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?