I can't confirm, but I have the suspicion that 'neck' joints (I don't know what the proper term is in English, unfortunately) or bridle joints (maybe that's correct? In German it's called Sattel or Hals, saddle or neck, depending on whose writing) have their origins in round log framing, and they make a great deal of sense in this context.

Your post has a fork on its end, that fits over a nut cut into the cross timber. This joint is common in Norway, in framing systems that presumably evolved from Stavverk or stave contruction. I don't really know what types of joints are used in the Stave churches however...

Then I also know of some round work from switzerland, mostly from Italian areas or poorer mountain regions. Connections in horizontal member are very often accomplished with the exact same passed notch joint used in log construction.

Hopefully this is useful, it's just a few things i have observed in traditional practices.