 Corythosaurus started developing its crest when half the size of adults , but Parasaurolophus juveniles grew crests when only 25 % as long as adults . Juvenile Corythosaurus , along with adults , had a premaxilla @-@ nasal fontanelle . Young and adult Corythosaurus are similar to Lambeosaurus and Hypacrosaurus but dissimilar to Parasaurolophus in that the sutures of the skull are sinuous , and not smooth and straight . This feature helps differentiate parasaurolophins from lambeosaurins . Generally , the crests of juveniles of lambeosaurines like Corythosaurus , Lambeosaurus , Hypacrosaurus stebingeri , parasaurolophines like Parasaurolophus , and primitive lambeosaurines like Kazaklambia are quite alike , although other features can be used to distinguish them . 
 Corythosaurus started developing its crest when half the size of adults , but Parasaurolophus juveniles grew crests when only 25 % as long as adults . Juvenile Corythosaurus , along with adults , had a premaxilla @-@ nasal fontanelle . Young and adult Corythosaurus <a href='drop_aux' title='1'><mark>are</mark></a>similar to Lambeosaurus and Hypacrosaurus but dissimilar to Parasaurolophus in that the sutures of the skull <a href='drop_aux' title='2'><mark>are</mark></a>sinuous , and not smooth and straight . This feature <a href='uninflect' title='3'><mark>helps</mark></a> differentiate parasaurolophins from lambeosaurins . Generally , the crests of juveniles of lambeosaurines like Corythosaurus , Lambeosaurus , Hypacrosaurus stebingeri , parasaurolophines like Parasaurolophus , and primitive lambeosaurines like Kazaklambia <a href='drop_aux' title='4'><mark>are</mark></a>quite alike , although other features can be used to distinguish them . 
Corythosaurus started developing its crest when half da size of adults , but Parasaurolophus juveniles grew crests when only 25 % as long as adults . Juvenile Corythosaurus , along with adults , had a premaxilla @-@ nasal fontanelle . Young and adult Corythosaurus similar to Lambeosaurus and Hypacrosaurus but dissimilar to Parasaurolophus in that tdasutures of the skull sinuous , and not smooth and str8 . dis feature help differentiate parasaurolophins from lambeosaurins . Generally , the crests of juveniles of lambeosaurines like Corythosaurus , Lambeosaurus , Hypacrosaurus stebingeri , parasaurolophines like Parasaurolophus , and primitive lambeosaurines like Kazaklambia quite alike , although other features can be used to distinguish them .