The helmeted hornbill casque is reinforced by a bundle of exceptionally thick, rod-like trabeculae.

ABSTRACT: Among hornbill birds, the critically endangered helmeted hornbill (Rhinoplax vigil) is notable for its casque (a bulbous beak protrusion) being filled with trabeculae and fronted by a very thick keratin layer. Casque function is debated but appears central to aerial jousting, where birds (typically males) collide casques at high speeds in a mid-flight display that is audible for more than 100 m. We characterized the structural relationship between the skull and casque anatomy using X-ray microtomography and quantitative trabecular network analysis to examine how the casque sustains extreme impact. The casque comprises a keratin veneer (rhamphotheca, ∼8× thicker than beak keratin), which slots over the internal bony casque like a tight-fitting sheath. The bony casque's central cavity contai

SUBMITTER: Surapaneni VA 

PROVIDER: S-EPMC11829324 | biostudies-literature | 2025 Feb

REPOSITORIES: biostudies-literature