The game has recently undergone a name change and with it came a new directory for the game's save files but since this is using Steam Auto-Cloud you need to manually copy the previous save files into the new directory in order to restore them to your Steam Auto-Cloud for the game.
With the Primeval game closed do the following:
Go to the following folder on your windows drive:
C:/Users/Username/AppData/LocalLow/Exhibyte/IslesOfPangaea
Copy all of the files within that folder.
Then paste them into the Primeval folder (you may need to create it)
C:/Users/Username/AppData/LocalLow/Exhibyte/Primeval
Now when you start the game your save files will be available once again.