I have this vision of dinosaur astronauts, clinging to the rock that has been ejected into space, on their way to Mars to establish a new life there. I have always found the pan-spermia theories interesting. It still doesn't answer the 'where first' question but it allows for many places to share similar lifeforms without requiring a recreation of an improbable event in all of them. Of course it would be really weird…
So kind of like the stargate SG1 plot line where instead of the ancients spreading life across the universe using stargates you have meteros doing the work
(sorry I couldn't resist)