Histomorphologic and Radiologic Study of Southern Cassowary Casque (Casuarius casuarius)

Cassowaries are large, black-plumaged ratite birds, endemic to the rainforest habitats of New Guinea, Queensland (Australia) and various of the Aru Islands (Indonesia). The bird is characterized by the presence of large process above its head called casque. The casque possesses brownish color and measures 13 cm high and 13.5 cm width at the casque base and 5 cm thick (in the cross section). The rostral border is thick, rounded and curved backward to meet the caudal border, which is also rounded and nearly straight. X-ray image shows that the inner structure of the casque is formed of irregularly arranged, sparse thin trabeculae, looks like a sponge with the naked eye. Trabeculae are densely packed and adheres to the outer layer of the casque except in its most upper caudal part, which is less densely packed. The spaces between the bony trabeculae were not occupied by any liquid or solidified material and contains only those visible filaments. Surrounding the internal mass of trabecular fibers is a bony shell composed of denser bone, the external surface of which is marked with foramina and shallow, dorsoventrally aligned, divaricating canals for the reception of blood vessels and nerves. Histological examination confirmed the X-ray image findings.