 = Corythosaurus = 
 
 Corythosaurus / ˌkɒrᵻθoʊˈsɔːrəs / 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 κόρυς . It was named and described in 1914 by Barnum Brown . Corythosaurus is now thought to be a lambeosaurine , related to Nipponosaurus , Velafrons , 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 Belly River Group of the province . The left or underside of the skeleton was preserved in carbonaceous 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 scapulae and coracoids are preserved in position , but the rest of the forelimbs are gone , except for phalanges and pieces of humeri , ulnae and radii . Apparently the remaining forelimbs were weathered or eroded away . Impressions of the integument were preserved covering over a large part of the skeletons outlining , and shows the form of the body . Another specimen , AMNH 5338 , was found in 1914 by Brown and Peter Kaisen . 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 5338 , which specimen is therefore the plesiotype . 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 κόρυθος , korythos , " Corinthian helmet " , and means " helmeted lizard " . The specific name casuarius refers to the cassowary , a bird with a similar skull crest . The full binomial of Corythosaurus casuarius thus means " Cassowary @-@ 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 raider SMS Möwe in the middle of the ocean . 
 There were formerly up to seven species described , including C. casuarius , C. bicristatus Parks 1935 , C. brevicristatus Parks 1935 , C. excavatus Gilmore 1923 , C. frontalis 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 776 , a skull found by Levi Sternberg in 1920 and was named by William Parks in 1923 , who had originally named it Stephanosaurus 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 Swann 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. Colbert used models of specific dinosaurs , including Corythosaurus , to estimate their weight . The Corythosaurus model used , was modelled by Vincent Fusco 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 Shantungosaurus and Parasaurolophus . The total length of Corythosaurus specimen AMNH 5240 was found to be 8 @.@ 1 m ( 27 ft ) , with a weight of 3 @.@ 0785 tonnes ( 3 @.@ 0299 long tons ; 3 @.@ 3935 short tons ) . 
 Proportionally , 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 . 
 
 = = = Skull = = = 
 
 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 elongate 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 suture . 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 squamosals in a hooked , short process . The prefrontals also make up part of the crest ; however , Brown mistook the lower upper branch of the praemaxilla 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 enclose 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 sockets . As in Saurolophus , the expanded portion of the premaxillary in front of the pseudonaris ' opening is elongate : 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 lacrimal , another difference from those genera . The praemaxilla actually does touch the lacrimal and extends to the rear until well behind the eye socket . 
 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 . Polygonal tuberculate scales , covered in small bumps , vary in size over the body . Conical limpet @-@ 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 . Separating the polygonal scales of C. casuarius are shieldlike scales , arranged close together in rows . Ossified 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 tendon is flattened at its origin , and transversely ovoid in the central rod , ending at a rounded point . 
 Aside from those found on Corythosaurus casuarius , extensive skin impressions have been found on Edmontosaurus annectens and notable integument has also been found on Brachylophosaurus canadensis , Gryposaurus notabilis , Parasaurolophus walkeri , Lambeosaurus magnicristatus , L. lambei , Saurolophus angustirsotris and on unidentified ornithopods . Of these , L. lambei , C. casuarius , G. notabilis , P. walkeri , and S. angustirsotris have preserved polygonal scales . The scales on L. lambei , S. angustirostris 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 angustirostris preserved the best and most complete foot and limb integument , although other species like S. osborni , Edmontosaurus annectens and Lambeosaurus lambei ( = L. clavinitialis ) 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 webbed hands and feet . However , it was later discovered that the so @-@ called " webs " were in fact deflated padding , much like that found on many modern mammals . 
 
 = = = Distinguishing 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 naris ; 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 vertebral formula of 15 cervicals , 19 dorsals , 8 sacrals , and 61 + caudals ; possession of dorsal spines of a medium height ; high anterior caudal spines ; long chevrons ; long scapulae , possessing a blade of medium width ; a radius considerably longer than humerus ; comparatively short metacarpals ; an anteriorly decurved ilium ; a long ischium with a foot @-@ like terminal expansion ; a pubis with an anterior blade that is short and broadly expanded at end ; a femur that is longer than the tibia ; the phalanges of pes are short ; that the integument over the sides and tail composed of polygonal tuberculate scales without pattern but graded in size in different parts of the body ; and a belly with longitudinal rows of large conical limpet @-@ 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 postcranial traits are today known to be shared with other lambeosaurines . 
 
 = = Classification = = 
 
 Originally , Brown referred to Corythosaurus as a member of the family Trachodontidae ( now Hadrosauridae ) . Inside Trachodontidae were the subfamilies Trachodontinae and Saurolophinae . Brown classified Hadrosaurus , Trachodon , Claosaurus , and Kritosaurus in Trachodontinae , and Corythosaurus , Stephanosaurus , and Saurolophus in Saurolophinae . 
 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 dinosaurian ilia in the 1920s , Alfred Sherwood Romer proposed that the two orders of dinosaurs might have evolved separately , and that birds , based on the shape and proportions of their ilia might truly be specialized ornithischians . He used both Tyrannosaurus and Corythosaurus as a base model to analyze which theory is more likely true . He found that even though birds are thought of as saurischians , it is very plausible for them to have evolved their specific pelvic musculature and anatomy if they evolved from ornithschians like Corythosaurus . However , even though Corythosaurus does resemble modern birds in pelvic structure more than saurischians , birds are now thought to have descended from the latter . 
 Corythosaurus is currently classified as a hadrosaurid , in the subfamily Lambeosaurinae . 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 Velafrons , Nipponosaurus , and Hypacrosaurus , and said that they formed a group of fan @-@ crested lambeosaurines . 
 In 2014 , a study including the description of Zhanghenglong was published in the journal PLOS ONE . The study included an almost complete cladogram of hadrosauroid relationships , including Corythosaurus as the most derived lambeosaurine , as sister taxon to Hypacrosaurus . The below cladogram is a simplified version including only Lambeosaurini . 
 
 = = Paleobiology = = 
 
 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 . 
 
 = = = Crest 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 . Nasal 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 webbing 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 inflate . 
 
 = = = Growth = = = 
 
 Corythosaurus casuarius is one of a few lambeosaurines , along with Lambeosaurus lambei , Hypacrosaurus stebingeri and H. altispinus , to have had surviving fossilized 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 Procheneosaurus , 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 Cheneosaurus . 
 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 . 
 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. erectofrons was assigned to Corythosaurus based largely on biometric information . The only non @-@ typic specimen of Tetragonosaurus , assigned to T. erectofrons , was found later to be referable to Hypacrosaurus , although the holotype of the species was still found to be assignable 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 feeder , eating only the juiciest 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 . 
 
 = = Paleoecology = = 
 
 Fossils 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 carcass that had floated up on a beach , as Unio shells , water @-@ worn bones , and a baenid 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 Saurornitholestes , the hadrosaurids Brachylophosaurus , Gryposaurus and Parasaurolophus , and the ankylosaurid Scolosaurus , and the ceratopsians Coronosaurus 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 apertus . Their associating was found in the Dinosaur Park , Judith River , and Mesaverde formations , and also in the Wind River Basin and the Wheatland County area . Corythosaurus lived alongside numerous other giant herbivores , such as the hadrosaurids Gryposaurus and Parasaurolophus , the ceratopsids Centrosaurus and Chasmosaurus , and ankylosaurids Scolosaurus , Edmontonia and Dyoplosaurus in the earliest stages of the formation , Dyoplosaurus , Panoplosaurus and Euoplocephalus in the middle age , and Euoplocephalus 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 tyrannosaurids Gorgosaurus libratus and an unnamed species of Daspletosaurus . 
 Thomas M. Lehman has observed that Corythosaurus hasn 't been discovered outside of southern Alberta even though it is one of the most abundant Judithian 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 faunas whose large herbivores ' ranges " typical [ ly ] ... span much of a continent . " 
 
 