climatic conditions is one reason for extinction
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Atticus & Aunt Alexandra don't attend the pageant because they are both too tired.
Aunt Alexandra is too tired because she helped make the preparations for the pageant, and helped put it together. Of course, she is exhausted so she heads to the Finch's house and stays there.
However, we are not told of why Atticus is tired, but it is probably because he is getting old.
~Hope I helped!~
Trivial details are details that have little to no relation to the evidence you are supporting. Supporting details back up you evidence strongly. Trivial details will often be used to keep the audience interested (ex: A fun fact about the moon.)
Hope this helps!