What are the plot chains for the book a sound of thunder by Ray Bradbury?

1) A rich man wants to travel back in time. He gets to go on a safari hunt to kill a T-Rex since the T-Rex is going to die in a few minutes anyway. He has been warned not to stray off the anti-gravity path but he gets excited and falls off the path.

2) Scientists are afraid he may have stepped on something which would change its population and are truly angry.

3) They want to leave him in the past. They intend to force him off the Time Machine.

4) They are afraid they will loose their insurance if the company finds out. They have to make a report to the government. They force Ekels outside.

5 Ekels has to retrieve the bullets because they don't belong in the past. Leaving them could change everything.

6) They return back to 2055. Things feel different. When Ekels investigates, he finds a particular butterfly has been crushed on the bottom of his shoe.

7) Ekels realizes the killing of one small butterfly has changed history.