No, although Aliens could well have been responsible for the extinction of the dinosaurs. Cro Magnon did not arrive on the Earth until 60, 000, 000 years after the dinosaurs were wiped out. The time scale is too large. Also for there to be two planets in the same galaxy at the same time with intelligent life is hard to accept.
Cro-Magnon man only arrived around 65, 000 years ago, coinciding with the warming of the last ice age.
If it IS the case (remember, I only wrote a story) that we (cro-magnon) came from Mars then it must have happened around this time scale. The unexplained shift from neanderthal to cro-magnon happened around 65, 000 years ago.
I actually read once that cro-magnon were supposed to be the bastards of every tribe (neanderthals) that were sent away, exiled to colder climates. This was a scientific theory, and quite laughable as it implied that we all somehow banded together after evolving completely differently and overthrew the Neanderthals. This is not true, and it is believed now that Cro-magnon and Neanderthals could and did breed.
My story encompassed this theory which was just a mish mash of things I had read. Like I said, it was just a story, I'm not a fanatic or anything.