Skeletons of hadrosaurids (“duck-billed dinosaurs”) are usually mounted with palms facing caudally (posteriorly). To achieve this, the radius is articulated with the medial (ulnar) condyle of the humerus instead of the lateral (radial) condyle, which would be unique among vertebrates if it were correct. However, articulated specimens reveal that in hadrosaurids the radius articulates with the lateral condyle of the humerus, as in other vertebrates, and the palms face caudomedially, though more medially than caudally. Active pronation is prevented by the shapes of the radial and ulnar shafts and by the lack of rolling articulations between radius and ulna. This makes the caudomedial orientation of the palm permanent. This finding contradicts many museum mounts but agrees with trackway evidence.