 Comparisons between the scleral rings of Corythosaurus and modern birds and reptiles suggest that it may have been cathemeral , active throughout the day at short intervals . The sense of hearing in hadrosaurids , specifically such as Lophorhothon , also seems to have been greatly developed because of an elongated lagena . The presence of a thin stapes ( an ear bone that is rod @-@ like in reptiles ) , combined with a large eardrum implies the existence of a sensitive middle ear . It is possible that hadrosaurid ears are sensitive enough to detect as much sound as a modern crocodilian . 
