Corythosaurus

Craniata

Corythosaurus Temporal range: Late Cretaceous, 77–76.5 Ma PreЄ Є O S D C P T J K Pg N ↓
Fossil skeleton partially covered in skin impressions
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Superorder:	Dinosauria
Order:	†Ornithischia
Suborder:	†Ornithopoda
Family:	†Hadrosauridae
Subfamily:	†Lambeosaurinae
Tribe:	†Lambeosaurini
Genus:	†Corythosaurus Brown, 1914
Species:	†C. casuarius
Binomial name
Corythosaurus casuarius Brown, 1914

Corythosaurus ( /ˌkɒrɨθɵˈsɔrəs/) is a genus of duck-billed dinosaur from the Upper Cretaceous Period, about 77-76.5 million years ago.^[1] It lived in what is now North America. Its name means "helmet lizard", from the Greek κορυθως/korythos meaning "helmet" and σαυρος/sauros meaning "lizard", because the crest shape resembled a Corinthian soldier's helmet).

Discovery and species

The first specimen was discovered in 1912 by Barnum Brown in Red Deer River, Alberta, Canada. As well as an almost complete skeleton, the find was remarkable because much of the creature's fossilized skin had also survived. In 1916, the Canadian (Canadian Pacific Lines) ship Mount Temple was carrying two specimens and other fossils from today's Dinosaur Provincial Park, Alberta, Canada to Britain. It was sunk by the German surface raider SMS Möwe, sending its 75 million year old cargo to the bottom of the North Atlantic, where it rests to this day.^[2]

There were originally up to seven species described including C. casaurius, C. bicristatus, C. brevicristatus, C. excavatus, C. frontalis, and C. intermedius. 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, C. casuarius.^[3]

Classification

Cast of a juvenile skull

Corythosaurus is 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, recent research has suggested that Olorotitan is Corythosaurus closest known relative even though it doesn't share as many skull characteristics as other lambeosaurs.^[4]

Paleobiology

Corythosaurus weighed in at 4 tonnes and measured roughly 10 metres (33 ft) from nose to tail. Like other hadrosaurs it had a toothless beak, the back of the jaws contained a dental battery composed of hundreds of small, interlocking teeth. These were used to crush and grind plant matter and were continually replaced as they wore away.

Over 20 skulls have been found from this dinosaur. As with other lambeosaurs, the animal bore a tall, elaborate bony crest atop its skull, which contained the elongate nasal passages.^[5] The nasal passages extended into the crest, first into separate pockets in the sides, then into a single central chamber and onward into the respiratory system.^[5]

Any vocalization would travel through these elaborate chambers, and probably get amplified.^[5] Scientists speculate that Corythosaurus could make loud, low pitched cries "[L]ike a wind or brass instrument."^[5] The sounds could serve to alert other Corythosaurus to the presence of food or a potential threat from a predator.^[5]

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.

Fossils have been found in the upper Oldman Formation and lower Dinosaur Park Formation of Canada.^[1]

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.^[6]

Paleobiogeography

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.^[7] 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.^[7] This restricted distribution strongly contrasts with modern mammalian faunas whose large herbivores' ranges "typical[ly] ... span much of a continent."^[7]

Footnotes

1. ^ ^{a b} Arbour, et al. (2009).
2. ^ Dinosaurs in the Deep
3. ^ Dodson (1975).
4. ^ Godefroit, et al. (2003).
5. ^ ^{a b c d e} "Corythosaurus," Dodson, et al. (1994); page 137.
6. ^ Schmitz and Motani (2011)
7. ^ ^{a b c} "Endemism Among Herbivorous Dinosaurs," Lehman (2001); page 311.

References

• Arbour, V. M.; Burns, M. E.; and Sissons, R. L. (2009). "A redescription of the ankylosaurid dinosaur Dyoplosaurus acutosquameus Parks, 1924 (Ornithischia: Ankylosauria) and a revision of the genus". Journal of Vertebrate Paleontology 29 (4): 1117–1135. doi:10.1671/039.029.0405. 
• Dinosaurs in the Deep
• Dodson, Peter (1975). "Taxonomic implications of relative growth in lambeosaurine dinosaurs". Systematic Zoology 24 (1): 37–54. doi:10.2307/2412696. JSTOR 2412696. 
• Dodson, Peter & Britt, Brooks & Carpenter, Kenneth & Forster, Catherine A. & Gillette, David D. & Norell, Mark A. & Olshevsky, George & Parrish, J. Michael & Weishampel, David B. The Age of Dinosaurs. Publications International, LTD. p. 137. ISBN 0-7853-0443-6.
• Godefroit, Pascal; Bolotsky, Yuri; and Alifanov, Vladimir (2003). "A remarkable hollow-crested hadrosaur from Russia: an Asian origin for lambeosaurines". Comptes Rendus Palevol 2 (2): 143–151. doi:10.1016/S1631-0683(03)00017-4. 
• Lehman, T. M., 2001, Late Cretaceous dinosaur provinciality: In: Mesozoic Vertebrate Life, edited by Tanke, D. H., and Carpenter, K., Indiana University Press, pp. 310-328.
• Schmitz, L. and Motani, R. (2011). "Nocturnality in Dinosaurs Inferred from Scleral Ring and Orbit Morphology". Science in press (6030): 705–8. doi:10.1126/science.1200043. PMID 21493820. 

External links

Dinosaurs portal

• Dinosaurs in the Deep