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Malay Mail
25-04-2025
- Science
- Malay Mail
New techniques uncover how climate ‘upheaval' led to the extinction of Australia's giant kangaroos
SYDNEY, April 25 — Giant prehistoric kangaroos perished when 'climate upheaval' turned lush Australian rainforest into desert, scientists said yesterday after studying ancient fossils with new techniques. Weighing as much as 170 kilogrammes (375 pounds) — almost twice as hefty as the chunkiest living kangaroos — the extinct 'Protemnodon' bounded across Australia as many as five million years ago. Researchers were able to recreate the foraging habits of one population by matching long-lived chemicals from fossilised teeth to recently unearthed rocks. Similarities in chemical composition helped to mark how far the kangaroos hopped in search of food. 'Imagine ancient GPS trackers,' said Queensland Museum scientist Scott Hocknull. 'We can use the fossils to track individuals, where they moved, what they ate, who they lived with and how they died — it's like Palaeo Big Brother.' Lead researcher and UOW PhD candidate Chris Laurikainen Gaete with a tooth fossil from a giant kangaroo. — Picture by Chris Laurikainen Gaete and Scott Hocknull Scientists found the mega-herbivores lived in what was then a verdant rainforest — barely venturing far from home to forage. The rainforest started to wither around 300,000 years ago as the region's climate turned 'increasingly dry and unstable'. 'The giant kangaroos' desire to stay close to home, during a time of major climate upheaval 300,000 years ago, likely contributed to their demise,' the researchers said. Species of giant kangaroo survived in other parts of Australia and Papua New Guinea, with the last populations surviving until around 40,000 years ago. Scientist Anthony Dosseto said the new techniques could be used to better understand the disappearance of Australia's megafauna. Prehistoric species of giant echidna, wombat-like marsupials weighing over two tonnes, and hulking flesh-eating lizards once roamed the Australian continent. 'The debate about the extinction of the Australian megafauna has been going on for decades, but now we can take it to an individual and species-by-species perspective,' said Dosseto, from the Wollongong Isotope Geochronology Lab. 'With these precise techniques, each site and each individual can now be used to test and build more accurate extinction scenarios.' The findings were published in peer-reviewed journal PLOS One. — ETX Studio
ABC News
24-04-2025
- Science
- ABC News
Australia once had giant kangaroos — here's what experts think happened to them
EMBARGOED UNTIL THU 4AM AEST More than 300,000 years ago, giant kangaroos roamed the Australian outback, but didn't travel far from home, which experts say may have led to them disappearing entirely. The general rule is that the larger a mammal herbivore is, the further it travels for food. It's a trend seen with most modern kangaroo species. However, new peer-reviewed research published in PLOS One has found that, unlike modern kangaroos, the extinct marsupial megafauna Protemnodon was less mobile and had smaller home ranges than its size would have suggested. The continent was once home to a suite of giant creatures ranging from 2-metre-tall birds to 2-tonne lizards. ABC TV explores the drivers behind their demise. The study was a collaboration between the University of Wollongong, the University of Adelaide, Queensland Museum and Monash University. Lead researcher Chris Laurikainen Gaete, from the University of Wollongong, said the study measured the isotopes in the teeth of fossil giant kangaroos to estimate their foraging ranges over 300,000 years ago. The expectations were that these giant kangaroos standing at about two metres tall, would be mobile, but the results were that they moved very little and remained in the same geological substrate where their fossils were found. "This idea of home range is pretty important, because well, your dispersal capacity will kind of dictate your vulnerability to extinction should something change in your environment," Mr Laurikainen Gaete told the ABC. "We know that at this point in time, they lived in a rainforest habitat, so potentially they had an abundance of resources right around the cave. "But as the habitat changed, potentially these small home ranges [were] predisposed to extinction, meaning they couldn't walk in a more arid habitat for large distances to get their food." An illustration of a giant kangaroo from hundreds of thousands of years ago. ( Supplied: Capricorn Caves, Atuchin, Lawrence, Hocknull ) Change in climate led to giant kangaroos' extinction, research says Researchers examined the fossil records of the site where some giant kangaroos lived in Mount Etna in Queensland. For hundreds of thousands of years, the area was a stable rainforest environment, akin to those in New Guinea and other wet tropics in Australia. Mt. Etna in Queensland was once home to giant kangaroos until a change in climate saw rainforest disappear and be replaced by a more arid climate. ( Supplied: Scott Hocknull ) According to Mr Laurikainen Gaete, in this habitat, these giant kangaroos could live with a very small home range. "So this behavioural trait evolved over hundreds of thousands of years, but then around 280,000 years ago, the climate changed, and it became more arid," he said. "So this rainforest disappeared and was replaced by a kind of more dry-adapted species, which means resources become more patchy. " And a big kangaroo, who can't move these now larger distances between resources, and therefore that's why we assume they go extinct. " What is megafauna? Megafauna were large land animals that roamed the Earth during the Pleistocene, existing millions of years after dinosaurs became extinct. They were an integral part of the ecosystem and evolved to include some very large animals. Australian megafauna ranged from huge herbivorous marsupials, such as Diprotodon, to carnivorous reptiles such as Megalania. We need more research on our megafauna Lead researcher Mr Laurikainen Gaete believes the most significant finding for this study was that the template used to better understand the specific giant kangaroo species could be replicated. "The Australian ecosystem used to be dominated by megafauna, marsupials, but at different points in time, virtually all these species died out. And there's no clear answer as to why," he said. "The key thing from that is the techniques that we have employed here show that we can reconstruct these individual or local population responses to environmental change. " If we apply this to more fossil sites across Australia, we can have a more inclusive and nuanced interpretation of the unique factors driving local extinction events, rather than that kind of unknown that we have now. " An image of a giant kangaroo tooth used in the research. ( Supplied: Chris Laurikainen Gaete ) Some experts such as Isaac Kerr from Flinders University, agree. Mr Kerr, whose "In Australia, we are only starting to scratch the surface. And by the kind of thing, I mean the proxies for individual life history and palaeoecology in our fossil fauna," he said. "In America, they've known what we're just finding out for decades. And it's the kind of thing that is very useful in terms of recreating our past environment." Photo shows A skeleton of a giant extinct kangaroo placed over a white background. The bones are brown and arranged horizontally. Researchers from Flinders University have described three new species of extinct kangaroo, helping to solve a nearly 150-year-long scientific mystery. Mr Kerr explained his work focuses on skeletal comparative morphology, which means looking through the shape of bones to figure out how an extinct animal moved, comparing them to modern animals. It means he can contrast the similarities and differences to make a "very general hypotheses" about how that extinct animal moved and lived in their environment. He said the methodology used in the research goes further. "They have the ability to look at this actual species or actual individual animal's life history. So this is where this animal specifically went and where it fed," he said. "Which is powerful … [it] needs to be done more because it gives us this completely separate but parallel set of data for how these animals lived. " It's essential to painting a more complete picture of megafauna. "
The Guardian
23-04-2025
- Science
- The Guardian
Giant prehistoric kangaroos preferred to ‘chill at home' and didn't like to go out much, scientists say
Despite their immense size, species of prehistoric giant kangaroos from a site in Queensland were probably homebodies with a surprisingly small range compared to other kangaroos, according to new Australian research. Protemnodon, which roamed the Australian continent between 5m and 40,000 years ago and is now extinct, was significantly larger than its modern relatives. Some species weighed up to 170kg, making them more than twice as heavy as the largest red kangaroo. Given their size, researchers expected they might have an expansive territory, said University of Wollongong palaeo-ecologist Chris Laurikainen Gaete, the co-author of the study published in PLOS One. That's because in most modern plant-eating mammals, including kangaroos and other macropods, larger body size correlated with geographic range, he said. A small marsupial such as the pademelon, for example, occupies an area smaller than a kilometre squared, whereas the red kangaroo – the largest of all kinds – in outback Australia can hop long distances, sometimes further than 20km. But analysis of fossil teeth found near Mt Etna, 30km north of Rockhampton in Queensland, revealed something quite different. These protemnodon kept to close quarters, living and dying near the caves where their remains were found. Co-author Dr Scott Hocknull, a vertebrate palaeontologist and senior curator at the Queensland Museum, said the individuals from Mt Etna seemed to be 'real homebodies' that stayed within 'a tiny pocket' in and around the limestone caves. 'These gigantic kangaroos were just chilling at home, eating the rainforest leaves, because there were heaps of them around. That also means that the environment was quite stable. It meant that over hundreds of thousands of years, these animals decided that staying put was a good bet.' Sign up for the Afternoon Update: Election 2025 email newsletter The population at Mt Etna was 'probably quite happy' for some time, Hocknull said. The rainforest probably provided a reliable source of food, while the caves offered protection from prehistoric predators, such as marsupial lions. But their restricted range was a 'bad bet' in the end, Hocknull said, because it pre-disposed them to a risk of extinction when a changing climate and increasing aridity disrupted the rainforest environment about 280,000 years ago. Dr Isaac Kerr, who specialises in kangaroo palaeontology at Flinders University and was not involved with the study, said protemnodon fossils – found mainly in the south and east of the country – indicated there were several species adapted to different environments. 'Probably they were all over the whole continent, including New Guinea,' he said. A site in Tasmania had one of the latest surviving species, dated to 41,000 years ago. Sign up to Afternoon Update: Election 2025 Our Australian afternoon update breaks down the key election campaign stories of the day, telling you what's happening and why it matters after newsletter promotion Kerr said these megafauna kangaroos ranged in size but were generally stockier than their modern counterparts, with shorter feet. Protemnodon probably looked something like a wallaroo, he said, 'squat and muscular but still quite large compared to a modern kangaroo'. Mt Etna is one of Australia's richest fossil sites, containing evidence of ancient Pleistocene rainforests and records covering periods of past environmental change when rainforests gave way to open, arid environments. The researchers' next step was to apply similar techniques to fossils of smaller kangaroos such as tree kangaroos, pademelons and rock wallabies from Mt Etna, which still have living descendants, to understand how they survived the environmental changes while protemnodon died out. The study compared the unique chemical signatures found in the local geology with those found in the fossilised teeth to establish the range of each animal, Gaete said. 'Strontium is an element that varies in the environment, specifically in underlying bedrocks – so a limestone will have a significantly different strontium signature compared to something like volcanic rock or basalt,' he said. These unique signatures made their way into soil and plants, and were reflected in the fossilised teeth of herbivores that ate those plants. Laurikainen Gaete said the technique could be used to understand, on a site-by-site basis, why certain species of megafauna disappeared from particular places. Hocknull said: 'It fundamentally shifts how palaeontologists and ecologists look at the fossil record.'
