Parasaurolophus had one of the strangest head shapes in the dinosaur world. Curving back from its skull was a long hollow tube - up to 5 feet long - full of branching air channels. For years, scientists weren’t sure what it was for.
In the 1990s, researchers ran air through CT scans of Parasaurolophus crests and discovered something amazing: the crest worked like a brass instrument. Air flowing through the tubes produced a deep, low, booming honk. Parasaurolophus was a built-in trumpet.
It probably used those calls to keep in touch with the rest of its herd across long distances - a foghorn cutting through Cretaceous forests. Different ages and sexes had different-sized crests, so they would have honked in slightly different pitches, like a brass band.
