Paleontology
The study of ancient life!
Fossil Picture Here
How is evidence of life preserved?
• Body fossils
• Trace fossils
Trace Fossil
Picture Here
Body Fossil
Picture Here
Body Fossils
• Body fossils are any direct evidence of
prehistoric life:
– This includes whole bodies of animals, plants, or other
organisms
Petrified wood
picture here
Shark tooth
picture here
Fossilized
Shells
picture here
– Or any parts of bodies such as shells, bones, or teeth
Trace Fossils
• Trace fossils are any indirect evidence of
prehistoric life.
• This includes tracks, trails, burrows,
boreholes, bite marks, and coprolites
• Trace fossils are useful for studying the
behavior of ancient organisms.
BITE MARKS
Bite Marks picture here
TRACKS
Footprints of tracks picture here
TRAILS
Trail picture here
BURROWS
Burrow picture here
COPROLITES (fossil poop)
Coprolite picture here
Fossilization
• What is necessary to preserve a body
fossil?
1.Hard parts! (bone, teeth, shell, wood)…
• Hard parts stand a greater chance of preservation than do
soft tissues (skin and muscle) because soft parts readily
decay or decompose after death.
2. Rapid burial
Rapid burial helps to prevent decomposition,
erosion, and disarticulation (separation of the body
parts or bones).
Picture of disarticulation
here
Fossilization
• Body fossils are preserved as:
– Unaltered remains
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Calcified skeletons
Mummification
Fossils in amber
Frozen fossils
Fossils in tar
– Altered remains
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Petrification (Replacement)
Permineralization or Recrystallization
Dissolution
Carbonization
Unaltered remains
• Many marine organisms build their skeletons
with the mineral calcite, which is stable over
geologic time.
Unaltered fossil
picture here
MUMMIFICATION
• An organism may dry out so fast that their
soft parts don’t have time to decay
Mummy picture here
FOSSILS IN AMBER
• Amber is fossilized tree sap. If an insect gets
caught in the sap, it may become part of the
fossil.
Insect in amber
picture here
FROZEN FOSSILS
• Animals may get trapped in ice and preserved.
Wooly mammoths have been found preserved
this way.
Frozen animal (wooly
mammoth) picture here
FOSSILS IN TAR
• Animals may have been stuck in naturally
occurring pools of tar. A famous example is the
La Brea tar pits in CA.
Fossil in tar
picture
Altered: Petrification or
Replacement
• This is the removal of the original skeleton
material and replacement by another mineral.
– Example: calcite shells that are replaced with pyrite.
Fossil replaced by pyrite
Altered: Permineralization and
Recrystallization
• This is the filling of pore spaces in porous
material such as wood or bone by the
precipitation of minerals from water.
– Example: petrified wood, or dinosaur bones
Petrified wood picture
here
Altered: Dissolution
• This is the dissolving of
the original skeleton,
leaving a hollow
impression called a mold.
• A cast of the object is
formed when the
sediment fills in the mold
and becomes rock.
Mold and Cast
pictures
Altered: Carbonization
• This is where the only compounds left of the
organism is a carbon film in rock.
Carbon film fossil
picture here
INDEX FOSSILS
• Fossils of organisms that lived during a relatively
short time. They help to give a relative age to
rock layers.
– Ammonites and Trilobites are examples of index fossils.
Ammonite
and Trilobite
fossil here
Stratigraphic column
Picture of a real stratigraphic column,
preferably with fossils labeled