element5

Whether or not there is an actual planet inbound, is besides the point when you look at the Archaeological and Geological evidence that exists. If anyone here has not read Immanuel Velikovsky's work (specifically Earth in Upheaval) then i highly suggest picking up a copy where you can find one.
There were other theories to explain the evidences gathered in these fields, and the Planet X model explains them just as well.
So in the end it appears that a massive displacement of the weaker portions of the Earth's crust can explain a myriad of problems that exists within the sciences. Now whether or not this was due to an extra-solar planet, this evidence has mainly been through ancient lore, mythology, insider sources and prophecies.