Editing Corythosaurus (section)

==Description==
===Size=== 
[[File:Corythosaurus_Scale.svg|thumb|left|Size of ''C. casuarius'' (left, red) and ''C. intermedius'' (right, yellow) compared to a human.]]
Benson ''et al.'' (2012) estimated that ''Corythosaurus'' has an average length of {{convert|9|m|ft}}.<ref name="benson2012"/> 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 {{convert|3.82|t|LT ST|abbr=off|sigfig=3}}.<ref name="colbert1962">{{cite journal|last=Colbert|first=E.H.|year=1962|title=The Weight of Dinosaurs|url=http://digitallibrary.amnh.org/dspace/bitstream/handle/2246/3451//v2/dspace/ingest/pdfSource/nov/N2076.pdf?sequence=1|journal=American Museum Novitates|issue=2076|pages=1–16}}</ref> The total length of ''Corythosaurus'' specimen AMNH 5240 was found to be {{convert|8.1|m|ft|abbr=on}} long, with a weight close to {{convert|3.1|t|LT ST|abbr=off|sigfig=5}}.<ref name="seebacher2001">{{cite journal|last=Seebacher|first=F.|year=2001|title=A New Method to Calculate Allometric Length-Mass Relationships of Dinosaurs|url=http://dinoweb.ucoz.ru/_fr/4/A_new_method_to.pdf|journal=Journal of Vertebrate Paleontology|volume=21|issue=1|pages=51–60|doi=10.1671/0272-4634(2001)021[0051:ANMTCA]2.0.CO;2|citeseerx=10.1.1.462.255|s2cid=53446536 }}</ref> In 2016, Gregory S. Paul estimated that ''C. casuarius'' reached {{convert|8|m|ft}} long and {{convert|2.8|MT|ST}} in weight and that ''C. intermedius'' reached {{convert|7.7|m|ft}} in length and {{convert|2.5|MT|ST}} in weight.<ref>{{Cite book|last=Paul|first=Gregory S.|url=http://worldcat.org/oclc/985402380|title=The Princeton Field Guide to Dinosaurs|year=2016|publisher=Princeton University Press|isbn=978-1-78684-190-2|oclc=985402380|pages=344}}</ref> A "morphologically adult-sized specimen" of ''C. casuarius'' measured approximately {{convert|9|m|ft}} long.<ref>{{cite journal|author1=Wosik, M.|author2=Chiba, K.|author3=Therrien, F.|author4=Evans, D.C.|year=2020|title=Testing Size–frequency Distributions As a Method of Ontogenetic Aging: A Life-history Assessment of Hadrosaurid Dinosaurs from the Dinosaur Park Formation of Alberta, Canada, with Implications for Hadrosaurid Paleoecology|journal=Paleobiology|volume=46|issue=3|pages=379–404|doi=10.1017/pab.2020.2|s2cid=221666530 |doi-access=free|bibcode=2020Pbio...46..379W }}</ref>

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.<ref name="brown1914p561"/>

===Skull===
[[File:Life reconstruction of Corythosaurus casuarius.png|thumb|right|[[Life restoration]] of ''C. casuarius'']] 
Over twenty skulls have been found from this dinosaur. As with other lambeosaurines, the animal bore a tall, elaborate, bony crest atop its skull that contained the elongate narial passages.<ref name="ageofdinosaurscorythosaurus"/> 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.<ref name="benson2012"/><ref name="ageofdinosaurscorythosaurus"/> The skull of the type specimen has no dermal impressions on it. During preservation, it was compressed laterally and the width is now about two-thirds of 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.<ref name="brown1914p561"/> Apart from the compression, the skull appears to be normal.<ref name="brown1914p561"/> Contrary to what Brown assumed, the areas concerned were fully part of the praemaxillae.

As aforementioned, the crests of ''Corythosaurus'' resemble that of a [[cassowary]] or a [[Corinthian helmet]].<ref name="benson2012"/> 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.<ref name="brown1914p561"/>
[[File:Corythosaurus Hendrickx2.jpg|left|thumb|Skull of the type specimen]]
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 center and are not separated in front by an ascending premaxillary process. However, Brown 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, as 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.<ref name="brown1914p561"/> 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, which is triangular in shape, is located at the side of the crest base. It was seen by Brown as a part of the frontal. The real frontals, which are largely internal to the crest base structure, are not visible from the side.<ref>Weishampel, D.B., Dodson, P., Osmólska, H., & Hilton, Richard P., 2004, ''The Dinosauria''. University of California Press. p. 450</ref>

The mouth of the holotype of ''Corythosaurus'' is narrow. The praemaxillae each form two long folds that enclose air passages extending the narial passages to the front of the snout. There, they end in narrow openings, sometimes called "pseudonares", which are 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, the bill of ''Kritosaurus'' is short and the pseudonares extend far forward. At the end of the ''Corythosaurus'' bill, the two pseudonares unite into one.<ref name="brown1914p561"/> 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 gland|lacrimal]], which is another difference from those genera.<ref name="brown1914p561"/> 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 {{convert|66.9|cm|in}} long and {{convert|10|cm|in}} deep. The total length of the crest from the beak to the uppermost tip of the type specimen is {{convert|83.7|cm|in}}, its total length is {{convert|81.2|cm|in}}, and its height is {{convert|70.8|cm|in}}.<ref name="brown1914p563"/>

===Soft tissue===
[[File:CorythosaurCMNSkin.jpg|thumb|Replica of skin impressions]]
[[File:Corythosaurus skin impression.png|thumb|Abdominal skin impressions from Brown (1916)]]
In the holotype of ''C. casuarius'', the sides and tail are covered in scales of several types. Polygonal tuberculate scales, covered in small bumps, vary in size across the body. Conical limpet-like scales are only preserved on a fold of skin preserved on the back of the tibia, but this was probably from the bottom of the belly instead of the leg.<ref name="brown1914p563"/> Separating the polygonal scales of ''C. casuarius'' are shieldlike scales, arranged close together in rows.<ref name="bell2013">{{Cite journal | last1 = Bell | first1 = P. R. | title = Standardized terminology and potential taxonomic utility for hadrosaurid skin impressions: A case study for ''Saurolophus'' from Canada and Mongolia | doi = 10.1371/journal.pone.0031295 | journal = PLOS ONE | volume = 7 | issue = 2 | pages = e31295 | year = 2012 | pmid =  22319623| pmc = 3272031| bibcode = 2012PLoSO...731295B | doi-access = free }}</ref> 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, transversely ovoid in the central rod, and ends at a rounded point.<ref name="brown1916p711"/>

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 ''[[Saurolophus osborni|S. osborni]]'', ''[[Edmontosaurus annectens]]'', and ''Lambeosaurus lambei'' (= ''L. clavinitialis'') share a fair amount of preserved tissue on those regions.<ref name="bell2013"/>

It was once thought that this dinosaur lived mostly in the water, due to the appearance of webbed hands and feet.<ref name="brown1916p712"/> However, it was later discovered that the so-called "webs" were in fact deflated padding, much like that found on many modern mammals.<ref name="benson2012"/><ref name="Schmitz2011"/>

===Distinguishing characteristics===
[[File:Corythosaurus AMNH.jpg|left|thumb|Skeleton at [[AMNH]]]]
A set of characters were indicated by Barnum Brown in 1914 to distinguish ''Corythosaurus'' from all other [[hadrosaurid]]s from Alberta. These include a comparatively short skull with a high helmet-like crest formed by the [[nasal bone|nasals]], [[prefrontal bone|prefrontal]]s, and [[frontal bone|frontals]]; the nasals not being separated in front by the [[premaxilla]]ries; a narrow beak with an expansion in front of an elongated naris; and a small narial opening.<ref name="brown1914p560"/>

In 1916, Brown expanded the character set to include even more features. In the revised version, these extra features include 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 that possess a blade of medium width; a radius considerably longer than the 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 the 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.<ref name="brown1916p710"/> 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 various other lambeosaurines.