[blam]

"I'm impressed. I hadn't realized wood fragments from the construction had been recovered.:

It looks like I've picked up that date from dendrochronologist Mike Baillie and he does not connect it to tree ring data either. I suspect he has just conveniently 'grabbed' it from someone else just like I did from him.

[RightWhale]

A time-machine paradox, that's what you have. You take your time machine back in time and invent the time machine then, so you can wait a while and take the time machine back in time to invent the time machine then, etc.