[SunkenCiv]

I have my doubts that the cause of the fire can be figured out, but it does kind of figure that the natural causes of forest fires probably haven’t changed much.

[Bernard Marx]

As someone who works a lot with petrified wood and other natural silicated materials, my guess is there are many similar examples that predate this one. Fossilized woods are found all over the planet and have been collected for hundreds or even thousands of years. The probable difference with this occurrence is that the "finder" knew how to interpret the "find."

Years ago I collected many pink chalcedony root "casts" deposited by water-borne silica in "molds" left by hardened lava after it had burned away the original trees and roots. I'll bet someone with a little time on his hands (and permission from the Park Service, the EPA, the IRS, the CIA and A.G. Holder) could find many similar examples in the Yellowstone Park region alone.