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Chapter 14 The History of Life Section 1: Fossil Evidence of Change Section 2: The Origin of Life Main Idea: Fossils provide evidence of the change in organisms. Click on a lesson name to select. 1. fossil-any preserved evidence of an organism 2. sedimentary rock- all fossils are formed in this type of rock 3. paleontologist – scientist who studies fossils 4. relative dating – method used to determine the age of a rock by comparing it to other rocks in the surrounding layers 5. geological time scale- model that expresses the major geological and biological events in Earth’s history Click on a lesson name to select. 6. Plate tectonics- describes the movements of several large plates that make up the surface of the Earth. Click on a lesson name to select. Chapter 14 The History of Life 14.1 Fossil Evidence of Change Clues in Rocks 1. A fossil is any preserved evidence of an organism. 2. The fossil record is like a book with many missing pages. Perhaps more than 99 percent of the species that have ever lived are now extinct, but only a tiny percentage of these organisms are preserved as fossils. 3. Most organisms decompose before they have a chance to become fossilized. Chapter 14 The History of Life 14.1 Fossil Evidence of Change 4. Only those organisms buried rapidly in sediment are readily preserved. 5. This occurs more frequently with organisms living in water because the sediment in aquatic environments is constantly settling, covering, and preserving remains of organisms. 6. Nearly all fossils are formed in sedimentary rock. 7. Sedimentary rock is formed from accumulated sediments settling over time. These sediments eventually harden and form rock. 8. Fossils formed by: • Organism dies and is buried in sediment • Minerals may replace the organic matter or fill the empty pore spaces of the organism. • In other cases, the organism decays, leaving behind an impression of his body. • Sediments eventually harden into rock. The Fossilization Process • Sediments from upstream rapidly cover the body, slowing its decomposition. Minerals from the sediments seep into the body. • Over time, additional layers of sediment compress the sediments around the body, forming rock. Minerals eventually replace all the body’s bone material. • A Protoceratops drinking at a river falls into the water and drowns (dies). • Earth movements or erosion may expose the fossil millions of years after it formed. Chapter 14 The History of Life Fossil Formation 9. A paleontologist is a scientist who studies fossils. From fossil evidence, paleontologists infer the diet of an organism and the environment in which it lived. 10. To determine the age of a fossil, scientist’s use two methods relative dating and radiometric dating. 11. Relative dating is a method used to determine the age of rocks by comparing them with those in other layers. 12. Relative dating is based on the law of superposition, which states that younger layers of rock are deposited on top of older layers. 13. Radiometric dating uses the decay of radioactive isotopes to measure the age of the rock. 14. The geologic time scale is a model that expresses the major geological and biological events in Earth’s history. It is made of epochs, eras and periods. The geologic time scale • The divisions in the geologic time scale are distinguished by the organisms that lived during that time interval. 15. Geology is the scientific study of the origin, history, and structure of the earth Theory of continental drift - the world was made up of a single continent through most of geologic and eventually separated and drifted apart, forming into the seven continents we have today. 16. Plate tectonics describes the movement of several large plates that make up the surface of Earth. Chapter 14 The History of Life 17. Early ideas on the origin of life– spontaneous generation is the idea that life arises from nonlife. Theory of biogenesis- only living organisms can produce other living organisms. 18. Modern ideas of the origin of life— primordial soup theory in 1920’s proposed that the early atmosphere of earth had a mix of gases and organic molecules with energy from the sun or lightning could have started life. 19. Some scientists theorized that life could have come from organic reactions in deep sea vents in the ocean. 20. Cellular evolution—first cells were prokaryotes. Scientists believe that photosynthetic prokaryotes like cyanobacteria evolved from the first bacteria. 21. Eukaryotic cells appeared in fossil record much later. Scientist use the endosymbiont theory to explain how more complex cells developed. This theory states that the mitochondria and chloroplasts of a eukaryotic cell were once bacteria that entered another bacteria as either food or a parasite. Chapter 14 The History of Life Chapter Resource Menu Chapter Diagnostic Questions Formative Test Questions Chapter Assessment Questions Standardized Test Practice biologygmh.com Glencoe Biology Transparencies Image Bank Vocabulary Animation Click on a hyperlink to view the corresponding lesson. Chapter 14 The History of Life 14.1 Formative Questions In which type of rock do paleontologists search for fossils? A. igneous B. metamorphic C. sedimentary D. volcanic Chapter 14 The History of Life 14.1 Formative Questions Which dating method determines the age of rocks by comparing them to rocks in other layers? A. absolute dating B. geological dating C. relative dating D. sedimentary dating Chapter 14 The History of Life Glencoe Biology Transparencies Chapter 14 The History of Life Image Bank Chapter 14 The History of Life Vocabulary Section 1 fossil era paleontologist period relative dating Cambrian explosion law of superposition K-T boundary radiometric dating plate tectonics half-life geologic time scale Chapter 14 The History of Life Vocabulary Section 2 spontaneous generation theory of biogenesis endosymbiont theory Chapter 14 The History of Life Animation Visualizing Geologic Time Continental Drift Miller-Urey Experiment