Corythosaurus

*Corythosaurus casuarius*

* Timothy Bradley Artwork
* Robert F Walters Artwork

***Corythosaurus*** was a late Cretaceous hadrosaur that lived in what is now North America, about 77-76.5 million years ago.

## Description

It was about 30–33 feet long from nose to tail, weighed in at 4 tonnes, and had a circular crest on its head formed from long nasal passages, in the shape of a helmet flattened on the sides (*Corythosaurus* means "helmet lizard"). Males had larger crests than females and juveniles. Like all hadrosaurs it could switch between two legs and four. The beak of *Corythosaurus* had no teeth, but the back of the jaws had hundreds. These were used to crush and grind plants and when teeth were lost, it grew new ones.

More than 20 skulls have been found from this dinosaur. As with all lambeosaurs, it bore a tall, bony crest on top of its skull, which had the long nasal passages.

## Classification

*Corythosaurus* is classified as a hadrosaurid, in the subfamily Lambeosaurinae. It is related to other hadrosaurs such as *Hypacrosaurus*, *Lambeosaurus* and *Olorotitan*, aside from *Olorotitan*, they all share similar looking skulls and crests. But, recent research has shown that *Olorotitan* is *Corythosaurus* closest known relative even though it lacks most of the skull traits of most lambeosaurs.

## History

The first specimen was discovered in 1912 by Barnum Brown in Red Deer River, Alberta. Fossils have been found in the upper Oldman Formation and lower Dinosaur Park Formation of Canada.

## Paleobiology

Its nasal passages extended to the crest, first to separate pockets in the sides, then into a central chamber in the respiratory system.

Any vocalization would go through these chambers, and probably get louder. Scientists think that *Corythosaurus* could make loud, low pitched cries "[L]ike a wind or brass instrument." The sounds could serve to alert other *Corythosaurus* if they found food or saw a predator.

It was once thought that this dinosaur lived most of its time in the water, due to the webbed hands and feet. However, it was later found that the so-called "webs" were in fact deflated padding, much like that found on many modern mammals.

The bony rings in *Corythosaurus'*s eyes were compared to those of modern birds and reptiles, which shows that it may have been active through the day at short times.

## JPInstitute.com Description

Corythosaurus is a member of the plant-eating, duck-billed dinosaur family that is sometimes referred to as hadrosaurs. It had a toothless, wide beak and hundreds of teeth in the back part of its mouth that it used for grinding tough plants to mush. Like other duckbills, it was a herd-animal that traveled in large groups. Fossils of this dinosaur are sometimes found together with other plant-eating dinosaurs, which leads scientists to believe that different types of plant-eaters grouped together to feed, drink and maybe even migrate (moving from one area to another).

Corythosaurus gets its name from the bony crest on top of its head because it brings to mind the helmets worn by ancient Corinthian warriors. The crest grew until adulthood and was likely used as a mating ritual ornament. There appears to be gender differentiation regarding the size of the crest, with males having a larger crest. At least 10 skulls have been identified from this species, giving scientists a good look at individual and gender differentiation. Fossilized skin remains have also been found, further contributing to the knowledge of Corythosaurus.

## Dinosaur Field Guide Description

Corythosaurus ("Corinthian helmet lizard") is one of the crested duck-bill dinosaurs. At one time, over six species were named based on slight differences in the crest on the skull. But in 1975, paleontologist Peter Dodson showed that these changes are due to sexual dimorphism and growth allome-try. In other words, they were all the same species, and the differences in the skulls and crests were normal among a large population of juveniles and adults of both sexes. The famous crest of Corythosaurus is formed from the upper lip bone and the nasal bone. These two bones have grown back and up over the skull, taking the nasal passage with them. The result is a folded nasal passage comparable to a woodwind instrument, such as a clarinet. Each species of crested duckbill dinosaur would have made its own unique sound, like different instruments in an orchestra. The crest also housed the enlarged olfactory lobes of the brain, increasing the duckbill's sense of smell. In some species, the olfactory lobes are actually bent toward the hollow crest in order to be closer to the nasal chambers!

### Fun Facts

This was the first dinosaur found with an almost complete skin!

### Trivia

The most beautiful and complete Corythosaurus skeleton is on display at the American Museum of Natural History in New York City.

## Fact Card

https://web.archive.org/web/20040215085004/http://www.jpinstitute.com/dinopedia/dino\_factcards/dfcoryt.html

## Links

http://web.archive.org/web/20040214161025fw\_/http://www.jpinstitute.com/dinopedia/dinocards/dc\_coryt.html

## References

1. ↑ 1.0 1.1 Arbour, et al. (2009).
2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 "Corythosaurus," Dodson, et al. (1994); page 137.
3. ↑ Godefroit, et al. (2003).
4. ↑ Dinosaurs in the Deep
5. ↑ Schmitz and Motani (2011)