to form a
  replica of the shell thats the cast.

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Molds and Casts
Trilobite
Nautilus
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Impressions
Sometimes the plant or animals decays, but leaves
an impression of itself in the sediment. Just
like you can make a leaf impression in clay, a
leaf can make an impression in mud that hardens
to rock. There are also skin impressions.
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Impressions
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Impressions
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Impressions
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Trace Fossils
These are remains of the activity of an animal.
Footprints show where animals walked. Tunnels
show where worms funneled in the oceans bottom.
Petrified tree trunks show insect borings.
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Amber
Sticky tree sap sometimes traps insects like ants
wasps, and bees. The sap can petrify into a
mineral called amber, preserving the trapped
insect inside.
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Fossils to Find
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Horn Coral
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Brachiopods
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Cephalopods
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Leaf Impressions
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Trilobite
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How to Look for Fossils

• Find a place to start looking.
• Sit down and start looking.
• Stay in one place and look, look, look!!
• Be careful when walking on the rocks. Remember
  people will be below you so dont cause a rock
  slide.
• Only take what you can fit in a closed plastic
  bag and what you can carry.

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Have Fun Fossil Hunting!!!