Comparative morphological studies of the pelvic limb bones in ostrich (Struthio camelus), emu (Dromaius novaehollandiae), domestic fowl (Gallus gallus domesticus) and duck (Anas platyrhynchos domesticus)

Morphological and morphometrical study of pelvic limb bones from adult birds viz ostrich (n=4), emu (n=6), domestic fowl (n=8) and duck (n=8) were carried out. Pubic symphysis was a distinctive feature of os coxae in ostrich. Medial surface of ilium was united to lumbosacral mass in ostrich and emu, whereas, only medial border made fusion in domestic fowl and duck. Post acetabular ilium was an elongated triangle in ostrich and emu, whereas, quadrilateral plate in domestic fowl and duck. Iliac fossae for kidneys were lacking in ostrich and emu. Ischium was a long rod in ostrich and emu. Ilioischiatic notch was present in ostrich and emu, while, ilio-ischiatic foramen was found in domestic fowl and duck. Caudal extremity of pubis was free in all the species studied excluding ostrich. Ostrich and emu exhibited a distinct pneumatic foramen on femur which was lacking in domestic fowl and duck. Length ratio of femur to tibiotarsus was 1: 1.75, 1: 1.88, 1: 1.38 and 1: 1.69 in ostrich, emu, domestic fowl and duck correspondingly. Lateral cnemial crest was a large tuberosity in ostrich; whereas, in other species it was a thick curved spine. Hypotarsus was in the form of spine in ostrich and emu. Bony spur of tarsometatarsus observed in male domestic fowl was lacking in the other species. Distal extremity showed two trochleae in ostrich, whereas, three trochleae, in the other species. Ostrich is the only didactyl bird with two digits. Emu possessed three digits, while, domestic fowl and duck possessed four. Our present study revealed pneumatic femur, longer tibiotarsus and tarsometatarsus and less number of digits in ostrich and emu. Reduction in number of phalanges also led to reduce the number of muscles andtendonsassociated to digits. The above mentioned featuresmay aidostrich andemu for high-speed locomotion.