2. What is a fossil?
A fossil is the ___________ ______of a once _______organism.

3. What do fossils tell us?
Fossils give _____about organisms that lived long ago. They help to show that ______has occurred.
They also provide ______about how Earth’s surface has ________over ______.
Fossils help scientists _________ what ______environments may have been like.

4. HOW IS A FOSSIL FORMED? 1. ________ 2. ________ 3. ________
An animal is buried by sediment, such as volcanic ash or silt, shortly after it dies. Its bones are protected from rotting by the layer of sediment.
2. ________
More sediment layers accumulate above the animal’s remains, and minerals, such as silica (a compound of silicon and oxygen), slowly replace the calcium phosphate in the bones.
3. ________
Movement of tectonic plates, or giant rock slabs that make up Earth’s surface, lifts up the sediments and pushes the fossil closer to the surface.
4. ________
Erosion from rain, rivers, and wind wears away the remaining rock layers. Eventually, erosion or people digging for fossils will expose the preserved remains.

5. FIVE MAIN TYPES OF FOSSILS
_______
______
______ ____
______
_________ ______
______
_________
__________
________

6. PETRIFIED FOSSILS The word “________” means “turning into _______.”
PETRIFIED FOSSIL The Field Museum in Chicago displays a fossil of a Tyrannosaurus rex.
The word “________” means “turning into _______.”
Petrified fossils form when minerals ______all or part of an organism.
_______is full of dissolved minerals. It seeps through the layers of sediment to reach the ____organism. When the water ________, only the _________minerals are left behind.

7. MOLDS AND CASTS MOLD FOSSIL
This mold, or imprint, is of an extinct mollusk called an ammonite.
A mold forms when _____parts of an organism are ______in sediment, such as sand, silt, or clay.
The hard parts completely ______over time, ______behind a hollow area with the organism’s shape.
A cast forms as the _______of a mold.
Water with dissolved minerals and sediment _____the mold’s ______ spaces.
Minerals and sediment that are left in the mold make a cast.
A cast is the opposite of its mold.
CAST FOSSIL This ammonite cast was discovered in the United Kingdom.

8. CARBON FILMS
FERN FOSSIL This carbon-film fossil of a fern is more than 300 million years old.
_____living things contain an element called ______.
When an organism ____and is buried in sediment, the materials that make up the organism ____________.
Eventually, ______carbon remains.
The thin layer of carbon left behind can show an organism’s delicate parts, like leaves on a plant.

9. FANCY FOOTWORK This dinosaur footprint was found in Namibia, Africa.
TRACE FOSSILS
_____fossils show the _______ of organisms.
An animal makes a _______ when it steps in sand or mud.
Over _____the footprint is ______in layers of sediment. Then, the sediment becomes solid ______.
FANCY FOOTWORK This dinosaur footprint was found in Namibia, Africa.

10. PRESERVED REMAINS
Some organisms get preserved in or close to their original states. Here are some ways that can happen.
_______
An organism, such as a mammoth, is trapped in a tar pit and dies. The tar soaks into its bones and stops the bones from decaying.
_______
An organism, such as a woolly mammoth, dies in a very cold region. Its body is frozen in ice, which preserves the organism—even its hair!
_________
An organism, such as an insect, is trapped in a tree’s sticky resin and dies. More resin covers it, sealing the insect inside. It hardens into amber.

11. Methods Used to Estimate Geologic Time/Age of Earth

12. Superposition Principle
Superposition Principle = the principle that in a series of stratified (______) sedimentary rocks the _______stratum is the _______
_______layer is the _______

13. Which is oldest/newest?

15. For more on fossils visit:
Video: Becoming a Fossil
PBSwww.pbs.org/wgbh/evolution/library/04/3/l_043_01.html
Article: Major Fossil Find
Scholastic News Online
Online Exhibit: Fossil Halls
American Museum of Natural History
Interactive Game: Fossil Hunt
National Geographic
Scholastic Classroom Magazines. Photo Credits: PAGE 1: UTAH MUSEUM OF NATURAL HISTORY (DINOSAUR); PHOTOTAKE INC./ALAMY (ANT). PAGE 3: 5W INFORGRAPHIC (GRAPHIC). PAGE 4: Jason Lindsey/Alamy (DINOSAUR); Peter Bowater/Alamy (MOLD); David Lyons/Alamy (FERN); Hoberman Collection UK/Alamy (FOOTPRINT); John Cancalosi/Alamy (MANTIS). PAGE 5: Gary Crabbe/Alamy (DINOSAUR). PAGE 6: Peter Bowater/Alamy (MOLD); Detail Heritage/Alamy (CAST). PAGE 7: David Lyons/Alamy (FERN). PAGE 8: Hoberman Collection UK/Alamy (FOOTPRINT). PAGE 9: John Cancalosi/Alamy (MANTIS); R1/Alamy (TAR PITS); Gianni Dagli Orti/Corbis (MAMMOTH).