Fossils
Fossils
• Fossils- the preserved remains
or evidence of living things
Types of Fossils
• Original Remains- Unchanged
remains of plants and animals
– Examples
• Hard parts: Bones, Shells
• Animals trapped in ice: Wooly Mammoth
• Animals trapped in tar or in amber
Amber with an insect
Frog in Amber
Sabertoothed
Tiger
Woolly
Mammoth
in ice
Fossilized dinosaur bones in sandstone
(sedimentary rock)
The La
Brea tar
pit in Los
Angeles,
California
is famous
for its
many
fossils!
Tar is
thick
and
sticky
Types of Fossils
• Replaced Remains: Hard
parts of plants or animals are
replaced by minerals over
time. The minerals are in the
shape of the organism.
– This occurs when water
containing minerals seeps
through the plant/animal material.
– Petrified wood forms in this way
Example:
Petrified Wood
Minerals have
replaced all of
the wood cells
and turned this
wood into rock!
Types of Fossils
• Molds and Casts: Impressions and copies
• Molds are created as mud or sediment
becomes rock around dead organisms.
• Casts are created as minerals get deposited
into the molds and then harden. They make a
copy of the fossil.
Ice cube
tray=
Mold
Ice=
Cast
Example: Cast of an Ammonite
Types of Fossils
• Trace Fossils: Evidence of organisms
–Footprints, teeth marks, tunnels
–Carbonaceous film: thin film of carbon
resembling a silhouette of the organism
Trilobite:
Index fossil
of Paleozoic
• Graptolite:
Index fossil of
the Silurian
Question:
• Fossils are usually formed when the
organism dies and gets buried in mud or
sand. As a result, What type of rock are
fossils usually found in?
Questions:
• Why are fossils NOT usually found
in igneous rock?
Questions:
• What 4 settings (environments) could
fossils be preserved?
Questions:
• What are the 5 types of fossils?