fossils - mrs. buckner's science...
TRANSCRIPT
April 09, 2015
Fossils
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What are fossils? pg A-45Preserved remains or traces of living thingsThey provide evidence of how life has changed over timeThey give us clues to what past environments were like
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How do fossils form? A-47Most form when living things die and are buried in sediment. The sediment then hardens into rock- This is called sedimentary rockMost fossils form near where water was because the water helps cover it with sediment
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What part of an organism is fossilized?The soft part usually decays or is eaten by other animalsThe hard part of the animal is usually the fossil (bones, shells, teeth, seeds etc)
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Types of fossils found in rock:molds and castspetrifiedcarbon filmspreservedtrace
pg. A-48
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What is a mold?Hollow area in the sediment that leaves the shape of an organism.It forms when something gets buried in sedimentIt's like if you were to lay down in the snow, it would leave your impression in the snow
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What is a cast?This is a solid 3-d copy of an organism. It forms when sediment and minerals (mud/sand) fill in the empty space in the mold.Think-an ice cube tray is like a mold and the ice cube is like the cast
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Petrified (permineralized) fossil-This means "Turned to Stone"minerals replace all or part of the organismObject is covered by sediment then mineral rich water fills the holes where the cells wereThe minerals harden and preserve the object
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Carbonized or Carbon Film Fossils-When organisms die, almost all of the organism is decomposed
Sometimes they are pressed between mud and clay and then the carbon that was in the organism leaves a thin film of carbon behindThink-Like a stamp or imprint
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Trace fossil-These fossils are not WHOLE organisms. They show evidence of activities of organisms like footprintsThe footprint gets buried and covered in sediment until the sediment hardens and preserves it
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Trace fossils can tell us.......general size of an organismbehaviorwhere the organism livedIf the organism lived alonetwo or four legs etc.
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What about fossils not found in rocks? pg A-46These are called preserved fossils
The organism can become trapped in tar, tree sap(amber), or frozen in iceOtzi the ice man was discovered by hikers in the Alps because the glacier he had spent ~5300 years in was melting
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What are scientists called that study fossils?PaleontologistsThey collect fossils and sediment to learn all about organisms or their nicheThey use fossils to draw pictures about what organisms would have looked like or what they did
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What is the fossil record?
ALL the information that paleontologists have gathered about past lifeIt shows how organisms changed over time or evolvedOlder fossils are simpler than younger fossils
BrainPop
Mr. Parr songslide show
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