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35 Cards in this Set
- Front
- Back
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Paleontologist
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scientist who studies fossils
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fossil
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preserved evidence of an organism
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Trace fossils
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indirect evidence of an organism
ex. footprints, burrows, feces |
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Molds and Casts
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impression of an organism
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Replacement
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original organism is replaced with mineral crystals
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Pretrified
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Empty pore spaces are filled by minerals
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Amber
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Preserved hardened tree sap
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Original Material
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Mummification or freezing
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where do fossils form
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formed in sedimantary rocks
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Relative dating
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determine the age of rocks by comparing thiem to those in layers around it
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Law of superposition
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younger layers are deposited on top of older layers
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Radiometric Dating
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uses the decay of radioactive isotopes to measure the age of rocks
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Half life
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amount of time it takes for half of the original isotope to decay
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Geologic Time Scale
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model that expresses the major geological and biological events in earths history, divided into precambrian and phanerozoic
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How long ago did earth form?
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4.6 billion years
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Whats an Era?
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Paleozoic, Mesezoic, and Cenozoic times
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Whats a period?
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smaller division of time
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Precambrian
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90% of earths history, goes from the beginning of Earths formation until 542 million years ago
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Stromatolites
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bacteria that produced oxygen and released it into the atmosphere, because of this oxygen became plentiful & allowed new organisms
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Paleozoic
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Cambrian explosion, most major animal groups diversified, marine species moved to the land. There was a mass extinction & 90% organisms disappeared
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Mesozoic
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Time of Dinosaurs, birds, and flowering plants. eteorite struck earth possible causing another mass etinction
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Plate tectonics
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movement of plates that make up earths surface
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Cenozoic
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Time of the mammals, humans and other mammals roamed earth
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What are the types of fossils
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Trace, molds & casts, replacement, petrified, amber, original material
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What are the types of historic periods?
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Precambrian, Paleozoic, Mesozoic, Cenozoic
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Spontaneous generation
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Idea that life arises from nonlife
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Theory of biogenesis
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States that only living organisms can produce other living organisms
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Deep sea vents
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hydro thermal vents produced sulfer, and other elements that supported a food chain for early organisms
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Meteorites
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some believe this could be the source of life
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Clay
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Some believe clay was used by amino acids to hold chains of AA's together
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Genetic code
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RNA was lifes first coding system, and can also behave like enzymes
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Archea
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Prokaryotic cells that are restricted to volcanic & other x-treme environments, get their nutriens from inorganic molecules like sulfer..do not need to produce oxygen
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Oxygen was...
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not present in atmosphere until after 1.8 billion years ago
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Cyanobacteria
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photosynthesizing prokaryotes , formed ozone later, made conditions on earth habitable
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Endosymbiont Theory
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prokaryotes lived inside eukaryotic cells and performed cell functions just as mitochondria/ chloroplast would
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