These don't look like bone to me. When we've had things found in coal deliveries in the past, they've turned out to be resin, which I've since been told is derived from man-made resin used to support the pit structure that somehow ends up with the coal. Those specimens didn't look too dissimilar to this, but there is a lot I can't tll about this specimen from the picture; the size, weight, or what the other surfaces not shown in the images look like. To find out more you could post some more images from different angles or email me on firstname.lastname@example.org to arrange to bring or post the specimen in to the museum for a better look.
The thing about that is they were not found in the coal. What the photos don't show you is that the 2 pieces are incased in coal. I have tried numerous times to upload the photos with no success. But i will try to e-mail them to you.