The History of Australia Podcast

Episode 1 - Formation

September 06, 2020 Jasmin O'Connor Season 1 Episode 2
The History of Australia Podcast
Episode 1 - Formation
Show Notes Transcript

This episode traces Australia through the Precambrian and Triassic including the worst mass extinction to ever threaten life on Earth.

The History of Australia Podcast

Transcript - Episode 1 Formation

Welcome to the History of Australia Podcast, Episode 1, Formation. In this episode we trace the geological origins of the stage on which our play is set. The actors are the climate, the flora, the fauna and, of course, humans. 

Australia is an ancient land, in fact it is the most ancient land on all the earth. The sediments that aggregate to form this landmass are dated back 4.4. billion years into the Precambrian Eon. By point of reference, the formation of the earth is dated to 4.6 billion years ago. 
So, this is as old as it gets. 

I think it’s really interesting to learn about how really ancient Australia is, because I think that feeling of ancient wisdom is one that would resonate with anyone who’s had the privilege to live or visit Australia. It is such a wide, flat country. All our mountain ranges, thought to have been originally as high as any mountain on Earth, have been eroded down to these little nubs of their former selves. Climbing Mount Kosciuszko, our tallest mountain, isn’t so much a mountaineering marvel and a nice summer’s afternoon stroll. Mount Kosciuszko stands at only 2,228 metres high, that’s equivalent to 7,310 feet. The walk from base to summit is paved most of the way.

It’s such a contrast to our neighbour New Zealand, that’s a short hop across the Tasman sea to our right. It’s one of the youngest countries and most recently inhabited by people. At the junction of the Australian and Pacific plates, it’s at a really geologically active spot on the Earth’s crust. In the last 1.8 million years, the Southern Alps have risen thousands of metres and volcanoes have violently erupted creating new land. The sharp mountain peaks and black igneous rocks contrast so sharply to the weathered hills and red sands that define Australia. New Zealand’s tallest mountain, Aorako, also known as Mount Cook, is 3,724 metres high, equivalent to 12,218 feet. It’s not a short summer’s stroll to the summit. It’s a multi-day, mountaineering feet that involves an ascent on ice, snow and rock. 

That’s enough about New Zealand. Australia was part of the super-continent Pangea about 300 - 250 million years ago during the Permian. It was at this time that there was actually the worst mass extinction on record, killing 96 per cent of marine life and 70 per cent of terrestrial life. This is theorised to have been caused by massive volcanic activity. When I say massive, there probably isn’t a superlative that I can conjure up that is going to allow us to picture what that would have been like. We are talking about 2 million years of volcanic activity in the area of the world now known as Siberia. 

This mass extinction really was doomsday stuff. The geological record  indicates that there was this sudden  cataclysmic event. The timescale in which all of this land and sea life went extinct is narrowed down to only 200,000 years. And the extinct event occurred simultaneously in both the oceans and on land. 

A charcoal dense geological layer indicates that on the land there were these raging, massive wildfires triggered by the volcanic activity. In Australia we’ve just lived through the worst bushfire season ever recorded and I think we can draw on that to start to imagine what this extinction event would have been like. Last summer, every day, hundreds of fires were burning around the country. The sky was brown, clogged with soot and the air was so polluted outside you just really couldn’t breathe. You had to stay indoors, and even then you could still smell and taste the poisonous particles that just clung in the air. So imagine how distressing it would have been for the animals during the Permian if there are so many wildfires raging that that’s actually still captured in the geological record over 250 million years later. Two further impacts of the wildfires were soil erosion and, get this, massive fungal virulence. The burning of the rainforests that would have existed at that time basically meant that there was so much dead and decaying plant matter that fungi went wild. 

This radical change in the landscape really knocked around the fauna, with a lot of types of animals just never recovering. For example during the Permian, the dominant land animals were actually giant amphibians. This can seem strange because when you think amphibian, you’re probably thinking tiny frogs and salamanders and such. But actually there were amphibians at this time that would have looked to you or I like crocodiles and ruled the land. Amphibians just didn’t do as well as reptiles during the mass extinction. Which is interesting, because amphibians today are also really impacted by habitat change and climate change. These ancient amphibians would have been like their modern relatives, laying eggs in the water, and spending their infancy in the water, before moving onto the land at maturation. So this makes amphibians sensitive to changes in the water cycle, the drying or changing of water bodies, and changes in temperature.  

Aside from the raging wildfires and the kick on effects of that for life on land, the volcanic activity is thought to have caused the heating of the world’s oceans. Oceans around the equator reached 40 degrees Celsius, that’s 104 degrees Fahrenheit. That’s a spa bath, not an ocean temperature. So it’s no surprise that the prolific sponge and coral species of the Permian, and the fish and sharks and rays that lived in that ecosystem, really suffered from this and many species just didn’t survive. Trilobites, imagine a giant sea slater, had been a dominant life form in the ocean for 290 million years, but became extinct by the end of the Permian.

Australia might have fared better than some of the other regions of the world during the mass extinction because it was further down towards the south pole, and it was the equatorial regions that were really hardest hit because that’s the region that was warmed so much so quickly, life just couldn’t be sustained in the same way. That said, some of the evidence of widespread wildfires comes from western Australia.

During the early Triassic period, Australia was still part of Pangea and there was recovery and diversification after the mass extinction at the end of the previous period. So there is this long, slow, re-establishment of life on Earth. Australia had a warm, monsoonal climate due to carbon dioxide levels that were about three times higher than today. Ferns and conifers made up the bulk of regrown forests and fish and amphibians dominated. There were also some reptiles. 

One animal that stands out from the Triassic is the Dicynodont. It was clearly a tough animal because it was one of the very few animals that survived the mass extinction at the end of the Permian, and it lived all the way through the Triassic period which they really dominated. One type of Dicynodont, the Lystrosaurus, has a fossil record that spans every continent. So this guy had some staying power for sure. 

The Dicynodont looks like a mini hippo. That’s to say, it’s fat with short legs and a really big head. It also had a tortoise like beak and two small tusks on males. The name dicynodont means ‘two dog teeth’ and was given to them because their tusks are like canine teeth, or dog teeth.

It was a mammal-like reptile, a therapsid. One of the things that made it “mammal-like” is that its front legs are bowed like a lizard, but it’s back legs are pointing forward like a mammal’s. 

So what were dicynodonts like? Like hippos, these big boys were plant eaters. They would have snipped off tough plants with their beaks and ground them down with their jaws. Given the males have tusks, it’s also surmised that they probably lived together in small herds, with the males fighting each other to establish dominance. But in some regards, it was still very much a reptile and would have lived like one. For example it didn’t have any ears, and so would only have been able to sense vibrations through the ground. 

The palaeontological story of dicynodonts in Australia is juicy, but ultimately disappointing. There had been some pieces of fossil fragments stored in the Queensland Museum for nearly ninety years. They had been discovered in 1914 donated to the Queensland Museum along with a bunch of other fossils, and then sat in the archives without much further thought for the rest of the 20th century. Then in 2003, two palaeontologists finally decided to take a closer look and realised wow these are skull fragments might come from a dicynodont and it looks like they have been found in Cretaceous rock.

It was an amazing find because the date of the fossil showed that this animal which had lived during the Permian survived all the way into the Cretaceous, only 105 million years ago. That means they would have been living alongside dinosaurs as well. It was a find that made headlines at the time because it was a really significant and new part of the dicynodont story, and story of life in Australia. It was the only evidence for post Triassic dicynodonts anywhere in the world. Australia has been proven a refuge for many of the animals that did go extinct at the end of the Triassic,so this was adding a piece to that picture. 

But in 2019, some super sleuthing done by two palaeontologists called Knutsen and Oerlemans (apologies if I just butchered both your names) showed that it wasn’t actually a dicynodont but a mega-fauna fossil, only about 2 million years old. These palaeontologists examined the original fossil discovery, including looking at original correspondence about the fossil find and the donation of material to the Museum. They were also able to use new, high tech CT  scanning and geochemical analysis to analyse and date the fossil find more accurately. 

So unfortunately, I can’t tell you that the dicynodont managed to survive all the way from the Permian into the Cretaceous. Nevertheless, I can safely say that dicynodont was a badass hippo-reptile that survived the most epic mass extinction ever and is therefore worth your respect. 

We are going to leave it there for today. I’d like to thank Dr Espen Knutsen for his help in unravelling the story of Dicynodont in Australia. 

Tune in next time to learn about the creation stories of Bunjil and about the Dreaming and Dreamtime stories.

Stay safe and I’ll see you again soon.


Bibliography
Archer, M., Flannery, T.F., Ritchie, A. & Molnar, R.E. 1985. First Mesozoic mammal from Australia - an early Cretaceous monotreme. Nature 318, 363-366.

Arizona State University 2020, ‘Coal-burning in Siberia led to climate change 250 million years ago’, phys.org, https://phys.org/news/2020-06-coal-burning-siberia-climate-million-years.html, (Accessed 30 August 2020)

Australian Age of Dinosaurs, n.d., ‘Muttaburrasaurus Langdoni’, https://www.australianageofdinosaurs.com/page/86/australian-age-of-dinosaurs-muttaburrasaurus-langdoni (Accessed 15 August 2020)

Australian Museum 2019, ‘The Cretaceous Period (146 - 65 million years ago), Australian Museum, https://australian.museum/learn/australia-over-time/evolving-landscape/the-cretaceous-period/ (accessed 15 August 2020)

Bagley, M. 2014, ‘Permian Period: Climate, Animals & Plants’, Live Science, https://www.livescience.com/43219-permian-period-climate-animals-plants.html, (Accessed 30 August 2020)

Bell PR, Herne MC, Brougham T, Smith ET. 2018. Ornithopod diversity in the Griman Creek Formation (Cenomanian), New South Wales, Australia. PeerJ 6:e6008 DOI 10.7717/peerj.6008 

Chu, J. 2018, ‘End-Permian extinction, which wiped out most of Earth’s species, was instantaneous in geological time’, Phys.org, https://phys.org/news/2018-09-end-permian-extinction-earth-species-instantaneous.html (viewed 15 August 2020)

E.M. Knutsen, E. Oerlemans / Gondwana Research 77 (2020) 184–203, https://www.sciencedirect.com/science/article/pii/S1342937X19302254

Eileen McSaveney and Simon Nathan, 'Geology – overview', Te Ara - the Encyclopedia of New Zealand, http://www.TeAra.govt.nz/en/geology-overview (accessed 15 August 2020)

Molnar, R., 2000, Muttaburrasaurus, Queensland Museum, Brisbane

Musser, A. 2018, ‘Muttaburrasaurus langdoni’, Australian Museum, https://australian.museum/learn/dinosaurs/fact-sheets/muttaburrasaurus-langdoni/ (Accessed 15 August 2020)

Musser, A. 2018, ‘Steropodon galmani’, Australian Museum, https://australian.museum/learn/australia-over-time/extinct-animals/steropodon-galmani/ (Accessed 15 August 2020) 

Roberts, Ainslie, The Dreamtime: Australian Aboriginal Myths in Paintings by Ainslie Roberts with Text by Charles P. Mountford, Rigby Limited, Adelaide, First published 1965, reprinted 1974

Salleh, A. 2003, ‘Extinct reptile species lived on in Australia’, News in Science, ABC, Monday 24 March, https://www.abc.net.au/science/news/stories/s812979.htm, (Accessed 16 August 2020)

Senckenberg Research Institute and Natural History Museum 2020, ‘Extreme environmental conditions can lead to a massive global reshuffling of biodiversity, phys.org, https://phys.org/news/2020-07-extreme-environmental-conditions-massive-global.html (Accessed 30 August 2020)

Shu-zhong Shen, et al. 2011, CAlibrating the End-Permian Mass Extinction, Science 334, 1367, DOI: 10.1126/science.1213454, https://repository.si.edu/bitstream/handle/10088/17625/paleo_Shen_et_al_2011.pdf?sequence=1&isAllowed=y

The Age of Reptiles, ABC, https://www.abc.net.au/science/ozfossil/ageofreptiles/northern/dicynodont.htm, (Accessed 16 August 2020)

Thulborn, T., Turner, S., 2003. The last dicynodont: an Australian cretaceous relict. Proc. R. Soc. B Biol. Sci. 270, 985–993. https://doi.org/10.1098/rspb.2002.2296.

Windley, B. F. 2020, ‘The Pregeologic Period’, Britannica, https://www.britannica.com/science/geologic-history-of-Earth/The-pregeologic-period (accessed 15 August 2020)