Species that arrive first in the newly created environment or available ecosystem are called PIONEER SPECIES
<span>It sounds like he has post tramatic stress disorder from coming back from overseas. He would be recommend to take medicine and go to therapy to help him know how to get back into his regular family life. I'm sure it's extremely hard.</span>
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The answer is number two extinction happened, this was the time dinosaurs went extinct ebcause lack of sun because oh how much dirt was blown into the earth atmosphere becuase of the asteriod, third option is talking about big bang theroy so that dosnt apply!
Explanation:
