I did it my way, I think.

I can't figure out how anything can survive in 3000 degrees F. plus for zillions of years. I don't think there is life on the sun for instance. Then how did we get here under those conditions? Here is my opinion.
 When the earth was molten it was rather dry and dead. I mean grave yard dead and Death Valley dry and magma hot.
Comets are ice balls this is a fact. Giant ice balls must have come in contact with the still hot but kinda cooling down earth a while back. It's a fact that some organisms can be frozen and then thawed out and come back to life.  The ice balls that fell to earth must have contained such organisms and after enough ice fell and shock cooled areas of the earth enough that puddles formed, life must have thawed out and thought "damn". So the Star Trek Next Generation episode where "Q" takes Picard to watch life begin on earth is false. I thought Q would have known the truth being as smart as he is.
 It's also a fact that ice traps air. With the amount of water on the earth that would explain our atmosphere. It's possible that large ice balls fell to earth given the depth of some parts of the oceans, many miles in a few spots. So when the dinosaurs saw the comet coming down they probably thought "oh well another ice ball", WRONG O!!!!
  So in conclusion some monstrously huge water world planet came apart, the big bang maybe, and all it's water froze into huge ice balls preserving organisms, and eventually found it's was to earth and here we are. I'm glad the other world had balsa trees.