Yeah, that would change the game. (The players simply accepted the presence of raptors and went on with the game, just hoping not to get eviscerated.)
My slow NaNoWriMo progress included 774 words last night, reaching 6,267 total. I realized something was happening but didn't know why, so I didn't know what to write...then realized that figuring out why that paticular something was happening could be a mystery I could solve later. That got me unblocked!