Extinction

 No creature ever goes extinct.  That is an illusion of a three dimensional view of time. Viewed in the fourth dimension every species would look like a hydra with a million heads.  The DNA base four code never loses information it only accumulates information. In fact this is its true function. The code for every creature that ever lived is still to be found in DNA.  This is why by manipulating genetic switches we can create chickens with scaley tales and reptilian teeth. This is why rice DNA has far more information than human DNA.  It has accumulated this information over eons.  Life is like a boiling stew of potential and each bubble that rises and then pops is a species.  They are all made of the same substance, they form, rise, exist for awhile then sink back into the formless yet they remain in substance.  In this way life responds to changes in environment.  Life existed when the atmosphere of this planet would have been instantly toxic to human beings.  Life created the oxygen and the seas. Life has terraformed this planet to suit life.  The Earth was once a barren rock.  Life made it the blue green haven it is today.