Several of the hadrosaur dinosaurs are noted for the spacious and bizarre-shaped sinus regions in their skulls. In particular, the Lambeosaurinae had a crest on the skull; the Hadrosaurinae, such as the Maiasaura and Edmontosaurus, lacked a crest.

The crest on the lambeosaur’s skull contained nasal passages looping through the crest and into some very large chambers before they went into the airway. There have been many suggestions as to the reason for such a crest, including its use as a snorkel (but it had no opening to the outside) or as a way to warm the air they breathed (but the climate was already warm). But the most accepted idea is that the crest acted like a resonance chamber, allowing the animals to make deep, loud calls to attract mates (either by the noise, by the odd shapes, or both), scare away predators, or keep a herd of young together.