January 20,University of Colorado at Boulder A menagerie of megafauna that inhabited Australia some 45, years ago. Peter Trusler, Monash University New evidence involving the ancient poop of some of the huge and astonishing creatures that once roamed Australia indicates the primary cause of their extinction around 45, years ago was likely a result of humans, not climate change. Led by Monash University in Victoria, Australia and the University of Colorado Boulder, the team used information from a sediment core drilled in the Indian Ocean off the coast of southwest Australia to help reconstruct past climate and ecosystems on the continent.
Highlighting recently published papers selected by Academy members Journal Club: Illustration by Peter Trusler, Monash University.
A huge flightless bird known as Genyornis newtoni once roamed the Australian Outback along with a host of other giant animals. Now scientists have unearthed what may be the first reliable evidence that humans contributed to the extinction of these gigantic birds: Genyornis was a 2-meter bird that some estimates suggest could reach up to kilograms in weight.
Previous research suggests that happened about 50, years ago on rafts launched from Indonesian islands several hundred kilometers away. The lack of clear evidence for humans preying on megafauna despite roughly 50 years of archaeological fieldwork has led some to question a human role in their extinction in Australia.
However, while Australia did see gradual drying between 60, and 40, years ago, megafauna there survived more extreme previous climate shifts, which suggests that aridity alone could not explain their extinction.
Now study lead author Gifford Miller at the University of Colorado, Boulder, and his colleagues suggest they have found the first reliable evidence that people once hunted the extinct Australian megafauna — cooked Genyornis eggs. The findings appear in the Jan 29 issue of Nature Communications.
The scientists analyzed blackened Genyornis eggshell fragments from more than sites across most of the arid zone of Australia, from its west coast to its central deserts, mostly from sand dunes where the birds nested.
Previous research suggested the eggs were about the size of cantaloupes, weighing about 1.
The scientists used the eggshell of Genyornis and Dromaius the emu to date ancient shorelines and sand dunes tied to expanded lakes.
But in the process, they accidentally dated when the big bird became extinct. Later they discovered the evidence that humans had eaten the eggs.
The eggshell fragments were frequently blackened at only one end. Moreover, amino acid decomposition decreased away from the blackened ends.
Both these findings suggest the eggs were in contact with a very hot, concentrated source of heat, such as an ember, instead of wildfires that would likely cook them all over. In addition, the researchers found that many of the burnt eggshell fragments in tight clusters less than 3 meters in diameter.
Some clusters had both burnt and unburnt eggshell fragments, a situation that would almost certainly never happen with natural wildfires. The researchers suggest these fragments are evidence that humans preyed on the bird as they dispersed across the continent.
Miller suspects that this paucity of fossil clues stems from not only the rarity of well-preserved kill sites, but the chemistry of Australian soils.8 - Megafauna in the Southern Lake Eyre Basin: A Case Study Pages - In a book of this nature there was a need to provide some detail of how megafauna lived in what is now seen as the most arid part of the most arid continent.
8 - Megafauna in the Southern Lake Eyre Basin: A Case Study Pages - In a book of this nature there was a need to provide some detail of how megafauna lived in what is now seen as the most arid part of the most arid continent.
A case of mistaken identity for Australia’s extinct big bird January 13, pm EST An artist’s reconstruction of what the giant bird Dromornis would look like.
In the case of megafauna (with no minifauna), the type of equilibrium is almost always a focus (except for the case of S = 2).
Thus, overshooting would be possible under each parameter scenario, depending on the starting values of humans and megafauna, but again, we do not find this to be the case given the starting values we considered. The case is mounting for a human role in the mass extinction of giant animals that once ranged across Australia according to new research which challenges results from a site long claimed to clear.
Especially in the case of extinction of megafauna in Australia, several questions like the reasons for the disappearance of these creatures before humans even arrived and the reasons why the few survivors shrunk in size yet remain to be answered and the researches continue in .