 Corythosaurus is known from many complete specimens , including the nearly complete holotype found by Brown in 1911 . The holotype skeleton is only missing the last section of the tail , and part of the forelimbs , but was preserved with impressions of polygonal scales . Corythosaurus is known from many skulls with tall crests . The crests resemble the crests of the cassowary and a Corinthian helmet . The most likely function of the crest is thought to be vocalization . As in a trombone , sound waves would travel through many chambers in the crest , and then get amplified when Corythosaurus exhaled . A Corythosaurus specimen has been preserved with its last meal in its chest cavity . Inside the cavity were remains of conifer needles , seeds , twigs , and fruits : Corythosaurus probably fed on all of these . 
