I Know Dino Podcast: Corythosaurus

Episode 31 is all about Corythosaurus, a “duck-billed” hadrosaur.

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In this episode, we discuss:

The dinosaur of the day: Corythosaurus, a hadrosaur (“duck-billed”) dinosaur that lived in the Cretaceous, in North America
Fossils found in Canada (southern Alberta)

But it seems no bones found outside southern Alberta, so may have only lived in one small area
Name means “helmet lizard”
Type species is Corythosaurus casuarius

Name casuarius comes from cassowary
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
May have weighed up to 5 tons

Barnum Brown described Corythosaurus in 1914
Brown found the holotype specimen in 1911 (though there are many complete specimens); holotype is missing last part of tail and part of forelimbs, but has impressions of scales
30 feet (9 m) long, with a skull (including crest) that is about 28 in (71 cm) tall

Corythosaurus crests look like crests of a cassowary
Crest probably used for vocalization (amplifies sound)
Holotype specimen is now in the American Museum of Natural History, along with a second specimen Brown and Peter Kaisen found in 1914. They are “in their original death poses”

Brown described the second specimen in 1916 (more detailed description of Corythosaurus)
Charles H. Sternberg found 2 well preserved specimens in 1912, but they were lost in 1916 as they were being shipped to paleontologist Arthur Smith Woodward the UK, during WWI (ship was sunk by German merchant raider)
Holotype specimen sides and tail had scales

Use to be 7 different Corythosaurus species (C. casuarius, C. bicristatus, C. brevicristatus, C. excavatus, C. frontalis, C. intermedius
More than 20 Corythossaurus skulls have been found
In 1975 Peter Dodson studied the species and found that the different sizes and shapes may have been due to gender and age, so now only one species is recognized. However, some studies say C. intermedius is its own species because it lived slightly later than C. casuarius, and it slightly different

Brown originally classified Corythosaurus as part of the family Trachodontidae (now Hadrosauridae), but then he found it was possbily an ancestor to Hypacrosaurus (very similar except for development of vertebrae and limb proportions),. Now Corythosaurus is part of the family Lambeosaurinae (most of which have similar skulls and crests)
Holotype specimen was a carcass that floated up on a beach (shells, water-worn bones and baenid turtle preserved near it
Scientists used to think Corythosaurus lived in water (seemed to have webbed hands and feet), but the webs were actually deflated padding, seen on modern mammals; theory was that they could swim in deep water and use the crest to store air

Corythosaurus probably lived in woodland forest, may have visited swampy areas
Probably bipedal, with short arms and long tail (could walk on all fours, possibly to eat low-lying plants
Probably picky about what it ate (juicy fruits and young leaves)

Narrow, toothless beak with hundreds of cheek teeth
Used its beak to eat soft vegetation
One Corythosaurus has been preserved with its last meal in its chest cavity. Found remains of conifer needles, seeds, twigs, and fruits (debate over what it actually ate)

Probably was cathemeral, great sense of hearing
Cathemeral based on sclerotic rings (bony circles), which are in many reptiles, birds and dinosaurs (probably help with pupil)
Being cathemeral, may have eaten small amounts of food at a time to digest quickly, also easier to live alongside other herbivores that were diurnal or nocturnal

Herding animal, may have gone to higher ground to reproduce
Predators may have been Albertosaurus or Tyrannosaurus, or Troodon (especially to juveniles)
Crest has extended tubes (complex nasal passages)

May have called out warnings or to attract mates or to let others know about food
Males had larger crests than females
Size and shape of crest varied based on gender and age

Scientists think it made loud, low pitch sounds “like a wind or brass instrument” (trombone)
Started growing its crests when it reached half the size of adults
Ohio University did a CT scan in 2008 that found Corythosaurus had a “delicate inner ear” and could “hear low-frequency” sounds

No real defense mechanisms
Scott Persons from the University of Alberta found that Corythosaurus had smaller strides than tyrannosaurids, but they had more endurance so for long pursuits they lasted longer
Matt Davis from Yale University suggested there are so many fossilized impressions/skin samples of hadrosaurs because they had tougher textures compared to other dinosaurs

He reviewed reports about dinosaur skin from 1841 and found that in 180 reports, 46 percent of the fossils with skin were hadrosaurs
Also looked at data from 343 dinosaurs from the Hell Creek Formation, 20 of the 22 dinosaurs with skin fossils were hadrosaurs (91 percent)
Hadrosauridae (duck billed dinosaurs) is a family of common herbivores from the Cretaceous whose fossils have been found in Asia, Europe, and North America

Descendants of iguanodontian dinosaurs and had a similar body layout
Hadrosauids were the first dinosaur family identified in North America (1855-56 found fossil teeth); Joseph Leidy studied the teeth and named the genera Trachodon and Thespesius, though Trachodon had ceratopsids too and is no longer considered a valid genus
In 1858, associated those teeth with Hadrosaurus foulkii (named after William Parker Foulke)

Edward Drinker Cope used the name Hadrosauridae in 1869
One nearly complete specimen found in 1999 in the Hell Creek Formation (nicknamed “Dakota”), scientists were able to calculate its muscle mass. Had fossilized skin, ligaments, tendons and some internal organs
Two subfamilies: lambeosaurins (hollow crests) and saurolophines with solid crests (pre-2010 most hardosaurines classified as saurolophines)

Had lots of teeth in the back of the mouth to chew up food (made this group very successful, compared to sauropods in the Cretaceous)
Mark Purnell found in 2009 that hadrosaurs had a hinge between its upper haws and skull, and the upper jaw pushed outwards and sideways when chewing while the lower jaw slid against the upper teeth
Vincent Williams, Paul Barrett and Mark Purnell found in 2009 that hadrosaurids probably ate horsetails and low lying vegetation (based on how it chews), instead of twigs or stems

But this contradicts the finding of the hadrosaur with stomach contents, so it’s up for debate
Coprolites found some hadrosaurs ate rotting wood (had fungi and detritus-eating invertebrates)
Fun fact: Dinosaurs may have been brightly colored (even red or pink)

I Know Dino Podcast Show Notes: Corythosaurus (Episode 31)