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Fossils What is a fossil… fos·sil ˈfäsəl/ noun 1. the remains or impression of a prehistoric organism preserved in petrified form or as a mold or cast in rock. Types of fossils… There are two main types of fossils; body and trace. Body: Trace: Include the remains of organisms that were once living. Signs that organisms were present (ie. footprints etc.) Fossil origins… Fossils can come from plants or animals. Invertebrate Vertebrate Vertebrate fossils come from animals who had bones. Invertebrate fossils come from plants or animals that didn’t have bones. Modes of preservation… The two types of preservation are preservation w/ alteration and preservation w/o alteration. W/O alteration W/ alteration Freezing Mummification Unaltered shell remains Permineralization Other types of preservation: Molds (shell material is progressively removed by leaching and it leaves a void in the rock in the shape of the original organism) Casts (void between internal and external mold is filled with mineral matter, creating a replica of the original organism) (molecular exchange of substances that were once part of an organism w/ minerals carried in by percolating water solutions) (chemical precipitating into pore space) Replacement Carbonization (carbonization occurs when soft tissues are preserved as films of carbon Radiometric and Relative Dating… Relative dating Sedimentary Rock Layers of sediment are arranged in a sequence in order of when they happened (youngestoldest) Fossils are given ages based on the relative age of the layer of sediment it is found in Radiometric dating Traces of radiometric elements are present in certain types of rock These elements can be analyzed to determine the age of these rocks and also the fossils in them Sedimentary Rocks… Fossils are mostly found in sedimentary rock sedimentary rock noun 1.Rock that has formed through the deposition and solidification of sediment, especially sediment transported by water (rivers, lakes, and oceans), ice (glaciers), and wind. Sedimentary rocks are often deposited in layers, and frequently contain fossils. Some facts about sedimentary rocks: Sedimentary rocks are formed by sediment that is deposited over time, usually as layers at the bottom of lakes and oceans. This sediment can include minerals, small pieces of plants and other organic matter. The sediment is compressed over a long period of time before consolidating into solid layers of rock. Sedimentary rocks forms layers called strata which can often be seen in exposed cliffs. Sedimentary rocks cover the majority of the Earth's rocky surface but only make up a small percentage of the Earth’s crust compared to metamorphic and igneous types of rocks. Examples of sedimentary rocks include limestone, sandstone, mudstone, greywacke, chalk, coal, claystone and flint. Limestone forms the metamorphic rock marble when subjected to extreme heat and pressure over time (metamorphism). Sandstone forms the metamorphic rock quartzite. Mudstone forms the metamorphic rock slate. Chalk is a soft, white form of limestone. Flint is a hard, sedimentary form of the mineral quartz. http://www.sciencekids.co.nz/sciencefacts/earth/sedimentaryrocks.html Fossil Organisms timeline… Paleontology… Paleontology is the study of fossils Paleontologists use techniques from a variety of different areas such as biochemistry, mathematics and engineering. Paleontologists have been able to discover a lot about the evolution of the earth, they have discovered things as far back in history as 3,800 million years. There are sub-divisions of paleontology, some which focus on fossil organisms and others that focus on the environment. Fossil Fuels… Fossil fuels are fuels made from naturally decomposed organisms which can be millions of years old Contain large percentages of carbon. Fossil fuels are a nonrenewable source because the organisms that create the fuels can take millions of years to form. • Coal • Petroleum • Natural gas “Fossil fuels are of great importance because they can be burned (oxidized to carbon dioxide and water), producing significant amounts of energy per unit weight.” http://en.wikipedia.org/wiki/Fossil_fuel Pictures… Body fossil Trace fossil Invertebrate fossil Vertebrate fossil Fossil mold Fossil cast Bibliography • • • • • http://www.fossilsforkids.com/ http://imnh.isu.edu/digitalatlas/geo/basics/fossil.htm http://www.wacona.com/promote/fossils/facts.htm http://www.bbc.co.uk/nature/fossils http://www.mnh.si.edu/exhibits/backyarddinosaurs/questions-answers.cfm?know=a24 • http://en.wikipedia.org/wiki/Paleontology • http://dictionary.reference.com/browse/sedimentary+rock • http://en.wikipedia.org/wiki/Fossil_fuel