fossil evidence of change
Post on 24-Feb-2016
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Fossil Evidence Of Change
Fossil Record
• A fossil is any preserved evidence of an organism.
• Plants, animals and bacteria can form fossils
• About 99% of species that ever existed are now extinct, but only a tiny percentage are preserved as fossils
Thinking Time!!!
• Why do you think only a small percentage of organisms are preserved as fossils?
Relative Dating• Relative dating is
a method used to determine the age of rocks by comparing them with those in other layers
Where in the picture do you think a terrestrial ecosystem replaced an aquatic one?
How evolution takes place• Punctuated Equilibrium- Suggests
that species evolve very rapidly and then stay the same for a large period of time
• Gradualism- Suggests that organisms evolve through a process of slow and constant change
Speciation• Cannot accurately determine when one
species becomes another species.• Two hypotheses:
–Phyletic speciation- Suggests that abrupt mutations occur after a species has existed for a long period of time. Results in a shifting to new species.
–Divergent speciation- Suggests that a gradual accumulation of small changes that eventually turns into a new species.
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