SCIENCE

When Helmet Head Was a Necessity, Not a Fashion Faux Pas

Science Correspondent

October 17, 2008

Many kinds of hadrosaurs, plant-eating dinosaurs often called the “cows of the Mesozoic,” sported impressive crests. From the short, dome-shaped “helmet” of Corythosaurus to the long tube-shaped crest of Parasaurolophus, these hadrosaurs have long puzzled scientists. What was all that fancy headgear for?

In the past, some paleontologists thought that the crests could be used as snorkels or air tanks while these animals hid from predators underwater. The fact that these dinosaurs were terrestrial and did not have nasal openings on their crests sunk these ideas. Then it was suggested that the crests were more for display purposes. Perhaps potential mates could recognize each other based upon their crests. Or the crests could have even aided in communication: research carried out by paleontologists James Hopson and David Weishampel in the 1970’s and 1980’s demonstrated that they could have been used as resonating chambers.

Unfortunately, since there are no living hadrosaurs to observe, figuring out the functions of their crests can be difficult. A clue, however, can be found in what evidence we have of their brains. Using CT-scan technology to look inside the skulls of crested hadrosaurs, scientists from the University of Toronto, Ohio University, and Montana State University looked at nasal passages and braincases of these animals to reconstruct their soft anatomy. They announced their findings today at the Society of Vertebrate Paleontology Meeting in Cleveland, Ohio.

Although the actual brains of these dinosaurs are long gone, their skulls preserve the shape of the brain and allows for it to be reconstructed. These reconstructions, in turn, can indicate what senses were important to an animal.

An animal with excellent eyesight but a poor sense of smell, for instance, will have a brain that has enlarged portions that deal with vision but diminished portions related to scent detection. The researchers found that in crested hadrosaurs, the area of the brain dealing with sense of smell was diminished, meaning that it was unlikely that the elongated nasal passages running through the crests made the animals especially sensitive to scents.

What was surprising, however, was that these animals had larger areas of the brain that, according to paleontologist Larry Witmer, are associated with higher cognitive functions. Combined with inner ears that would have been sensitive to just the sort of sounds these dinosaurs could have made, they were probably highly communicative creatures. Indeed, if you could visit the Cretaceous landscape occupied by these animals, you would probably hear their deep bellows and wails as they called out to one another.