fossils Flashcards
what are fossils?
any preserved trace left by an organism that lived long ago
what are some examples of fossils?
bones, shells, teeth, footprints, burrows, feces, impressions
what information do body remains or imprint fossils provide?
can determine what the species was like
- transitional forms, extinct vs modern species
what information do fossils from something made by the organisms while it was living to provide us?
tell us what was in the past - food, other organisms, climate
what information do fossils give us?
- provide evidence of which organisms lived on Earth in the past
- provides examples of organisms that may now be extinct
- provide examples of transitional organisms between species
- prove that life on earth is old and has changed
what are the 7 perfect fossil conditions?
- organisms must be protected from microorganisms
- protected from scavengers
- rapid burial
- Lack of O2 in low pH soils
- no O2 left in alkaline soils
- left undisturbed for a very long time
- most fossils are only created from hard parts, soft body parts are often destroyed
why is it so hard to find fossils? (5 points)
- often destroyed by earth movements, weathering, erosion, and human activity
- fossils rarely recognized by people
- looking in the wrong place
- buried too deep, hard to access
- not everyone becomes a fossil
what is the effect of wet and acidic soils containing O2 on fossilization?
mineral in bone is dissolved and no fossilization occurs
what is the effect of wet and acidic soils containing no O2 on fossilization?
preservation of soft tissues and bones
where are fossils often found and why (2 places)?
lakes and rivers - can be buried rapidly, preventing decomposition
caves - CaCO3 can be deposited around dead organisms
where is it unusual to find fossils?
near volcanic eruptions - heat from volcanic material destroys the organism but ash falls can preserve many ancestors
what is the use of fossils?
useless until its age can be revealed
once dated - they allow for a timeline to be established
what does it mean when the soil conditions are wet and acidic WITH O2?
bone minerals dissolve
no fossil
what does it mean when the soil conditions are wet and acidic WITHOUT O2?
complete preservation of soft tissue + bones
good fossil
what does it mean when the soil conditions are alkaline (not acidic)?
bone minerals not dissovled
new minerals deposited in pores of bone
bone turns to rock (best fossil)
