The Flying, Bouncing Amazing Parietal Bone? 
Chad Zimmerman © Copyright 2003. All Rights Reserved.
 
Researchers Paul Seaton and Steve Barber clued me in on this one. So, I took another look. You can be the judge. It certainly appears to be a piece of bone from the front right of Kennedy's head. The problem is that Abraham Zapruder brought a good portion of the limo out of the frame when filming. So, during several frames, nothing is seen. However, when the camera was lowered a bit, we see a very awkward 'thing'. It is the correct color and is markedly different from the red roses. A closer look shows the image of something peach colored (bloodied bone?) bouncing on the back of John Connally's seat and then falling out of view. You be the judge.