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Small species back-up giant marsupial climate change extinction claim
May 30, 2005Thinking small in a time when everything was big has helped Queensland researchers to unearth new evidence that climate change, instead of humans, was responsible for wiping out Australian giant marsupials or megafauna 40,000 years ago.
Instead of only excavating 'trophy specimens' such as giant kangaroos and wombats, the researchers from Queensland University of Technology (QUT) and Queensland Museum performed the first systematic analysis of a site in the fossil rich Darling Downs region of south-eastern Queensland.
Reported in the journal Memoirs of the Queensland Museum tomorrow (Tuesday 31 May) they found smaller species, dependent on a wetter environment, had also disappeared.
By systematically analysing a 10 metre deep section of creek bed, the team uncovered 44 species, ranging from land snails, frogs, lizards and small mammals to giant wombats and kangaroos including many species previously unknown to have occurred in the Darling Downs fossil record.
The results suggest that the extinction of Darling Downs megafauna was caused by a massive shift in climate rather than by the arrival of humans who over hunted animals or destroyed habitats by burning the landscape.
The findings, which were unearthed with the help of amateur fossil hunter, Ian Sobbe, are of particular significance because the Darling Downs fossil deposits are among the youngest Australian megafauna deposits-laid down on the cusp of the extinction event.
PhD researcher Gilbert Price, of QUT's School of Natural Resource Science who led the study, says:
"Unravelling the cause of the late Ice Age extinction has occupied scientists for centuries. It is essential to know if the risks faced by species and ecosystems today are the same as those in the past.
"If we can document past environmental change and its influence on the extinction of species, it might have predictive value in estimating the effects of possible future climate changes and its impacts on modern species."
Megafauna roamed the globe in the Pleistocene epoch, between 1.8 million and 10,000 years ago.
In the northern hemisphere species such as the woolly mammoth and sabretooth tiger dominated the landscape, while in Australia-which evolved for 40 million years in isolation-giant marsupials ruled.
Current theories suggest that between 50,000 and 20,000 years ago, increasing aridity in Australia led to cooler and drier conditions that decreased wooded habitats and expanded deserts and grasslands, but researchers are still not clear what impact it had on fauna.
The Darling Downs contain some of the most extensive and significant Pleistocene megafauna deposits in Australia but because it's been excavated since the 1840s it was assumed that the palaeoenvironment record was well established.
Closer examination revealed a bias in sample collection in favour of larger animals and there had been few attempts to document ecological and sediment data.
"Our samples show that species dependent on habitats such as woodlands and vine thickets dominate the lowest section of the trench, which dates to around 45,000 years ago," says Mr Price.
"Other younger sections have a mixture of both large and small species that are habitat generalists or are species found in open areas, suggesting the landscape was evolving towards open grassland.
"By the latest Pleistocene species dependent on wetter conditions disappear from the fossil record while animals such as long-nosed bandicoots that aren't habitat specific remain."
Analysis of sediment and ecological data shows that it became increasingly arid during the late Pleistocene, which led to the disappearance of woodland and scrubland and expansion of grassland.
To verify their results carbon dating was performed on samples. And further work, due to be published later in the year, on other sites in the region confirm the stratification of fossils in the creek bed.
The dig also failed to unearth evidence of human activity, suggesting they didn't inhabit the region at the same time as megafauna.
Queensland Museum Assistant Curator in Geosciences, Scott Hocknull added:
"We're not just digging up a pile of old bones. These amazing fossil deposits are providing us with the key to understanding Australia's past, something integral when developing long term strategies for a sustainable future."
Research Australia
By systematically analysing a 10 metre deep section of creek bed, the team uncovered 44 species, ranging from land snails, frogs, lizards and small mammals to giant wombats and kangaroos including many species previously unknown to have occurred in the Darling Downs fossil record.
The results suggest that the extinction of Darling Downs megafauna was caused by a massive shift in climate rather than by the arrival of humans who over hunted animals or destroyed habitats by burning the landscape.
The findings, which were unearthed with the help of amateur fossil hunter, Ian Sobbe, are of particular significance because the Darling Downs fossil deposits are among the youngest Australian megafauna deposits-laid down on the cusp of the extinction event.
PhD researcher Gilbert Price, of QUT's School of Natural Resource Science who led the study, says:
"Unravelling the cause of the late Ice Age extinction has occupied scientists for centuries. It is essential to know if the risks faced by species and ecosystems today are the same as those in the past.
"If we can document past environmental change and its influence on the extinction of species, it might have predictive value in estimating the effects of possible future climate changes and its impacts on modern species."
Megafauna roamed the globe in the Pleistocene epoch, between 1.8 million and 10,000 years ago.
In the northern hemisphere species such as the woolly mammoth and sabretooth tiger dominated the landscape, while in Australia-which evolved for 40 million years in isolation-giant marsupials ruled.
Current theories suggest that between 50,000 and 20,000 years ago, increasing aridity in Australia led to cooler and drier conditions that decreased wooded habitats and expanded deserts and grasslands, but researchers are still not clear what impact it had on fauna.
The Darling Downs contain some of the most extensive and significant Pleistocene megafauna deposits in Australia but because it's been excavated since the 1840s it was assumed that the palaeoenvironment record was well established.
Closer examination revealed a bias in sample collection in favour of larger animals and there had been few attempts to document ecological and sediment data.
"Our samples show that species dependent on habitats such as woodlands and vine thickets dominate the lowest section of the trench, which dates to around 45,000 years ago," says Mr Price.
"Other younger sections have a mixture of both large and small species that are habitat generalists or are species found in open areas, suggesting the landscape was evolving towards open grassland.
"By the latest Pleistocene species dependent on wetter conditions disappear from the fossil record while animals such as long-nosed bandicoots that aren't habitat specific remain."
Analysis of sediment and ecological data shows that it became increasingly arid during the late Pleistocene, which led to the disappearance of woodland and scrubland and expansion of grassland.
To verify their results carbon dating was performed on samples. And further work, due to be published later in the year, on other sites in the region confirm the stratification of fossils in the creek bed.
The dig also failed to unearth evidence of human activity, suggesting they didn't inhabit the region at the same time as megafauna.
Queensland Museum Assistant Curator in Geosciences, Scott Hocknull added:
"We're not just digging up a pile of old bones. These amazing fossil deposits are providing us with the key to understanding Australia's past, something integral when developing long term strategies for a sustainable future."
Research Australia
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New evidence implicates humans in prehistoric animal extinctions
Research led by UK and Australian scientists sheds new light on the role that our ancestors played in the extinction of Australia's prehistoric animals. The study, published this week in the journal Proceedings of the National Academy of Sciences of the USA, provides the first evidence that Tasmania's giant kangaroos and marsupial 'rhinos' and 'leopards' were still roaming the island when humans first arrived.
Extraterrestrial Impact Likely Source of Sudden Ice Age Extinctions
At the end of the Pleistocene era, wooly mammoths roamed North America along with a cast of fantastic creatures - giant sloths, saber-toothed cats, camels, lions, tapirs and the incredible teratorn, a condor with a 16-foot wingspan.
Research team says extraterrestrial impact to blame for Ice Age extinctions
What caused the extinction of mammoths and the decline of Stone Age people about 13,000 years ago remains hotly debated. Overhunting by Paleoindians, climate change and disease lead the list of probable causes. But an idea once considered a little out there is now hitting closer to home.
A plan for reintroducing megafauna to North America
Dozens of megafauna (large animals over 100 pounds) - such as giant tortoises, horses, elephants, and cheetah - went extinct in North America13,000 years ago during the end of the Pleistocene.
Seal rookeries could provide a reliable food source for endangered California condors, study finds
A team of scientists is proposing that endangered California condors raised in captivity be released near seal and sea lion rookeries so that the birds can once again feast on the carcasses of marine mammals as their ancestors did centuries ago.
Cornell conservationists propose allowing wild animals to roam parts of North America
If Cornell University researchers and their colleagues have their way, cheetahs, lions, elephants, camels and other large wild animals may soon roam parts of North America.
Madagascar`s lost wilderness @ the London `Catastrophes` conference
In the last 2000 years Madagascar has lost its entire endemic megafauna. This includes giant lemurs, pygmy hippos, elephant birds, and giant tortoises. This loss is the planet`s most recent prehistoric extinction event affecting a region with continental-scale diversity.
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American Megafaunal Extinctions at the End of the Pleistocene (Vertebrate Paleobiology and Paleoanthropology) by Gary Haynes (Editor) |
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Megafauna by Yoga Understand this: Yoga dispenses a sinister frailty of howling swells in hissing static that combusts into crawling shock heaps, to the effect of Mayhem performing Twin Peaks incidentals in a prairie recorded by The KLF. A brief description casts them as black metal's answer to Throbbing Gristle. The texture-based rendering of their compositions sails them on a strange sea between song and sound effect as it bobs along the waves like a dead man's bottled message. Aspects of Goblin rehearsals in dead hills is interrupted as Monster Zero carves mountain sides with lightning breath. Oscillating leads pummel into churning riffs as if Caledonia was performed in an echo chamber near Lodi, New Jersey. The extrinsic properties of this work may result in disambiguation. |
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National Geographic Prehistoric Mammals by Alan Turner (Author) |
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American Megafauna by Sierra Madre Games A quarter of a billion years ago, four legged survivors of a global catastrophe cautiously left their watery homes for the shores. There were two basic types, the reptiles and the mammals. Over the ages, they mutated and matured, and always struggling with each other for dominion. The reptiles were the clear leaders for 170 million years, only to be upset by mammals for the last 80 million years. Yet the race for supremacy is not over. Each player takes 1 of four primitive species, called arch-types. As the ages go by, players bid on DNA and genotype cards to mutate their species into more advanced animals. The goal is to raise a species that not only can survive the harsh new world, but to thrive and expand. Game includes rules and historical commentary. Excellent... |
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Megafauna Troxum (Primary Contributor) |
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