The Dinosaur Mystery (The Boxcar Children Series #44)

The four Aldens like visiting the large old museum owned by their grandfather's friend. But then Jessie sees a huge, scary shadow moving in the room where the dinosaur skeletons are on display. And bones from the enormous Tyrannosaurus rex disappear. They must find the missing bones and solve the mystery before an exhibit is scheduled to open - or there might not be a dinosaur exhibit at all!