 Comparisons between the <unk> rings of Corythosaurus and modern birds and reptiles suggest that it may have been <unk> , active throughout the day at short intervals . The sense of hearing in hadrosaurids , specifically such as <unk> , also seems to have been greatly developed because of an elongated <unk> . The presence of a thin <unk> ( an ear bone that is rod @-@ like in reptiles ) , combined with a large <unk> 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 <unk> . 
