Veterinarian Bob George sliced open the dead shark and saw the outline of a fish. It was a perfectly formed, 10-inch-long shark pup that was almost ready to be born.He had been examining the shark, Tidbit, to figure out why she reacted badly to routine sedatives during a physical and died, hours after biting an aquarium curator on the shin.But sharks only breed with sharks of the same species, and there were no male blacktip reef sharks at the Virginia Aquarium & Marine Science Center in Virginia Beach.Could Tidbit have defied nature, resulting in the first known shark hybrid?The other possibility