8.E.6A.5 Construct explanations for why most individual organisms, as well as some entire taxonomic groups of organisms, that lived in the past were never fossilized.
Why were some fossils never fossilized?
Essential Knowledge
Because of the conditions necessary for their preservation, not all types of organisms that existed in the past have left fossils that can be retrieved. > In order for a fossil to form, the organism’s remains must not be significantly disturbed by a scavenger/decomposer or destroyed by erosion and other natural forces. Therefore, organisms or parts of organisms that make up fossils are most likely buried quickly and deeply. >Example: woolly mammoth found in ice, insects found in amber, animals found in peat bogs, mass burials from flash floods or volcanic ash falls > Soft body parts, such as skin, muscle, fat, and internal organs, deteriorate rapidly and leave no trace. Casts of such tissues are rarely found. Similarly, organisms that are soft-bodied creatures, like jellyfish, are very uncommon fossils while hard body parts (such as teeth and shells) fossilize easier. > Molds can be made of organisms. However, the organism must be buried in sediment after which its tissues dissolve and are replaced by dissolved minerals which make it a solid. Without the correct minerals this process cannot take place. > The fact that extremely few living things are preserved long enough after death to become fossils makes the large collections of fossils in the museums of the world quite remarkable. |
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