More Megafaunal Depictions in Bradshaw Rock Art:

Lee Scott-Virtue1, Jack Pettigrew2, Dean Goodgame1

1Kimberley Specialists, Nicholson Station, Kununurra 6743, Australia, [email protected] 2Queensland Brain Institute, University of Queensland 4072, Australia, [email protected]

The fine brush strokes, veridical representations and longevity of Bradshaw rock art can enable a positive identification of a depicted extinct mammal (e.g. the stripe-faced flying fox. Pettigrew et al 2008). In this report, we present a clear example of Palorchestes, the “marsupial tapir”, from the extinct Australian megafauna, depicted in Bradshaw rock art from the NW Kimberley of Australia (Fig. 1). Two depictions were found on sheltered rock walls in the Wade Creek formation (14.394 S.128.291 E), 30 m from other Bradshaw art with the same colour of biofilm that suggested the same artist, but not close enough that we could be sure that the animal depiction came from the same Bradshaw style as the figures. A number of features were diagnostic for Palorchestes, whose skeletons are well known and reconstructed by paleontologists (Long et al 2002): (Fig. 2). 1. Massive recurved talons on both forelimbs and hindlimbs; (thought to be browsing aids, perhaps for bark).: 2. Enlargement of the snout for browsing, with a widened mandibular symphysis to accommodate a large tongue (like a giraffe); (this inference from the fossils is here confirmed by the strangely enlarged snout, depicted from life by the artist (Fig. 2; 1); 3. Small, erect, dorsally-placed ears: 4. Massive size, shown by the depiction’s stout limbs; (guided by allometry from large extant mammals (Alexander and Pond 1992), their diameters roughly predict a massive overall size (0.4 – 1 t) despite the small scale of the depiction).

Fig. 1: Bradshaw Depiction of Palorchestes: Estimated extinction 46.5 ka. Scale bar = 1 cm

A favored dating technique is radiocarbon dating, but is subject to contamination by more recent organic material such as fungi and microrganisms growing on the sample, or organic debris that has been washed into cracks in the bone as it has lain waiting for the archeologist over the millennia. Roberts et al (2001) used both optical dating methods and U/Th series and addressed the problem of contamination by drilling into the teeth of the extinct megafanua. A sample of Palorchestes studied in this way was excavated in Victoria, Australia, and had a date of 60 Ka. This was an earlier, smaller species from the genus, perhaps suggesting a later age for our depicted species in view of its apparently large size. We therefore suggest an age of 46.5 Ka to deal with this possibility because there are different megafaunal species, including Palorchestes, in the study by Roberts et al (2001) that all have the same precise date at 46.5 Ka, indicating a high degree of synchrony of the extinction. Recent work provides independent confirmation of this synchrony from studies on the aridification of the central Australian mega-Frome and Lake Eyre systems, which dried up at this time (Cohen et al. 2012). There are thus a number of independent confirmations of the minimal age of our Palorchestes depiction, which contrasts with some uncertainty over another Pleistocene megafauna depiction, of Thylacoleo, whose identity and age are both under question because of possible confusion with Thylacinus and an unsubstantiated speculation that tropical Thylacoleo survived beyond the major megafaunal extinction (Akerman 2009, Akerman and Willing 2009). Two previous reports of Aboriginal rock art depictions of Palorchestes from Arnhemland (e.g. Murray and Chaloupka (1984)) propose a similar age to our estimate. Although both of these incomplete depictions are contentious, (e.g. because of loss of ochre), a notable feature of one Arnhemland Palorchestes depiction is a large, striated, protrusible tongue, in line both with reconstructions of the split fossil mandible and with the modified snout in our depiction. The clarity and completeness of the fine brush strokes and durable biofilm of the Bradshaw technique (Pettigrew et al 2010) is an advance on these less complete, worn, depictions in ochre because it has enabled all of the unique four distinguishing features of Palorchestes to be displayed in the same work of art.

a

Fig. 2: Tracings and reconstructions of Palrchestes azael alongside the Bradshaw depiction. Note the robust limbs, which enable a very approximate estimate of mass using allometric equations developed for other large mammals. Characteristic Palorchestes features include very powerful claws, especially on the forelimbs (c1), large, specialized snout (hence “marsupial tapir”) (c2), erect, dorsally-located ears (c3), massive size, around 400-1000 Kg (c4): b): Reconstruction of one of the earlier, smaller palorchestids, probably Palorchestes painei, excavated in Victoria and dated accurately by Roberts et al at 60 Ka.. c). Reconstruction of Queensland Palorchestes azael, the largest known palorchestid as well as the most recent, with a late Pleistocene extinction at 46.5 Ka based on aridification of mega-lakes and the synchronous age of teeth from manyother megafauna.

References: Akerman, K. & Willing, T. 2009. An ancient rock painting of a marsupial lion, Thylacoleo carnifex, from the Kimberley, Western Australia Antiquity 083 Issue 319 March 2009

Akerman, K., 2009. Interaction between humans and megafauna depicted in Australianrock art? Antiquity 83 (322). http://antiquity.ac.uk/projgall/akerman322/. Alexander, R.McN.; Pond, C.M., 1992. Locomotion and bone strength of the white rhinoceros Ceratotherium simum. Journal of Zoology, London 227: 63-69, fig. 1, tables

Cohen TJ et al 2012 Late Quaternary mega-lakes fed by the northern and southern river systems of central Australia: Varying moisture sources and increased continental aridity. Palaeogeography, Palaeoclimatology, Palaeoecology 356–357:89–108

Long, J., Archer, M., Flannery, T., and Hand, S. J. (2002) Prehistoric Mammals of Australia and New Guinea: One Hundred Million Years of Evolution. Kensington: University of New South Wales. (pg 100)

Murray, P. & Chaloupka G. 1984. The Dreamtime animals: extinct megafauna in Arnhemland rock art. Archaeology in Oceania 19: 105-16.1-3

Pettigrew JD, Nugent M, McPhee A,Wallman J, (2008) An Unexpected, Stripe-faced Flying Fox in Ice Age Rock Art of Australia’s Kimberley. Antiquity 82: 318

Pettigrew JD. Iconography in Bradshaw rock art: Breaking the circularity (2010). Clinical and Experimental Optometry 88: 39-45

Pettigrew JD, Callistemon C, Weiler A, Gorbushina A, Krumbein W & Weiler R (2010) Living Pigments in Australian Bradshaw Rock Art. Antiquity 84: 326

Pike AWG et al. 2012. U-Series Dating of Paleolithic Art in 11 Caves in Spain. Science 336: (6087) 1409-1413

Roberts RG et al 2001 New Ages for the Last Australian Megafauna: Continent-Wide Extinction About 46,000 Years Ago. Science 292: 1888-1892

Acknowledgements: This work was supported by Kimberley Specialists, Kununurra, WA and by the Hanse-Wissenschaftskolleg, Institute for Advanced Study (HWK), Delmenhorst, Germany.