Giant kangaroos. Killer wombats. Carnivorous lions. These beasts once roamed the barren landscape of Ice Age Australia - a vast supercontinent stretching from Papua New Guinea to Tasmania.Continuing our Ice Age miniseries, host of The Ancients Tristan Hughes heads down under to uncover this lost world. Joined by palaeontologist Prof. Larisa DeSantis, he explores how these creatures survived both the challenges of a harsh climate and the arrival of humans 60,000 years ago, and discovers why Australia’s mammalian giants ultimately vanished.Presented by Tristan Hughes. Audio editor is Aidan Lonergan, the producer is Joseph Knight. The senior producer is Anne-Marie Luff.All music courtesy of Epidemic SoundsThe Ancients is a History Hit podcast.Sign up to History Hit for hundreds of hours of original documentaries, with a new release every week and ad-free podcasts. Sign up at https://www.historyhit.com/subscribe. You can take part in our listener survey here: https://insights.historyhit.com/history-hit-podcast-always-on
Chapter 1: What is Ice Age Australia?
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The woolly mammoth, the saber-toothed tiger, the giant ground sloth. When someone mentions the Ice Age, you might immediately think of great beasts like these, these large animals that roamed the Pleistocene landscape and are today extinct. But what about the Procoptodon goliath, a giant short-faced kangaroo? Or the Deprotodon, a massive herbivorous marsupial, also known as the killer wombat?
Or perhaps the Wunambi, a huge species of snake similar to modern-day pythons. These frightening, lesser-known megafauna that lived on the supercontinent that was Ice Age Australia. It's the Ancients on History Hit. I'm Tristan Hughes, your host. Today we're exploring the extraordinary world of Ice Age Australia.
We'll explore the climate, the many different individual beasts that once roamed the land, the arrival of humans around 60,000 years ago and why many of these megafauna ultimately went extinct. Our guest today is Professor Larissa DeSantis from Vanderbilt University.
Larissa is a paleontologist who has been studying the megafauna of Ice Age Australia, looking at the fossil record, including those from a remarkable site in New South Wales called Cuddy Springs. Larissa has examined how climate change may well have contributed to the extinction of these giant kangaroos, killer wombats, flightless birds and so on.
She's here to give us an introduction to the amazing world of Ice Age Australia and why its story deserves to be better known. Larissa, it is such a pleasure to have you on the podcast today.
Thanks so much for having me.
What an intriguing topic. Ice Age Australia. When I first think of the Ice Age, I will think of Europe or North America of woolly mammoths. Don't instinctively think of Australia, but this was a place that had a great variety of these extraordinary, quite unique megafauna.
Absolutely. And it still had a lot of the large effects that we faced across the globe. You know, the Ice Age phenomenon was really a global phenomenon, not a localized phenomenon.
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Chapter 2: What megafauna existed in Ice Age Australia?
And so essentially, when we're doing any carbon dating, we are fundamentally limited to the last roughly about 50,000 years. 40,000 is probably where we get good dates. Other places in the world, we can get really nice chronologies leading up to sort of extinction events. But in Australia, it's a bit more challenging. And so other methods are used.
The other, you know, a lot of times when you hear about radiometric dating during the time of the dinosaurs, that's using volcanic ash layers. So you have these volcanic events and you're using a different, you're usually looking at potassium argon dating or a different metric. And so different amounts of decay that's happening at different rates.
That's giving us some sort of indicator of what time those events are happening. But again, that precision, those tools are a lot harder to use in Australia. We don't have a lot of the volcanic ash layer in events, especially in the late Pleistocene.
Well, it's very commendable for yourself and others in the field then who are analyzing sediments or whatever, for those sites which are older than 50,000 years ago. And I'm guessing it's looking at sediments from there and other evidence surviving Larissa to get more of an understanding of the great amount and variety of megafauna that existed in Australia for much of the Ice Age.
And I've got lots of different things on my sheet in front of me, lots of different animals that hopefully we can get through. But can you give us an idea of What types of great beasts of megafauna existed in Ice Age Australia?
Sure. There was all sorts of amazing animals. One of my favorite illustrations is actually one that was commissioned by the Australian Postal Service. It ended up making a series of stamps. On that image, you get to see some of the classic ones. You get to see diprotodons, which are giant wombat-like animals the size of rhinos.
Giant rhino-sized wombats. Wow.
Yes, or wombat-like animals. They're not quite wombats, exactly. But they were massive. We don't think of large megafauna of that scale in places like Australia today. You also had giant kangaroos. And when I mean giant, I mean giants. Taller than the average person, several meters in height. You would be looking eye to eye or actually looking up at them in many cases.
We also had things like giant goannas. So if you think of the goannas that you might see in Australia today, imagine them the size of a saltwater crocodile.
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Chapter 3: How did climate change affect Ice Age Australia?
And so when researchers started actually kind of looking at the isotopic signature, so this is a way to get at what the animal was actually eating. So a lot of the research that we do in our lab is, you know, you can use morphology or what you look like to infer diet. And that's one approximation. If people did an approximation of our diets, we would be omnivores. We are the classic omnivores.
We have teeth that are ideal for, you know, crushing and grinding, we're not hyper carnivorous, we're not obligate herbivores, we're not just eating plants. Now, that being said, right, I might eat lots of sushi, and someone else might eat, you know, lots of steak, and someone else might be vegan. And Those are all, you know, variation.
And you do have variation within natural populations as well, maybe not as extreme as human populations, but you do. And so we can use different tools. We can use the microscopic wear patterns on teeth. We can use the chemicals within the teeth themselves. to begin to piece together what those animals were doing when they were alive.
So morphology gives us that first approximation, but then we can actually drill their teeth and say, oh, this animal was eating a C4 plant or a C3 plant. And those are plants that photosynthesize a little bit differently. And then we can look at the microwear and say, oh, they were eating shrubs, not grass, or they were eating grass, not shrubs. And
In Australia, things get really complicated really quickly because there's such a diversity of vegetation. And when I work in places like Florida or colleagues of mine who work in places like East Africa, it's a very simple system. You have essentially C4 grasses. So when you get a C4 signal, that means the animal's eating grass. And you have C3 plants.
But in Australia, we have C3 grasses and C4 grasses. We have C3 shrubs and C4 shrubs. And so you can't really see anything unless you're both looking at the isotopes and looking at the microware. And you're probably at this point saying, well, why do I care if an animal was eating C4 shrubs or C3 grass or what that diet was?
And it can tell us a lot about the environment, but it can also tell us about the vulnerability of that animal to that environment. So- In the case of Procter and Goliath, we end up finding that they are eating C4 shrubs. And this is based on both the microware and the isotopes. What that tells us is that they're consuming saltbush, right?
They're consuming a lot of this species called, or this from the genus Atroplex. And as the name or the common name implies, saltbush has salts. And so if you're out hiking all day and you've got a bag of potato chips and you've got an apple in your bag, right? Which one are you going to go for if you haven't had water in the last few hours?
I would probably go for an apple because an apple's got water in it.
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Chapter 4: What evidence do we have of megafauna in Australia?
We think it's probably stayed on the landscape. But what we do are learning is that these animals are likely unable to eat those resources, eat that C4 saltbush anymore. So they're having to sort of not eat that food and now having to compete for more similar resources. So with the drying out of the continent that's happening sort of globally, but also locally, the Lake Erie Basin is drying out.
You have the weakening of the monsoon signal, for example. You're seeing this shift in the kangaroos that's being recorded via climate, but you're also seeing sort of a dietary shift away from certain resources. And so aside from everything, I think what it's telling us is that animals are vulnerable to changes in the climate, that we do need to consider what the impacts are of a ratification.
And the funny thing is, whenever I talk about this, whenever I give seminars and I show these data, I sort of, you know, I look at the room and the room sort of like, yeah, okay, well, what new thing are you telling us? Like, this doesn't seem earth shattering or groundbreaking. You know, the animals are vulnerable to climate change.
I said, yeah, but when we published that paper, the paper took us a while to get out. We want to make sure it was done right. I was also... I went transitioning from a grad student to a junior faculty setting at my lab, getting the machinery and equipment to be able to properly, you know, ask and answer the questions.
But when that paper came out, about a week prior, the paper came out that said, so January of 2017, January 20th of 2017, papers from Nature Communications said, humans rather than climate, the primary cause of Pleistocene megafaunal extinctions in Australia.
And then our paper came out about a week later and said, didn't say anything about causal factors, but said dietary responses of Sahul, licensing Australia, New Guinea, megafauna to climate environmental change and talked about those impacts.
What was interesting is that within a few weeks of our paper coming out, another paper came out in February 2017 saying at least 17,000 years of coexistence between modern humans and megafauna. And this is from the Lake Mungo Willandra Lakes site that was led in the paper that was led by Michael Westaway.
But essentially, they demonstrated another site that showed an animal called Zygomaturis and megafauna coexisting for some period of time. So now it's not just Cuddy Springs that's showing this, that people were sort of so eager to just kind of throw out to fit their theory. You now have an additional site that's showing prolonged coexistence.
And then later that year, July 20th of 2017, a paper came out in Nature saying human occupation of northern Australia by 65,000 years ago. And so we're starting to see this sort of more complete picture of coexistence. of what's sort of happening, in which case there might be, you know, more prolonged coexistence of humans, a variety of causal factors.
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Chapter 5: How did humans impact Australian megafauna?
Thanks so much for your interest in this topic and for having me.
Well, Diego, there was Professor Larissa DeSantis giving you an introduction to the amazing world that was Ice Age Australia. I hope you enjoyed the episode. Next week, we're moving from Ice Age Australia to Europe and Western Asia to explore the story of the last Neanderthals. That episode, featuring Dr Chris Stringer, promises to be a big one, so stay tuned.
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