Comparative Morphology of the os Coxae in Black Swan (Cygnus atratus) and Domestic Fowl (Gallus gallus)

This study investigates the anatomical differences in the os coxae of black swans and domestic fowl. Specimens were collected from three black swans during post-mortem examination and six domestic fowl from a local butcher shop. In both species, the os coxae consisted of three fused bones—ilium, ischium, and pubis—forming the acetabulum. The ilium showed a preacetabular and postacetabular part wherein the preacetabular part was slightly longer than the postacetabular part in fowl while the postacetabular part was much longer than the preacetabular part in the black swan. The dorsal surface of the preacetabular part presented a fossa in both the species which was deeper in case of the black swan. The crest of the preacetabular part of the ilium and spinous processes of the lumbosacral mass fused and formed the canalesilioneurales anteriorly in the both the species which was long and narrow in the black swan. The cranial border of the preacetabular part was much wider and strongly convex in the domestic fowl than in the black swan. Anterolateral to the acetabulum, the pubis gives off a short and blunt process, the prepubic/preacetabular/pectineal process. Pectineal process was prominent in the fowl while it was rudimentary in the black swan. Acetabulum was perforated in both the species.