I have to agree.
I mean, they could go out right now and find fossil remains of a land creature even older than this one. Also, there could have been some sort of really old land animal whose bones disinigrated or something? Is that possible? I really don't know.
But the point is it can't be proven. It might be the oldest land creature that we know of, but that's about it.
I'm not exactly sure if that's the way that man_in_mudboots was thinking of when he posted, but it still goes along with the 'hard to prove' thing. Maybe more like impossible to prove.
Cya!