Inside the Restless Earth Chapter 3 Section 4 Fossils Inside the Restless Earth Chapter 3 Section 4

What are fossils? A fossil of a preserved remains of once living organisms. Fossils give clues about organisms that lived long ago. They help to show that evolution has occurred. They also provide evidence about how Earth’s surface has changed over time. Fossils help scientists understand what past environments may have been like.

Q:What fossils are in rocks? A:Fossils are the remains of organisms that are preserved. Hard parts (bones, shells) get buried in sediment Soft parts of the organism decays

Q:What is petrifaction? A:Petrifaction is the process in which minerals replace an organisms tissues. Replacement-organism’s tissues are completely replaced by minerals Permineralization-minerals fill spaces

What is petrifaction?

Q: How do fossils get preserved in amber? A: An organism gets stuck in soft, sticky tree sap and then gets covered in more sap. The sap then hardens. Hardened tree sap is called amber. Insects, frogs, lizards have been found in amber. Organism land on sap Gets stuck Gets covered in more sap Sap hardens

Q: How do fossils get preserved in amber?

Q: What are frozen fossils? A: Frozen fossils are the remains of organisms that have been preserved in ice. Usually during the ice age. Cold temperatures slow down decay Organism falls-freezes Makes good fossils

Q: What are frozen fossils?

Q: How do fossils end up in tar/asphalt? A: Fossils are in asphalt because organisms got stuck in the thick, sticky substance. La Brea asphalt/tar pits in California are over 38,000 years old. Scientists learned a lot about the past environment in California.

Q: How do fossils end up in tar/asphalt? La Brea Tar Pits

Q:What are trace fossils? A: These form when animal footprints, burrow, or coprolite are filled in with sediment and are preserved in rock. Tell how big the animal was How fast the animal moved Borrows that animals made are an example Coprolite is preserved animal dung

What are trace fossils?

What are trace fossils?

Q: What are casts and molds? A: A mold is a cavity (hole-space) where a plant or animal was buried. A: A cast is an object created when sediment fills a mold and becomes a rock. Mold-impression in ground or rock Cast—sediment filled mold

What are molds? Internal and External mold

What are casts?

Q: What information do scientists obtain from the fossil record. A: The fossil record provides evidence about the past. We know more about organisms with hard parts (ex. Shells) The fossil record is incomplete. Many organisms never become fossils Many fossil haven’t been discovered

Q:How does the environment affect fossils? A: Fossil records provide evidence of changes in the environment. Marine fossils were found on a mountain top. This suggests that the mountain top was once the ocean floor. Fossils show evidence of climate

Q: How do fossils show the history of the way organisms changed? A: Fossils show how organisms have changed over time. Scientists study the relationship between fossils. Fossils in different rock layers suggest that fossils can be younger or older depending on the layer they are found in. Only a fraction of organisms in history have been fossilized = incomplete fossil record

Q: How are fossils used to date rocks? A: Fossils are used to date rocks because certain types of fossils can be used to estimate the absolute (exact) age of the sedimentary rock they are found in. An index fossil is a fossil used to estimate the absolute age of rock layers. An index fossil lived for a short period of time. Ammonites and Trilobites (index fossils)

Q: What is mummification? A:Mummification is the preservation of a body, either animal or human. Some mummies are preserved wet, some are frozen, and some are dried. It can be a natural process or it may be deliberately achieved. Eliminate moisture