Since Western naturalists first encountered the cassowary, the elusive but deadly bird has been shrouded in mysteries.

Chief among them: the purpose of the cassowary’s large, rudder-like crest, known as a "casque".

The distinctive crest of the cassowary - an iconic species of north Queensland - has long puzzled scientists. Credit:Alamy

Over nearly 200 years, theories abounded. Some believed it was part of a formidable arsenal, which includes the bird’s lethal, dagger-like claw. Some claimed the casque was a tool of seduction, a spade for foraging, or a helmet for crashing through the underbrush.

Others believed it was used to amplify the birds’ low frequency “boom” calls.