Piqued by the title and the frisky cover picture of Cam's fifth-grade class ogling a coelophysis skeleton, newly-independent readers will follow the group through their museum tour and into the ever-popular dinosaur room--where Cain's photographic memory tells her that three bones are missing from the coelophysis' tail. Janet Tyler, the museum guide, has no patience for Cain's disclosure, but later Cam and her friend Eric follow a suspicious milk truck from the museum to a small house. . . where, by golly, the milkman and his wife Janet Tyler are plotting to bury the bones and get famous digging them up. Critical readers might well question the villains' reasoning; but just as in last year's . . . Mystery of the UFO and . . . Mystery of the Stolen Diamonds, Cain's persistence, special talent, and nimble footwork carry the story.