 A set of characters were indicated by Barnum Brown in 1914 to distinguish Corythosaurus from all other hadrosaurids from Alberta : a comparatively short skull with a high helmet @-@ like crest formed by the nasals , prefrontals and frontals ; the nasals not being separated in front by the premaxillaries ; a narrow beak , with an expansion in front of an elongated <unk> ; and a small narial opening . 
