Demo, about the only predator that dumps bones all in one place is the human kind. Bears, wolves and coyote pretty much eat there prey where they kill it and scatter the bones. My guess would be you found someones bone yard dump sight. Other possibilities could be they got trapped there, maybe in deep snow like the ones I found, they all froze to death, lightning strike or poisoned. Judging from time of year, with record amounts of snow in Dec. and extreme cold weather we had in Jan. froze to death is a good possibility. A group of deer having a bad day, get wet and bed down, temps drop and they never wake up.
American by birth, hunter by choice.