The identification of extinct megafauna in rock art using geometric morphometrics: A Genyornis newtoni painting in Arnhem Land, northern Australia?

Identifying extinct fauna in rock art is a common but difficult exercise. Here we use geometric morphometric analysis of shape to examine the oft-cited painting from Arnhem Land attributed by Gunn et al. to the long-extinct species Genyornis newtoni. We compare the shape of key anatomical features in this painting to anatomical depictions of Genyornis as well as to two other possible candidates - the emu and the magpie goose. Comparisons are also made to rock art depictions of these birds from northern Australia. We find that while the so-called 'Genyornis' painting does more closely resemble anatomical depictions of Genyornis than any other bird examined, all rock art images overlap in shape to such a degree that confident assignment of this image to any avian species is problematic.