This just happened to me for the first time:
during the mini game, at some point direct hit dot was exactly on top of its fin, I hit it twice in a row with direct hit and twice my dart was deflected, but when I shoot just next to the fin it was ok.
Initially I thought it was some sort of bug, or maybe it’s not?
Technically that’s exactly why some dinosaurs had enormous fin at the back.
To deflect aerial attacks