I like this discussion.

There were a previous mentions, that they live on smaller planet with a dimmer star. However a short stature may suggest a larger planet than our own, because a taller animal will hit the ground harder. Shorter is better with more gravity. With larger planet, means more atmosphere, which may indicate a dimmer surface, hence larger more sensitive eyes. Consider also the legendary saucer shape of the ship. Like the bank of a curve on a highway or race track, rotating the ship while visiting Earth will induce a greater G-force, the conic or parabolic shape of the craft would feel perfectly up and down. Are there any accounts as to diameter, approximate angle, and rotational speed that we can cross reference to come up with a common constant for their gravity?

I found the four digits thing interesting. My dog has four digits on its paws. The fifth one is useless 1/4 the way up the leg. This may be a timeline clue or an indicator of their evolutionary split.

I do however lean my speculations toward a common ancestor. A little naive to think we are the first intelligent life on this planet. I find it hard to believe that a vertebrate class animal evolved off of Earth. Personally, I think that the dexterity of tentacles would be cool, like Doc Oc, but without the tentacles taking over my mind. I don't think there has to be a cookie cutter form for the evolution of space traveling life off of this planet.

One thing that I'd like to throw in, at the risk of stretching this topic, is that it would take a few weeks short of a year on a ship to achieve "near light speed" a constant acceleration of 1 G. At that speed, a day passes on a ship but a year passes in universe around. Maybe these guys aren't that ancient, but are just frequent (space)flyers, that have observed us actually evolve. Their life expectancy does not necessarily need to be as short as ours either

Finally, I want to close with the mother of all... Roswell. Well actually, it is not the mother. I have read another forum at ATS (which I am too tired to find right now), that details numerous UFO sitings that are documented in newspapers from around the globe before Roswell. These seemed to have stopped abruptly with the Roswell event.

Great thread, and if you've read this far, thanks for reading my post.