ewwwwww!!

I wasn't very nice to Corki

     We were out in the back yard and I saw her chewing something.  So I went over and took a bone out of her mouth.
     That was suspicious because I had a bit of steak for lunch.  I threw the bone in the trash.
     So, either Corki took it out of the trash and carried it outside, or I missed the bag.
     Or so I thought.
     I told Jackie that Corki had the bone, showed it to her, and tossed it out.
     I went back outside, and there is old Corki, chewing away.
     I went over and took another piece of bone out of her mouth.  I tossed that away.
     When I got back, holy crap, she was chewing on another piece of bone!
     I pried it out of her mouth and it was a section of vertebrae!!  About two inches long and somewhere between a quarter and half inch in diameter.  Where she found that, and what it was from, baffled me.
     So I tossed that out, came back and guess what?
     She has another chunk of bone in her mouth!  This was a smallish, round bone and she had it way back in her mouth.  I tried to get it out, but she would not give it up.  I didn't want to push it for fear it would go down her throat.
     So there we are, sitting on the ground, me holding her mouth open waiting for her to drop the bone, she waiting for me to take my fingers out of her mouth.
     I won.
     I have no idea where the bones came from.  I have no idea what kind of animal it was.
     I kept an eye on her, but she did not seem to find any other bones.  I also searched the grass where she was sitting, but couldn't find a thing.
     We have let her out back every morning, and I don't know if she had found bones before.  It never seemed like she was chewing anything....so I am confused.
     Animal skeletons don't just drop out of the sky, do they?
     I  think it's a mystery I will never solve.