Blast to the Past: Australian Megafauna Extinction
Image credit: Peter Trusler, Monash University
Dream it
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Dream it 〰️
Just imagine, after a strenuous day at work, you come home and decide to head of straight to bed. Suddenly, loud drumming noises shake you awake. You wake up from your afternoon slumber, and still in your dreamy state, you peer to the side of the bed, only to realise you are not in bed anymore, you are seeing a group of Indigenous Australians, preparing for a late night ambush. Suddenly, a shrill scream sends shivers down your spine. You are shaken, but the hunters are focused.
Suddenly, a hunter hands you a spear.
Australian grasslands
They hand you a spear as you make your way past the shrubs. You decide to embark on this ‘dream’ and follow them, being careful not to snap any twigs or make any noise. Through the shrubbery, you see something and let out a shriek. Suddenly, a gigantic wombat storms at you and wallops you over the head. You wake up, only to realise it was a lucid dream, but is it? Frightening right! A night hunt may have been like this a couple of thousand years ago. In prehistoric Australia, many ancestors of creatures you see today existed, such as the Diprotodon, otherwise known as the giant wombat, and many more such as the Procoptodon, otherwise known as the giant kangaroo.
Giant short-faced kangaroo (Procoptodon goliah) :
Evidence suggests that the giant short-faced kangaroo existed 45,000 years ago, and could have existed up to 18,000 years ago. It is distinct to the modern-day kangaroo due to its facial features. The difference in facial features was a direct result of its diet and foraging behaviors. As they can be mainly described as browsers, which means they feed on leaves and fruits from trees, which was typical in the semi-arid environment that they lived in, hence their eyes were partly facing forward. They also had very well-developed jaws, with the lower jaw slightly below the upper jaw, forming a ‘chin’. They are spread across Australia, except for Tasmania, however, no fossils have been found in the Northern Territory, suggesting that they must have migrated into more suitable habitats. The modern-day Banded hare wallaby is the closest living relative of the colossus.
Image Credit: Nobu Tamura
Image Credit: Australian Museum
Giant Wombat (Diprotodon optatum):
Height: 1.8m Weight: 2,200-3,000kg
Like many large living herbivores, fossil remains show that these things were built very heavily, large-bellied and had four feet, and were very resilient, probably making them hard to take down. It had two forwardly directed lower incisors, and three upper incisors along with 4 simple molars in each jaw. One skeleton from Lake Callabonna had the remains of saltbush in its stomach. The Diprotodon may have eaten as much as 100 to 150 kilograms of vegetation daily. It’s plyer-like incisors may have been used to pull plants out of the ground. The limbs of the giant wombat were powerful and pillar-like. The upper limb bones were longer than the lower limb bones. The Diprotodon’s feet were unusually tiny relative to its size, and were inverted, like in modern wombats. The downside of having such limbs, was a much slower speed, compared to large four-legged mammals today. Although it’s large frame protected it, it’s slow speed made it a target from hunters. It’s closest modern-day relative is the wombat.
What happened? Where are they now?
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What happened? Where are they now? 〰️
Why are we discussing these amazing animals if they are not alive today?
Well, learning about the demise of the great megafauna, not only let’s us admire the characteristics of these marvels, but it also gives us insight into the past, which could give cues to the future on how to protect the animals we have today.
What information do they give us?
Learning about the fall of megafauna can only be theorized through studying and dating fossils, as well as historical events. Although certain Australian megafauna, such as the emu and red kangaroo, are still living today, the majority are now extinct.
Extinction by human hunting
One theory with quite some evidence that experts argue, is that the extinction of Australia's megafauna was caused by human-driven ecological instability, which they call the ‘blitzkrieg’ theory. This suggests that humans were responsible for the demise of the megafauna.
This theory is based on inferences, such as
On the timing of the extinction of the megafauna occurring about the same period as the arrival of humans into Australia.
Humans hunted them to extinction because they were easy targets
These creatures were particularly vulnerable, because of their big frames suggesting they were the largest and slowest in the habitat
Weapons, such as the woomera, had the ability to take these animals down due to the ability to generate much more power than throwing a spear by hand.
Image credit: Gift of Tairawhiti Museum, Te Whare Taonga O Tairawhiti
There is, however, data that contradicts this theory. It has been discovered that there was a considerable period of time between the appearance of megafauna and the arrival of people in Australia. Humans and megafauna coexisted for thousands of years before the megafauna became extinct, according to the evidence.
Another well-supported theory is climate change.
New evidence has come to light that they survived with humans for over 35,000 years, so being hunted to extinction is highly unlikely. The theory of climate change hypothesized that the changing of the Australian weather from having water inland to severe droughts is to blame. Dr. Judith Field, a researcher from the University of Sydney, says that a much longer period of drought would have resulted in the megafauna not being able to survive, and hence would have died out. More evidence has come to light, through the finding of mass fossils near possible ancient watering holes. In an event of extreme drought, most creatures would migrate to areas such as watering holes and ponds, where water and vegetation is plentiful. In May, 2011, a group of researchers from flinders university, went to Alcoota, which is an area that was thought to be a past watering hole as a part of their research.
Who could guess what they found, in this old, dried-up watering hole?
MASS FOSSILS of the Dromornic stironi, which is a giant demon duck!
Such an event seen here at Alcoota, could have occurred throughout the whole continent. This may be the explanation for fossils near old river beds, and more broadly, the effect of climate change on the extinction of big megafauna in Australia.
Didn’t you say that these insights could give us future cues?
Yes! Well, we can see the effect of climate change on the megafauna has led to the extinction of many. Climate change is an ever-increasing issue in the modern world, with the main factor contributing to the rising of these issues being humans. Since the Industrial Revolution, the Earth’s temperature has been slowly rising, mainly due to the emissions of heat-trapping greenhouse gases.
This could be detrimental, and bring a new wave of extinction. If there was a 4.5 °C global mean temperature rise, half the species of birds and reptiles, two-thirds of mammals, and nearly 80 amphibians could disappear in Australia by the next generation.
We could observe the past and learn techniques to prevent this from happening, which can come down to individual efforts.
Planting local plants not only helps with saving oxygen, and lowering carbon dioxide in some cases, but it also helps bees and migratory bird species which have been thrown off their usual migratory schedule due to changing temperatures and arrive at times when their usual food sources are not naturally around.
Drive less, cycle and walk as much as possible, and avoid flying. Flying is especially bad because not only does it release big amounts of greenhouse gasses but it does so at a high altitude where they have a bigger impact than those released closer to the ground, so avoid flying as much as possible, such as when going on vacation to Queensland, Victoria or Canberra.
Also, be careful who you vote for, pressure your representatives and politicians to take action, and research their opinions and agendas on climate change
References
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Divyesh Lal is a third year medical science student at Macquarie University. Under the supervision of Sally Hurst, founder of Found a Fossil, Divyesh undertook a practical experience subject as part of his studies which aims to give his science communication and event planning skills. Divyesh chose to take a step away from medical sciences, and has joined Sally in delving into the mysteries of the past, with this being his first time researching and presenting about topics regarding Australian heritage.
This work was submitted as part of a Professional and Community Engagement (PACE) subject and internship with Found a Fossil in conjunction with Macquarie University for the Australian Heritage Festival.