[EdwardDiego]

Actually was thinking on this, I suspect you're right that this is another potential stressor that should be considered.

Not so much diseases from animals brought by humans, but rather diseases/parasites from related animals who just mosied onto and sometimes over Beringia of their own accord.

E.g., wooly mammoths on the Eurasian steppes and American mastodons spent a lot of time developing in isolation, they could've had their own diseases they'd evolved to resist, then Beringia arises from the seas, and 100 years later, a mastodon catches the Mammmoth-flu or something.

From what little I understand, some of the N. American megafauna have been shown to have limited genetic diversity due to small founder populations, which we know can increase the vulnerability of a population to a novel disease.

I'm wondering how you'd be able to prove or disprove this though, maybe coprolites? Googling this briefly turned up this amazing website with the even more amazing tagline "#1 for fossilized #2"...

https://poozeum.com/

Brb doing a PhD in paleoepizootiology.