In the Dinosaur gallery on the second floor of ROM, there are three very special skulls of the Corythosaurus. They lived during the late Cretaceous period about 76 million years ago. This series shows how these dinosaurs changed as they grew.
Three Corythosaurus skulls are lined up from left to right: small, medium and extra large. Each one is from a different age, from juvenile to adult. The smallest of the three skulls is from a young Corythosaurus. It's shaped like a pear laid on its side, with the pointed end where its mouth used to be. More than 20 stubby teeth are still visible in its clenched jaw.
The middle skull is from an immature Corythosaurus. Its nose is longer and has a curved semicircle at the top.
The third and final skull is from an adult Corythosaurus. It has a massive semicircular shaped crest arches across the top of its skull. This crest accounts for about half the height of the skull and is the inspiration for the name Corythosaurus.
Behind the glass case is a complete skeleton of an adult Corythosaurus. It is about 2.5 meters high and 8 meters long. The bones of its long tail extend about a meter. Its skull is smaller than the other adult skull in the box.
These specimens played a very important role in recording the growth stages of Corythosaurus from juvenile to adult. And because these crests only fully mature when the animal is old enough, they help us understand the function of these bizarre structures.
The juvenile Corythosaurus all look similar, but the adults look very different. This is because the function of the crown changes as the animal grows. Once these animals approach sexual maturity and they begin to compete for mates, rank and social hierarchy, this head crest becomes a very important signal. Therefore, when an animal matures, it takes on its unique species-specific shape.
Scientists believe these crests helped Corythosaurus communicate, compete for territory and identify others of their own kind.