New techniques uncover how climate ‘upheaval' led to the extinction of Australia's giant kangaroos
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
Hashtags
Try Our AI Features
Explore what Daily8 AI can do for you:
Comments
No comments yet...
Related Articles
The Star
6 hours ago
- The Star
Australia opens facility to protect 13 mln biodiversity specimens
CANBERRA, Aug. 14 (Xinhua) -- Australia's national science agency has opened a biodiversity center to safeguard over 13 million specimens. The new building, named Diversity, in the capital Canberra, unites the Australian National Wildlife Collection and the Australian National Insect Collection under one roof in temperature-controlled, bushfire- and pest-resistant vaults, according to a statement released Thursday by the Commonwealth Scientific and Industrial Research Organization (CSIRO). Diversity houses one of the world's largest collections of Australian and Papua New Guinean birds, a vast archive of insects, and other preserved specimens spanning 150 years, to aid biosecurity, conservation, climate resilience and environmental management. "They are a hidden powerhouse, supporting everything from tracking pest incursions to discovering new species and understanding the genetic diversity of Australia's native ecosystems," said CSIRO Chief Executive Doug Hilton. Equipped with advanced genomics and digitization labs, the 90 million-Australian dollar (59 million-U.S. dollar) center will allow researchers and citizen scientists worldwide to extract DNA, capture high resolution images and share data, according to the CSIRO. Jointly funded by the CSIRO and the Department of Education, the project began in 2022, with construction taking just over two years and a further year to relocate the 13 million specimens, it said.
The Star
19 hours ago
- The Star
Seals sing 'otherworldly' songs structured like nursery rhymes
During the spring breeding season, male leopard seals dive underwater and perform their songs for two minutes before returning to the surface for air.— BRIAN/Pixabay When male leopard seals dive down into icy Antarctic waters, they sing songs structured like nursery rhymes in performances that can last up to 13 hours, scientists said July 31. The Australian-led team of researchers compared the complexity of the songs composed by the big blubbery mammals to those of other animals - as well as human musicians like the Beatles and Mozart. Lucinda Chambers, a bioacoustics PhD student at Australia's University of New South Wales, said that people are often surprised when they hear the "otherworldly" hoots and trills sung by leopard seals. "It kind of sounds like sound effects from an '80s sci-fi" movie, said the lead author of a new study in the journal Scientific Reports. During the spring breeding season, male leopard seals dive underwater and perform their songs for two minutes before returning to the surface for air. They then repeat this performance for up to 13 hours a day, according to the study. The researchers determined that all leopard seals share the same set of five "notes" which are impossible to distinguish between individuals. However each seal arranges these notes in a unique way to compose their own personal song. "We theorise that they're using that structure as a way to broadcast their individual identity, kind of like shouting their name out into the void," Chambers said. The researchers believe the males use these songs to woo potential female mates - and ward off rivals. 'Songbirds of the ocean' The team studied recordings of 26 seals captured by study co-author Tracey Rogers off the coast of Eastern Antarctica throughout the 1990s. "They're like the songbirds of the Southern Ocean," Rogers, who is also from the University of New South Wales, said in a statement. "During the breeding season, if you drop a hydrophone into the water anywhere in the region, you'll hear them singing." The team analysed how random the seals' sequences of notes were, finding that their songs were less predictable than the calls of humpback whales or the whistles of dolphins. But they were still more predictable than the more complex music of the Beatles or Mozart. "They fall into the ballpark of human nursery rhymes," Chambers said. This made sense, because the songs need to be simple enough so that each seal can remember their composition to perform it every day, she explained. She compared it to how "nursery rhymes have to be predictable enough that a child can memorise them". But each seal song also needs to be unpredictable enough to stand out from those of the other males. Leopard seals, which are the apex predator in Antarctic waters, swim alone and cover vast distances. They likely evolved their particular kind of song so that their message travels long distances, the researchers theorised. Varying pitch or frequency might not travel as far in their environment, Chambers said. Female seals also sing sometimes, though the scientists do not know why. Chambers suggested it could be to teach their pups how to sing - exactly how this talent is passed down is also a mystery. But she added that this behaviour has never been observed in the wild. The females could also just be communicating with each other, she said. – AFP
The Star
21 hours ago
- The Star
Scientists find surprising sex reversal in Australian birds
SYDNEY: Scientists have documented a surprising rate of sex reversal in wild Australian birds, a phenomenon that could be explained by rising pollution or other environmental triggers. A study of five common Australian species, including kookaburras, magpies and lorikeets, found around six per cent of birds had the chromosomes of one sex but the reproductive organs of another. The findings indicated a surprisingly high number of birds had reversed their sex after birth, said researchers from the University of the Sunshine Coast. "This indicates that sex determination in wild birds is more fluid than we thought, and can persist into adulthood," said study co-author Dominique Potvin. The study performed DNA tests on almost 500 birds. The overwhelming majority of sex reversals involved genetically female birds growing male gonads. "We also discovered a genetically male kookaburra who was reproductively active with large follicles and a distended oviduct, indicating recent egg production," said Potvin. Sex reversal is well known in certain species of reptile and fish but is thought to be rare in wild birds and mammals. Scientists have documented how pollutants and even warm temperatures can trigger sex reversal in frogs. The cause of sex reversal in wild birds was not clear, the University of the Sunshine Coast study said. But it could be due to environmental factors, such as hormone-disrupting chemicals building up in wild areas. "Understanding how and why sex reversal occurs is vital for conservation and for improving the accuracy of bird research," added Potvin. The study was published this week in peer-reviewed journal Biology Letters. - AFP
