Geochemical analysis of the painted panels at the "Geyornis" rock art site, Arnhem Land, Australia

The so-called “Genyornis” rockshelter site on the Arnhem Land plateau, northern Australia, features a painting of a large bird that some archaeologists and paleontologists have suggested could be an image of the megafaunal species Genyornis newtoni, until recently widely thought to have become extinct some 45,000 years ago. However, a recent archaeological–geomorphological study has concluded that the rock surface that contains the large, enigmatic bird painting only became exposed during overhang collapse between 13,739–13,976 cal BP, so the rock art on this panel can only be more recent than this age. It is, therefore, most unlikely to represent a Genyornis bird. Using a range of analytical techniques, here we report on the geochemistry (microstructure and chemistry) of the sequence of microlayers that makes up the “surface” of the rock at the “Genyornis” site. Our aim is to provide insights into the composition, preparation, source, application, weathering and preservation of pigment used in the making of the paintings, and to clarify the superimpositional order and relationships between the enigmatic large bird painting originally thought to possibly be of a Genyornis, and other nearby images. Micro-stratigraphic superimpositions show that the earliest painting was of a large anthropomorph, followed sometime later by the simultaneous painting of the large enigmatic (“Genyornis”) bird image together with a barbed spear image embedded in it. This significantly alters the perception of the paintings on the wall of this rockshelter, with relegation of the anthropomorph to the background, followed by the image of a speared large bird.