The date changes things.
this would be above the k-t line and to this YEC dude it means a post flood event.
So it could be from events lasting over a few years and so scavenging could happen.
Still water actions can do anything where segregated flow events are going on.
What happened here was either volcanic coverings or the movement of sediment over the land that covered the creatures to a small depth. then later more movement of sediment would of followed and covered the rest.
indeed the fossils are likely not to have been turned to stone as this happens from great pressure upon deposition like in the great flood.
these later actions are not as powerful and so bones not so encased.
I see these events as happening at most over a few years but probably less then ten years and this about a few centuries after the flood.
So about 2100 to 1900 BC.