The extreme wet and dry periods Mongolia has experienced in the late 20th and early 21st centuries are rare but not unprecedented and future droughts may be no worse, according to an international research team that includes a University of Arizona scientist.

Kevin Anchukaitis (plaid shirt) and Oyunsanaa Byambasuren (orange chainsaw chaps) taking pieces of wood from dead trees on Mongolia's Uurgat lava field. The researchers use tree rings to create a record of Mongolia's droughts stretching two centuries into the past [Credit: Neil Pederson © 2013]

The research team developed a climate record stretching 2,060 years into Mongolia's past by using the natural archive of weather conditions stored in the annual rings of Siberian pines. The 10 researchers then combined that information on past climate with computer models that can project future regional climate.

The most recent extended drought in Mongolia lasted from 2000 to 2010 and resulted in major livestock die-offs and a massive migration of nomadic herders to the capital city.

"We were able to quantify how unusual this drought was," said co-author Kevin J. Anchukaitis, a University of Arizona associate professor of geography and development. "The drought was not unprecedented, but it has a 900-year return interval. It's a once-in-a-millennium drought."

Finding that future droughts would likely be no worse than those of the past was a surprise, said Anchukaitis, who led the modeling team. In other semi-arid regions of the world that he has studied such as California and the Mediterranean, global warming has already changed precipitation and temperature patterns and thereby increased the risk of long-term drought.

Mongolia, a landlocked country in central Asia, has long, cold winters and short summers. Much of the country is cold, semi-arid grasslands that resemble eastern Montana.

Lead author Amy Hessl of West Virginia University said, "You would expect, based on everything we've been thinking about and reading as climate scientists, that elevated temperatures are going to lead to more severe droughts in semi-arid regions. But the models did not project increased frequency or severity of droughts."

Researchers Kevin Anchukaitis and Amy Hessl walk across the Khorgo lava field in central Mongolia to collect cross-sections of dead trees. The researchers use tree rings to create a record of Mongolia's droughts stretching two centuries into the past [Credit: Neil Pederson © 2012]

The timing of the rainy season is the likely cause, the researchers said. Mongolia's rainy season is in the summer, the warmer time of the year, whereas California and the Mediterranean have winter rains and dry summers. As global temperatures increase, continental regions with summer rains may get more precipitation, offsetting the effects on plants of higher temperatures.

The team's research paper, "Past and Future Drought in Mongolia," has been published in Science Advances. A complete list of the authors is at the bottom of this release. National Geographic and the National Science Foundation funded the research.

Anchukaitis, who also has appointments in geosciences and in the UA Laboratory of Tree-Ring Research, is interested in how past and current civilizations dealt with drought and climate variability. This new research is an outgrowth of previous research he, Hessl and their colleagues conducted to figure out how past climate influenced the Mongol civilization.

Anchukaitis and his colleagues used their tree-ring record of past climate in Mongolia to reconstruct what the annual Palmer Drought Severity Index, or PDSI, would have been going back in time 2,060 years. The PDSI combines both temperature and precipitation to get a measure of soil moisture, one measure of how water-stressed a plant would be.

He and his colleagues combined the reconstruction of past annual PDSI measures with a set of climate model simulations called the Community Earth System Model to understand what influenced the Mongolian droughts for the period from 850 to 2100.

The Uurgat lava field with the Khangai Mountains in the background and the seasonal homes of nomadic herders in the lower right. An international team of researchers took wood samples of the Siberian pines growing on the lava field to construct a drought chronology reaching two centuries into the past [Credit: Scott Nichols]

The model incorporates information about past solar variability, volcanic eruptions, land use changes and carbon dioxide emissions. For projections to the end of the 21st century, the model uses the future emissions scenario called RCP 8.5, in which the rate of emissions of greenhouse gases continues to increase.

Even with the highest level of greenhouse gas emissions and rising global temperatures, the model simulations indicate that future droughts in Mongolia would be no more severe than those of the past.

"There's a tug of war between trends toward increased rainfall and more evaporative demand because of hotter temperatures. There's uncertainty about which will win this tug of war," Anchukaitis said.

"The simulations say that Mongolia dries between now and about 2050 because of higher temperatures, but then it turns around because of the increase in precipitation," he said.

Many people in Mongolia are nomadic pastoralists. They are particularly affected by the vagaries of weather and climate, because the combination of winter and summer temperatures plus rainfall controls the number of cattle the grassland can support.

"What to me stands out is this deep uncertainty about the future, particularly when you have a society that is so vulnerable to climate variability," he said, adding that uncertainty makes it hard to plan for coping with future climate change.

Anchukaitis said one of his next steps is translating the team's estimates of future soil moisture into estimates of the future productivity of Mongolia's grasslands.

Author: Mari N. Jensen | Source: University of Arizona [March 14, 2018]

Scientists have peered into the brain of a prehistoric creature that lived around 520 million years ago. Fifteen fossils of the ancient predator were recently discovered in Greenland, which had fortunately escaped the ravages of time and elements.

An artist's reconstruction of the 520-million-year-old Kerygmachela kierkegaardi depicts the ancient species as a formidable ocean predator [Credit: Nature Communications (2018)]

This allowed the creature’s nervous tissue to be fossilized, providing researchers with new insights into panarthropods' evolutionary developments. Panarthropods are an animal group that include creatures such as tardigrades or water bears, velvet worms and arthropods, such as insects.

“The findings shed light on the ancestral condition of the panarthropod brain and the origin of complex arthropod compound eyes. The new material, furthermore, provides novel information on the overall anatomy of Kerygmachela,” the researchers wrote in the new study, published in the journal Nature Communications.

The newly discovered fossils belonged to a now-extinct species called Kerygmachela kierkegaardi. The prehistoric creature swam across the Earth’s oceans during the Cambrian explosion — an era that saw the emergence of incredible and rapid diversity among life forms over a short period of time.

The ancient creature measured between one to ten inches and is flanked by 11 wrinkly flaps on both sides of the body. The predator also sported a round head and an elongated tail spine. United Kingdom-based paleontologist Jakob Vinther, who led the study along with Tae-Yoon Park of the Korea Polar Research Institute, told National Geographic the creature’s forward-facing appendages grabbed onto prey, “making lives miserable for other animals.”

The ancient creature measures between one to ten inches and is flanked by 11 wrinkly flaps on both sides of the body [Credit: Tae-Yoon Park/Nature Communications]

The new study challenges previous theories that claimed the common ancestor of all panarthropods had complex three-part brain. Instead, the researchers argue the new evidence indicated the common ancestor of panarthropods, as well as invertebrate panarthropods and vertebrates, did not have complex brains.

Researchers believe despite its simple brain, the Kerygmachela’s eyes were likely complex enough to form images. The ancient predator’s eyes likely mirror the smaller and much simpler eyes of modern-day tardigrades and velvet worms.

However, some scientists appear to be unconvinced of the new details.

“If they’re going to say that the brain of Kerygmachela is like that of a tardigrade, you have to be really, really careful,” Nicholas Strausfeld told National Geographic. “Because it might not be.”

“The discovery of the simple unipartite brain in stem-group euarthropods corroborates the ancestral simplicity of the panarthropod brain, and also suggests that the complex neural concentrations, such as tripartite brains in euarthropods and chordates, are the result of convergent adaptations,” the researchers concluded.

Author: India Aishani Ashok | Source: International Business Times [March 13, 2018]

The question of whether the Late Jurassic dino-bird Archaeopteryx was an elaborately feathered ground dweller, a glider, or an active flyer has fascinated palaeontologists for decades. Valuable new information obtained with state-of-the-art synchrotron microtomography at the ESRF, the European Synchrotron (Grenoble, France), allowed an international team of scientists to answer this question in Nature Communications. The wing bones of Archaeopteryx were shaped for incidental active flight, but not for the advanced style of flying mastered by today's birds.

The Munich specimen of the transitional bird Archaeopteryx. It preserves a partial skull (top left), shoulder girdle and both  wings slightly raised up (most left to center left), the ribcage (center), and the pelvic girdle and both legs in a 'cycling' posture (right); all connected by the vertebral column from the neck (top left, under the skull) to the tip of the tail (most right). Imprints of its wing feathers are visible radiating from below the shoulder and vague imprints of the tail plumage can be recognized extending from the tip of the tail [Credit: ESRF/Pascal Goetgheluck]

Was Archaeopteryx capable of flying, and if so, how? Although it is common knowledge that modern-day birds descended from extinct dinosaurs, many questions on their early evolution and the development of avian flight remain unanswered. Traditional research methods have thus far been unable to answer the question whether Archaeopteryx flew or not. Using synchrotron microtomography at the ESRF's beamline ID19 to probe inside Archaeopteryx fossils, an international team of scientists from the ESRF, Palacký University, Czech Republic, CNRS and Sorbonne University, France, Uppsala University, Sweden, and Bürgermeister-Müller-Museum Solnhofen, Germany, shed new light on this earliest of birds.

Reconstructing extinct behaviour poses substantial challenges for palaeontologists, especially when it comes to enigmatic animals such as the famous Archaeopteryx from the Late Jurassic sediments of southeastern Germany that is considered the oldest potentially free-flying dinosaur. This well-preserved fossil taxon shows a mosaic anatomy that illustrates the close family relations between extinct raptorial dinosaurs and living dinosaurs: the birds. Most modern bird skeletons are highly specialised for powered flight, yet many of their characteristic adaptations in particularly the shoulder are absent in the Bavarian fossils of Archaeopteryx. Although its feathered wings resemble those of modern birds flying overhead every day, the primitive shoulder structure is incompatible with the modern avian wing beat cycle.

The Munich specimen of Archaeopteryx at beamline ID19 at the ESRF. The limestone plate was mounted on a rotating sample stage and the beam is here centered on the skull using lasers. The X-ray beam, coming from the right of the picture, travels through the sample and arrives at the detector (visible left) where a camera records the signal [Credit: ESRF/Pascal Goetgheluck]

"The cross-sectional architecture of limb bones is strongly influenced by evolutionary adaptation towards optimal strength at minimal mass, and functional adaptation to the forces experienced during life," explains Prof. Jorge Cubo of the Sorbonne University in Paris. "By statistically comparing the bones of living animals that engage in observable habits with those of cryptic fossils, it is possible to bring new information into an old discussion," says senior author Dr. Sophie Sanchez from Uppsala University, Sweden

Archaeopteryx skeletons are preserved in and on limestone slabs that reveal only part of their morphology. Since these fossils are among the most valuable in the world, invasive probing to reveal obscured or internal structures is therefore highly discouraged. "Fortunately, today it is no longer necessary to damage precious fossils," states Dr. Paul Tafforeau, beamline scientist at the ESRF. "The exceptional sensitivity of X-ray imaging techniques for investigating large specimens that is available at the ESRF offers harmless microscopic insight into fossil bones and allows virtual 3D reconstructions of extraordinary quality. Exciting upgrades are underway, including a substantial improvement of the properties of our synchrotron source and a brand new beamline designated for tomography. These developments promise to give even better results on much larger specimens in the future."

Dennis Voeten indicates the bone wall thickness of the 'Chicken Wing' specimen of Archaeopteryx on the top computer screen for comparison against the bone walls of a primitive pterosaur on the bottom screen. A three-dimensional model of the 'Chicken Wing' is held up, the referred bone cross section is that of the humerus, the uppermost arm bone visible most right on the 3-D-printed model [Credit: ESRF]

Scanning data unexpectedly revealed that the wing bones of Archaeopteryx, contrary to its shoulder girdle, shared important adaptations with those of modern flying birds. "We focused on the middle part of the arm bones because we knew those sections contain clear flight-related signals in birds," says Dr. Emmanuel de Margerie, CNRS, France. "We immediately noticed that the bone walls of Archaeopteryx were much thinner than those of earthbound dinosaurs but looked a lot like conventional bird bones," continues lead author Dennis Voeten of the ESRF. "Data analysis furthermore demonstrated that the bones of Archaeopteryx plot closest to those of birds like pheasants that occasionally use active flight to cross barriers or dodge predators, but not to those of gliding and soaring forms such as many birds of prey and some seabirds that are optimised for enduring flight."

"We know that the region around Solnhofen in southeastern Germany was a tropical archipelago, and such an environment appears highly suitable for island hopping or escape flight," remarks Dr. Martin Röper, Archaeopteryx curator and co-author of the report. "Archaeopteryx shared the Jurassic skies with primitive pterosaurs that would ultimately evolve into the gigantic pterosaurs of the Cretaceous. We found similar differences in wing bone geometry between primitive and advanced pterosaurs as those between actively flying and soaring birds," adds Vincent Beyrand of the ESRF.

Since Archaeopteryx represents the oldest known flying member of the avialan lineage that also includes modern birds, these findings not only illustrate aspects of the lifestyle of Archaeopteryx but also provide insight into the early evolution of dinosaurian flight. "Indeed, we now know that Archaeopteryx was already actively flying around 150 million years ago, which implies that active dinosaurian flight had evolved even earlier!" says Prof. Stanislav Bureš of Palacký University in Olomouc. "However, because Archaeopteryx lacked the pectoral adaptations to fly like modern birds, the way it achieved powered flight must also have been different. We will need to return to the fossils to answer the question on exactly how this Bavarian icon of evolution used its wings," concludes Voeten.

It is now clear that Archaeopteryx is a representative of the first wave of dinosaurian flight strategies that eventually went extinct, leaving only the modern avian flight stroke directly observable today.

Source: European Synchrotron Radiation Facility [March 13, 2018]

Fossils of six new species of pterosaurs - giant flying reptiles that flew over the heads of the dinosaurs - have been discovered by a research team led by the Milner Centre for Evolution at the University of Bath, revealing that this lineage was killed off in its prime. An analysis of the fossils, published in the open access journal PLOS Biology shows that, contrary to previous studies, there was still remarkable diversity among pterosaurs up to the point of their extinction.

Some of the Moroccan pterosaur fossils from the study. Top: the mandible (lower jaw) of Alcione elainus, a small pterosaur newly described in this paper. Bottom: part of the ulna (forearm bone) from a giant pterosaur, tentatively identified as Arambourgiania. Note the different scales - the mandible is less than 20 cm long, while the ulna is more than 40 cm long; Arambourgiania would have had a wingspan more than three times that of Alcione [Credit: pbio.2001663]

Pterosaurs - prehistoric reptiles popularly known as pterodactyls - were flying cousins of the dinosaurs. Soaring on skin wings supported by a single huge finger, they were the largest animals ever to take wing.

The pterosaurs were previously thought to be declining before the mass extinction at the end of the Cretaceous period, which was caused by an asteroid impact 66 million years ago. However, hundreds of new fossils from the end of the Cretaceous, discovered at sites in northern Morocco, show that the region supported seven species of pterosaur from three different families. It was thought that the rarity of pterosaur fossils from the end of the dinosaur era meant that they were slowly going extinct. But the new study shows that the data had been misleadingly skewed by the dearth of fossils and that the pterosaurs at this time were actually far more diverse than thought.

The new pterosaurs ranged in wingspan from a little over two meters to almost ten meters (from 6 to 30 feet) - almost three times bigger than the largest living bird - and weighed up to 200 kg (440 pounds). The fossils date to just over 66 million years ago, the very end of the Cretaceous period, making these pterosaurs among the last of their kind on Earth. As well as the diversity in size, the authors were also able to show that the species differed significantly in the shape and size of parts of their bodies (such as beak shape, neck length, and wing proportions), suggesting that they occupied distinct ecological niches.

Dr Nick Longrich, from the Milner Centre for Evolution and the Department of Biology & Biochemistry at the University of Bath, and the study's lead author, said: "To grow so large and still be able to fly, pterosaurs evolved incredibly lightweight skeletons, with the bones reduced to thin-walled, hollow tubes like the frame of a carbon-fiber racing bike.

"But unfortunately, that means these bones are fragile, and so almost none survive as fossils."

Longrich said he had always found pterosaurs fascinating, and as a university student had dreamed of studying them. Years later in Morocco, he would stumble across a single, small bone mixed in with fossil fish dug up from a phosphate mine. "It was like a light went off," he said. "I remembered back to the Illustrated Encyclopedia of Pterosaurs, a book I'd practically memorized as an undergraduate. And I thought 'that's a nyctosaur.'"

Nyctosaurs, a family of small pterosaurs, hadn't been proven to survive to the end of the Cretaceous. On a hunch, he looked for more pterosaurs, and found more species - including Tethydraco, a member of the pteranodontids, a family that had been thought to disappear fifteen million years earlier. In addition to the single species previously found in the area, six additional species turned up. "I believe there are many more species to find," he said.

Co-author of the study, Professor David Martill from the University of Portsmouth said: "Exciting discoveries are being made all the time, and sometimes, just the smallest of bones can radically change our perception of the history of life on Earth."

Dr Brian Andres, Research Associate at The University of Texas at Austin, also a co-author of the study, added: "The Moroccan fossils tell the last chapter of the pterosaurs' story - and they tell us pterosaurs dominated the skies over the land and sea, as they had for the previous 150 million years."

Moroccan paleontologist Professor Nour-Eddine Jalil from the Muséum national d'Histoire naturelle, France commented: "This is a fabulous discovery of pterosaurs from Morocco - they tell us their amazing diversity while we thought them in decline. "The Moroccan phosphates are an open window on a key moment in the history of the Earth, one that shortly preceded the global crisis that swept away, among others, dinosaurs and marine reptiles."

Source: Public Library of Science [March 13, 2018]

It may not rank among the all-time greatest dramas, but the history of ice on Greenland has been a source of scientific controversy for more than a decade.

Iceberg off the coast of Greenland [Credit: Drew Avery/WikiCommons]

A study led by UCLA climate scientist Aradhna Tripati appears to put the debate to rest, with major implications for future research across a range of disciplines, from climate science to geology. The paper, which is published today in the journal Nature Communications, also sheds light on how global climate may change as people continue emitting greenhouse gases, revealing a potential tipping point: atmospheric carbon dioxide concentrations of 500 parts per million or more. Beyond that threshold, major ice sheets at both poles could melt significantly. Current levels are near 400 parts per million.

For years, the prevailing belief was that glaciers first appeared on Greenland between 5 million and 11 million years ago. Then, in 2005, Tripati authored a study suggesting the ice had been present there much earlier: about 35 to 40 million years ago.

Though Tripati's paper was published in Nature—one of the most-respected scientific journals—it was considered controversial. At the heart of the conflict was a simple question: Why weren't similar observations made by other studies? Because the findings were not in line with previous knowledge, the paper was regarded as an outlier.

Tripati, who was then a postdoctoral fellow, admits that her research, which was based on the chemistry of Pacific Ocean samples and what they implied about ancient seawater, was "a pretty indirect indicator." Still, she had confidence in the results. She, her students and other researchers conducted a series of studies using different climate indicators, and they kept reaching the same conclusion.

"Understanding the history of ice at both poles and how they respond to changing carbon dioxide levels is so important that, as we published these papers, controversy built up," said Tripati, who is a member of the UCLA Institute of the Environment and Sustainability. "We dug in and continued to try to understand what the history, in fact, was."

In 2014, Tripati sent Dennis Darby, an Arctic paleoclimate specialist at Old Dominion University who became her co-author on the new paper, promising samples taken from a site in the Greenland Sea where icebergs that broke off—a process known as "calving"—from glaciers on the island would have drifted by.

"As glaciers move across land, they incorporate pieces of sediment," Tripati said. "As glaciers produce icebergs and those icebergs drift through the ocean, those little fragments of rock get released as the ice melts. Each rock fragment has a unique chemistry. That chemistry is a fingerprint—each grain tells you something about where the ice came from."

Those samples are dated based on what fossils are present and their magnetic properties, allowing researchers to reconstruct where and when there was ice present on Greenland and other land masses in the Arctic, as well as when there was sea ice in the ocean.

Data visualization showing changes in Greenland’s ice sheet from 2003 to 2012. Rapidly thinning coastal regions are shown in green, blue and purple [Credit: NASA]

Tripati chose to send those new samples to Darby because he had published a study that corroborated her 2005 findings. Using a method he pioneered, Darby analyzed them without knowing what he was looking at, where it came from or how old it was—sort of like a blind taste test.

He found that the samples contained "very high matches" to east Greenland source sites, again confirming Tripati's earlier research. In fact, his analysis showed that large glaciers were present on Greenland even earlier: up to 47.1 million years ago. That was right at the beginning of the middle Eocene epoch, about 20 million years after dinosaurs went extinct.

Darby was also able to match ice from the samples to other locations across the Arctic region.

"That's important," Darby said. "It shows this was not just a local or regional effect in Greenland. It was something climatically induced on a much larger scale, a polar event."

With their new study, Tripati and Darby think the mystery is solved. Darby's technique was rigorously tested in a 2012 study and found to be accurate 98.5 percent of the time. They examined 100 sediment samples and fingerprinted the chemistry of more than 2,000 rock fragments.

Today's paper also contains revelations about how atmospheric conditions relate to the presence or absence of ice. In the years since that first freeze, ice formed and retreated from Greenland several times. The researchers found that ice was usually present when carbon dioxide levels were lower than 500 parts per million.

"What happens if carbon dioxide levels get sustained at 800 parts per million, where some carbon emissions scenarios have us going?" Tripati asked. "Greenland has a lot of ice. If it all melted, it could raise sea level globally by about 20 feet."

Ice comes and goes at both poles under those conditions, the study found. Tripati's research from 2016 that suggested massive ice shelves on Antarctica are also at risk of melting supports this.

Understanding tipping points is important because Earth's climate can change quickly, Darby said. He pointed to 10,000 years ago in Greenland, when temperatures rose 10 degrees Celsius in 10 years.

"Those thresholds need to be researched," Darby said. "They are largely ignored by climate scientists because these things happened way in the past. Many of them are sort of stuck in the past 50 years. And in that time, we don't see any big changes except in the past two decades, when we see very rapid changes that are concerning."

Tripati said that controversies are good for science in general, she said—it shows the scientific process is healthy. She recalled cat-sitting for renowned scientist Sir Nicholas Shackleton around the time she was conducting the early study.

"He said to me 'When you discover something surprising, remember that it's OK to be wrong, but ideally you should be the person to find out. Always try to prove yourself wrong instead of trying to prove yourself right,' " Tripati recalled.

"I think that's excellent advice. With this study, I didn't know what we were going to find. If it didn't work out, fine—we could have written a paper that definitively said 'no evidence for this.' And then we're on the right side of science."

The process also underscored the importance of including diverse perspectives in science, Tripati said. Last summer she launched the UCLA Center for Diverse Leadership in Science—the first initiative of its kind devoted to including people of all backgrounds in environmental science. Dogma that endured for decades can shift dramatically if the scientific community is inclusive and welcomes new perspectives, she said. Inclusion and social belonging will foster diversity, and research shows that leads to more creative approaches and ideas, fueling innovation and scientific breakthroughs.

Tripati and Darby both hope today's findings inspire future research to better understand what will happen to Earth's climate, species and human communities if we continue on our current carbon emissions trajectory.

They also hope it will inform policies aimed at preventing a climate catastrophe—particularly efforts to reduce carbon emissions, Darby said.

"We need to start looking at what we're doing," Darby said. "Some people stick their heads in the sand because they think we'll come up with technology to save us at the last minute. But that's provided we don't hit one of these thresholds first."

Author: David Colgan | Source: University of California, Los Angeles [March 13, 2018]

Researchers led by Nagoya University discover penetrative trace fossils from the late Ediacaran of western Mongolia, revealing earlier onset of the “agronomic revolution”.

This bedding surface was once the surface of the sea floor, which was densely colonized by unidentified animals that lived inside these burrows. The sizes of these openings range from a few millimeters to 1 cm, suggesting that these animals were relatively large [Credit: Tatsuo Oji]

In the history of life on Earth, a dramatic and revolutionary change in the nature of the sea floor occurred in the early Cambrian (541–485 million years ago): the “agronomic revolution.” This phenomenon was coupled with the diversification of marine animals that could burrow into seafloor sediments. Previously, the sea floor was covered by hard microbial mats, and animals were limited to standing on, resting on, or moving horizontally along those mats. In the agronomic revolution, part of the so-called Cambrian Explosion of animal diversity and complexity, vertical burrowers began to churn up the underlying sediments, which softened and oxygenated the subsurface, created new ecological niches, and thus radically transformed the marine ecosystem into one more like that observed today.

This event has long been considered to have occurred in the early Cambrian Period. However, new evidence obtained from western Mongolia shows that the agronomic revolution began in the late Ediacaran, the final period of the Precambrian, at least locally.

When a bed with burrows is cut perpendicular to the bedding plane, the burrows are 'U-shaped', with two openings toward the sea floor. The depth of the burrows reaches up to 4 cm. The animals that lived inside the burrows were  presumably elongated in shape, with the mouth at one end and the anus at the other. Animals with such active burrowing capability are inferred to have been bilaterians, and have not been clearly identified from the previous fossil record [Credit: Tatsuo Oji]

A team of researchers, primarily based in Japan, surveyed Bayan Gol Valley, western Mongolia, and found late Ediacaran trace fossils in marine carbonate rocks. They identified U-shaped, penetrative trace fossils, called Arenicolites, from 11 beds located more than 130 meters below the lowermost occurrence of Treptichnus pedum, widely recognized as the marker of the Ediacaran–Cambrian boundary. The researchers confirmed the late Ediacaran age of the rocks, estimated to be between 555 and 541 million years old, based on the stable carbon isotope record.

“It is impossible to identify the kind of animal that produced the Arenicolites traces,” lead author Tatsuo Oji says. “However, they were certainly bilaterian animals based on the complexity of the traces, and were probably worm-like in nature. These fossils are the earliest evidence for animals making semi-permanent domiciles in sediment. The evolution of macrophagous predation was probably the selective pressure for these trace makers to build such semi-permanent infaunal structures, as they would have provided safety from many predators.”

Reconstruction of the late Ediacaran (ca. 550 million years ago) sea floor with burrows of a worm-like animal. This was the first discovery of such deeply penetrating burrows [Credit: Nagoya University]

These Arenicolites also reached unusually large sizes, greater than one centimeter in diameter. The discovery of these large-sized, penetrative trace fossils contradicts the conclusions of previous studies that small-sized penetrative traces emerged only in the earliest Cambrian.

“These trace fossils indicate that the agronomic revolution actually began in the latest Ediacaran in at least one setting,” co-author Stephen Dornbos explains. “Thus, this revolution did not proceed in a uniform pattern across all depositional environments during the Cambrian radiation, but rather in a patchwork of varying bioturbation levels across marine seafloors that lasted well into the early Paleozoic.”

The findings are published in Royal Society Open Science.

Source: Nagoya University [March 12, 2018]

A new experiment by Iowa State University's Elizabeth Swanner that evaluates the reduction of iron in prehistoric oceans may reinterpret the conditions under which iron-rich sedimentary rock is formed.

Graduated cylinder model of the ocean. The green shows cyanobacteria and the brown shows the oxidized iron [Credit: Iowa State University's College of Liberal Arts and Sciences]

Swanner, an assistant professor of geological and atmospheric sciences, was part of an international research team including researchers from the University of Tuebingen in Germany and the Chinese Academy of Sciences in Beijing. The team modeled the prehistoric ocean, similar to that of the Archean Era 2.5 billion years ago within a graduated cylinder.

"We really only wanted to simulate it in the vertical dimension, so we used a graduated cylinder and modified it," Swanner said.

In a previous experiment, the researchers had modified the cylinder to simulate an Archean ocean with large amounts of iron and no oxygen except for what was made by cyanobacteria. Ports along the cylinder's side allowed for sampling at various levels.

"We were studying cyanobacteria because these are the organisms which we think put all of the oxygen in the atmosphere originally," she said.

The research, recently published by Scientific Reports, showed that despite the oxygenation by the cyanobacteria, much of the iron did not remain oxidized but was reduced again into its dissolved form.

This unexpected result may be explained by an enzyme on cyanobacteria which reduces iron. In the modern ocean, which contains at least 1,000 times less iron, cyanobacteria reduce a small amount of iron, but the experiment showed a larger amount of iron reduction than the researchers anticipated. Another possible explanation is that the iron is reduced by a photochemical reaction occurring when the iron is hit by light.

The implications of this finding could change the conditions under which iron-rich sedimentary rocks are thought to be formed from the ancient oceans.

"Traditionally if you see iron enriched in sediments from the ocean you tend to think it was deposited under anoxic conditions," Swanner said. "But potentially we have a way to still deposit a lot of iron but have it be deposited under fully oxygenated conditions."

The initial results in the laboratory prompt new questions for Swanner, including whether she will find evidence of this process in the Midwestern lakes that her research group is now studying. These lakes have iron at the bottom and oxygen only in the top of the water column, and also contain cyanobacteria.

Source: Iowa State University [March 09, 2018]

Core samples taken during an international ocean drilling expedition are yielding the most high-resolution, extended record of continental rifting ever obtained.

IODP Expedition 381 collected 1.6 kilometers of sediment core from the Corinth Rift in Greece [Credit: University of Southampton]

A team of researchers from around the world, working as part of the Corinth Active Rift Development expedition, collected 1.6 kilometers (one mile) of sediment core and data from boreholes at three different locations in the Gulf of Corinth in Central Greece. The samples provide a continuous, high resolution record of complex changes in past environment and rift-faulting rates over at least the last one million years.

The Corinth Rift is one of the most seismically active areas in Europe where one of the Earth's tectonic plates is being ripped apart causing geological hazards including earthquakes, tsunamis and landslides. This rifting process is the focus of the International Ocean Discovery Program (IODP) Expedition 381 led by Co-Chief Scientists Professor Lisa McNeill from the University of Southampton and Professor Donna Shillington of the Lamont-Doherty Earth Observatory of Columbia University in the USA.

The Expedition team collected the core samples whilst aboard the drilling vessel Fugro Synergy between October and December 2017. The cores were then opened, analysed and sampled by the scientific team in February 2018 during a month of intensive work at the University of Bremen in Germany.

Analysis of the cores recovered from deep below the seafloor reveals a series of very complex changes in the chemical and biological conditions within the waters of the basin over the last approximately 0.5 million years. These changes are driven by the global growth and shrinkage of the Earth's ice sheets, which in turn control the height of global sea level.

Fluctuations in sea level cause the Gulf of Corinth basin to switch between a normal marine environment, when the Gulf was connected to the world's oceans, and a wide range of more complex conditions when sea level is low. The rift's sediments show that an unusual range of organisms lived within the basin under these complex conditions.

The data collected will be used to calculate how quickly the active earthquake-generating faults are slipping within the rift. This can be used to assess the earthquake hazard potential of the region, which has a populated coastal zone around the Gulf and the city of Athens nearby that can be impacted by future earthquakes.

"The new cores are revealing exactly what we hoped: The potential to accurately calculate the activity of important faults that regularly generate earthquakes with magnitudes 6 to 7 in the area," said Professor McNeill. "Researchers have been working in the Corinth Rift region for many decades, examining sediments and active fault traces exposed on land and using marine geophysics to image the basin and its structure below the seafloor. The missing piece of the jigsaw puzzle has been the age of the basin sediments that record the history of rifting. We know now that the core samples will enable us to complete this piece of the puzzle. This in turn can be used to calculate fault earthquake potential, and, on a longer timescale, unravel the sequence of events as the rift has evolved."

Professor Shillington added: "The new discoveries resulting from this expedition will help us to understand other active and ancient rift zones around the world, including others with high hazard potential. The complex story from the microfossils preserved in the sediments and their implications for the living conditions in the basin was unexpected and will significantly widen the impact of the project. Analysis of these results will take many months and we are excited to see what they reveal."

Continental rifting is fundamental for the formation of new ocean basins, and active rift zones are dynamic regions of high hazard potential. The Corinth Rift is one such location and serves as a unique laboratory in an area of Europe with some of the highest levels of earthquake activity. Geologically the Corinth Rift is very young (only a few million years old) and provides a unique chance to study the very first stages of the splitting apart of a continent and changing climate in the eastern Mediterranean. Young rift basins fill with eroded sediments that are also sensitive recorders of past changes in climate and sea level and of the chemical and biological conditions of the rift basin.

Source: University of Southampton [March 09, 2018]

Researchers from Cardiff University have revealed how sea ice has been contributing to the waxing and waning of ice sheets over the last million years.

Credit: Cardiff University

In a new study published in the journal Nature Communications, the team have shown for the first time that ice ages, occurring every 100,000 years, are accompanied by a rapid build-up of sea ice in the Earth's oceans.

Our planet's ice ages used to occur at intervals of every 40,000 years, which made sense to scientists as the Earth's seasons vary in a predictable way, with colder summers occurring at these intervals. However there was a point, about a million years ago, called the 'Mid-Pleistocene transition', in which the ice age intervals changed from every 40,000 years to every 100,000 years.

The reason why ice ages occur at these timescales has been a mystery to scientists for a long time.

By tracking molecules produced by tiny marine algae preserved in ocean sediments, the team have been able to reconstruct sea-ice conditions during the Mid-Pleistocene transition.

Their results showed that at the same time as the cycles of ice ages changed from 40,000 years to 100,000 years there was a distinct increase in sea ice extent and a change in the rhythm of sea ice build-up across climate cycles.

"Prior to the Mid-Pleistocene transition, sea ice build-up and decay during ice ages was more gradual, whereas in the late Pleistocene, when the cyclicity of ice ages changed, we observed conditions characterised by a prominent short-lived peak in sea ice extent during late ice ages," said Henrieka Detlef, a postgraduate researcher at Cardiff University School of Earth and Ocean Sciences who led the study.

With less water evaporating into the atmosphere, there would be less moisture being transported to continental glaciers which, in turn, would cause them to retreat and help in the transition from an ice age to a warm period.

"It's clear that sea ice plays a fundamental role in the transition from an ice age into a warm stage every 100,000 years," Detlef continued.

"Understanding the interactions of sea ice with the regional ecosystem and oceanography is particularly important with respect to anthropogenic climate change and a rapidly shrinking sea ice cover in the Arctic Ocean. Our study is an important step forward in understanding the role of sea ice for long-term climate change."

Source: Cardiff University [March 09, 2018]

There's a particular feeling of excitement that comes from receiving a gift. It's a feeling of the unknown, of anticipation – and then you unwrap the package and find something spectacular.

Reconstruction of a Permian swamp [Credit: Rose Prevec]

As palaeontologists, rocks are our idea of a great gift. That's because when you crack them open, you might well find a fossil. And we aren't talking about dinosaurs: our area of specialisation is palaeobotany. This involves hunting for plant fossils which can tell us a great deal about the landscapes of past ages.

South Africa is home to a range of lesser known and neglected plant fossils, called the glossopterids. These trees once grew in vast swamps along with ancient plant groups such as ferns, horsetail ferns and clubmosses. We know from a few scattered reports that this amazingly rich fossil resource extends across much of Africa, particularly in Namibia, Zimbabwe, Mozambique and further north into Zambia, Tanzania, Kenya and even Madagascar.

Some may wonder why fossils matter. Plants never get as much attention as South Africa's famous rich and diverse fossil heritage that range from some of the earliest evidence of life through to its famous hominid collections. Glossopteris, for instance, has not been well studied in South Africa. It's still poorly understood.

There has been work done in different parts of the world. However, it is not detailed and each region uses its own system to try and understand these fossil plants. South Africa is lagging behind: there are two employed palaeobotanists in the country, while entire research teams exist in other parts of the world.

Yet plants can reveal a great deal about past environments and climates. If we have any hope of understanding South Africa's ancient past, scientists need to be able to reconstruct entire ecosystems, starting at the bottom of the food chain. Glossopteris dotted ancient landscapes before dinosaurs ever walked the earth, and before a single flower had bloomed. As such, it should be closely studied.

What we know

About 300 million years ago Earth entered what's known as the Permian period. During this time, and until about 252 million years ago, the Glossopteris plant became a common sight throughout Gondwana. This was a super continent that included regions known today as Africa, Antarctica, Australia, India and South America.

The presence of Glossopteris was used as supporting evidence for the revolutionary theory of "continental drift" during the mid 20th century. They literally reveal how the world we recognise today took shape.

Glossopteris leaves [Credit: Albany Museum]

Glossopteris was easy to recognise because of its distinctive leaves; the name means "tongue-fern"in Greek, because of its shape. Fossil evidence suggests that the plants probably grew in diverse habitats and came in different forms. These ranged from short shrubs to trees as tall as a five-story building.

Scientists suggest that at least some of these plants were deciduous because their leaves are often found preserved in thick mats thought to be the result of seasonal shedding. At that point, they became not only important for understanding our history: they started contributing to fuels and materials that are still used today.

Power plants

Dead material from these plants accumulated in swamp environments, was buried, and over time formed South Africa's vast coal reserves.

Under normal conditions, when plants die or shed their leaves these fall to the ground and decompose. Under special environmental conditions – such as those that occurred in the vast Permian swamps of Gondwana (which were a bit like today's mangrove swamps) – the process differs. Once Glossopteris shed their leaves, the plant material accumulated in acidic water with high levels of tannins and low oxygen concentrations.

This retarded the activity of the bacteria, fungi and other organisms that would otherwise lead to decomposition. Over time layers of mud, silt and sand washed into the swamp and buried the waterlogged peat layers. Millions of years passed. During this period the mud, silt, sand and the encased plant material experienced great pressure and high temperatures. It was compressed and changed into rock, and underwent various chemical changes.

The result? Coal seams. This is why coal is referred to as a fossil fuel. It is also a reminder that coal is finite.

Apart from being the major source of fuel in the production of South Africa's electricity, Glossopteris influences our lives in many ways. The carbon atoms harvested from the air as carbon dioxide by these trees during the process of photosynthesis, hundreds of millions of years ago, can also be found in petrol, waxes, plastics, and a host of other products used in everyday life.

New finds

South Africa has a huge potential for new fossil discoveries, with vast territories still waiting to be explored, yet very few researchers are studying fossil plants and insects.

We are part of a small group of researchers based at the Albany Museum in Grahamstown in the Eastern Cape province who are determined to change this by shedding more light on Glossopteris and fossil plants in general.

At the moment we're working on a few small road cuttings near a Northern Cape town called Sutherland. This is revealing a depth of knowledge about Permian ecosystems that has not been seen before in South Africa, and is very rare on a global scale.

New discoveries are not only about bringing a wonderful piece of the country's heritage to light. This work is also opening up new scientific fields and opportunities for skills development that the country desperately needs.

Author: Aviwe Matiwane And Rosemary Prevec | Source: The Conversation [March 08, 2018]

This article was originally published on The Conversation. Read the original article.

A scientific team has discovered the geological footprint of earthquakes and tsunamis that affected the Aysen region (southern Chile) up to 9,000 years ago. This new study improves the assessment of seismic hazard in a wide area of the American continent prone to large earthquakes.

The new study is a first step forward to improve the evaluation of the seismic hazard in Andean regions [Credit: Universidad de Barcelona]

The study, published in Journal of Geophysical Research: Solid Earth, enabled the researchers to establish the first paleoseismological record of the Liquine-Ofqui Fault Zone (LOFZ), a large geological structure that crosses southern Chile and is partially responsible for the seismic activity of the Andean country.

The LOFZ fracture area, which stretches over more than 1,000 kilometres north-south in Chile, is a geological structure associated with volcanism and that has an impact on the relief of the Andean country. This seismically hazardous area has some active volcanoes –such as Maca, Hudson and Mentolat- and steep reliefs that can enlarge the effects of the most violent geological phenomena.

In this area, Aysen fjord is a model to study geological processes –earthquakes, tsunamis, etc.— that can be a threat to the local population. According to Galderic Lastras, "the Aysen fjord is cross-cut by the strike-slip fault system (LOFZ) that causes local earthquakes, such as the crisis in 2007. The main earthquake of this crisis —magnitude 6.2— caused dozens of landslides and a local tsunami, with some casualties and important damage to fish farms."

"Moreover, this fjord is quite close to the plate boundary between the South American and the Nazca Plates, an active subduction zone that causes large magnitude earthquakes," says Lastras, expert on submarine cartography and head of the oceanographic survey DETSUFA that worked on the cartography of the geological footprint of submarine landslides in Aysen.

Aysen fjord: earthquakes and tsunamis in a natural laboratory

When an earthquake occurs –moderate or strong-, it can destabilize the mountain slopes that surround the fjord. Rock masses can slide and fall until reaching the fjord bottom, causing local tsunamis. This forms an increased risk for the population since there is an extremely short warning time. The geological footprint of these landslides -piled up at the bottom of the fjord and separated by sediments- is then visible in the sedimentary record.

The geological footprints of the last seismic crisis ─April 21, 2007─ are still visible in the Aysén fjord [Credit: G. Lastras]

According to Maarten Van Daele, postdoctoral researcher and expert on sedimentary deposits created by earthquakes, "strong seismic shaking triggers both onshore and subaquatic landslides. These are buried in the fjord and we can image and map them using geophysical methods. In this study, we also retrieved sediment cores, which allowed us to determine ages for the landslide events using radiocarbon dating of organic material in the sediment."

Combining different geophysical techniques —reflection seismics, geochemistry of volcanic ashes, etc.— the scientific team constructed the first paleoseismic record of the Liquine-Ofqui Fault Zone. "For the first time —adds Van Daele— we have a rough idea of earthquake recurrence rates along this fault. Other similar studies are needed along the fault trace, but this is an important first step to improve the assessment of the seismic hazard in the region."

Looking for the most violent seismic episodes

Earthquakes can destabilize fjord slopes and cause landslides, but other factors such as heavy rainfall can also be involved and enhance slope instability. As a result, the experts could identify evidence of ten earthquakes in Aysen fjord –including the most recent one in 2007— but the amount of such earthquake events is probably even higher since not every earthquake will cause a significant landslide.

The study presents the first paleoseismological record of the Liquiñe-Ofqui Fault Zone (LOFZ), a geological structure that crosses southern Chile [Credit: University of Barcelona]

According to Katleen Wils, predoctoral researcher at Ghent University and first author of the study, "we know these landslides occurred due to a common trigger: an earthquake. In the Aysen region, the main source of seismic hazard comes from the LOFZ fault rather than the subduction zone. Those earthquakes had intensities similar to those occurring during the 2007 main episode, which was up to IX, corresponding to violent shaking and considerable damage."

"According to the data, six of the analysed earthquake events took place in the fjord during the last 9,000 years, while the other four occurred before that. This shows that there is an important seismic hazard in the region, mainly originating from the LOFZ, but also from the subduction zone," notes Wils, expert on geophysics and the study of earthquakes and seismic hazard.

The number of earthquakes recorded in Aysen fjord may be clear, but "it is more difficult to have a clear idea of their magnitude," warns Galderic Lastras. "One of the identified events has a similar age (about 2,000 years before present) to a tsunami deposit described in the coastal Lake Huelde, in Chiloe Island, and with a turbidite in Lake Rinihue. Identifying signs of an earthquake in different locations far away from each other is a sign of a large magnitude earthquake, which has likely originated in the subduction zone."

According to the authors, their study reveals that LOFZ is an active fault system that should be characterized in more detail in future studies in order to have more knowledge on the complete seismic system.

Paleoseismology: the unwritten history of great earthquakes

The paleoseismological record of Aysen fjord is an important part of the geological history of the region as a written record of past earthquakes in the area is non-existent. Understanding the rate at which earthquakes took place in the past is essential to infer the occurrence of future earthquakes.

Because of this uncertainty, "geological research is an essential tool to explain the unwritten history of the most violent earthquake events that affected a certain area. It is important to know as much as possible about past seismic activity of a region. This means that technology and scientific knowledge are the key to improve the assessment of seismic hazard, mitigate the effects of natural disasters and help society directly," the authors write.

Source: University of Barcelona [March 07, 2018]

The East Asian summer monsoon and desertification in Eurasia is driven by fluctuating Northern Hemisphere ice volume and global sea level during the Ice Age, as shown in a study published in Nature Communications. Today, two thirds of the world's population is dependent on agriculture sustained by rains of the East Asian summer monsoon, and future climate change in this region can therefore have a major impact on global food production.

The East Asian summer monsoon and desertification in Eurasia is driven by fluctuating Northern Hemisphere ice volume and global sea level during the Ice Age, as shown in a study published in Nature Communications. Today, two thirds of the world's population is dependent on agriculture sustained by rains of the East Asian summer monsoon, and future climate change in this region can therefore have a major impact on global food production [Credit: Thomas Stevens]

Huge areas of central China is covered by a plateau consisting of a fine grained soil type called loess - a sediment deposited here by winds during the Ice Age. The soils formed on loess are very fertile and have been one of the key factors driving cultural development and population growth in China for thousands of years. Additionally, the loess plateau also contains a geological archive that can be used to decipher past climate changes.

Through detailed examination of the loess sediments, a group led by researchers at Uppsala Univirsity together with colleagues from Denmark has identified how changes in climatological phenomena such as ice volume and sea level also affected the extent of deserts in China, as well as the behavior of the East Asian summer monsoon.

"We have conducted the most detailed dating of the loess to date, which has enabled us to identify changes in the monsoon and desertification processes in more detail and with much greater accuracy than previously possible. We can now compare these changes to other known climate changes such as variation in ice volume, sea level and even the Earth's orbit during the Ice Age", says Dr. Thomas Stevens, first author and researcher at Uppsala University.

"We can now show that when ice volume decreased and sea level rose, the summer monsoon rainfalls in East Asia intensified and spread further inland, while sandy deserts in China retreated", says Dr. Stevens.

With today's shrinking ice caps and rising sea levels, this has implications for how the Eurasian continent will once again experience changes in the summer monsoon rainfall and desertification.

Source: Uppsala University [March 07, 2018]

A new NASA study has, for the first time, cut a clear path through a nettlesome problem: accurately measuring a powerful effect on global sea level that lingers from the last ice age.

Glacial isostatic adjustment is the ongoing movement of land once burdened by ice-age glaciers [Credit: NASA/John Sonntag]

Just how quickly Earth's deep, rocky mantle is rebounding from the heavy burden of ancient ice sheets and oceans remains somewhat uncertain. But this rebound effect, known as glacial isostatic adjustment (GIA), is critical to properly understanding the causes of sea level change.

Even getting a solid handle on the level of uncertainty associated with estimates of GIA has proven elusive. The new study offers a more rigorous way out of this thicket – establishing a formal system for assessing this uncertainty. That should lead to more realistic estimates of sea level change, and greater precision in projections of future sea level rise, according to the study's authors.

"Knowing how much we don't know is the first step," said Lambert Caron, a post-doctoral researcher at NASA's Jet Propulsion Laboratory in Pasadena, California and lead author of the new study published today in Geophysical Research Letters, a journal of the American Geophysical Union,

Try out a NASA simulation of GIA from JPL’s Virtual Earth Systems Laboratory here.

While new findings based on strong data get most of the headlines, gauging levels of uncertainty also is important to scientific investigations. It's an especially thorny problem in the study of sea level change.

Interpreting data from NASA's twin GRACE (Gravity Recovery and Climate Experiment) satellites offers one example. By measuring subtle shifts in gravity across Earth's surface, the GRACE satellites gathered an important 15-year-long data set, now being used to help determine how much sea level rise is caused by additional water mass. GRACE also can be used to track varying quantities of ocean water, changes in polar ice and the movement of water between oceans and land.

GIA looms in the background of such measurements. Pinning down the uncertainty connected with it more precisely helps scientists separate ice age and present-day processes, including how much of sea-level rise is driven by expansion of ocean water as it warms. Knowledge of GIA also helps clarify trends in water storage on land, measured by satellite as well as ground-based instruments. Another question it can help clear up: how alterations in the shape of ocean basins caused by GIA contributes to apparent sea level changes.

Measurement and uncertainty

Previous studies attempted to put a fence around uncertainty using various methods, Caron said. These included running repeated computer models and culling out all but a handful that seemed to provide the best match, or "fit," to what the data gathered by GRACE and other observation platforms show.

Differences among the "best fit" models then can be used to reveal likely levels of uncertainty in interpreting the data.

"People started comparing a handful of models, some of them relying on similar assumptions and setups, and concluding that the differences between them were essentially how much uncertainty we had over GIA," Caron said. "That's fine, but it doesn't allow us to explore the entire range of possible scenarios. We need a more formal approach."

The new study relies on technological improvements, which have only become possible within the past decade, to carry out a high number of computer simulations – in this case, more than 100,000. By more systematically exploring the range of GIA scenarios, Caron's team seeks to turn discrepancies among different models into a virtue. They framed the question in a new way: How different can models be while still matching the data? From this spread of models and a method called the Bayesian approach, better statistics on uncertainty can be retrieved.

The new assessment also is based on GPS time series measurements from 459 sites in Europe, North America and Antarctica, and more than 11,000 records of relative sea level – that is, sea level in relation to coastal elevation. This allows the parameters controlling the GIA rebound to be more thoroughly scrutinized.

The new framework translates into what Caron calls the first formal uncertainties for GIA on a global scale.

The study reveals an underestimate of uncertainty levels for GIA estimates, he said – from a typical 20 percent uncertainty in previous studies to a median value of 44 percent. In polar regions, GIA has a large impact on the interpretation of gravity data.

That leads to refinements in uncertainty levels for sea level rise in specific locations around the world. In the New Orleans region, for example, applying the new method yields a prediction of a 1 millimeter rise in relative sea level per year, with an uncertainty of 0.4 millimeters per year.

Caron said he hopes the new formal uncertainties will be a useful tool not only for researchers, but for city planners as well.

"We want to give them a measure of confidence for the average scenario, and what is the worst-case scenario they would have to plan for – how much the country has to invest in modernizing infrastructure, reconstructing piers, or to mitigate flooding," he said.

Author: Pat Brennan | Source: American Geophysical Union [March 07, 2018]

This story is republished courtesy of AGU Blogs, hosted by the American Geophysical Union. Read the original story here.

Imagine that you're a voracious carnivore who sinks its teeth into the tail of a small reptile and anticipates a delicious lunch, when, in a flash, the reptile is gone and you are left holding a wiggling tail between your jaws.

This is an illustration of Captorhinus showing breakable tail vertebrae [Credit: Courtesy Robert Reisz]

A new study by the University of Toronto Mississauga research team led by Professor Robert Reisz and PhD student Aaron LeBlanc, published in the open source journal, Scientific Reports, shows how a group of small reptiles who lived 289 million years ago could detach their tails to escape the grasp of their would-be predators -- the oldest known example of such behaviour. The reptiles, called Captorhinus, weighed less than 2 kilograms and were smaller than the predators of the time. They were abundant in terrestrial communities during the Early Permian period and are distant relatives of all the reptiles today.

As small omnivores and herbivores, Captorhinus and its relatives had to scrounge for food while avoiding being preyed upon by large meat-eating amphibians and ancient relatives of mammals. "One of the ways captorhinids could do this," says first author LeBlanc, "was by having breakable tail vertebrae." Like many present-day lizard species, such as skinks, that can detach their tails to escape or distract a predator, the middle of many tail vertebrae had cracks in them.

It is likely that these cracks acted like the perforated lines between two paper towel sheets, allowing vertebrae to break in half along planes of weakness. "If a predator grabbed hold of one of these reptiles, the vertebra would break at the crack and the tail would drop off, allowing the captorhinid to escape relatively unharmed," says Reisz, a Distinguished Professor of Biology at the University of Toronto Mississauga.

The present day spiny-tailed iguana is similar to captorhinids, small reptiles that lived 289 million years ago and could detach their tails to escape the grasp of predators [Credit: University of Toronto]

The authors note that being the only reptiles with such an escape strategy may have been a key to their success, because they were the most common reptiles of their time, and by the end of the Permian period 251 million years ago, captorhinids had dispersed across the ancient supercontinent of Pangaea. This trait disappeared from the fossil record when Captorhinus died out; it re-evolved in lizards only 70 million years ago.

They were able to examine more than 70 tail vertebrae -- both juveniles and adults -- and partial tail skeletons with splits that ran through their vertebrae. They compared these skeletons to those of other reptilian relatives of captorhinids, but it appears that this ability is restricted to this family of reptiles in the Permian period.

Using various paleontological and histological techniques, the authors discovered that the cracks were features that formed naturally as the vertebrae were developing. Interestingly, the research team found that young captorhinids had well-formed cracks, while those in some adults tended to fuse up. This makes sense, since predation is much greater on young individuals and they need this ability to defend themselves.

This study was possible thanks to the treasure trove of fossils available at the cave deposits near Richards Spur, Oklahoma.

Source: University of Toronto [March 06, 2018]