Fossils• Fossils are preserved remains or traces of

living things. • Most fossils form when living things:

1. die

2. buried by sediments quickly.

3. bones are replaced by minerals.

4. sediments slowly harden into rock and preserve the shapes of the organisms.

Can all dead things become a fossil?

I can: Describe and identify different types of fossils

Types of Fossils

• Mold • Cast• Permineralized remains• Preserved • Carbonaceous film• Trace fossil• Index fossil

Mold Fossil

• A mold is a hollow area in sediment in the shape of an organism or part of the organism.

• Forms when sediments bury an organism and the sediments change into rock.– The organism then decays leaving a cavity in

the shape of the organism

Cast Fossil

• Cast is a copy of the shape of an organism.

• Forms when a mold is filled with sand or mud that hardens into the shape of the organism.

Website

• http://www.classzone.com/books/earth_science/terc/content/visualizations/es2901/es2901page01.cfm?chapter_no=visualization

I can: Describe and identify different types of fossils

Do Now: Which fossil is a cast and which is a mold?

Trilobites

Mold – hollow area that takes the shape of an organismCast – copy of the shape of an organism

Mold Cast

Placoderm Armored Fish -from Morocco -about 20 feet long-bony blades as teeth for slicing and dicing

Types of Fossils

1. Mold

2. Cast

3. Permineralized remains

4. Preserved (original remains)

5. Carbon film

6. Trace fossil

[Index fossil]

Permineralized remains

• Fossils in which spaces inside of the dead organism are filled with minerals from ground water

Permineralized remains

Preserved FossilsOriginal remains

• Forms when entire organisms or parts of organisms are trapped in ice, tar, or amber and are prevented from decaying.

– Decay means to rot or decompose

Ötzi the Iceman

Preserved in ice

Lived 5,300 years ago

Found in glacier between Austria and Italy

Megladon Shark

Body length: 100 ft

Body Weight: 80 tons

Baby elephant

Preserved in tar

Sweet Bee

Preserved in amber (a tree resin)

Extinct

Carbon Film Fossils• Forms when dead organisms are

squeezed between layers of rock• Leaves behind the organism’s carbon

imprint in the rock.

Sycamore leaf Fern

Trace Fossils• Form when a footprint, trail, or burrow of

an organism was left behind.• Provides evidence of the activities of

ancient organisms.– Size and behavior– Did it walk on two or four legs?– Did it travel alone or with others?

Megalosaurus footprint

A B

C

D

HW: p127 #1-5

Index Fossil• Lived for a short time• Found in many places• any of the six types of fossils• Found in only one rock layer• Can be used to estimate the age of rock

layers

Trilobite