Archeologists actually have their own versions of UUIDs and massive books/databases cataloguing them. Since dates are constantly subject to revision though, they don't generally use timestamps.
The very fact that scientists have had to come up with their own identifiers is testimony to the woeful inadequacy of what we're calling "universal" identifiers.
Archeologists of the year 8017 might also thank us if we were kind enough to label each piece of our data in a way that makes sense to them, including precise timestamps. Heck, they might still be using the same format if we did come up with something truly universal!
We've been using roughly the same formats for a couple hundred years already, well before computers were a thing. Problem is, that also means every government has its own slightly different databases that that no one wants to integrate.
I've rarely seen dates encoded because they don't provide much useful information. Sites themselves rarely have firm dates and individual excavations get their own (infinite) ID blocks. Each feature and artifact within that excavation is tagged with the block, alongside a bunch of metadata and paperwork. Every artifact carries with it a stack of paperwork documenting where it came from and how it was buried, making shipping the things expensive.
These collections eventually get bundled into larger site or regional packages alongside computational models and research papers, adding yet another hierarchial later.
The whole thing is very bureaucratic and a bit crusty at times, but still very scalable for a system designed before computers were even imagined. As with most things, the friction comes from trying to move things between the physical and digital worlds, not the IDs themselves (which are just guaranteed unique tags).
