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Fossils
Fossils• Fossils- the preserved remains
or evidence of livingliving 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
Saber-toothed Tiger
Amber with an insect
Frog in AmberWoolly Woolly Mammoth Mammoth in icein ice
Fossilized dinosaur bones in sandstone Fossilized dinosaur bones in sandstone (sedimentary rock)(sedimentary rock)
Tar is thick and sticky
The La Brea tar pit in Los Angeles, California is famous for its many fossils!
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 WoodPetrified 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?