In the Eye of the Sphinx
                                                                          Part 1 of
                                                  Multiverse Journeys
The Parallel Universes bridge sounds very much like what MacGuffin used in the TV show Fringe. I like the YinYang duality scene you describe -- perhaps a reptilian look at the current donkey-elephant party system of ours?

Fred Alan Wolf Ph.D aka Dr. Quantum 
What would we expect today if in some world where dinosaurs roamed and only the smartest of them survived and evolved?
What if they returned to lead humanity to higher reality? Do we follow them? Ignore them? Do we have a choice?
Two starship crews from opposite worlds encounter the unexpected. Can these astronauts ever find their way home without the help of these dinosaurians?

Cover Description:

You will notice upon closer scrutiny that the cover depicts two constellations in the night sky: above the right shoulder of the Sphinx is Orion and above the left shoulder is Draco the Dragon.

At a later age the Great Pyramid was constructed behind the Sphinx on the Giza plateau that contained two astronomical shafts, one was aimed at Orion's Belt and the other at the Pole Star of the day called Thuban.

Sci Fi Fantasy Romance Novella about space exploration where the souls of astronauts from parallel worlds become entangled after they encounter a futuristic species of the legendary Dragon.