We already know Parasaurolophus and other lambeosaurines used their complicated nasal passages to produce elaborate calls. Now, it seems that ankylosaurs may have done the same thing.
A CT scan has proved that Euoplocephalus, at least, didn´t have expanded nasal chambers as was thought, but rather convoluted nasal passages similar to those of lambeosaurs.
This, and the fact that its ear seems adapted to detect low-frequency sounds, suggest that Euoplocephalus may have used elaborate calls to communicate over long distances, maybe to attract a mate. :> Although there may be other uses for the nasal passages.