The mystery of the role of people and climate in the fate of Australian megafauna might have been solved in a breakthrough study.
Pleistocene kangaroo was the largest and most heavily built kangaroo known [Credit: Flinders University]
'Megafauna', giant beasts that once roamed the continent -- including wombat-like creatures as big as cars, birds more than two metres tall, and lizards more than seven metres long -- became extinct about 42,000 years ago. But the role of people in their demise has been hotly debated for decades.
For the first time, the research suggests a combination of climate change and the impact of people sealed the fate of megafauna, at least in south-eastern Australia. And that distribution of freshwater -- a precious commodity for animals and people alike as the climate warmed -- can explain regional differences in the timing at which megafauna died out.
The new study, led by a team of researchers from the ARC Centre of Excellence for Australian Biodiversity and Heritage (CABAH), analysed fossil data, climate reconstructions, and archaeological information describing patterns in human migration across south-eastern Australia.
The team developed and applied sophisticated mathematical models to test scenarios to explain regional variation in the periods during which people and megafauna coexisted.
"There has been much debate among scientists about what conditions led to this extinction event," said lead author Dr Frederik Saltre, Research Fellow and Coordinator of the Global Ecology Lab at Flinders University.
"Resolving this question is important because it is one of the oldest such extinction events anywhere after modern human beings evolved and left Africa", he added.
The findings, published in Nature Communications, are the result of analysis and complex modelling based on data including more than 10,000 fossils and archaeological records. Using high-quality fossil data and archaeological evidence of human activity, the researchers were able to map regional patterns of megafauna extinction.
They developed sophisticated models to test the impact of factors including climate, water availability, and human activity on localised patterns of megafauna extinction.
Credit: Flinders University
The extinction pattern could only be explained by the combination of people sharing the environment and the reduced of availability of freshwater due to climate change.
"The regional patterns in extinction are best explained by the hypothesis that people migrated across Australia, exploiting lakes and other sources of drinking water connecting the drier regions in between," said co-investigator Professor Corey Bradshaw of the Global Ecology Lab at Flinders University.
"It is plausible that megafauna species were attracted to the same freshwater sources as humans, thus increasing the chance of interactions."
The new insight that human pressure and climate change work together to trigger species extinction is a "stark warning" for the immediate future of the planet's biodiversity facing even stronger climate and habitat disruption, Dr Saltre concluded.
New fossils of an ancient legged snake, called Najash, shed light on the origin of the slithering reptiles.
Lifelike rendition of Najash [Credit: Raul O. Gomez, Universidad de Buenos Aires]
The fossil discoveries published in Science Advances have revealed they possessed hind legs during the first 70 million years of their evolution. They also provide details about how the flexible skull of snakes evolved from their lizard ancestors.
The evolution of the snake body has captivated researchers for a long time - representing one of the most dramatic examples of the vertebrate body's ability to adapt - but a limited fossil record has obscured our understanding of their early evolution until now.
Dr Alessandro Palci, from Flinders University, was part of the international research team that performed high-resolution (CT) scanning and light microscopy of the preserved skulls of Najash to reveal substantial new anatomical data on the early evolution of snakes.
Najash specimens from LBPA [Credit: Garberoglio et al. 2019]
"Snakes are famously legless, but then so are many lizards. What truly sets snakes apart is their highly mobile skull, which allows them to swallow large prey items. For a long time we have been lacking detailed information about the transition from the relatively rigid skull of a lizard to the super flexible skull of snakes".
"Najash has the most complete, three-dimensionally preserved skull of any ancient snake, and this is providing an amazing amount of new information on how the head of snakes evolved. It has some, but not all of the flexible joints found in the skull of modern snakes. Its middle ear is intermediate between that of lizards and living snakes, and unlike all living snakes it retains a well-developed cheekbone, which again is reminiscent of that of lizards."
Flinders University and South Australian Museum researcher Professor Mike Lee, was also part of the study, and adds "Najash shows how snakes evolved from lizards in incremental evolutionary steps, just like Darwin predicted."
CT scan reconstructions of the articulated skull of Najash [Credit: Garberoglio et al. 2019]
The new snake family tree also reveals that snakes possessed small but perfectly formed hind legs for the first 70 million years of their evolution.
"These primitive snakes with little legs weren't just a transient evolutionary stage on the way to something better. Rather, they had a highly successful body plan that persisted across many millions of years, and diversified into a range of terrestrial, burowing and aquatic niches," says Professor Lee.
As any geologist worth his or her salt will tell you, there are rocks, and then there are rocks. Next July, NASA and the European Space Agency (ESA) are launching rovers to Mars that will search for signs of past microbial life, and to find them, the scientists with NASA's Mars 2020 mission and ESA's ExoMars will need to examine different kinds of rocks that lend compelling insights into the environment in which they were made—all from 100 million miles away.
Scientists from NASA's Mars 2020 and ESA's ExoMars projects study stromatolites, the oldest confirmed fossilized lifeforms on Earth, in the Pilbara region of North West Australia. The image was taken on Aug. 19, 2019 [Credit: NASA/JPL-Caltech]
"While we expect to find many significant rocks during both Mars 2020 and ExoMars missions, we also have to leave open the possibility we could find one or more very special rocks,the kind whose discovery would not only speak volumes about the history of Mars but contribute significantly to the discussion of life elsewhere in the universe," said Ken Farley, Mars 2020 project scientist at Caltech in Pasadena.
Guided by Martin Van Kranendonk, director of the Australian Centre for Astrobiology at the University of New South Wales, members of the two missions' science teams went on an expedition to northwestern Australia's Pilbara region to analyze, discuss and debate stromatolites—structures preserved in rock that formed in water on early Earth and contain a fossilized record of ancient microbial life. Among the science teams' stops: a stromatolite cluster in a grouping of rock called the Dresser Formation that contains some of the oldest known fossilized records of life on our world.
"Some 3.48 billion years ago, this area was home to a caldera, or collapsed volcano, filled with hot, bubbling seawater," said Van Kranendonk. "At the same time, this location was also home to structures called microbial mats—visible to the naked eye but composed of microscopic organisms. Today you would know them as simple pond scum, but back then they were the most complex lifeforms on Earth."
Likely powered by photosynthesis, along with the heat and chemical energy in the caldera, these mats lived at the water's edge, secreting a mucous that would trap grains of sediment swirling around in the water. Over time, sheet after sheet of these microbes trapped sediment on top of previous layers. When the seawater receded and the pond scum dried up and disappeared millennia later, what remained was striking evidence of this co-evolution of geology and biology.
"A stromatolite is quite subtle to the untrained eye," said Van Kranendonk. "But once you know the details, you recognize that these wavy, wrinkly rocks have a structure different from that which can be explained by just geology."
Past Life on Mars?
Of course, the Outback isn't Mars, but what happened in the Dresser Formation a billion years ago and what happened on the Red Planet at roughly the same time share some eerie similarities.
Could Mars ever have supported life? In the Australian Outback, scientists from NASA's upcoming Mars 2020 mission
and their counterparts from the joint European-Russian ExoMars mission visited the oldest convincing evidence for
life on Earth to prepare for their own searches for signs of ancient life on Mars. The field lesson in astrobiology
in the Pilbara region is being applied in the near term by NASA, ESA and Roscosmos for mission planning,
and will also pay dividends when both rovers begin to send back science data and imagery
from the Red Planet [Credit: NASA/JPL-Caltech]
Between 3 billion and 4 billion years ago at the Mars 2020 landing site, Jezero Crater, a river flowed into a body of water the size of Lake Tahoe, depositing delta sediments packed with clay and carbonate minerals. The conditions were ideal for stromatolites to form on the shorelines, which is one key reason the rover team will be touching down there in February 2021. "It's hard to think of a better recipe for life to thrive—and for its record to be preserved—than the one we see at Jezero," said Ken Williford, deputy project scientist for Mars 2020 at JPL.
If stromatolites ever existed in Jezero or at Oxia Planum, the ExoMars landing site, the teams need to know what to look for, hence this trip to the Outback. But that's not the only reason they came.
"I organized this first joint Mars 2020-ExoMars science expedition so scientists from our two great missions could gain a new perspective on these one-of-a-kind stromatolites; a laboratory setting just can't provide the same context," said Mitch Schulte, Mars 2020 program scientist at NASA Headquarters in Washington. "That applies to the experience as a whole, too—the conversations, comparing of notes and planning for future exchanges that was done here in the Pilbara will go a long way to advance Mars science."
Two Missions, Two Rovers
While the two missions both seek to find evidence of past life, each is approaching the challenge in its own way. Touching down about a week after Mars 2020, the ExoMars rover, otherwise known as the Rosalind Franklin, carries a core drill that on two or more occasions will bore almost 7 feet (2 meters) into the Martian crust. The rover will analyze the samples onsite with a sophisticated suite of scientific instruments.
The coring mechanism on NASA's Mars 2020 rover drills shallower holes but is designed to collect more than 40 rock and soil core samples. There will be on-site analysis of rocks at the coring sites, and the samples themselves will be sealed in metal tubes that will ultimately be deposited by the rover at specific sites. Future missions could then retrieve those samples and return them to Earth for the sort of laboratory analysis that just isn't possible on Mars.
"These two Mars missions will be revolutionary because they are complementary," said Teresa Fornaro, a science team member for the Mars Organic Molecule Analyzer instrument aboard ExoMars. "Two different rovers with two different sets of instruments, exploring at the same time two different landing sites. Some of the capabilities of Mars 2020 in characterizing the surface environment could help guide ExoMars on where to drill. Conversely, knowledge of the alteration of possible organics as a function of depth by ExoMars could help Mars 2020 select the most interesting surface samples to collect for future return to Earth."
When the joint Mars 2020-ExoMars science Outback expedition concluded in late August, the science teams went their separate ways. But to those who honed their stromatolite-hunting skills in the Pilbara, the influence of the trip continues.
"What is happening working out here in the field is also happening in the halls of NASA and ESA," said Schulte. "Finding evidence of life on another world, if it ever existed, will require tenacity and a whole lot of brainpower. If there is a stromatolite in the range of the rovers, I think we have a good chance of finding it ... and we'll find it together. This trip will have helped with that."
The launch window for Mars 2020 opens on July 17, 2020. It will land at Mars' Jezero Crater on Feb. 18, 2021. The launch window for ExoMars opens July 25, 2020. It will land at Oxia Planum in March 2021.
A cache of 118 million-year-old fossilized dinosaur and bird feathers has been recovered from an ancient lake deposit that once lay beyond the southern polar circle.
Australian Feathered Polar Dinosaur [Credit: Peter Trusler]
Feathered dinosaur fossils are famous, but known from a handful of localities worldwide. Examples from the Southern Hemisphere are especially rare, and mainly include only isolated feathers.
An international team of scientists has analyzed a collection of 10 such fossil feathers found in Australia, which reveal an unexpected diversity of tufted hair-like 'proto-feathers' from meat-eating dinosaurs, together with downy body feathers, and wing feathers from primitive birds that would have been used for flight.
Uniquely, the fossil feathers from Australia were all entombed in fine muddy sediments that accumulated at the bottom of a shallow lake close to the South Pole during the Age of Dinosaurs.
"Dinosaur skeletons and even the fragile bones of early birds have been found at ancient high-latitudes before. Yet, to date, no directly attributable integumentary remains have been discovered to show that dinosaurs used feathers to survive in extreme polar habitats", said Dr Benjamin Kear from Uppsala University in Sweden, a leading author on the study.
"These Australian fossil feathers are therefore highly significant because they came from dinosaurs and small birds that were living in a seasonally very cold environment with months of polar darkness every year".
The fossil feathers were discovered in the Koonwarra Fish Beds Geological Reserve, which is a heritage listed site 145 km southeast of Melbourne in Victoria, Australia.
Carnivourous Dinosaur Protofeather from Koonwarra [Credit: Melbourne Museum]
"Fossil feathers have been known from Koonwarra since the early 1960s, and were recognized as evidence of ancient birds, but have otherwise received very little scientific attention. Our study is thus the first to comprehensively document these remains, which include new specimens that were examined using cutting-edge technologies", said Dr Thomas Rich of the Melbourne Museum in Australia, who has led numerous expeditions to the Koonwarra locality.
A suite of advanced microscopic and spectroscopic techniques was employed to determine the anatomy and preservation of the Koonwarra fossil dinosaur and bird feathers.
"The Koonwarra feathers are preserved in incredible detail", said fossil bird expert Professor Patricia Vickers-Rich of Monash University and the Swinburne University of Technology in Melbourne.
"There are even tiny filament-like structures that would have 'zipped' the feather vanes together, just as in the flight feathers of modern birds".
However, unlike the structurally complex feathers of birds today, which are characterized by interlocking branches called barbs and barbules, different kinds of small dinosaurs had coverings that comprised much more simpler hair-like 'proto-feathers'.
"Dinosaur 'proto-feathers' would have been used for insulation", said Dr Martin Kundrat, of Pavol Jozef Safarik University in Slovakia, a leading author on the study.
Early Bird Feather with Colour Patterning from Koonwarra [Credit: Melbourne Museum]
"The discovery of 'proto-feathers' at Koonwarra therefore suggests that fluffy feather coats might have helped small dinosaurs keep warm in ancient polar habitats".
Microscopic remains of possible melanosomes - cellular structures that contain colour pigments - were also detected on several of the fossil feathers found at Koonwarra.
These traces occurred across the uniformly dark feather surfaces, as well as in distinct bands that might represent original patterning from the polar dinosaurs and birds.
Melanic residues have been reported on fossil feathers from elsewhere around the world, and are widely acknowledged as indicators of dinosaur colouration.
The densely packed fossil melanosomes occurring on the Koonwarra feathers could suggest dark colours that perhaps assisted in camouflage, visual communication, and/or heat absorbance in cold polar climates.
Possible preservation of biomolecules was also assessed, but proved to be too degraded, and were apparently lost during weathering of the rock.
The Koonwarra fossil feathers provide the first record of dinosaur integument from the ancient polar regions, and hint what was once a global distribution of feathered dinosaurs and early birds.
Some of the fossil feathers found at Koonwarra are on display in the '600 Million Years' exhibition at the Melbourne Museum in Australia.
Despite bearing witness to its own increase in Earth's atmosphere by around 2.5 to 2.3 billion years ago, oxygen has had relatively little to say about its own early history until now. A recent EU-funded study provides a fresh perspective on one of Earth history's most significant stories—the rise of oxygen.
While the recent history of Earth's atmosphere can be accessed by directly measuring atmospheric gases trapped in ice cores, it may be surprising to know that a similarly faithful time capsule of atmospheric oxygen is not yet known for the majority of Earth history.
The rise of atmospheric oxygen is one of Earth history's greatest stories but this story is typically told through secondhand evidence, such as from proxies of sulfur stable isotope evidence from ancient rocks. Stable isotopes of sulfur are particularly helpful for understanding the time when oxygen first accumulated in Earth's atmosphere because they show a characteristic response to the increase in oxygen above 0.001% of today's atmospheric levels.
However, the record of how the sulfur isotope record in rocks responds to the first increases in atmospheric oxygen does not have a completely straightforward interpretation. Competition between global versus local, and original versus secondary, processes influence the preservation of chemical signals in ancient rocks. Accordingly, additional evidence is needed to support current interpretations of early atmospheric oxygen that are based on different proxies.
In a European-funded project involving an international team of researchers, newly published evidence from rocks younger than 2.31 billion years old from W. Australia now shows how stable isotope signals of sulfur that indicate exceedingly low oxygen may be recycled into rocks formed under increasing oxygen levels.
Oxygen itself is witness to this recycling. In fact, it is a characteristic isotope signal in oxygen that implies the formation of sulfur- and oxygen- bearing sulfates on the ancient continental surface at around 2.3 billion years ago. This sulfate was preserved in minerals, barites, in rocks that were formed in a marine environment close to shore, as evidenced by their coexistence with fossils from microbial mats, or stromatolites, unique wrinkly concave features (pictured in center of photo). Stable isotope results of oxygen and sulfur from the barites show how weathering of ancient rocks on the ancient Earth surface may prolong a signal that indicates a lack of atmospheric oxygen even after the rise of atmospheric oxygen.
The unique chemical, isotopic, signatures preserved in the reported barites hold further promise for unraveling the earliest history of oxygen gas production. Before substantial oxygen accumulated in the atmosphere, localized production of oxygen gas by microbial organisms (including the microbes that contributed to the aforementioned stromatolites) may have already been contributing to the oxidation, or the "rusting," of the Earth's surface. This early imprint of oxygen may, in the future, be similarly detected by the specific combination of sulfur and oxygen isotope signals that are detailed in the new study published in Nature Communications.
Swinburne and Museums Victoria have announced the discovery of several theropod bones, including a 20 centimeter long hand claw, from the Otway Coast of Victoria.
Fossilised 20 centimetre long hand claw of theropod discovered at Eric the West site on Victoria’s Otway Coast [Credit: Stephen Poropat/Museums Victoria]
The bones were found in the Eumeralla Formation, a geological deposit that is approximately 107 million years old.
Fossils of theropods—the group of dinosaurs that includes such famous predators as Tyrannosaurus and Velociraptor, as well as modern birds—are relatively rare in Australia. The new Victorian specimens were discovered at a site known as "Eric the Red West' on the Otway Coast between 2011 and 2017, by volunteers working on Dinosaur Dreaming team's annual digs.
These digs are held each February and are coordinated by husband and wife paleontologists, Swinburne's Professor Patricia Vickers-Rich and Dr. Thomas Rich from Museums Victoria.
Previously, the Eric the Red West site had produced the skeleton of Diluvicursor pickeringi, a unique species of ornithopod dinosaur that was described and named in 2018.
The new theropod fossils were found isolated rather than as part of a skeleton. This is because they were carried some distance from where the theropods died by ancient, deep, fast-flowing rivers. These rivers snaked through the then-narrow rift valley (now Bass Strait) that opened as Australia and Tasmania separated during the Early Cretaceous period, more than 110 million years ago.
Many of the theropod bones found at the Eric the Red West site are from a group of theropods called megaraptorids. Intriguingly, they look almost identical to those of the Australian megaraptorid theropod Australovenator wintonensis from western Queensland.
Australovenator lived around ten million years after—and thousands of kilometers further north than—the Victorian megaraptorid. This suggests that megaraptorid theropods roamed over a large part of Australia and for a long period of time.
The research on the new Victorian theropod remains was led by Swinburne's Dr. Stephen Poropat as part of a postdoctoral research fellowship in vertebrate palaeontology.
Artist's impression of Australovenator Wintonensis [Credit: Travis R. Tischler/ Australian Age of Dinosaurs Museum in Winton, Queensland]
According to Dr. Poropat, who has conducted research on Australian dinosaurs for several years, the presence of megaraptorid theropods in Victoria that are nearly indistinguishable from Australovenator—but older than it by around ten million years—is unusual.
"The similarities between the Victorian megaraptorid remains and Australovenator are striking," Dr. Poropat says.
"If we had found these theropod bones in Queensland, we would probably have called them Australovenator wintonensis. But they're from Victoria, which prompts the question: "Could one dinosaur species exist for more than ten million years, across eastern Australia?" Maybe."
Australovenator lived in Queensland around 95 million years ago, alongside several species of long-necked sauropod dinosaur (like Diamantinasaurus matildae and Savannasaurus elliottorum). However, the 107 million year-old rocks of western Victoria that produced the new theropod bones have not yielded a single scrap of sauropod bone.
"This is important, because it tells us that Australian megaraptorid theropods weren't entirely dependent on sauropods for food," says Dr. Poropat.
"We find megaraptorid teeth with sauropod carcasses in central Queensland all the time, but they seem to have been doing just fine in Victoria where sauropods seem to have been absent."
So were megaraptorid theropods relying on another food source in Victoria? Dr. Poropat thinks so. "Adult sauropods were many times heavier than adult megaraptorids, so attacking them would have been dangerous. What we do know is that another group of plant-eating dinosaurs—the ornithopods—were abundant in Victoria (based on bones) and in central Queensland (based on footprints).
"Although ornithopods might have been ideal meals for megaraptorids in both regions, Queensland's megaraptorids had another food choice—sauropod steaks! Whether they were fresh or on rotting carcasses, they would have been a pretty tempting item to have on the menu!"
The new theropod bones are held at Melbourne Museum. Another field trip to the Eric the Red West site is planned for November 2019. Dr. Poropat hopes that more megaraptorid bones might yet be found there.
New research into the chemistry of the oceans during ice ages is helping to solve a puzzle that has engaged scientists for more than two decades.
The Southern ocean, south-east of Tasmania [Credit: IMAS]
At issue is how much of the CO2 that entered the ocean during ice ages can be attributed to the 'biological pump', where atmospheric carbon is absorbed by phytoplankton and sequestered to the seafloor as organisms die and sink.
Solving the puzzle is important to improve the accuracy of climate models and inform understanding of how ocean processes may react to future climate change.
Led by IMAS and University of Liverpool scientists and published in Nature Communications, the study found ice age phytoplankton in the tropics absorbed high levels of CO2 due to fertilisation by iron-rich dust blowing into the ocean.
Lead author Dr Pearse Buchanan said that until now models had only been able to explain a portion of the CO2 that entered ice age oceans via the biological pump.
"During past ice ages, carbon levels were lower in the atmosphere and higher in the oceans than today, but scientific models aren't able to account for all of the additional CO2 that entered the ocean," Dr Buchanan said.
"The leading hypothesis has been that iron-rich dust blown from glacial landscapes stimulated phytoplankton growth in high latitudes, but this only explained around one-third of the extra CO2 absorbed through the biological pump: the other two-thirds was effectively 'missing'.
"We used an ocean model to look at the response to iron rich dust of phytoplankton in tropical waters, particularly a group of phytoplankton called "nitrogen fixers".
"These are able to biochemically 'fix' nitrogen from the atmosphere, much like nitrogen fixing bacteria that help legume crops thrive in nutrient poor soil.
"Marine nitrogen fixers are known to be important in the marine nitrogen cycle, and now we've shown they're also critically important in the marine carbon cycle.
"When we added iron to our ocean model, nitrogen fixers thrived, and their growth and subsequent sinking to the deep ocean can account for much of the missing CO2," Dr Buchanan said.
IMAS Associate Professor Zanna Chase said this solution was first proposed in 1997 but had gained little traction over the last two decades.
"The beauty of this approach is that it can explain almost all of the additional CO2 that phytoplankton transported into the oceans during the last Ice Age," Associate Professor Chase said.
"The increased activity of the biological pump in the tropics complemented that happening in colder waters, drawing higher levels of CO2 into the oceans and locking it away in the deep ocean.
"This pathway for carbon to the deep ocean is reduced today because less fertilising iron is being circulated by the wind and phytoplankton growth, including that of nitrogen fixers, is correspondingly limited, although there are signs that it has strengthened within the Pacific since the industrial revolution.
"Taking account of these links between the cycles of iron, nitrogen and carbon in our ocean and climate change models will make them better able to explain ocean processes and predict future changes.
"But how iron fertilisation of phytoplankton will evolve is currently uncertain, undermining our ability to predict the ocean's role in drawing CO2 out of the atmosphere in the coming centuries," Associate Professor Chase said.
Slime has been present on Earth for a very long time—almost 2 billion years, according to a recent reassessment of fossil evidence.
Credit: University of Oregon
In a study published this month in the journal Palaeogeography, Palaeoclimatology, Palaeoecology, UO geologist Greg Retallack and Xuegang Mao of China's Fujian Normal University confirm that a fossil from Western Australia is the planet's oldest known land-dwelling slime mold.
The fossil in question, Myxomitodes stirlingensi, is a hairpin-shaped trace of biological activity found in the rocks of the Stirling Range, a mountain region 200 miles southeast of Perth. Long the subject of scholarly controversy, the fossil has sparked debate both about the specific life form it represents as well as the paleoenvironment it inhabited.
"They have been interpreted as trails of metazoan animals and often as marine organisms," said Retallack, who is director of the Condon Fossil Collection at the Museum of Natural and Cultural History. "Though they resemble animal trails they probably were not. Slime molds make similar trails but lack any animal organization: no mouth, no gut, no anus, no nerves, no veins. And we are seeing these fossils at the surface of ancient terrestrial soils, making them additional evidence of life on land during the Paleoproterozoic Period."
Retallack said that while slime molds are not themselves multicellular, they might hold important clues about how multicellular organisms evolved.
"Myxomitodes were amoebae that live dispersed in soil, but these traces of their movement demonstrate that they could coalesce into a slug that wandered over the soil as a unit, possibly to sense better feeding opportunities or a place to sporulate, and then disaggregate once again into single cells," he said. "This may demonstrate an early stage in the evolution of multicellular creatures, bridging the gap between microbes and more complex life forms."
Australian researchers have found a new species of pterosaur in outback Queensland. The pterosaur, a prehistoric flying reptile, lived amongst the dinosaurs which roamed the Winton region around 96 million years ago. The apex aerial predator had a 4-metre wingspan and walked on all four limbs when on land.
Artist's impression of what the newly discovered pterosaur Ferrodraco lentoni looked like [Credit: Travis R. Tischler]
Fossilised pterosaur bones were found by grazier Bob Elliot on Belmont Station outside the tiny town in 2017, the first find of a pterosaur from the Winton Formation. A two-week dig at the site uncovered the most complete specimen of its kind in Australia.
The well-preserved find includes five partial vertebrae, eight limb bones, a large part of the jaw and skull, and 40 full and partial teeth of a previously unknown pterosaur species, with the findings published in Scientific Reports.
Lead author and Swinburne University of Technology PhD candidate Adele Pentland said it was incredible to be part of the discovery.
"We didn't really know what we were in for and we just kept on finding more material and it felt great," she said. "Pterosaurs are quite rare in the fossil record because their bones are hollow and the outer bone is normally only about a millimetre thick."
Reconstruction showing which parts of the skeleton the pterosaur fossils came from [Credit: Australian Age of Dinosaurs Museum]
Previously there were only 15 known fragmentary specimens of pterosaurs in Australia's fossil record, which makes it exciting to see this new pterosaur described, said palaeontologist Steven Salisbury of the University of Queensland, who was not involved in the study.
"Every new little bit makes a big difference to understanding their evolutionary relationships and significance," Dr Salisbury said.
Another reason pterosaur fossils are so rare is because scientists suspect they were soaring animals, so they would have spent a lot of their time over the ocean.
"Probably a lot of the time they died on the wing," Dr Salisbury said. "And then for their carcasses to get preserved as fossils they would have to survive and get to the bottom of the ocean. There's plenty of things in the ocean that would love to munch on a pterosaur."
A volunteer working on part of the Ferrodraco lentoni fossil [Credit: Australian Age of Dinosaurs Museum]
In Australia, the smaller pterosaur fossils would have to survive in amongst all the dinosaur bones and other fossils.
"Pterosaurs aren't always obvious, but you know slowly as more and more people are looking, things like this are emerging which is good," Dr Salisbury said.
The researchers has dubbed the new species Ferrodraco lentoni, or Lenton's Iron Dragon. It's been nicknamed "Butch" for short, in honour of former Winton mayor Graham "Butch" Lenton.
Butch looks quite similar to some of the pterosaurs found in England, Dr Salisbury said, which is what scientists have long suspected based on previous pterosaur fossil finds.
The pterosaur's small front teeth showed it was a new species [Credit: Australian Age of Dinosaurs Museum]
Given their flight capabilities, researchers expect to see closely related pterosaur species found all over the world. But Butch's unique teeth set it apart from other similar species found elsewhere, Ms Pentland said.
This pterosaur was found to have a smaller first-tooth pair and smaller teeth further back in the mouth, compared to previously discovered species. Researcher aren't yet sure why it has smaller teeth than usual.
"It might have something to do with the type of fish that it fed on," Ms Pentland said. "Hopefully with more material that we [might] find ... we'll have a better idea of the bigger picture."
While some groups of pterosaurs persisted right up until the end of the Cretaceous period 65 million years ago, this group of pterosaurs was thought to have died out 94 million years ago. But this find, in the slightly younger Winton Formation, suggests they might have survived later in Australia than elsewhere, perhaps as late as 90 million years ago.
The discovery was the first find of pterosaur fossils in the area [Credit: Australian Age of Dinosaurs Museum]
But Dr Salisbury warns we have to remember we don't have a very substantial pterosaur fossil record to speculate on here. "It's very much piecing together little pieces of a probably much larger puzzle," he said. "You have to be careful how you read it, because it's very likely that a lot of these groups of pterosaurs persisted longer, but we just don't have the fossil record to show for it. For instance in Australia, anything younger than this part of the Winton Formation, so from about 92 million years ago until the end of the age of dinosaurs we've got virtually nothing in terms of any potential fossil record."
The Winton region is a treasure trove of prehistoric fossils and world-renowned dinosaur trackways. But Australian Age of Dinosaurs Museum executive chairman David Elliot said it was still a huge find.
"We hold digs every year but it's not often that we get something different, that's so different and so exciting," he said. "What makes it really exciting now is we're just starting to get a whole ecosystem of dinosaurs together."
Mr Elliot said there's been a lot of work to get the find to this stage. "We're so lucky to have Adele," he said. "I think it's got to be the coolest PhD project that's ever been done in Australia and she's done an amazing job of it."
Coral reefs around the world are under increasing stress due to a combination of local and global factors. As such, long-term investigation is becoming increasingly important to understanding ecosystem responses.
Soft coral are now dominating large areas of the shadow reef which in 1928 had many species of hard corals too [Credit: Professor Maoz Fine, Bar-Ilan University]
A new study -- the longest coral reef survey to date - provides an in-depth look at Australia's Great Barrier Reef over the past 91 years. Published today in the journal Nature Communications by researchers at Bar-Ilan University and Interuniversity Institute for Marine Sciences in Israel, and the University of Queensland in Australia, the study concludes that since 1928 intertidal communities have experienced major phase-shifts as a result of local and global environmental change, leaving few signs that reefs will return to their initial state in the near future.
"This is a unique opportunity to look at long-term changes on an inshore reef system," said author Prof. Hoegh-Guldberg from the University of Queensland. "Most studies are only a few decades in length - this one is just short of 100 years of study."
In 1928 the Great Barrier Reef Committee and the Royal Society of London sent an expedition to study the Great Barrier Reef. Members of the expedition, pioneers in coral biology and reef studies, lived on Low Isles for over a year. During this time they documented environmental conditions surrounding the coral reefs of the Low Isles, as well as the community structure of tidal and subtidal communities, using, for the first time, a diving helmet.
The reef-flat at the Low Isles, which was covered with living branching Acropora corals in 1928 is now mostly dead [Credit: Professor Maoz Fine, Bar-Ilan University]
"What was critical to our study was how carefully the expedition in 1928 undertook their study," said lead author Prof. Maoz Fine, of the Mina and Everard Goodman Faculty of Life Sciences at Bar-Ilan University and the Interuniversity Institute for Marine Sciences. "We were literally able to go the exact spot and identify features that the 1928 expedition saw."
Members of the expedition produced aerial photography-based mapping of the island. This highly-accurate mapping enabled researchers in the current study to follow in their footsteps and revisit and sample the exact intertidal and subtidal locations previously explored 76, 87 and 91 years later, thereby forming the longest ecological survey to date.
In the latest investigation, carried out in three phases in 2004, 2015 and 2019, researchers discovered that intertidal communities have experienced major phase-shifts over nearly a century. Species richness and diversity of these communities systematically declined for corals and other invertebrates. Specifically, massive corals have replaced branching corals, and soft corals have become much more numerous.
These are patches of branching Acropora corals during low tide at Low Isles [Credit: Professor Maoz Fine, Bar-Ilan University]
"The degree to which reefs may shift from one state to another following environment change was overwhelming," said Prof. Fine. "The long-term implications of these changes highlight the importance of avoiding phase shifts in coral reefs which may take many decades to repair, if at all." According to Fine the multi-year study also illustrates the importance of considering multiple factors in the decline, and potential recovery, of coral reefs, and the importance of tracking changes in community structure, as well as coral abundance, over long periods.
Coral reefs are highly sensitive to environmental change. Multiple stressors, in isolation or in combination, may lead to dramatic deterioration that can result in loss of reefs and their ecological services for many years. In the future the researchers hope to use the same methods to reconstruct data from other parts of the world where historical expeditions accurately documented similar communities.
Scientists have found exceptionally preserved microbial remains in some of Earth's oldest rocks in Western Australia - a major advance in the field, offering clues for how life on Earth originated. The UNSW researchers found the organic matter in stromatolites - fossilised microbial structures - from the ancient Dresser Formation in the Pilbara region of Western Australia.
Photomicrograph of pyritized stromatolites from the 3.5 billion-year-old Dresser Formation. The stromatolites are delineated by pyrite, also known as fool's gold [Credit: UNSW Sydney]
The stromatolites have been thought to be of biogenic origin ever since they were discovered in the 1980s. However, despite strong textural evidence, that theory was unproven for nearly four decades, because scientists hadn't been able to show the definitive presence of preserved organic matter remains - until today's publication in prestigious journal Geology.
"This is an exciting discovery - for the first time, we're able to show the world that these stromatolites are definitive evidence for the earliest life on Earth," says lead researcher Dr Raphael Baumgartner, a research associate of the Australian Centre for Astrobiology in Professor Martin Van Kranendonk's team at UNSW.
Professor Van Kranendonk says the discovery is the closest the team have come to a "smoking gun" to prove the existence of such ancient life.
"This represents a major advance in our knowledge of these rocks, in the science of early life investigations generally, and - more specifically - in the search for life on Mars. We now have a new target and new methodology to search for ancient life traces," Professor Van Kranendonk says.
Drilling deep, looking closely
Ever since the Dresser Formation was discovered in the 1980, scientists have wondered whether the structures were truly microbial and therefore the earliest signs of life.
"Unfortunately, there is a climate of mistrust of textural biosignatures in the research community. Hence, the origin of the stromatolites in the Dresser Formation has been a hotly debated topic," Dr Baumgartner says.
"In this study, I spent a lot of time in the lab, using micro-analytical techniques to look very closely at the rock samples, to prove our theory once and for all."
Stromatolites in the Dresser Formation are usually sourced from the rock surface, and are therefore highly weathered. For this study, the scientists worked with samples that were taken from further down into the rock, below the weathering profile, where the stromatolites are exceptionally well preserved.
"Looking at drill core samples allowed us to look at a perfect snapshot of ancient microbial life," Dr Baumgartner says.
Using a variety of cutting-edge micro-analytical tools and techniques - including high-powered electron microscopy, spectroscopy and isotope analysis - Dr Baumgartner analysed the rocks.
He found that the stromatolites are essentially composed of pyrite - a mineral also known as 'fool's gold' - that contains organic matter.
"The organic matter that we found preserved within pyrite of the stromatolites is exciting - we're looking at exceptionally preserved coherent filaments and strands that are typically remains of microbial biofilms," Dr Baumgartner says.
The researchers say that such remains have never been observed before in the Dresser Formation, and that actually seeing the evidence down the microscope was incredibly exciting.
"I was pretty surprised - we never expected to find this level of evidence before I started this project. I remember the night at the electron microscope where I finally figured out that I was looking at biofilm remains. I think it was around 11pm when I had this 'eureka' moment, and I stayed until three or four o'clock in the morning, just imaging and imaging because I was so excited. I totally lost track of time," Dr Baumgartner says.
Clues for search for life on Mars
Just over two years ago, Dr Baumgartner's colleague Tara Djokic, a UNSW PhD candidate, found stromatolites in hot spring deposits in the same region in WA, pushing back the earliest known existence of microbial life on land by 580 million years.
"Tara's main findings were these exceptional geyserite deposits that indicate that there have been geysers in this area, and therefore fluid expulsions on exposed land surface," Dr Baumgartner says.
"Her study was focused on the broader geological setting of the paleo-environment - lending support to the theory that life originated on land, rather than in the ocean - whereas my study really went deeper on the finer details of the stromatolite structures from the area."
The scientists say that both studies are helping us answer a central question: where did humanity come from?
"Understanding where life could have emerged is really important in order to understand our ancestry. And from there, it could help us understand where else life could have occurred - for example, where it was kick-started on other planets," Dr Baumgartner says.
Just last month, NASA and European Space Agency (ESA) scientists spent as week in the Pilbara with Martin Van Kranendonk for specialist training in identifying signs of life in these same ancient rocks. It was the first time that Van Kranendonk shared the region's insights with a dedicated team of Mars specialists - a group including the Heads of NASA and ESA Mars 2020 missions.
"It is deeply satisfying that Australia's ancient rocks and our scientific know-how is making such a significant contribution to our search for extra-terrestrial life and unlocking the secrets of Mars," says Professor Van Kranendonk.
The Tasmanian tiger, or thylacine, was one of Australia's most enigmatic native species. It was the largest marsupial predator to survive until the arrival of Europeans but carried its babies in a pouch like a kangaroo or koala.
Early naturalists named the Tasmanian tiger Thylacinus cynocephalus, which could be translated roughly as a ‘pouched dog-head’ [Credit: TMAG Tasmanian Museum and Art Gallery]
Tragically, the last known thylacine died in Hobart in 1936 after a bounty was placed on its head and after decades of hunting by farmers.
Haunting photographs and film of the last known thylacines and a wealth of museum specimens, reveal an uncanny animal with its wolf head and tiger stripes.
A new study led by by Professor Andrew Pask and myself at the University of Melbourne, published in the journal Genome Research, has made the first headway into answering this question by comparing the complete DNA sequences of the thylacine and wolf. And it confirms that the resemblance between the two isn't just skin deep.
The thylacine and placental canids such as wolves, dogs and foxes, are perhaps the most striking example of convergent evolution. Through this process, distantly related animals can evolve similar forms in response to shared environmental challenges.
Despite having a last common ancestor at least 160 million years ago, these apex predators—who are at the top of the food chain and are not preyed upon by other animals—had nearly identical skull shapes with similar biomechanical properties.
Their resemblance was so evident to early naturalists that they gave it the scientific name, Thylacinus cynocephalus, which could be translated roughly as a 'pouched dog-head'. There is even evidence that they filled similar ecological niches, with the arrival of the dingo in Australia implicated in the thylacine's extinction on the mainland.
How did the marsupial thylacine and the wolf, a placental mammal, come to look so similar? [Credit: TMAG Tasmanian Museum and Art Gallery]
In 2018, our team first sequenced the DNA of thylacine from a joey, labelled C5757, and assembled a draft genome sequence. However, analysis of genes revealed little evidence of molecular similarities or similar pressures imposed by natural selection. This presented a conundrum, as protein-coding genes have critically important biological functions.
Now, by analysing rates of evolution across the genomes of 61 vertebrate species, our research has discovered hundreds of non-coding DNA elements in the thylacine and wolf. These elements, called 'TWARs' (thylacine-wolf accelerated regions), show evidence of natural selection in both species, but lay outside of the much-better understood protein-coding regions of the genome.
In the past, these non-coding regions were considered 'junk DNA', but today it is recognised that they play important roles as regulators of genes during development, when most of the traits that make species unique arise.
TWARs were particularly abundant near genes involved in the development of bone, cartilage and muscles of the facial region. This suggests that natural selection acted in very similar ways in both species, building their shared facial structure by tweaking the same underlying developmental processes.
These findings lend support to one side of a long-running debate in the field of evolutionary developmental biology (known as 'Evo-Devo'), regarding the relative importance of protein-coding genes and non-coding regulatory elements in evolution.
Paradoxically, the very fact that genes do so much heavy lifting may actually limit their role in adaptation. Because one gene may be important for the development of multiple structures during development, a mutation can cause collateral damage throughout the body.
The heads of the thylacine and wolf were nearly identical in shape. During their development, their similarities became most pronounced as they approached weaning and transitioned to their carnivorous adult feeding ecology [Credit: Dr Charles Feigin]
In contrast, non-coding regulatory elements typically control a gene's activity in just one or a few body regions, making them more tolerant of mutations than the genes themselves. This unique molecular property gives regulatory regions greater evolutionary 'flexibility' and increases the chances of acquiring a beneficial mutation without any negative side effects.
So-called 'junk DNA' may actually be the primary driver of diversity in animals and could be the key to understanding convergent evolution between the thylacine and wolf. Unexpectedly, in the course of this work, our team also found that the thylacine and wolf showed evidence of convergence in regulatory elements of brain genes. This finding was startling, as the brains of marsupials and placentals show major structural differences.
Little was documented about the thylacine's hunting or social behaviours before their untimely extinction, but these signatures of convergent evolution present the tantalising possibility that these distant cousins may have shared more than just their looks.
Palorchestid marsupials, an extinct group of Australian megafauna, had strange bodies and lifestyles unlike any living species, according to a study published in the open-access journal PLOS ONE by Hazel Richards of Monash University, Australia and colleagues.
Ancient Australia was home to strange marsupial giants, some weighing over 1,000 kg [Credit: Hazel Richards (2019)]
For most of the last 25 million years, eastern Australia was home to a now-extinct group of marsupials called palorchestids. These animals are well known for their large size, strange tapir-like skulls, and large claws, but so far there has been no detailed study of their limb morphology.
In this study, Richards and colleagues examined more than 60 fossil specimens of palorchestids of varying geologic ages to characterize the function and evolution of their arms and legs.
Over the course of their evolution, palorchestids grew larger and stranger. Using limb proportions as a proxy for body size, these authors estimated that the latest and largest of the palorchestids may have weighed over 1,000kg. Furthermore, their forelimbs were extremely muscular and were likely adapted for grabbing or scraping at leaves and branches.
Uniquely among known mammals, the elbow joints of the largest palorchestids appear to have been immobile and fixed at roughly a 100-degree angle, so that the arms served as permanently flexed food-gathering tools.
This study provides the first formal description of limb morphology in palorchestid marsupials and reveals a group of giant herbivores that probably filled a niche no longer occupied in modern Australian ecosystems.
Fossil remains are still missing for certain parts of the palorchestid body, such as the shoulders and wrists, but the authors are hopeful that more material may be found in existing museum collections.
The authors add: "This study has allowed us for the first time to appreciate just how huge these mega-marsupial palorchestids were, while also providing the first comprehensive view of a strange limb anatomy unprecedented in the mammalian world. This research reveals yet more about the diversity of unique large marsupials that once roamed Australia not so long ago."
An in-depth analysis of the skull biomechanics of a giant extinct kangaroo indicates that the animal had a capacity for high-performance crushing of foods, suggesting feeding behaviours more similar to a giant panda than modern-day kangaroo.
Artist's representation of a short-faced kangaroo species that persisted in Australia up until about 42,000 years ago [Credit: Copyright Nobu Tamura]
The new findings, published in PLOS ONE, support the hypothesis that some short-faced kangaroos were capable of persisting on tough, poor-quality vegetation, when more desirable foods were scarce because of droughts or glacial periods.
"The skull of the extinct kangaroo studied here differs from those of today's kangaroos in many of the ways a giant panda's skull differs from other bears," said Rex Mitchell, post-doctoral fellow in the Department of Anthropology at the University of Arkansas. "So, it seems that the strange skull of this kangaroo was, in a functional sense, less like a modern-day kangaroo's and more like a giant panda's."
There are substantial differences in skull morphology between the giant panda, which is adapted to browsing tough vegetation, and other bears [Credit: D. Rex Mitchell]
Mitchell used computed tomography scans to create three-dimensional models of the skull of Simosthenurus occidentalis, a well-represented species of short-faced kangaroo that persisted until about 42,000 years ago. Working with the models, Mitchell performed bite simulations to examine biomechanical performance. The resulting forces at the jaw joints and biting teeth were measured, as well as stress experienced across the skull during biting.
Mitchell compared the findings from the short-faced kangaroo to those obtained from models of the koala, a species alive today with the most similar skull shape. These comparisons demonstrated the importance of the extinct kangaroo's bony, heavily reinforced skull features in producing and withstanding strong forces during biting, which likely helped the animal crush thick, resistant vegetation such as the older leaves, woody twigs and branches of trees and shrubs. This would be quite different than the feeding habits of modern Australian kangaroos, which tend to feed mostly on grasses, and would instead be more similar to how giant pandas crush bamboo.
In overall proportions, the skull of the short-faced kangaroo more closely resembled a koala than the modern-day Eastern Grey kangaroo [Credit: D. Rex Mitchell]
"Compared to the kangaroos of today, the extinct, short-faced kangaroos of ice age Australia would be a strange sight to behold," Mitchell said.
They included the largest kangaroo species ever discovered, with some species estimated to weigh more than 400 pounds. The bodies of these kangaroos were much more robust than those of today -- which top out at about 150 pounds -- with long muscular arms and large heads shaped like a koala's. Their short face offered increased mechanical efficiency during biting, a feature usually found in species that can bite harder into more resistant foods. Some species of these extinct kangaroos had massive skulls, with enormous cheek bones and wide foreheads.
Bite mechanical stress maps generated for koala, left, and short-faced kangaroo [Credit: D. Rex Mitchell]
"All this bone would have taken a lot of energy to produce and maintain, so it makes sense that such robust skulls wouldn't have evolved unless they really needed to bite hard into at least some more resistant foods that were important in their diets," Mitchell said.
The short face, large teeth, and broad attachment sites for biting muscles found in the skulls of the short-faced kangaroo and the giant panda are an example of convergent evolution, Mitchell said, meaning these features probably evolved in both animals for the purpose of performing similar feeding tasks.
