The other Megafaunal Extinction: The peopling of Australia I

In an interesting paper that came out at the end of January, Miller et al (1) provide the first unambiguous evidence that humans at least contributed to Australia’s Megafaunal extinctions. The latest evidence comes in the form of burnt eggs from the giant flightless bird Genyornis newtoni.

 

 

 Genyornis newtoni narrowly avoids another of Australia’s extinct megafauna, the 7m Megalania prisca Photo credit: Peter Trusler

Comparison of the statures of Homo sapiens and Genyornis newtoni from Murray and Vickers-Rich 2004 (2).

 

Here is the abstract:

 

Although the temporal overlap between human dispersal across Australia and the disappearance of its largest animals is well established, the lack of unambiguous evidence for human–megafauna interactions has led some to question a human role in megafaunal extinction. Here we show that diagnostic burn patterns on eggshell fragments of the megafaunal bird Genyornis newtoni, found at >200 sites across Australia, were created by humans discarding eggshell in and around transient fires, presumably made to cook the eggs. Dating by three methods restricts their occurrence to between 53.9 and 43.4 ka, and likely before 47 ka. Dromaius (emu) eggshell occur frequently in deposits from >100 ka to present; burnt Dromaius eggshell first appear in deposits the same age as those with burnt Genyornis eggshell, and then continually to modern time. Harvesting of their eggs by humans would have decreased Genyornis reproductive success, contributing to the bird’s extinction by ~47 ka.

 

A few of the selected quotes:

 

Although many elements of the Australian megafauna (those animals >45 kg body mass) lack firm extinction timelines, last appearance dates for taxa that occur most frequently in the fossil record are between 50 and 40 ka indicating a temporal overlap between humans and megafauna. The climate of Australia was drying gradually between 60 and 40 ka, but neither the rate nor magnitude of change were more severe than during earlier Pleistocene climate shifts. The lack of evidence for unprecedented climate change between 60 and 40 ka and survival of megafauna during earlier more extreme climate fluctuations implies that climate change is unlikely to be the sole cause of megafaunal extinction, leaving human agency more likely to have been the decisive factor, with modest additional stress from increasing aridity potentially a contributing factor.

 

The time interval during which Genyornis became extinct (50±5 ka)8 coincides with the interval when humans were consuming its eggs (53.9 to 43.4 ka), suggesting that predation contributed to the bird’s extinction.

 

The range of burn patterns found in clusters of Genyornis eggshell is most consistent with humans scattering eggshell fragments of consumed eggs in and around transient cooking fires, and the strong thermal gradients required to explain the observed burn patterns are incompatible with a wildfire cause.
 

 We found no in situ hearths or in situ stone artefacts directly associated with burnt Genyornis eggshell,.. This is expected because the alkaline dune sediments that preserve eggshell carbonate also degrade charcoal, and transient cooking fires in a sandy substrate leave no baked clays. Few regions provided Genyornis eggshell in stratigraphic sections where their association with artefacts could be securely evaluated; most samples were collected from the floors of deflation hollows. Lithic artefacts (commonly) and hearthstones (occasionally) are found in deflation hollows among surface scatters of burnt Genyornis eggshell, but because both occur as deflationary lags, temporal association cannot be demonstrated. However, the presence of hearthstones confirms that fire-using humans were in the same landscape, despite the lack of preserved hearths. At Garnpung [one of the sites from which burnt eggshell was collected during the study], one of the few sites with burnt Genyornis exposed in a stratigraphic section, an in situ hearthstone stratigraphically below the horizon containing burnt Genyornis eggshell demonstrates a temporal overlap with humans.
 

..none of the Genyornis eggshell collections from WA that predate 50±5 ka contain burnt fragments.

Verdict:
 

The authors present a fairly airtight case for human predation of Genyornis newtoni eggs as at least a contributing in the species’ extinction
 

With no samples of burn egg shells pre-dating to greater than 55,000BP this is fairly strong evidence for the peopling of Australia having begun only slightly earlier than this date

 

Rock art representation of Genyornis newtoni

In the western part of Arnhem Land in Australia’s Northern territory lies the Jawoyn site. This small rock shelter preserves a remarkable piece of rock art: the shape of an enormous bird. An analysis by palaeontologist Peter Murray, detailed in Gunn et al (3) concludes that flightless bird is Genyornis newtoni.

 

Aboriginal representation of Genyornis newtoni from western Arnhem Land.

Picture credit: R.G. Gunn (3).

 

Peter Murray made the identification based on the following points:

• a deep convex bill, very unlike any casuariiformes;

• a globular cranium;

• relatively thick neck;

• indication of a crop (emus and cassowaries lack crops);

• unusual posture of the wing (unlike the pendulous wing posture of emus);

• the proportions of the pelvic limb showing long tibiotarsi and stout tarsometatarsi;

• the short, broad toes terminating in blunt, robust claws; and

• a dorsal profile exactly paralleling that of reconstructed dromornithids and quite unlike an emu or a cassowary, in which the vertex of the back is more anterior.

The painting is tentatively dated as >25,000BP, thus raising the possibility of a late survival of this species.

Key points in the identification of Genyornis newtoni by Murray from Gunn (3) Figure 9. Original caption reads: Common distinctive traits between the painting and Genyornis.

What about other megafauna?

There is abundant rock art evidence that Aboriginals were well acquainted with, a number of other megafaunal species. The timing of the extinction has been much debated for a number of decades but according to Roberts et al (5) most occurred ca. 46,000BP. From their paper: “Twenty-three of the 24 genera of Australian land animals weighing more than 45 kg (which, along with a few smaller species, constituted the “megafauna”) were extinct by the late Quaternary.”

 

A few examples:

The Marsupial Lion, Thylacoleo carnifex. An interesting paper by Akerman and Willing identified one of the few paintings of this apex predator from the western shore of the Admiralty Gulf in the north-west Kimberley region of Western Australia.

 

Aboriginal defends himself from a Marsupial Lion Thylacoleo carnifex  from Akerman (4). Original caption: Figure 2. Panel showing hunter apparently spearing, or fending off, a large striped animal. Drysdale River, Kimberley, Western Australia (image courtesy of D. MacLeod).

 

 

Black and white rendition of painting from Akerman (4). Original caption reads:

Figure 3. Detailed black and white image taken from the original picture sent by D. MacLeod. Total width approximately 300 mm.

 

Although, not strictly part of the megafaunal extinction as it died out within recorded history in mainland Australia, the Tasmanian Devil, Sarchilus harrisii is well shown in Aboriginal art as seen here from Callaby and Lewis (6), also from Arnhem Land:

 

 

Callaby and Lewis Fig. 1

Original caption reads: Line drawing rendition of the painting in Figure 2. Note the long facial vibrissae, dog-like paws, marsupial genitalia, and long hairs on the dorsal side of the tail - a combination of features unique to the Tasmanian devil.

 

 

Callaby and Lewis Fig. 2

Original Caption reads: Red ochre painting identified as a Tasmanian Devil (Sarchilus harrisii). The left-hand ear and facial vibrissae extend around a Iedge on the ceiling and are therefore not visible in this photograph. Length = 83 cm

 

 

Other megafauna represented in Aboriginal art reported by Akerman:

 

• Tasmanian Devil (Sarcophilus harrisii: Chaloupka 1993; Lewis 1988);

• Thylacoleo, the marsupial lion (Thylacoleo carnifex: Murray and Chaloupka 1984);

• Sthenurus, a giant macropod (Sthenurus stirlingi: Murray and Chaloupka 1984);

• Zaglossus, a giant echidna (Zaglossus sp.: Murray and Chaloupka 1984); and

• Palorchestes, a marsupial tapir (Palorchestes azeal: Chaloupka 1984, 1993; Murray and Chaloupka 1984; Lewis 1986).

 

References

1. Miller, G. et al. 2016. Human predation contributed to the extinction of the Australian megafaunal bird Genyornis newtoni ~47 ka. Nature Communications  7, Article number: 10496 doi:10.1038/ncomms10496

Retrieved from: http://www.nature.com/ncomms/2016/160129/ncomms10496/full/ncomms10496.html

 

 

2. Murray, P.F. and P. Vickers-Rich 2004 Magnificent Mihirungs: The colossal

flightless birds of the Australian Dreamtime. Bloomington: Indian University Press.

3. Gunn, R.G. et al 2011. What Bird is that? Identifying a Probable Painting of Genyornis newtoni in Western Arnhem Land. Australian Archaeology Number 73, December 2011. Pdf retrieved from: http://connectingcountry.arts.monash.edu.au/wp-content/uploads/2011/10/2011-What-bird-is-that.pdf

4. Akerman, K. & T. Willing. 2009. An ancient rock painting of a marsupial lion, Thylacoleo carnifex, from the Kimberley, Western Australia. Antiquity 83;

Retrieved from: http://antiquity.ac.uk/projgall/akerman322/

5. Roberts R.G. et al 2001. New ages for the last Australian megafauna: continent-wide extinction about 46,000 years ago. Science. 292(5523):1888-92.

Retrieved from: http://www.ncbi.nlm.nih.gov/pubmed/11397939

6. Callaby, J.H. and D.J. Lewis. 1977. The Tasmanian Devil in Arnhem rock art.
Mankind 11(2):150-151. Downloadable from:
https://www.library.uq.edu.au/ojs/index.php/aa/article/viewFile/1467/1460
 

References from Akerman:

Callaby, J.H. and D.J. Lewis 1977 The Tasmanian Devil in Arnhem rock art.

Mankind 11(2):150-151.

Chaloupka, G. 1993 Journey in Time: The World’s Longest Continuing Art Tradition.

Chatswood, NSW: Reed.

Lewis, D. 1988 The Rock Paintings of Arnhem Land, Australia: Social, Ecological and Material Culture Change in the Post-Glacial Period. BAR International Series

415. Oxford: British Archaeological Reports.

Murray, P. and G. Chaloupka 1984 The Dreamtime animals: Extinct megafauna in

Arnhem Land rock art. Archaeology in Oceania 19(3):105-116.

Chaloupka, G. 1984 From Paleoart to Casual Paintings. Monograph Series 1.

Darwin: Northern Territory Museum of Arts and Sciences.

Lewis, D. 1986 The Dreamtime animals: A reply. Archaeology in Oceania 21(2):140-

145.