Alan E. Nourse 
PRoblem 

He was just dozing off when the fat lady up the aisle let out a scream. A huge reptilian head had materialized out of nowhere and was hanging in air, peering about uncertainly. A scaly green body followed, four feet away, complete with long razor talons, heavy hind legs, and a whiplash tail with a needle at the end. For a moment the creature floated upside down, legs thrashing. Then the head and body joined, executed a horizontal pirouette, and settled gently to the floor like an eight-foot circus balloon.