That would be me. Is it just me looking for bone or just me finding it ?
Like Will said, you could just be reaping the rewards of looking, and you could be the only one. I've never bothered trying to look, mainly because I followed the "official" line of the ground was too acidic to preserve bone, although I also know that river deposits can be one of the more likely places to find them.
Never underestimate the power of having your eye in. My other half can spot jet just like that, yet I never seem to see it.