Engineers dead bodies that had chest burster holes, a question

Before the storm come, they see images of the engineer running from some sort of outbreak in the hologram. Then they find engineers dead bodies that had chest burster holes. That means the aliens have pop out of the engineer chest, then where are all those aliens that pop out go then? Where it all goes? It certainly was not there anymore, all we see were just those some sort of worms like specie that attack the two crew. And another question, did anyone see the alternate blue-ray ending? I just see and it was the same as the theater-ending, not much difference. Perhaps I watch the wrong one? Thank you for answer my questions, and sorry for my terrible English. edit: add another question: I was thinking the chest buster that burst out of those engineers bodies are (adult Deacon Alien) like the one that burst out of the engineer in the Ending of the movie. If so, then I assume there be many of those "adult Deacon Alien" running around, I just curious where they all went, since all we see is dead bodies engineers. So the one that pop out of those engineer chest are smaller ones? and not those adult aliens Deacon type?