Prehistoric Floors Formula

[LyraParry12]

I understand that the overall chance for a dino floor after floor 6 is about 2.2% and they're predetermined at the start of the day, but does anyone know how this actually breaks down in the game code? I assume there's a set chance for a given floor number to be "set" as prehistoric, and then a separate calculation is made to determine what layout that floor is when you actually go there - with the effect of sometimes overriding the prehistoric designation bc some layouts can't be dino floors - but does anyone know the actual numbers? I'm curious

 

[Quvapu]

After level 6, the chance of a prehistoric floor is about 2.2% and is set at the beginning of the day. The game probably first determines whether the floor will be prehistoric, and then, when generating a specific layout, it can cancel this status if the selected template is incompatible with dinosaurs.