Croker, Sarah, Warren Reed & Denise Donlon (University of Sydney)

Identifying the bones: a radiographic comparison of the cortical bone thickness in the radius of humans and kangaroos

Identification of bones as human or non-human is often aided by an understanding of the different body proportions and bone shapes that result from the bipedal stance of humans compared with the quadrupedalism of most non-human mammals. This could possibly extend to a difference in thickness of the long bone cortex, used by some workers to aid identification of bone fragments. In Australia, bones of kangaroos, being bipedal hopping animals, can be confused with human remains, as similarities in function, particularly the upper body, are reflected in similar bone shapes. This is particularly notable in the radius, which is studied here to determine whether differences in the thickness of the bone cortex exist, despite the similar external morphology of the human and kangaroo radius. For this preliminary study, 20 human and 20 kangaroo (Macropus sp.) radii were radiographed, and measurements taken of the bone diameter, medulla cavity and cortices at three sites along the shaft. Both the raw cortical thickness dimensions and the proportion of cortical bone to the whole bone diameter were compared between the two groups. Significant differences were discovered at some, but not all, sites measured.

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