Sex differences in the bony pelvis of the fruit-eating bat, Eidolon helvum

Abstract

Investigation into the bony pelvis of the fruit-eating bat, Eidolon helvum, revealed differences in the pelvic dimensions. The pubic joint of the female consists of interpubic ligament that increased in length until puberty. In the juvenile male Eidolon the pubic joint consists of ligament. Ossification of the interpubic ligament in the male is not an adult phenomenon but begins at the juvenile stage. In the adult the distance from the ischial tuberosity to the iliac crest, from the ischial tuberosity to the medial end of the pubis, and the outlet anteroposterior diameter of the pelvis, were significantly higher in the male than in the female. This indicates that the hip bone in the male is longer in both the vertical (height) and transverse (width) measurements than in the female. The dimensions of the adult pelvic inlet and outlet transverse diameters were significantly higher in the female than in the male. This indicates that the female pelvic canal is wider than the male and this is a consequence of the female interpubic ligament.