Comparative study of sexual dimorphism of the innominate bone in rodents and amphibians

Sexual dimorphism in the shape of the innominate bone was demonstrated in the rat, mouse, Chinese hamster Cricetulus griseus, frog Ranna nigromaculata, and newt Cynops pyrrhogaster with a computer‐assisted morphometric technique. In the rat, mouse, and hamster, ratios of ischium and pubis widths to the innominate bone lenght (INL) were larger in the males than in the females; however, the ratio of pubis length to INL was larger in the females than in the males. In the frog, the ratio of distance between the upper edge of the acetabulum and the lower edge of the pubis to INL was larger in males than in females. In the newt, ratios of width of ischiopubis and the longitudinal length of the ischiopubis to INL were larger in females than in males.© Willey‐Liss, Inc.