Trampling/ intentionally flaked .

trampling Is responsible for the edgings.

When will the scientists wake up and look

Being very sarcastic

100% right baggy, A spinosourus probably pogo'd on one claw up and down on the that flint causing the flake removals, all bar one, which was when an uneducated archeologist dug it out of tertiary layers, realized it was too old to possibly be a flint tool, and chucked it over his shoulder, causing that one anomales break. That series of events is much more likely than it being a worked, human altered artifact.