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        Fossils are clues to the type of organisms that roamed or swam on the
        Earth. However, fossils provide us with more information. They can tell
        us about the paleoecology or the relationship between organisms
        and their environments, if we can decipher the clues. Paleontologists
        want to determine the physical, chemical and biological interactions
        that can limit the distribution and abundance of different species. They
        are always searching as to why an organism may have gone extinct. Today
        we know that when an organism’s environment changes or when other
        organisms invade another habit, extinction can occur.
         Fossils also indicate that organisms have changed through time. As we
        learn which fossils lived in what time, we can retrace how the
        environment looked and assign periods of time to each fossil group.
        Horseshoe crabs for instance have not changed since they were first
        recorded in the fossil record. Foraminifera a protist, changes
        shapes through time and help geologist age date rocks. 
         
          
        Horseshoe crab
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        Foraminifera change 
        through time
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