Fossil Record PDF

Warm-Up ? The Fossil Record Lesson Question How does the fossil record support the theory of evolution? Lesson Goals Identify how a fossil forms. W 2K Explain how scientists determine the age of a fossil. Examine how the fossil record indicates a long history of changing life forms. Words to Know Fi...

Warm-Up ? The Fossil Record Lesson Question How does the fossil record support the theory of evolution? Lesson Goals Identify how a fossil forms. W 2K Explain how scientists determine the age of a fossil. Examine how the fossil record indicates a long history of changing life forms. Words to Know Fill in this table as you work through the lesson. You may also use the glossary to help you. radioactive element an element that releases energy as it breaks down into a stable element absolute dating the process of determining the actual age of an event or fossil in years fossil record sediment cast relative dating © Edgenuity, Inc. the historical sequence of fossils found in Earth’s rock layers small pieces of rock a fossil formed when a mold fills with minerals and sediment the process of putting events or fossils in order from oldest to youngest without using actual dates trace fossil a fossil that shows the activity of ancient organisms mold a fossil formed when the hard parts of an organism dissolve, leaving behind an empty space descend to come from ancestor a single organism from which other organisms have descended 1 Warm-Up The Fossil Record Fossils A fossil is the preserved remains or evidence of an organism. Fossils can be used to: document changes in organisms over time. identify extinct © Edgenuity, Inc. species. 2 Instruction The Fossil Record Slide 2 Fossil Formation When an organism dies: the remains fall to the bottom of an ocean or lake. the soft portions of the organisms, like the skin and internal organs, typically break down. the Layers of 4 hard sediment portions, like bones or shells, are preserved. cover the organism and eventually become rock. Types of Fossils Mold : : The hard parts of an organism dissolve. The mold fills with minerals and sediment. Empty space in the shape of the organism is left behind. A solid copy of the organism’s shape is left behind. Minerals Organisms can replace the remains of an organism and change them into rock. © Edgenuity, Inc. Cast 3 can leave imprints on sediment, which later hardens into rock. Instruction The Fossil Record Slide 4 Types of Fossils Trace fossils show the Fossils can also be preserved in substances activity of ancient organisms. 7 other than sediment. Relative Dating Relative dating is the process of putting events or fossils in oldest to youngest without using actual The location dates order from. of the fossils within the rock layers indicates which fossils are older than others. The lower the rock layer, the older the fossil. Circle the younger organisms in the diagram. The fossils toward the © Edgenuity, Inc. bottom are older than the fossils toward the 4 top. Instruction The Fossil Record Slide 9 Absolute Dating Absolute dating is the process of determining the actual age of an event or fossil in years. Rocks contain radioactive elements that release energy as they break down into stable elements. Scientists know how long this process takes for different elements. Measuring the amount of radioactive element and can indicate the age of a fossil. stable Different elements are used for absolute dating. Carbon/nitrogen Potassium/argon Uranium/lead © Edgenuity, Inc. Radioactive Element Stable Element Age of Fossils (years) Carbon Nitrogen 100–50,000 Potassium Argon 100,000–4.5 billion Uranium Lead 10 million–4.5 billion 5 element Instruction The Fossil Record Slide 12 Fossils and Evolution The fossil record provides information on the history of life on Earth. By knowing the age and location of a fossil, scientists can show: how organisms have changed. which organisms lived during the same time period. which organisms have a common from which other organisms have ancestor , a single species descended. The Fossil Record and the Geologic Time Scale Circle the organisms that occurred in the last 600 million years of Earth. It is important to note that the fossil record is not organisms cannot be preserved 6. Some , mainly because they have soft bodies that decayed before they could be preserved. © Edgenuity, Inc. complete Instruction The Fossil Record Slide 14 Fossil Evidence for Evolution Sponges Fish Amphibians Reptiles Mammals Fossil Evidence for Evolution The fossil record shows evidence of how the reptile time. This fossil has no holes behind the eye. © Edgenuity, Inc. This fossil has one hole behind the eye. 7 skull changed over This fossil has two holes behind the eye. Summary ? The Fossil Record Lesson Question How does the fossil record support the theory of evolution? Answer (Sample answer) The fossil record supports the theory of evolution as it shows the changes in the organisms over time. Rocks and fossils can also be dated using relative or absolute dating so scientists can put the fossils in the correct order. Slide 2 Review: Key Concepts Fossil Formation Types of Fossils When an organism dies, the remains fall to the bottom of an ocean Layers of Molds or a lake. sediment cover Casts Mineral replacement of an organism’s remains the organism and eventually become rock. Imprints Trace fossils Organisms preserved in tar, ice, or amber © Edgenuity, Inc. 8 Summary The Fossil Record Slide 2 Review: Key Concepts The age of a fossil can be determined using: relative absolute dating, or the location of the fossil in relation to others. dating, or measuring the amount of radioactive element and stable element in a rock. Review: Key Concepts By knowing the age and location of a fossil, scientists can show: how organisms have changed. which organisms lived during the same time period. which organisms have a common which organisms have become © Edgenuity, Inc. 9 ancestor extinct.. Summary The Fossil Record Use this space to write any questions or thoughts about this lesson. © Edgenuity, Inc. 10