Morphological analysis and osteometry of the foramen magnum of the one-humped camel (Camelus dromedarius).

The foramen magnum (FM) has been an integral component of studies on the ontogeny and evolutionary transformation of the skull. While its shape is variable in different species and breeds, the morphological variations and metrical indices of the foramen have scarcely been studied in camels. A total of 30 adult camel heads with equal sex disparity from three different locations of Northern Nigeria were used in this study for determining the morphological characteristics and osteometry of their foramen magnum. The study reported a mean foramen magnum height and width of 4.04 ± 0.15 and 3.70 ± 0.16 cm, and 3.65 ± 0.27 and 3.45 ± 0.21 cm in the overall males and females, respectively, and a foramen magnum index (FMI) in adult camels, which was over 100. We propose a classification for the morphology of foramen magnum in camels demarcating them into three types. The dorsal border of the foramen presented either a smoothly curved bony margin (type I), a small, ventrally directed, median bony protrusion (type II) or a dorsal notch (type III). No significant osteometric differences were found in any of the variables of the foramen magnum measured in the adult camels (FMH, FMW and FMI) of the various geographical locations, nor between animals of either gender except for the FMH that had a significantly higher mean value in overall males.