 = Corythosaurus = 
 
 Corythosaurus / <unk> / is a genus of hadrosaurid " duck @-@ billed " dinosaur from the Upper Cretaceous Period , about 77 – 75 @.@ 7 million years ago . It lived in what is now North America . Its name means " helmet lizard " , derived from Greek <unk> . It was named and described in 1914 by Barnum Brown . Corythosaurus is now thought to be a lambeosaurine , related to <unk> , <unk> , Hypacrosaurus , and Olorotitan . Corythosaurus has an estimated length of 9 metres ( 30 ft ) , and has a skull , including the crest , that is 70 @.@ 8 centimetres ( 27 @.@ 9 in ) tall . 
 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 . 
 The two species of Corythosaurus are both present in slightly different levels of the Dinosaur Park Formation . Both still co @-@ existed with theropods and other ornithischians , like Daspletosaurus , Brachylophosaurus , Parasaurolophus , Scolosaurus , and Chasmosaurus . 
 
 = = Discovery and species = = 
 
 The first specimen , AMNH 5240 , was discovered in 1911 by Barnum Brown in Red Deer River , Alberta , Canada , and secured by him in the Fall of 1912 . As well as an almost complete skeleton , the find was notable because impressions of much of the creature 's skin had also survived . The specimen came from the <unk> River Group of the province . The left or underside of the skeleton was preserved in <unk> clay , making it difficult to expose the skin . The skeleton was articulated , and only missing about the last 0 @.@ 61 metres ( 2 @.@ 0 ft ) of the tail and the forelimbs . Both <unk> and <unk> are preserved in position , but the rest of the forelimbs are gone , except for phalanges and pieces of <unk> , <unk> and radii . Apparently the remaining forelimbs were weathered or eroded away . <unk> of the integument were preserved covering over a large part of the skeletons outlining , and shows the form of the body . Another specimen , AMNH <unk> , was found in 1914 by Brown and Peter <unk> . Both specimens are now housed in the American Museum of Natural History in their original death poses . 
 The type species Corythosaurus casuarius was named by Barnum Brown in 1914 , based on the first specimen collected by him in 1912 . AMNH 5240 is thus the holotype . In 1916 , the original author , Brown , published a more detailed description which was also based on AMNH <unk> , which specimen is therefore the <unk> . Corythosaurus is among many lambeosaurines that possess crests , and it was the crest that lends Corythosaurus its name . The generic name Corythosaurus is derived from Greek <unk> , <unk> , " Corinthian helmet " , and means " <unk> lizard " . The specific name casuarius refers to the cassowary , a bird with a similar skull crest . The full binomial of Corythosaurus casuarius thus means " <unk> @-@ like reptile , with a Corinthian helmet crest " . 
 The two best preserved specimens of Corythosaurus found , by Charles H. Sternberg in 1912 , were lost on 6 December 1916 while being carried to the United Kingdom , during World War One . They were being sent to Arthur Smith Woodward , a paleontologist of the British Museum of Natural History in England , when the ship transporting them was sunk by the German merchant <unk> SMS <unk> in the middle of the ocean . 
 There were formerly up to seven species described , including C. casuarius , C. <unk> Parks 1935 , C. <unk> Parks 1935 , C. <unk> Gilmore 1923 , C. <unk> Parks 1935 , and C. intermedius Parks 1923 . In 1975 Peter Dodson studied the differences between the skulls and crests of different species of lambeosaurine dinosaurs . He found that the differences in size and shape may have actually been related to the gender and age of the animal . Now only one species is recognized for certain , C. casuarius , although C. intermedius has been recognized as valid in some studies . It is based on specimen ROM <unk> , a skull found by Levi Sternberg in 1920 and was named by William Parks in 1923 , who had originally named it <unk> intermedius earlier that year . The specific name of C. intermedius is derived from its apparent intermediate position according to Parks . C. intermedius lived at a slightly later time in the Campanian than C. casuarius , and the two species are not identical , which supported the separation of them in a 2009 study . 
 
 = = Description = = 
 
 
 = = = Size = = = 
 
 Benson et al . ( 2012 ) estimated that Corythosaurus has an average length of 9 metres ( 30 ft ) . Richard <unk> Lull 's earlier length estimate , published in 1942 , found a slightly longer total length of 9 @.@ 4 m ( 31 ft ) , a size similar to Lambeosaurus lambei , another Canadian lambeosaurine . In 1962 , Edwin H. <unk> used models of specific dinosaurs , including Corythosaurus , to estimate their weight . The Corythosaurus model used , was modelled by Vincent <unk> after a mounted skeleton , and supervised by Barnum Brown . After testing , it was concluded that the average weight of Corythosaurus was 3 @.@ 82 tonnes ( 3 @.@ 76 long tons ; 4 @.@ 21 short tons ) . More recent size estimates of Corythosaurus , published in 2001 , find the genus to be among the largest hadrosaurids , only smaller than <unk> and Parasaurolophus . The total length of Corythosaurus specimen AMNH 5240 was found to be 8 @.@ 1 m ( 27 ft ) , with a weight of 3 @.@ <unk> tonnes ( 3 @.@ <unk> long tons ; 3 @.@ <unk> short tons ) . 
 <unk> , the skull is much shorter and smaller than that of Edmontosaurus ( formerly Trachodon ) , Kritosaurus , or Saurolophus , but when including its crest , its superficial area is almost as large . 
 
 = = = <unk> = = = 
 
 Over twenty skulls have been found from this dinosaur . As with other lambeosaurines , the animal bore a tall , elaborate bony crest atop its skull , which contained the <unk> narial passages . The narial passages extended into the crest , first into separate pockets in the sides , then into a single central chamber and onward into the respiratory system . The skull of the type specimen has no dermal impressions on it . During preservation it was compressed laterally , so now the width is about two @-@ thirds what it would have been in real life . According to Brown , the compression also caused the nasals to shift where they pressed down on the premaxillaries . Because they were pressed on the premaxillaries , the nasals would have closed the nares . Apart from the compression , the skull appears to be normal . Contrary to what Brown assumed , the areas concerned were fully part of the praemaxillae . 
 The crests of Corythosaurus resemble that of a cassowary , or a Corinthian helmet . They are formed by a combination of the praemaxillae , nasals , prefrontals and frontals , as in Saurolophus , but instead of projecting backwards as a spine , they rise up to make the highest point above the orbit . The two halves of the crest are separated by a median <unk> . In front of the orbit , the crest is made of thick bone . 
 The nasals make up most of the crest . Brown assumed that they extended from the beaks ' tip to the highest spot along the crest and that , unlike those in other genera , the nasals meet in the centre and are not separated in front by an ascending premaxillary process . Brown however , mistook the praemaxillae for the nasals ; the snout is actually largely formed by them and they do separate the nasals . Brown also thought that on the top and back of the crest , the whole external face is covered by the frontals . Again he made a mistake : what he assumed to be the frontals are in fact the nasals . The nasals end at the back of the <unk> in a hooked , short process . The prefrontals also make up part of the crest ; however , Brown mistook the lower upper branch of the <unk> for the prefrontal . The actual prefrontal , triangular in shape , is located at the side of the crest base ; it was by Brown seen as a part of the frontal . The real frontals , largely internal to the crest base structure , are not visible from the side . 
 The mouth of the holotype of Corythosaurus is narrow . The praemaxillae each form two long folds . The folds <unk> air passages extending the narial passages to the front of the snout . There they end in narrow openings , sometimes called " pseudonares " , false bony nostrils . These were mistaken by Brown for the real nares or nostrils . These are actually situated inside the crest , above the eye <unk> . As in Saurolophus , the expanded portion of the premaxillary in front of the <unk> ' opening is <unk> : by comparison , in Kritosaurus , the bill is short , and the pseudonares extend far forward . At the end of the Corythosaurus bill , the two pseudonares unite into one . Because of his incorrect identification , Brown assumed that the holotype 's inferior process of the premaxillary was shorter than in Kritosaurus and Saurolophus , and that the process does not unite with the <unk> , another difference from those genera . The <unk> actually does touch the <unk> and extends to the rear until well behind the eye <unk> . 
 The lower jaw of the holotype is 66 @.@ 9 centimetres ( 26 @.@ 3 in ) long , and 10 centimetres ( 3 @.@ 9 in ) deep . The total length of the crest from the beak to the uppermost tip of the type specimen is 83 @.@ 7 centimetres ( 33 @.@ 0 in ) , its total length is 81 @.@ 2 centimetres ( 32 @.@ 0 in ) , and height 70 @.@ 8 centimetres ( 27 @.@ 9 in ) . 
 
 = = = Soft tissue = = = 
 
 In the holotype of C. casuarius , the sides and tail of the body are covered in scales of several types . <unk> <unk> scales , covered in small <unk> , vary in size over the body . <unk> <unk> @-@ like scales are only preserved on a fold of skin preserved on the back of the tibia , but which was probably from the bottom of the belly , rather than the leg . <unk> the polygonal scales of C. casuarius are <unk> scales , arranged close together in rows . <unk> tendons are present on all the vertebrae , except for those in the cervical region . On no vertebrae do the tendons extend below the transverse processes . Each <unk> is flattened at its origin , and <unk> <unk> in the central rod , ending at a rounded point . 
 Aside from those found on Corythosaurus casuarius , extensive skin impressions have been found on Edmontosaurus <unk> and notable integument has also been found on Brachylophosaurus <unk> , Gryposaurus <unk> , Parasaurolophus <unk> , Lambeosaurus <unk> , L. lambei , Saurolophus <unk> and on unidentified ornithopods . Of these , L. lambei , C. casuarius , G. <unk> , P. <unk> , and S. <unk> have preserved polygonal scales . The scales on L. lambei , S. <unk> and C. casuarius are all similar . Corythosaurus is one of very few hadrosaurids which have preserved skin impressions on the hind limbs and feet . A study in 2013 showed that amongst hadrosaurids , Saurolophus <unk> preserved the best and most complete foot and limb integument , although other species like S. <unk> , Edmontosaurus <unk> and Lambeosaurus lambei ( = L. <unk> ) share a fair amount of preserved tissue on those regions . 
 It was once thought that this dinosaur lived mostly in the water , due to the appearance of <unk> hands and feet . However , it was later discovered that the so @-@ called " <unk> " were in fact <unk> padding , much like that found on many modern mammals . 
 
 = = = <unk> characteristics = = = 
 
 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 . 
 In 1916 , Brown expanded the character set to include more features ; in the revised version : a comparatively short skull with a high helmet @-@ like crest formed by nasals , prefrontals and frontals ; the nasals not being separated in front by premaxillaries ; a narrow beak , expanded section in front of the elongated nares ; a small narial opening ; a <unk> formula of 15 <unk> , 19 <unk> , 8 <unk> , and 61 + <unk> ; possession of dorsal spines of a medium height ; high anterior caudal spines ; long chevrons ; long <unk> , possessing a blade of medium width ; a radius considerably longer than humerus ; comparatively short <unk> ; an <unk> <unk> <unk> ; a long <unk> with a foot @-@ like terminal expansion ; a <unk> with an anterior blade that is short and broadly expanded at end ; a <unk> that is longer than the tibia ; the phalanges of <unk> are short ; that the integument over the sides and tail composed of polygonal <unk> scales without pattern but graded in size in different parts of the body ; and a belly with longitudinal rows of large conical <unk> @-@ like scales separated by uniformly large polygonal tubercles . Again , the presumed traits of the snout are incorrect because Brown confused the praemaxillae with the nasal bones and the nasal bones with the frontals . Most of the <unk> traits are today known to be shared with other lambeosaurines . 
 
 = = Classification = = 
 
 Originally , Brown referred to Corythosaurus as a member of the family <unk> ( now <unk> ) . Inside <unk> were the subfamilies <unk> and <unk> . Brown classified <unk> , Trachodon , <unk> , and Kritosaurus in <unk> , and Corythosaurus , <unk> , and Saurolophus in <unk> . 
 Later , Brown revised the phylogeny of Corythosaurus , and found that it was closely related , and possibly ancestral to Hypacrosaurus . The only differences he found between them were the development of the vertebrae , and the proportions of the limbs . During a study of <unk> <unk> in the 1920s , Alfred Sherwood <unk> proposed that the two orders of dinosaurs might have evolved separately , and that birds , based on the shape and proportions of their <unk> might truly be specialized ornithischians . He used both <unk> and Corythosaurus as a base model to analyze which theory is more likely true . He found that even though birds are thought of as <unk> , it is very plausible for them to have evolved their specific pelvic <unk> and anatomy if they evolved from <unk> like Corythosaurus . However , even though Corythosaurus does resemble modern birds in pelvic structure more than <unk> , birds are now thought to have descended from the latter . 
 Corythosaurus is currently classified as a hadrosaurid , in the subfamily <unk> . It is related to other hadrosaurs such as Hypacrosaurus , Lambeosaurus and Olorotitan , with the exception of Olorotitan they all share similar looking skulls and crests . However , research published in 2003 has suggested that even though it possesses a unique crest , Olorotitan is Corythosaurus closest known relative . Benson et al . ( 2012 ) found that Corythosaurus was closely related to <unk> , <unk> , and Hypacrosaurus , and said that they formed a group of fan @-@ crested lambeosaurines . 
 In 2014 , a study including the description of <unk> was published in the journal <unk> <unk> . The study included an almost complete cladogram of <unk> relationships , including Corythosaurus as the most derived lambeosaurine , as sister taxon to Hypacrosaurus . The below cladogram is a simplified version including only <unk> . 
 
 = = <unk> = = 
 
 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> . 
 
 = = = <unk> function = = = 
 
 The internal structures of the crest of Corythosaurus are quite complex , making possible a call that could be used for warning or attracting a mate . <unk> passageways of Corythosaurus , as well as Hypacrosaurus and Lambeosaurus are S @-@ shaped , with Parasaurolophus only possessing U @-@ shaped tubes . Any vocalization would travel through these elaborate chambers , and probably get amplified . Scientists speculate that Corythosaurus could make loud , low pitched cries " like a wind or brass instrument " , such as a trombone . The sounds could serve to alert other Corythosaurus to the presence of food or a potential threat from a predator . The nasal passages emit low @-@ frequency sounds when Corythosaurus exhaled . The individual crests would produce different sounds , so it is likely that each species of lambeosaurine would have had a unique sound . However , even though the range for different lambeosaurine nasal passages vary , they all probable made low @-@ pitched sounds . This might be because low sounds ( below 400 Hz ) travel a set distance in any environment , while higher ( above 400 Hz ) sounds have a larger spread in the distance travelled . 
 When they were first described , crested hadrosaurs were thought to be aquatic , an assessment based incorrectly on <unk> that is now known to be padding . The theory was that the animals could swim deep in the water , and use the crest to store air to breath . However , it has now been proven that the crest did not have any holes in the end , and the water pressure at even 3 metres ( 9 @.@ 8 ft ) would be too great for the lungs to be able to <unk> . 
 
 = = = Growth = = = 
 
 Corythosaurus casuarius is one of a few lambeosaurines , along with Lambeosaurus lambei , Hypacrosaurus <unk> and H. <unk> , to have had surviving <unk> juveniles assigned to it . Juveniles are harder to assign to species , because at a young age they lack the distinctive larger crests of adults . As they age , lambeosaurine crests tend to grow and become more prominent come maturity . In the Dinosaur Park Formation , over fifty articulated specimens have been found , coming from many different genera . Among them , juveniles are hard to identify at the species level . Earlier , four genera and thirteen species were recognized from the formation 's area , when paleontologists used differences in size and crest shape to differentiate taxa . The smallest specimens were identified as Tetragonosaurus , now seen as a synonym of <unk> , and the largest skeletons were called either Corythosaurus or Lambeosaurus ; an adult was identified as Parasaurolophus . Small lambeosaurines from the Horseshoe Canyon Formation were referred to <unk> . 
 Corythosaurus started developing its crest when half the size of adults , but Parasaurolophus juveniles grew crests when only 25 % as long as adults . <unk> Corythosaurus , along with adults , had a premaxilla @-@ nasal <unk> . Young and adult Corythosaurus are similar to Lambeosaurus and Hypacrosaurus but <unk> to Parasaurolophus in that the <unk> of the skull are <unk> , and not smooth and straight . This feature helps differentiate <unk> from <unk> . Generally , the crests of juveniles of lambeosaurines like Corythosaurus , Lambeosaurus , Hypacrosaurus <unk> , <unk> like Parasaurolophus , and primitive lambeosaurines like <unk> are quite alike , although other features can be used to distinguish them . 
 Work by Dodson ( 1975 ) recognized that there were many less taxa present in Alberta . Tetragonosaurus was found to be juveniles of Corythosaurus or Lambeosaurus . T. <unk> was assigned to Corythosaurus based largely on <unk> information . The only non @-@ <unk> specimen of Tetragonosaurus , assigned to T. <unk> , was found later to be <unk> to Hypacrosaurus , although the holotype of the species was still found to be <unk> to Corythosaurus . 
 
 = = = Diet = = = 
 
 Corythosaurus was an ornithopod , and therefore a herbivore . Benson et al . ( 2012 ) realized that the beak of Corythosaurus was shallow and delicate , and concluded that it must have been used to feed upon soft vegetation . Based on the climate of the Late Cretaceous , they guessed that Corythosaurus would have been a selective <unk> , eating only the <unk> fruits and youngest leaves . Corythosaurus specimens have been preserved with its last meal in its chest cavity . Inside the cavity were remains of conifer needles , seeds , twigs , and fruits , meaning that Corythosaurus probably fed on all of these . 
 
 = = <unk> = = 
 
 <unk> have been found in the upper Oldman Formation and lower Dinosaur Park Formation of Canada . The Oldman Formation dates to the Campanian , about 77 @.@ 5 to 76 @.@ 5 million years ago , and the Dinosaur Park Formation dates from 76 @.@ 6 to 74 @.@ 8 million years ago . Corythosaurus lived from ~ 77 – 75 @.@ 7 million years ago . In the Dinosaur Park Formation C. casuarius lived from 76 @.@ 6 to 75 @.@ 9 mya , with C. intermedius living from 75 @.@ 8 to 75 @.@ 7 mya . In the Oldman Formation C. casuarius , the only species of Corythosaurus from the deposits , lived about 77 to 76 @.@ 5 mya . The holotype specimen was clearly a <unk> that had floated up on a beach , as <unk> shells , water @-@ worn bones , and a <unk> turtle were preserved all around . Corythosaurus probably lived in a woodland forest , and might have occasionally wandered into swampy areas . 
 A limited fauna is known from the upper section of the Oldman Formation , and Corythosaurus casuarius as well as C. intermedius are among the taxa . Also from the section of the formation are the theropods Daspletosaurus , and <unk> , the hadrosaurids Brachylophosaurus , Gryposaurus and Parasaurolophus , and the <unk> Scolosaurus , and the ceratopsians <unk> and Chasmosaurus . Other genera are known , but do not persist from the upper section of the formation , and therefore are not contemporaries of Corythosaurus . 
 Corythosaurus casuarius is widespread throughout the lower unit of the Dinosaur Park Formation . In it , Corythosaurus was found to be closely associated with the ceratopsid Centrosaurus <unk> . Their associating was found in the Dinosaur Park , Judith River , and <unk> formations , and also in the Wind River Basin and the <unk> County area . Corythosaurus lived alongside numerous other giant herbivores , such as the hadrosaurids Gryposaurus and Parasaurolophus , the ceratopsids Centrosaurus and Chasmosaurus , and <unk> Scolosaurus , <unk> and <unk> in the earliest stages of the formation , <unk> , <unk> and <unk> in the middle age , and <unk> alone in later stages of the formation . Studies of the jaw anatomy and mechanics of these dinosaurs suggests they probably all occupied slightly different ecological niches in order to avoid direct competition for food in such a crowded eco @-@ space . The only large predators known from the same levels of the formation as Corythosaurus are the <unk> <unk> <unk> and an unnamed species of Daspletosaurus . 
 Thomas M. <unk> has observed that Corythosaurus hasn 't been discovered outside of southern Alberta even though it is one of the most abundant <unk> dinosaurs in the region . Large herbivores like the hadrosaurs living in North America during the Late Cretaceous had " remarkably small geographic ranges " despite their large body size and high mobility . This restricted distribution strongly contrasts with modern mammalian <unk> whose large herbivores ' ranges " typical [ ly ] ... span much of a continent . " 
 
 