For what it is worth here are a few ideas that may help you pin down the origins of your bone. First is it animal, fish, or bird. The weight of it may help. As you know bird bones are lighter than other bones. Does it have a spongey interior like an animal. All animals have basically the same skeleton, same jigsaw, different shaped pieces so perhaps look at any skeleton of an animal, then a bird, then a fish and see if you can find anything similar. And spare a thought for the poor palaeontologists who often have fish/land animal,reptile/bird, human/ape bones to identify. Good luck.