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Paleontology Test Review. How do scientists date material older than 50,000 years? Younger than 50,000 years?. Older than 50,000 years – uranium-lead method Younger than 50,000 years – carbon-14. What type of rock are most fossils found in?. sedimentary.
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How do scientists date material older than 50,000 years? Younger than 50,000 years? • Older than 50,000 years – uranium-lead method • Younger than 50,000 years – carbon-14
What type of rock are most fossils found in? • sedimentary
What can fossils tell us about an area’s history? • What the land looked like? • What type of climate? • What type of organisms lived there?
What does the law of superposition state? • Oldest rock is below younger rock
What is petrifaction? • When minerals replace soft tissues of dead organisms and form a rock
List the geologic era’s in order from earliest to most recent. • Precambrian, Paleozoic, Mesozoic, and Cenozoic
How old is the Earth’s history date back to? • 4.6 Billion years old
What is the difference between and index and trace fossil? Give examples of each. • Index fossil – fossil from one geologic time period that is used to date rock • Trace fossil – fossil that shows activity of an organism. Ex: footprints, nest, trail
What is relative age and how do you find the relative age of an object? • Relative age – age compared to other objects using the Law of Superposition
What is absolute age and how do you find the absolute age of an object? • Absolute age – method of measuring the age of an event or object in years using radioactive decay
What can scientist learn from studying fossil? • How life has changed over time
What is uniformitarianism? What is original horizontality? • Uniformitarianism – Principle that states geologic processes that occurred in the past occur today and happen gradually • Original horizontality – sediments deposit in horizontal layers
How is the geologic time scale broken down? • Era - Periods – Epoch (Manageable parts)
What type of conditions slow down an organism’s decay? • Cold and/or dry
What do scientists think caused the extinction of dinosaurs? • Climate change due to asteroid impact
Are fossil records complete or incomplete? Why? • Incomplete because most organisms do not fossilize
What is a catastrophic event? Give examples. • Big event that happens fast. Examples: Earthquakes, landslides, mudslides, floods
What is the difference between a cast and a mold? • Cast – fossil formed when sediments fill cavity left by a decomposed organism • Mold – mark or cavity made in sedimentary rock by a shell or other body part
How are fossils formed? • Organism dies • Buried fast • Mineral replaces tissues • Mineral harden and form a rock of that organism
What do fossil records tell us about organisms? • What the organism ate? • How they lived? • How organism changed over time?
Add to your study guide • Organisms have become more complex over time