author(s)
S Sathapathy, BS Dhote, I Singh, D Mahanta and S Tamil Selvan

abstract
The present study was carried out on the sacrum of adult Blue bull (Boselaphus tragocamelus) of either sex. It was found that the sacrum was almost triangular in shape and consisted of five segments. The lateral borders were thin, sharp, concave and irregular. Cranially, the centrum of S1 was flattened from above downwards and had a transversely elongated convex surface known as the promontory for articulation with the caudal extremity of the body of the sixth lumbar vertebra. The apex was formed by the caudal end of the fifth sacral vertebra. The neural canal gradually decreased in depth and width caudally and the posterior opening was found to be approximately half the size of the anterior one. The cranial articular processes were reported to be large, concave medially and convex laterally. The dorsal supraspinous processes of the sacral segments were fused with each other that extended to the summits forming the median sacral crest. Further, the two lateral sacral crests were located on either side of the median sacral crest on the dorsal surface of the sacrum that represented the fusion of the articular processes of all the sacral segments. The ventral or pelvic surface was concave and presented a ventral groove throughout its length. There were presence of four pairs of dorsal and ventral sacral foramina on the respective dorsal and ventral surfaces of sacrum. Biometrical observations on different parameters reflected significance (P<0.05) differences between the sexes of this species.