When I start on prehistoric I can't get access to these promotions. They are available if I start on Ancient.
Ground Weather Reports
Trench
Raider
Naval Weather Forecasts
Also other violet-coloured promotions that comes later in the game seems to be unavailable when starting on Prehistoric.
Tested on Build 9247 (30 May), as the in-game info says, however that's not correct as I've installed lots of updated SVN's after that date. I believe it's 9265 as it was installed 18 July. Ashurbanipal, Rev on, Size Matters, Start as Minor.
Next game will be on Deity, Size Matters and Rev on. Guess I'll be starting on Ancient.
Keep up the good work fellas!