Yeah personally, seeing as this will (likely) be the only pre-historical mod for Warband, I'd prefer it to be without dinosaurs, undead or stuff like that. Really go for the "primitive tribes" feel, with smaller number of troops, having to fend off beasts, etc. Prehistory has enough scary animals (like Sabertooth Tiger) without the need for dinosaurs. Haven't answered the new poll for this reason - an invasion of ultra-strong units doesn't exactly fit what I'm talking about anyway, my only answer would be "scrap it entirely".
But then again, obviously I'm not the author so I'm just giving my two cents, and I suppose I'm in the minoryt as far as the "No invasion is better" part at least.