Traces of paleotsunami at the lowland of the Ube River, Noda Village. The Sanriku Coast has been hit by tsunamis throughout its history, leaving behind tsunami deposits. Credit: Tohoku University
A research group comprising members from Tohoku University, Hokkaido University and the University of Tokyo have developed a high-resolution radiocarbon dating method that can accurately date tsunami deposits, offering a vital window into past disasters and enabling scientists to better understand how frequently tsunamis occur.
Tsunami deposits offer scientists important information on tsunamis that struck before records began. They reveal the frequency and size of tsunamis. But sometimes the sediment has been washed away or is incomplete.
The 2011 Great East Japan Earthquake and Tsunami thrust the Tohoku region into the international spotlight. Yet the area has been prone to earthquakes and tsunamis throughout its history.
Still, scientists are divided on what tsunamis reached the Sanriku Coast — the stretch of northeastern coastline along present day Iwate and parts of Aomori and Miyagi. Inconclusive data rendered scientists unable to determine whether sediments from the Sanriku Coast belong to the 1611 Keicho Oshu Tsunami or the 1454 Kyotoku Tsunami.
Tohoku University assistant professor Takashi Ishizawa, who led the research group, and his team applied their radiocarbon dating method to a village situated in Iwate Prefecture.
“The village of Noda is strategic for two reasons,” says Ishizawa. “Tsunami deposits formed between the 14th and 17th centuries have been preserved there, and Noda has inland areas where only giant tsunamis are capable of inundating.”
Analyzing the data, in addition to comparing the tsunami records from the surrounding area, the researchers determined that sediment belonged to the 1611 Keicho Oshu Tsunami, not the 1454 Kyotoku Tsunami.
Moreover, they found the prevalence of giant tsunamis since the 1611 Keicho Oshu Tsunami occurred at intervals between 100 to 200 years.
Ishizawa and his team are looking to apply this method to other locations, including the Sendai Plain to reconstruct a more reliable history of tsunamis along the entire Japan Trench.
Reference:
Takashi Ishizawa, Kazuhisa Goto, Yuichi Nishimura, Yosuke Miyairi, Chikako Sawada, Yusuke Yokoyama. Paleotsunami history along the northern Japan trench based on sequential dating of the continuous geological record potentially inundated only by large tsunamis. Quaternary Science Reviews, 2022; 279: 107381 DOI: 10.1016/j.quascirev.2022.107381
University of Manchester research fellow David Legg, in collaboration with a team of international scientists from China, Switzerland, and Sweden, has today announced a new fossil that reveals the origin of gills in arthropods.
Arthropods, the group of animals that includes creepy crawlies like spiders and woodlice, are the largest phylum in the animal kingdom and are found everywhere from the deepest ocean trench to the top of Mount Everest.
Research published today shows the newest addition to the group is a 520-million-year-old (about 10 times as old as the dinosaurs) organism called Erratus sperare. Erratus sperare was discovered in the Chengjiang Fossil Site, a UNESCO World Heritage Site located in Yunnan, China. The Chengjiang Fossil Site preserves an ancient underwater ecosystem which included the relatives of some well-known arthropod fossils like trilobites and anomalocarids.
Modern water dwelling arthropods have biramous limbs, legs that have two parts — one for breathing and one for walking — but how such specialised limbs evolved was a mystery. Some of the earliest fossil arthropods, like Anomalocaris, had swimming flaps that may have doubled as gills, but until now researchers didn’t know how arthropods made the jump from these specialised flaps to the biramous limbs of modern arthropods.
Erratus sperare provides the missing link between arthropods that used such specialised flaps and arthropods with biramous limbs. It has both legs and flaps.
Dr David Legg, one of the authors of this study, said: “Fish aren’t the only organisms that have gills! Arthropods have gills too… they just have them on their legs. When it came to arthropods, however, we just weren’t sure where these gills came from.
“Thanks to this new fossil, Erratus sperare, we now have a much clearer idea. These gills also probably went on to evolve into the wings of insects and the lungs of terrestrial arthropods like spiders so were a very important innovation.”
Reference:
Dongjing Fu, David A. Legg, Allison C. Daley, Graham E. Budd, Yu Wu, Xingliang Zhang. The evolution of biramous appendages revealed by a carapace-bearing Cambrian arthropod. Philosophical Transactions of the Royal Society B: Biological Sciences, 2022; 377 (1847) DOI: 10.1098/rstb.2021.0034
When you walk about your yard on a wet day, do your shoes stick in the mud? Could you make ceramic pots out of the soil in your garden? If the answers are yes to both, odds are you have clay soil, one of the biggest challenges for the home gardener.
Clay soils in the Willamette Valley are the result of geologic actions that took place during the end of the last ice age—some 10,000–14,000 years ago, said Linda Brewer, senior faculty research assistant in Oregon State University’s College of Agricultural Sciences. Repeated flooding on an apocalyptic scale overflowed into what is today the Willamette Valley.
Very fine clay particles take far longer to settle out of water than larger sand and silt particles, Brewer explained. On average, these larger particles settled out further north in the valley, although clays can certainly be found in the Portland area. The largest clay particle is more than 1,000 times smaller than the smallest sand particle. Gravity causes these larger particles to settle out first.
Clay soils are difficult to work up and develop into a good seedbed. Dry clay tends to be very hard and, if wet, it tends to be very sticky and difficult to manage. But clay soils have their attributes, Brewer said. Clay particles are so small that they have slight electrical charges. These charges hold on to plant nutrients, far better than sand. Clay soils also store large amounts of water in the very fine spaces between their particles. This ability contributes to their stickiness and plasticity.
However, this water, held in such small pores, becomes difficult for plants to take up as the soil dries. Sandy soils drain readily because the spaces between the particles of sand are much larger.
Bark, manure, leaf mold and compost are among the organic amendments commonly used to improve clay soil, Brewer noted. Applied to the soil surface, these materials form a protective blanket that slows evaporation and reduces soil hardening.
It’s common for people to want to rototill or dig these materials into their garden beds, Brewer said, but experience has shown that the best and easiest way is to apply two or three inches of organic materials to garden beds, without trying to mix them in.
“Like diamonds, clay soils are highly structured at the atomic level,” Brewer said. “No amount of sand added to a clay soil will change its texture. The large sand particles provide a surface onto which the tiny clay particles adhere. The result can be more difficult to manage than the original clay.
“Think of the action of a potter’s hands on the clay as the potter’s wheel turns. The potter pulls the clay against the rotation of the wheel. In addition to shaping the clay, this action aligns the individual clay particles, and increases the strength of the clay. I emphatically recommend against rototilling sand or vermiculite into clay soils. The action of the tiller is like the action of the potter’s wheel.”
Organic matter serves as food for earthworms, insects, bacteria and fungi that transform it to soil nutrients and humus. These soil dwellers decompose and break down organic matter. Decomposer bacteria give off “glues” that aggregate soil particles, improving drainage and make the soil easier to work.
When a large amount of organic material is added to the soil under warm and moist conditions, microorganisms multiply rapidly. Since they construct their bodies from the same nutrients that plants use, in the short term, they compete with plants for nutrients. Composted materials have been at least partially broken down and may have more nutrients available when applied.
To overcome the temporary lack of nutrients, gardeners might try adding low-nitrogen organic material like wood chips to the soil in the autumn, or smaller amounts at a time in the spring, when warm weather will hasten break down. Or apply a complete organic fertilizer as a source of nutrients.
Remember that nitrogen is highly soluble in water, Brewer said. Manures, which are high in nitrogen, should be added only when there are actively growing roots able to take up nitrogen. Applying manure in the autumn is a wasted effort. In areas with high-rainfall winters, the nitrogen will have run off or leached below the rooting zone by spring.
Gypsum—calcium sulfate—is an amendment that improves clay soils. After exposure to water, the calcium sulfate molecule will dissociate. Free calcium ions have a positive charge that attracts the negatively charged clay particles, encouraging aggregation. Ammonium lauryl sulfate is a surfactant that can encourage infiltration of water into dried clay, and may make it easier to mechanically aerate clay soils. Their commercial reputation as a “spray on aerator” is an exaggeration, Brewer said.
Fertile soil with good tilth does not come about with a single or even several additions of organic material, but from a consistent soil-building program.
“Repeated additions of organic matter do change clay soils, but these additions must be at least annual in order to maintain the changes,” Brewer said. “And the soil will remain clay—forever.”
Rapid erosion of supermountains released large amounts of nutrients, which were eventually carried into the oceans. Photo: Peter Campbell
Giant mountain ranges at least as high as the Himalayas and stretching up to 8,000 kilometres across entire supercontinents played a crucial role in the evolution of early life on Earth, according to a new study by researchers at The Australian National University (ANU).
The researchers tracked the formation of these supermountains throughout Earth’s history using traces of zircon with low lutetium content — a combination of mineral and rare earth element only found in the roots of high mountains where they form under intense pressure.
The study found the most giant of these supermountains only formed twice in Earth’s history — the first between 2,000 and 1,800 million years ago and the second between 650 and 500 million years ago. Both mountain ranges rose during periods of supercontinent formation.
Lead author, ANU PhD candidate Ziyi Zhu, said there are links between these two instances of supermountains and the two most important periods of evolution in Earth’s history.
“There’s nothing like these two supermountains today. It’s not just their height — if you can imagine the 2,400 km long Himalayas repeated three or four times you get an idea of the scale,” she said.
“We call the first example the Nuna Supermountain. It coincides with the likely appearance of eukaryotes, organisms that later gave rise to plants and animals.
“The second, known as the Transgondwanan Supermountain, coincides with the appearance of the first large animals 575 million years ago and the Cambrian explosion 45 million years later, when most animal groups appeared in the fossil record.”
Co-author Professor Jochen Brocks said: “What’s stunning is the entire record of mountain building through time is so clear. It shows these two huge spikes: one is linked to the emergence of animals and the other to the emergence of complex big cells.”
When the mountains eroded they provided essential nutrients like phosphorus and iron to the oceans, supercharging biological cycles and driving evolution to greater complexity.
The supermountains may also have boosted oxygen levels in the atmosphere, needed for complex life to breathe.
“The early Earth’s atmosphere contained almost no oxygen. Atmospheric oxygen levels are thought to have increased in a series of steps, two of which coincide with the supermountains,” Ms Zhu said.
“The increase in atmospheric oxygen associated with the erosion of the Transgondwanan Supermountain is the largest in Earth’s history and was an essential prerequisite for the appearance of animals.”
There is no evidence of other supermountains forming at any stage between these two events, making them even more significant.
“The time interval between 1,800 and 800 million years ago is known as the Boring Billion, because there was little or no advance in evolution,” co-author Professor Ian Campbell said.
“The slowing of evolution is attributed to the absence of supermountains during that period, reducing the supply of nutrients to the oceans.
“This study gives us markers, so we can better understand the evolution of early, complex life.”
Reference:
Ziyi Zhu, Ian H. Campbell, Charlotte M. Allen, Jochen J. Brocks, Bei Chen. The temporal distribution of Earth’s supermountains and their potential link to the rise of atmospheric oxygen and biological evolution. Earth and Planetary Science Letters, 2022; 580: 117391 DOI: 10.1016/j.epsl.2022.117391
Fault zone with broken rock inside stippled lines and faulting directions of each rock segment outlined by half arrows. Photo credit: Henrik Drake. Illustration: Mikael Tillberg.
In a new paper recently published in the journal Geology, researchers at the University of Massachusetts Amherst unveiled a physical model that yields an unprecedented, high-resolution look at the slip rates of faults, which determine the likelihood of earthquakes.
When most of us picture a fault line, we imagine a giant crack in the earth where two tectonic plates smash into each other. When geologists think of faults, however, they see a branching system made up of thousands of individual faults. “The closer you look,” says Michele Cooke, one of the paper’s co-authors and a professor of geosciences at UMass Amherst, “the more you find, and when you look in detail, the picture gets very complicated.”
Such complexity makes it difficult to accurately understand what is happening at any given place in the system — let alone to predict when an earthquake will occur, and where. To blur the picture even more, the vast majority of individual faults are buried under feet of dirt or obscured by vegetation, and so can’t be directly observed. Finally, fault systems evolve over the course of thousands, tens of thousands, or even millions of years. Therefore, geologists have traditionally generated generalized slip rates for entire fault systems and theorized broadly about how fault systems evolve.
In a new study, the authors used a physical model, “about the size of a kitchen sink,” says Hanna Elston, the paper’s lead author and a graduate student in geosciences at UMass Amherst, and filled it with a carefully composed kaolin clay, “about the consistency of Greek yogurt,” that behaves much like the earth’s crust. At the bottom of the model are two plates that can be precisely moved. Elston and her co-authors then carefully cut the clay, to form a fault, and, over the course of four hours, which simulated a million years, moved the plates 12 centimeters, all the while taking pictures with an array of overhead cameras, which they could then analyze to uncover the slip rates and mechanics of their modeled faults.
The precision of the first-of-its-kind technique that Elston and her co-authors developed allows them to track slip rates at specific locations along faults, with an unprecedented fidelity, which can then provide a record that researchers can directly compare to field studies to estimate the slip rate at any particular point along a fault.
Not only does the model perform in ways that mirror real-life faults, it allowed Elston and her colleagues, including Cooke and Alex Hatem, now at the U.S. Geological Survey, to observe two different phenomena that no one else has seen before. First, the model shows that slip rates can change at a particular site on the fault as that fault evolves. Second, the team showed that slip rates are interactive: the rate can change at many different points along one fault in response to changing slip rates at other, nearby faults.
“This study gives us the finest-grained picture yet into how faults evolve, which could be used to help the assessments of seismic hazards,” says Elston — and it’s only the start. The research in this paper, which was supported by the National Science Foundation, represents a proof-of-concept for the team’s analytical techniques. Future will detail make 3D reconstructions of different faults’ evolution.
Reference:
Hanna Elston, Michele Cooke, Alex Hatem. Non-steady-state slip rates emerge along evolving restraining bends under constant loading. Geology, 2022; DOI: 10.1130/G49745.1
Scientists have identified a mechanism through which important metals, crucial to the manufacturing of renewable energy technologies, are passed from the Earth’s mantle to the crust.
The team, including researchers from Cardiff University, has discovered a ‘Goldilocks zone’ at the base of the Earth’s crust where the temperate is just right at around 1000°C for metals to be transported to shallower levels near the surface, where they can be mined.
The metals in question — most notably copper, cobalt, tellurium and platinum — are highly-sought after due to their use in electrical wiring and technologies such as battery storage devices, solar panels and fuel cells.
Publishing their findings today in the journal Nature Communications, the team is hopeful that the results can lead to more targeted, less costly, and more environmentally friendly practices to explore for and extract the key metals.
The metals are primarily stored in the Earth’s mantle — a thick layer of rock that sits between the Earth’s core and crust — at depths of more than 25km, making them inaccessible for exploitation.
Yet in certain parts of the world, nature can bring these metals to the surface through the flow of liquid rock, known as magma, that originates in the Earth’s mantle and rises upwards into the crust.
However, up until now the journey of metals to their final deposition site has been uncertain.
In the new study, the team identified a temperature dependant zone, located at the base of the Earth’s crust, which acts like a valve and intermittently allows the metals to pass upwards to reach the upper crust.
Co-author of the study Dr Iain McDonald said: “When magmas reach the base of the crust the critical metals often get trapped here and cannot reach the surface if the temperature is either too hot or too cold.
“As with Goldilocks, we have discovered that if the temperature is ‘just right’ at around 1000°C, then metals like copper, gold and tellurium can escape the trap and rise up towards the surface to form ore deposits.”
The study forms a component of the NERC-funded FAMOS project (From Arc Magmas to Ore Systems), and involved collaborators from Cardiff University, Leicester University, the University of Western Australia and the international mining company BHP.
Professor Jamie Wilkinson, of the Natural History Museum, London, is Principal Investigator for the FAMOS project, and added: “This paper represents a fantastic piece of work from the project team that sheds new light on magmatic processes that operate deep in the Earth’s crust but which exert a first-order control on the accessibility of critical metals for humankind. The results will enable more targeted mineral exploration, thus lowering the environmental footprint associated with the discovery and extraction of green metals.”
Reference:
David A. Holwell, Marco L. Fiorentini, Thomas R. Knott, Iain McDonald, Daryl E. Blanks, T. Campbell McCuaig, Weronika Gorczyk. Mobilisation of deep crustal sulfide melts as a first order control on upper lithospheric metallogeny. Nature Communications, 2022; 13 (1) DOI: 10.1038/s41467-022-28275-y
A 250-million-year-old fossil of a marine snail shell in pristine condition. The shell was one of the thousands examined in the study. Scale bar = 100 µm. Credit: William Foster et al.
A collection of fossil shells from marine snails and clams is challenging a theory that says the world’s deadliest mass extinction was accompanied by severe ocean acidification.
Instead of showing damage or signs of repair—which would be expected if the mollusk was surviving in acidic conditions—the shells were in excellent shape, according to a study that was published on Jan. 24, 2022, in Scientific Reports.
William Foster, a scientist at the University of Hamburg and former postdoctoral researcher at The University of Texas at Austin Jackson School of Geosciences, led the research.
The study is the first to use shells from fossilized mollusks to investigate ocean chemistry, demonstrating a new tool that scientists can use to study the conditions of the planet’s deep past.
“For events that occurred millions of years ago, we have to rely on evidence such as the chemistry of marine rocks and fossils,” said co-author Rowan Martindale, an associate professor at the Jackson School. “Sometimes these proxies give conflicting results, so we need multiple, independent measures of ocean conditions.”
The world’s deadliest mass extinction wiped out about 90% of living species about 252 million years ago at the end of Permian Period. The extinction was triggered by huge volcanic eruptions in present-day Siberia, which released large amounts of carbon dioxide into the atmosphere in relatively short amount of time, causing rapid global warming.
When atmospheric carbon dioxide is high, the ocean can absorb some of the gas and become more acidic. However, the geologic record is inconclusive about whether this occurred during the end Permian extinction event.
“Some previous studies based on chemical analyses of rocks had suggested that the world’s seas were acidic at that time, but other geochemical evidence suggested the opposite,” said Foster.
The analysis of the mollusk shells offers a more thorough perspective, Foster said, because they capture the chemical state of the ocean shortly after the extinction event from top to bottom, not just where sediment settled. The s tested for acidification in surface waters by analyzing larval shells and tested for seafloor acidification by analyzing adult shells.
The research entailed examining more than 2,300 fossil shells from marine snails and bivalves from under a microscope. And although a handful of shells record some growth impairment, there were no signs of patched holes, a tell-tale sign of mollusks living in an acidic environment.
“None show repair marks that would indicate severe acidification in surface waters or on the seafloor,” Foster said.
The fossils were collected from a site in what is now Svalbard, Sweden. When the animals were alive, the site was covered by a shallow sea and the Earth contained just a single massive continent.
“It was really exciting to study organisms that lived when Pangea was a supercontinent,” said co-author Jaime Hirtz, who recently earned a master’s degree from the Jackson School but started working on these fossils when she was an undergraduate student.
Marine animals with shells made of aragonite (a type of calcium carbonate mineral) are particularly susceptible to ocean acidification. Scientists use shells from “sea butterflies,” a type of swimming sea snail, to study ocean acidification in the present and recent past. This study shows that shells from fossilized mollusk species can be analyzed in a similar manner, opening the door to more extensive research on ocean chemistry in Earth’s past and its connection to climatic events.
“One of the exciting aspects of this research is that we now know we can use fossil shells of aragonitic marine animals from millions of years ago as bioindicators of past ocean acidification,” said co-author Richard Twitchett, a professor at the Natural History Museum, London.
The study’s additional co-authors are Maria Reistroffer, who conducted the research while earning a bachelor’s degree from the Jackson School, and Conor Farrell, an undergraduate student at University College Dublin.
Reference:
William J. Foster et al, Bioindicators of severe ocean acidification are absent from the end-Permian mass extinction, Scientific Reports (2022). DOI: 10.1038/s41598-022-04991-9
Taken by the Himawari 8 satellite, this red-filter visible image of a volcanic eruption in Tonga was taken on 15 January 2022 at 04:50 (UTC) 5:50 PM (Tonga Local Time). This volcanic eruption produced a 3.9 foot (1.2 meter) tsunami which struck Nukuʻalofa, the capital of Tonga. The volcano also triggered tsunamis across the Pacific Ocean affecting countries and territories like Fiji, Samoa, Wallis and Futuna, Vanuatu, New Zealand, Australia, Japan, Russia, the United States, Canada, Mexico, Chile and Ecuador, and explosions and the shockwave from the eruption could be heard as far as Alaska and Canada. Also visible in this image is the remnants of Tropical Cyclone Cody to the southwest. Credit: Japan Meteorological Agency/NASA SPoRT. CC BY 4.0
The recent violent volcanic eruption on the Pacific island nation of Tonga is believed to be one of the strongest ever recorded, and future eruptions could be possible, according to a Texas A&M University geophysicist.
Andreas Kronenberg, professor and holder of the Michael T. Halbouty Chair in Geology at Texas A&M, said the eruption on Tonga likely ranks among the strongest in at least 30 years. The Polynesian country has about 170 islands, and is 500 miles east of Fiji.
The eruption caused a huge ash cloud to form on many of the islands, killed at least three people, and could be heard in New Zealand and seen from space.
“In general, the volcanoes around the Pacific Rim are much more powerful and explosive than Hawaiian-type volcanoes, mostly because of the volatile content and magma compositions in them,” Kronenberg said.
“This is why we are concerned about the volcanoes in the Oregon, Washington and Alaska regions,” Kronenberg said. “However, the Tonga subduction zone is a large one and the entire Southwest Pacific has what we call ‘stratovolcanoes.’ These are extremely powerful volcanoes and are also the kinds that include Mt. Vesuvius that covered Pompei in Italy and Mt. St. Helens, which exploded a few decades ago.”
Mt. St. Helens, which exploded in 1980, is considered the most powerful volcanic eruption in U.S. history and killed 57 people.
The largest eruption ever is believed to be the eruption of Krakatoa, which exploded near Indonesia in 1883 and killed more than 36,000 people.
Some have compared the Tonga eruption as similar to Krakatoa, and NASA has said the Tonga explosion was at least 500 times more powerful than the bomb dropped on Hiroshima in 1945.
“Krakatoa was truly epic, and Tonga was obviously devastating,” Kronenberg said. “And it appears that water entering into the volcano internally added to its explosiveness. The result can be tsunamis because they can be triggered by any disturbance of the seafloor that quickly moves large volumes of seawater, such as faults that suddenly change the shape of the seafloor.”
Could the Tonga explosion mean future eruptions in the area are possible?
“It is possible such an eruption could trigger nearby activity,” Kronenberg said. “But it is not necessarily guaranteed. This is a controversial topic when discussing earthquakes and subsequent eruptions, especially in areas over 10 to 15 miles from the original eruption.”
Researchers used thermochronometric data from four North American locations to determine the cause of the “Great Unconformity”—a massive loss of rock about 700 million years ago. Credit: Kalin McDannell
New research provides further evidence that rocks representing up to a billion years of geological time were carved away by ancient glaciers during the planet’s “Snowball Earth” period, according to a study published in Proceedings of the National Academy of Sciences.
The research presents the latest findings in a debate over what caused the Earth’s “Great Unconformity”—a time gap in the geological record associated with the erosion of rock up to 3 miles thick in areas across the globe.
“The fact that so many places are missing the sedimentary rocks from this time period has been one of the most puzzling features of the rock record,” said C. Brenhin Keller, an assistant professor of earth sciences and senior researcher on the study. “With these results, the pattern is starting to make a lot more sense.”
The massive amount of missing rock that has come to be known as the Great Unconformity was first named in the Grand Canyon in the late 1800s. The conspicuous geological feature is visible where rock layers from distant time periods are sandwiched together, and it is often identified where rocks with fossils sit directly above those that do not contain fossils.
“This was a fascinating time in Earth’s history,” said Kalin McDannell, a postdoctoral researcher at Dartmouth and the lead author of the paper. “The Great Unconformity sets the stage for the Cambrian explosion of life, which has always been puzzling since it is so abrupt in the fossil record—geological and evolutionary processes are usually gradual.”
For over a century, researchers have sought to explain the cause of the missing geological time.
In the last five years, two opposing theories have come into focus: One explains that the rock was carved away by ancient glaciers during the Snowball Earth period about 700 to 635 million years ago. The other focuses on a series of plate tectonic events over a much longer period during the assembly and breakup of the supercontinent Rodinia from about 1 billion to 550 million years ago.
Research led by Keller in 2019 first proposed that widespread erosion by continental ice sheets during the Cryogenian glacial interval caused the loss of rock. This was based on geochemical proxies that suggested that large amounts of mass erosion matched with the Snowball Earth period.
“The new research verifies and advances the findings in the earlier study,” said Keller. “Here we are providing independent evidence of rock cooling and miles of exhumation in the Cryogenian period across a large area of North America.”
The study relies on a detailed interpretation of thermochronology to make the assessment.
Thermochronology allows researchers to estimate the temperature that mineral crystals experience over time as well as their position in the continental crust given a particular thermal structure. Those histories can provide evidence of when missing rock was removed and when rocks currently exposed at the surface may have been exhumed.
The researchers used multiple measurements from previously published thermochronometric data taken across four North American locations. The areas, known as cratons, are parts of the continent that are chemically and physically stable, and where plate tectonic activity would not have been common during that time.
By running simulations that searched for the time-temperature path the rocks experienced, the research recorded a widespread signal of rapid, high magnitude cooling that is consistent with about 2-3 miles of erosion during Snowball Earth glaciations across the interior of North America.
“While other studies have used thermochronology to question the glacial origin, a global phenomenon like the Great Unconformity requires a global assessment,” said McDannell. “Glaciation is the simplest explanation for erosion across a vast area during the Snowball Earth period since ice sheets were believed to cover most of North America at that time and can be efficient excavators of rock.”
According to the research team, the competing theory that tectonic activity carved out the missing rock was put forth in 2020 when a separate research group questioned whether ancient glaciers were erosive enough to cause the massive loss of rock. While that research also used thermochronology, it applied an alternate technique at only a single tectonically active location and suggested that the erosion occurred prior to Snowball Earth.
“The underlying concept is pretty simple: Something removed a whole lot of rock, resulting in a whole lot of missing time,” said Keller. “Our research demonstrates that only glacial erosion could be responsible at this scale.”
According to the researchers, the new findings also help explain links between the erosion of rock and the emergence of complex organisms about 530 million years ago during the Cambrian explosion. It is believed that erosion during the Snowball Earth period deposited nutrient-rich sediment in the ocean that could have provided a fertile environment for the building blocks of complex life.
The study notes that the two hypotheses of how the rock eroded are not mutually exclusive—it is possible that both tectonics and glaciation contributed to global Earth system disruption during the formation of the Great Unconformity. It appears, however, that only glaciation can explain erosion in the center of the continent, far from the tectonic margins.
“Ultimately with respect to the Great Unconformity, it may be that the generally accepted reconstruction(s) of more concentrated equatorial packing of the Rodinian continents along with the unique environmental conditions of the Neoproterozoic, proved to be a time of geologic serendipity unlike most any other in Earth history,” the research paper says.
According to the team, this is the first research that uses their thermochronology modeling approach to study a period that extends well beyond a billion years. In the future, the team will repeat their work on other continents, where they hope to further test these hypotheses about how the Great Unconformity was created and preserved.
According to the team, resolving differences in the research is critical to understanding early Earth history and the interconnection of climatic, tectonic and biogeochemical processes.
“The fact that there may have been tectonic erosion along the craton margins does not rule out glaciation,” said McDannell. “Unconformities are composite features, and our work suggests Cryogenian erosion was a key contributor, but it is possible that both earlier and later erosion were involved in forming the unconformity surface in different places. A global examination will tell us more.”
William Guenthner, from the University of Illinois at Urbana-Champaign; Peter Zeitler from Lehigh University; and David Shuster from the University of California, Berkeley and the Berkeley Geochronology Center served as co-authors of the paper.
Paleontologist Dean Lomax with the fossilized ichthyosaur. (Matthew Power Photography/Anglian Water)
A gigantic prehistoric “sea dragon” discovered in the Midlands has been described as one of the greatest finds in the history of British palaeontology.
The fossil, identified as an ichthyosaur, an ancient marine reptile that swam in Earth’s prehistoric oceans when dinosaurs walked on land, was found poking out of the mud, and scientists say the ancient specimen is practically complete from tip to tail.
The ichthyosaur, which is about 180m years old with a skeleton measuring about 10 metres in length and a skull weighing about a tonne, is the largest and most complete fossil of its kind ever found in the UK. Joe Davis of the Leicestershire and Rutland Wildlife Trust discovered it during the routine draining of a lagoon island at the Rutland Water reservoir in February 2021.
The first ichthyosaurs, which are called sea dragons because they tend to have very large teeth and eyes, were discovered by the fossil hunter and palaeontologist Mary Anning in the early 19th century.
Ichthyosaurs, which were marine reptiles, first appeared about 250m years ago and went extinct 90m years ago. They varied in size from 1 to more than 25 metres in length and resembled dolphins in their general body shape.
The remains were dug out by a team of experts from around the UK in August and September.
“Our specimen, the Rutland Ichthyosaur or the Rutland Sea Dragon, is the biggest complete ichthyosaur ever found in Britain in over 200 years of collecting these things scientifically,” says paleontologist Dean Lomax who led the excavation.
Two incomplete and much smaller ichthyosaurs were found during the construction of Rutland Water in the 1970s, but the latest discovery is the first complete skeleton.
The spectacular specimen, only recently revealed to the public, is still wrapped in its plaster cast, stored in a secret location, and has not yet been studied in detail. The researchers plan to prepare academic papers describing the discovery once it has been cleaned up and conserved.
Natural History Museum of Los Angeles County (NHM) Dinosaur Institute volunteer Viji Shook lying next to the skull of Cymbospondylus youngorum for scale, during the preparation of the specimen. Photo by Martin Sander, courtesy of the Natural History Museum of Los Angeles County (NHM).
The two-meter skull of a newly discovered species of giant ichthyosaur, the earliest known, is shedding new light on the marine reptiles’ rapid growth into behemoths of the Dinosaurian oceans, and helping us better understand the journey of modern cetaceans (whales and dolphins) to becoming the largest animals to ever inhabit the Earth.
While dinosaurs ruled the land, ichthyosaurs and other aquatic reptiles (that were emphatically not dinosaurs) ruled the waves, reaching similarly gargantuan sizes and species diversity. Evolving fins and hydrodynamic body-shapes seen in both fish and whales, ichthyosaurs swam the ancient oceans for nearly the entirety of the Age of Dinosaurs.
“Ichthyosaurs derive from an as yet unknown group of land-living reptiles and were air-breathing themselves,” says lead author Dr. Martin Sander, paleontologist at the University of Bonn and Research Associate with the Dinosaur Institute at the Natural History Museum of Los Angeles County (NHM). “From the first skeleton discoveries in southern England and Germany over 250 years ago, these ‘fish-saurians’ were among the first large fossil reptiles known to science, long before the dinosaurs, and they have captured the popular imagination ever since.”
Excavated from a rock unit called the Fossil Hill Member in the Augusta Mountains of Nevada, the well-preserved skull, along with part of the backbone, shoulder, and forefin, date back to the Middle Triassic (247.2-237 million years ago), representing the earliest case of an ichthyosaur reaching epic proportions. As big as a large sperm whale at more than 17 meters (55.78 feet) long, the newly named Cymbospondylus youngorum is the largest animal yet discovered from that time period, on land or in the sea. In fact, it was the first giant creature to ever inhabit the Earth that we know of.
“The importance of the find was not immediately apparent,” notes Dr. Sander, “because only a few vertebrae were exposed on the side of the canyon. However, the anatomy of the vertebrae suggested that the front end of the animal might still be hidden in the rocks. Then, one cold September day in 2011, the crew needed a warm-up and tested this suggestion by excavation, finding the skull, forelimbs, and chest region.”
The new name for the species, C. youngorum, honors a happy coincidence, the sponsoring of the fieldwork by Great Basin Brewery of Reno, owned and operated by Tom and Bonda Young, the inventors of the locally famous Icky beer which features an ichthyosaur on its label.
In other mountain ranges of Nevada, paleontologists have been recovering fossils from the Fossil Hill Member’s limestone, shale, and siltstone since 1902, opening a window into the Triassic. The mountains connect our present to ancient oceans and have produced many species of ammonites, shelled ancestors of modern cephalopods like cuttlefish and octopuses, as well as marine reptiles. All these animal specimens are collectively known as the Fossil Hill Fauna, representing many of C. youngorum’s prey and competitors.
C. youngorum stalked the oceans some 246 million years ago, or only about three million years after the first ichthyosaurs got their fins wet, an amazingly short time to get this big. The elongated snout and conical teeth suggest that C. youngorum preyed on squid and fish, but its size meant that it could have hunted smaller and juvenile marine reptiles as well.
The giant predator probably had some hefty competition. Through sophisticated computational modeling, the authors examined the likely energy running through the Fossil Hill Fauna’s food web, recreating the ancient environment through data, finding that marine food webs were able to support a few more colossal meat-eating ichthyosaurs. Ichthyosaurs of different sizes and survival strategies proliferated, comparable to modern cetaceans’ — from relatively small dolphins to massive filter-feeding baleen whales, and giant squid-hunting sperm whales.
Co-author and ecological modeler Dr. Eva Maria Griebeler from the University of Mainz in Germany notes, “due to their large size and resulting energy demands, the densities of the largest ichthyosaurs from the Fossil Hill Fauna including C. youngourum must have been substantially lower than suggested by our field census. The ecological functioning of this food web from ecological modeling was very exciting as modern highly productive primary producers were absent in Mesozoic food webs and were an important driver in the size evolution of whales.”
Whales and ichthyosaurs share more than a size range. They have similar body plans, and both initially arose after mass extinctions. These similarities make them scientifically valuable for comparative study. The authors combined computer modeling and traditional paleontology to study how these marine animals reached record-setting sizes independently.
“One rather unique aspect of this project is the integrative nature of our approach. We first had to describe the anatomy of the giant skull in detail and determine how this animal is related to other ichthyosaurs,” says senior author Dr. Lars Schmitz, Associate Professor of Biology at Scripps College and Dinosaur Institute Research Associate. “We did not stop there, as we wanted to understand the significance of the new discovery in the context of the large-scale evolutionary pattern of ichthyosaur and whale body sizes, and how the fossil ecosystem of the Fossil Hill Fauna may have functioned. Both the evolutionary and ecological analyses required a substantial amount of computation, ultimately leading to a confluence of modeling with traditional paleontology.”
They found that while both cetaceans and ichthyosaurs evolved very large body sizes, their respective evolutionary trajectories toward gigantism were different. Ichthyosaurs had an initial boom in size, becoming giants early on in their evolutionary history, while whales took much longer to reach the outer limits of huge. They found a connection between large size and raptorial hunting — think of a sperm whale diving down to hunt giant squid — and a connection between large size and a loss of teeth — think of the giant filter-feeding whales that are the largest animals ever to live on Earth.
Ichthyosaurs’ initial foray into gigantism was likely thanks to the boom in ammonites and jawless eel-like conodonts filling the ecological void following the end-Permian mass extinction. While their evolutionary routes were different, both whales and ichthyosaurs relied on exploiting niches in the food chain to make it really big.
“As researchers, we often talk about similarities between ichthyosaurs and cetaceans, but rarely dive into the details. That’s one way this study stands out, as it allowed us to explore and gain some additional insight into body size evolution within these groups of marine tetrapods,” says NHM’s Associate Curator of Mammalogy (Marine Mammals), Dr. Jorge Velez-Juarbe. “Another interesting aspect is that Cymbospondylus youngorum and the rest of the Fossil Hill Fauna are a testament to the resilience of life in the oceans after the worst mass extinction in Earth’s history. You can say this is the first big splash for tetrapods in the oceans.”
C. youngorum will be permanently housed at the Natural History Museum of Los Angeles County, where it is currently on view.
Reference:
P. Martin Sander, Eva Maria Griebeler, Nicole Klein, Jorge Velez Juarbe, Tanja Wintrich, Liam J. Revell, Lars Schmitz. Early giant reveals faster evolution of large body size in ichthyosaurs than in cetaceans. Science, 2021; 374 (6575) DOI: 10.1126/science.abf5787
Turning one of the world’s finest gems—diamonds—into one of the worst greenhouse gasses—methane—does not seem a great idea. Yet this happened through the work of a group of researchers from the Universities of Bologna and Edimburgh (UK), the Centre National de la Recherche Scientifique (France) and HPSTAR (China). This outcome published in Nature Communications was not a clumsy lab mistake. In fact, this study might provide more insight on the deep carbon cycle and the formation of hydrocarbons through abiotic processes (i.e. unrelated to biological activities) in the deep Earth.
The deep earth’s carbon cycle accounts for about 90% of the whole carbon cycle. Despite this, to date the cycle happening beneath the earth’s surface is little known. This phenomenon is crucial to life on our planet as it allows carbon in the deep Earth to get back to the atmosphere.
“It is well known that the decomposition of methane may bring to diamond formation. What was less known until now is that the opposite process is also possible. Methane produced through the reaction between diamonds and hydrogen was the missing piece to a wider understanding of the deep carbon cycle”, explains Alberto Vitale Brovarone who is a professor a the Department of Biological, Geological and Environmental study at the University of Bologna and also one of the authors of the study.
The deep carbon cycle also includes the formation of hydrocarbons such as methane as the result of processes that do not involve biological activities. This theory has been under discussion for over a century. Wanting to test this theory, researchers started from diamonds that are essentially gems in the Earth’s mantle composed of solid carbon atoms in a crystal structure.
Scholars used a “diamond anvil cell” which is a high-pressure experimental apparatus used to press two diamond culets against each other and replicate the pressure conditions of the earth’s upper mantle, over 70 km deep. Then, by pushing one atmosphere of pure hydrogen at 300 °C, researchers observed methane rapidly forming with its molecules composed of one atom of carbon and four of hydrogen (CH4).
“We created an environment comparable to that of the outer layer of earth’s mantle in terms of temperature and pressure and observed that diamond and hydrogen reacted readily by producing methane within a few seconds”, states Vitale Bovarone. “This shows that hydrocarbons such as methane can form at abiotic depths. This phenomenon may play a key role in the deep Earth’s carbon cycle”.
Researchers replicated this experiment by adding graphite, which is composed of pure carbon too, and a glass-like carbon material. In both cases, they observed methane forming more rapidly and more copiously in comparison to when they used only diamonds. These results suggest that carbon-based graphitic materials may be very efficient reagents and can therefore act as sources of energy feeding methane reserves in the the earth’s upper mantle.
Reference:
Miriam Peña-Alvarez et al, In-situ abiogenic methane synthesis from diamond and graphite under geologically relevant conditions, Nature Communications (2021). DOI: 10.1038/s41467-021-26664-3
Igánâq, Greenland: view to the southwest from the Igánâq summit (~540m) towards Tunulliarfik and the snowy peaks of Ilímaussaq. Credit: University of St Andrews
A new understanding of how volcanic processes form deposits of rare earth metals, vital to everyday modern technology, is revealed in a new study from the University of St Andrews.
The research, led by a team from the School of Earth and Environmental Sciences at St Andrews and published in the journal Geology (Friday 3 December), provides new clues about how hot volcanic fluids concentrate rare earth metals and how these metals seep out from the magma body.
These rare metals, which include elements such as niobium and tantalum, are essential for the production of alloys, batteries, magnets and superconductors, and are vital for modern technologies ranging from mobile phones and laptops to MRI machines. These metals are also essential for green technologies and, crucially, the transition to a low-carbon economy must involve finding new sources of the rare earth metals.
Rare earth deposits are associated with extinct alkaline volcanoes. These volcanoes are unusual and only exposed in select regions around the world, such as south Greenland.
The team of researchers from the University of St Andrews wanted to understand why some volcanoes produce massive metals deposits, whilst others are devoid of mineralisation. By studying a metal-poor volcano in Greenland the researchers were able to show that fluids leaking from the magma body into the surrounding rocks can carry significant quantities of rare earth metals. Rather than concentrating metals, these fluids scatter them over a large area and significantly decrease the chances of forming an economically viable deposit.
Lead researcher Krzysztof Sokół from the School of Earth and Environmental Sciences said: “By measuring the chemical composition of the rocks around the chamber we showed that metals had been carried out of the magma chamber and into the surrounding rocks. This is the first time that the mass of material transported by this process was estimated. We also present a new way to visualize the distribution of metals in the surrounding rock.
“We show that during an episode of volcanic activity, the melts residing at shallow levels of the Earth’s crust can form a separate hot fluid enriched in critical metals, which subsequently leaks from the magma chamber into the surrounding rocks carrying a globally significant volume of the metals.”
The research team estimates that the total tonnage of the critical metals transported to the surrounding rocks by this processes is about 40 megatonnes, which is comparable to the mass of rare earth metals present in some of the world’s largest metal deposits.
Professor Adrian Finch and Dr. Will Hutchison, also from the School of Earth and Environmental Sciences at St Andrews, added: “We show that fluids can ‘leak’ from magma systems that would otherwise have crystallized to form large critical metal deposits within the chamber confines. Now that we understand this process more fully, we can predict more effectively how the deposits under these types of volcanoes formed. Armed with this information, we can guide far better exploration for the next generation of green technologies.”
Reference:
Krzysztof Sokół et al, Quantifying metasomatic high-field-strength and rare-earth element transport from alkaline magmas, Geology (2021). DOI: 10.1130/G49471.1
Vectiraptor greeni, a new fierce predatory dinosaur from the Isle of Wight. Image credit: Megan Jacobs
A new bird-like dinosaur that used brute strength to overcome its prey has been found by paleontologists combing through fossils found on the Isle of Wight, on the South Coast of Great Britain.
The new animal has been named Vectiraptor greeni after local collector Mick Green who discovered its bones after they became washed from the rocks on the island’s south coast. It was an older, more heavily built, relative of the predator Velociraptor. The fearsome animal was about the size of a wolf, about 3 metres (10 feet) long, from nose to tail, and would have used huge slashing talons on its feet to dispatch its prey. Its finely serrated teeth were then used to bite off pieces of the kill.
The dinosaur would have prowled through the forests that covered the land in the Early Cretaceous, 125 million years ago. It died and lay buried until 2004, when storms and waves eroded away the rocks that had kept its bones hidden. Yet another 20 years passed before scientists from the Universities of Bath and Portsmouth studied the fossils and made the surprising find that the bones represented a new species. Their discovery is described this week in the journal Cretaceous Research.
Vectiraptor belonged to a group of dinosaurs called dromaeosaurs, or raptors. These bird-like dinosaurs were specialist hunters and, like their modern-day avian relatives, were covered in long feathers. Their jaws were full of blade-like, serrated teeth and they had huge scythe-shaped claws on their feet, used to slash at their prey, causing it to rapidly bleed to death.
Well-known members of the raptors include Velociraptor from Mongolia, and Deinonychus, and the giant Utahraptor from the United States. A smaller raptor has previously been described from the Isle of Wight but Vectiraptor marks the first time a large raptor has been found in England. Although only fragments of the skeleton have survived- a pair of vertebrae from the back, and part of the hips — what is known suggests a large, powerfully built animal.
“This was a large, and very heavily constructed animal,” said Dr Nick Longrich, who led the study from the Milner Centre for Evolution at the University of Bath. “The bones are thick-walled and massive. It clearly didn’t hunt small prey, but animals as large or larger than itself.”
Although not the biggest predator in its environment — top predators included the allosaur Neovenator, spinosaurs like Baryonyx, and an early tyrannosaur called Eotyrannus — Vectiraptor would have been a threat both to smaller dinosaurs and juveniles of large dinosaurs. With strong arms and talons, it may have climbed trees like modern leopards. The heavy bones suggest an animal that relied less on speed and more on strength, and perhaps ambushes, to tackle its prey.
“It’s a tantalising hint at the diversity of dinosaurs in England at this time,” said Dr Longrich.
This is the first time a large raptor has been found in the UK. “There’s an extraordinary diversity of dinosaurs known in England in the Cretaceous, and even after more than a century of study, we continue to find new species,” said Dr Longrich. “Although palaeontologists have been studying these dinosaurs for a long time, it’s hard going. We have to wait for the sea cliffs to fall and expose bits of bone, or for the waves to wash them out of the rocks. We’ve spent two centuries on the Isle of Wight piecing together our picture of English dinosaurs.”
Co-author Professor Dave Martill of the University of Portsmouth notes that raptors closely related to Velociraptor have also been found in Mongolia, suggesting that England may have lain along an important dispersal route for dinosaurs. Professor Martill said, given the similarity between North American and Mongolian dinosaur faunas in the Early Cretaceous, it was only a matter of time before someone discovered a raptor dinosaur in England.
A remarkable number of dinosaur species originate from this small island off southern England. Ancient England was something of a crossroads for dinosaurs. At the time the continents were closer together, with some connected by land bridges. Dinosaurs likely wandered in from North America and Asia, or perhaps swam from Africa. Europe was a sort of crossroads linking the continents.
A chance encounter
Vectiraptor greeni was named after amateur paleontologist Mick Green, who discovered the remains in in 2004 but didn’t appreciate the importance of his find until he was forced by ill-health to stop collecting fossils in 2012. He then turned his attention to prising the dinosaur bones free from the hard ironstone surrounding them.
One day, chatting over a beer, he showed the fossils to Isle of Wight palaeontologist Megan Jacobs and Dr Longrich who puzzled over them, and at first struggled to make sense of them, until they noticed tell-tale similarities to other raptors. Mr Green allowed the bones to be studied, and they turned out to represent a new genus and species. The bones have now been donated to the Dinosaur Isle Museum at Sandown on the Isle of Wight.
“This dinosaur is incredibly exciting, adding to the huge diversity of dinosaurs here on the Isle of Wight, and helping to build a bigger picture of the Early Cretaceous world,” said Megan Jacobs, a collaborator on the project. “This little dinosaur also serves as an excellent example of the importance of amateur fossil collectors, and how working with them can produce important scientific research, which would otherwise not be possible.”
Without the dedication of Mick Green and others on the island, she noted, this dinosaur would have been lost to the sea.
Reference:
Nicholas R. Longrich, David M. Martill, Megan L. Jacobs. A new dromaeosaurid dinosaur from the Wessex Formation (Lower Cretaceous, Barremian) of the Isle of Wight, and implications for European palaeobiogeography. Cretaceous Research, 2021; 105123 DOI: 10.1016/j.cretres.2021.105123
Original artwork from scientific illustrator Emiliano Troco depicting a Brontosaurus (likely the most famous sauropod dinosaur) acting as an ecosystem engineer in a warm and vegetated landscape not dissimilar to modern-day savannah type biomes.
Giant, long-necked sauropods, thought to include the largest land animals ever to have existed, preferred to live in warmer, more tropical regions on Earth, suggesting they may have had a different physiology from other dinosaurs, according to a new study led by researchers at UCL and the University of Vigo.
The study, published in the journal Current Biology, investigated the enigma of why sauropod fossils are only found at lower latitudes, while fossils of other main dinosaur types seem ubiquitously present, with many located in the polar regions.
The researchers analysed the fossil record across the Mesozoic era (the time of the dinosaurs), lasting from around 230 to 66 million years ago, looking at occurrences of fossils of the three main dinosaur types: sauropods, which include the Brontosaurus and the Diplodocus, theropods (“lizard-hipped”), which include velociraptors and Tyrannosaurus rex, and ornithischians (“bird-hipped”) such as the Triceratops.
Combining this fossil data with data about climate throughout the period, along with information about how continents have moved across the globe, the researchers concluded that sauropods were restricted to warmer, drier habitats than other dinosaurs. These habitats were likely to be open, semi-arid landscapes, similar to today’s savannahs.
Co-author Dr Philip Mannion (UCL Earth Sciences) said: “Our research shows that some parts of the planet always seemed to be too cold for sauropods. They seem to have avoided any temperatures approaching freezing. Other dinosaur types, in contrast, could thrive in Earth’s polar regions, from innermost Antarctica to polar Alaska — which, due to the warmer climate, were ice-free, with lush vegetation.
“This suggests sauropods had different thermal requirements from other dinosaurs, relying more on their external environment to heat their bodies — slightly closer to being ‘cold-blooded’, like modern-day reptiles. Their grand size hints that this physiology may have been unique.”
First author Dr Alfio Alessandro Chiarenza, formerly of UCL who is now based at the University of Vigo, Spain, said: “It may be that sauropods were physiologically incapable of thriving in colder regions, or that they thrived less well in these areas than their dinosaurian cousins and were outcompeted.
“A mix of features may have helped sauropods shed heat more easily than mammals do today. Their long necks and tails would have given them a larger surface area, and they may have had a respiratory system more akin to birds, which is much more efficient.
“Some species of theropods and ornithischians are known to have had feathers or downy fur helping them retain body warmth. This suggests they may have generated their own body heat. For sauropods, however, there is no evidence of this kind of insulation.
“Sauropods’ strategies for keeping their eggs warm may also have differed from the other dinosaurs. Theropods probably warmed eggs by sitting on them, whereas ornithischians seem to have used heat generated by decaying plants. Sauropods, meanwhile, may have buried their eggs, relying on heat from the sun and the ground.”
In their paper, the researchers noted that the fossil record showed zero occurrences of sauropods above a latitude of 50 degrees north — an area encompassing most of Canada, Russia, northern Europe and the UK — or below 65 degrees south, encompassing Antarctica. In contrast, there are rich records for theropods and ornithischians living above 50 degrees north in later periods (from 145 million years ago).
To test if this was a true reflection of where sauropods lived, researchers used a statistical technique to adjust for gaps in the fossil record, and also analysed where the highest diversities of dinosaur types were in different periods throughout the Mesozoic era.
They combined fossil data with climate data, allowing an estimate of the temperature ranges of the dinosaur types’ habitats, finding that sauropods’ range across the latitudes was more restricted during colder periods.
They then used habitat modelling to infer which regions of the globe would likely be suitable for sauropods and the other dinosaur types to live.
While in the past it was believed that dinosaurs were ectothermic (“cold-blooded”), like reptiles today, relying on the external environment to heat their bodies, it is now thought they were closer to “warm-blooded” mammals, generating some of their own body heat (endothermic).
The study authors said sauropods may have had a unique in-between physiology, closer to being cold-blooded than other dinosaur types.
The study involved researchers from UCL, the University of Vigo, the University of Bristol, and the Natural Museum of Natural History, Smithsonian Institution, Washington, USA, and received funding from the European Research Council and the Royal Society.
Reference:
Alfio Alessandro Chiarenza, Philip D. Mannion, Alex Farnsworth, Matthew T. Carrano, Sara Varela. Climatic constraints on the biogeographic history of Mesozoic dinosaurs. Current Biology, 2021; DOI: 10.1016/j.cub.2021.11.061
The aftermath of a 2010 tsunami in Chile, which was analyzed in a new study in JGR Solid Earth. Earlier warnings made possible by the study of tsunami-generated magnetic fields could better prepare coastal areas for impending disasters. Credit: International Federation of Red Cross and Red Crescent Societies
A new study finds the magnetic field generated by a tsunami can be detected a few minutes earlier than changes in sea level and could improve warnings of these giant waves.
Tsunamis generate magnetic fields as they move conductive seawater through the Earth’s magnetic field. Researchers previously predicted that the tsunami’s magnetic field would arrive before a change in sea level, but they lacked simultaneous measurements of magnetics and sea level that are necessary to demonstrate the phenomenon.
The new study provides real-world evidence for using tsunamis’ magnetic fields to predict the height of tsunami waves using data from two real events — a 2009 tsunami in Samoa and a 2010 tsunami in Chile — that have both sets of necessary data. The new study was published in AGU’s Journal of Geophysical Research: Solid Earth, which focuses on the physics and chemistry of the solid Earth.
The study confirms the magnetic field generated by a tsunami arrives ahead of sea-level change and that its magnitude can be used to estimate the tsunami’s wave height. How much earlier the magnetic field arrives depends on water depth, but in their results, the study authors found the early arrival time to be about one minute prior to sea level change over a 4,800-meter deep sea.
This information could provide earlier disaster warning if incorporated into tsunami risk models, potentially saving lives.
“It is very exciting because in previous studies we didn’t have the observation [of] sea level change,” said Zhiheng Lin, senior study-author and a geophysicist at Kyoto University. “We have observations [of] sea level change, and we find that the observation agrees with our magnetic data as well as theoretical simulation.”
The research team looked at simultaneous measurements of sea level change from seafloor pressure data and magnetic fields during the two tsunamis. They found that the primary arrival of the magnetic field, similar to that of the beginning of a seismic wave, can be used for the purpose of early tsunami warning. The tsunami-generated magnetic field is so sensitive that even a wave height of a few centimeters can be detected.
“They did something that basically needed to be done,” said Neesha Schnepf, a researcher of geomagnetics at the University of Colorado, Boulder who was not involved in the study. “We’ve needed a study that compared the magnetic field data with the sea level change from the pressure data, and I’m pretty sure they’re the first to really compare how well the sea level from magnetic field matches the sea level from pressure, so that’s definitely very useful.”
When the researchers compared the horizontal and vertical components of the tsunami magnetic field with sea level change, they found that both components can precisely predict tsunami sea level change, if models include good estimates for ocean depth and the electrical structure below the seafloor.
This relationship between magnetic fields and wave height can be used to improve tsunami source models, which estimate the initial sea surface topography of a tsunami and then predict water wave arrival time and wave height — important data for informing disaster readiness and response.
The difficulty of maintaining already limited observational stations means these types of data from tsunamis are often not available. Furthermore, these findings only apply in deep-sea and not coastal environments, where deep water in the region filters out environmental noise to allow the tsunami signal to be detected.
However, providing warning for these severe events — which have the potential to cause intense damage to large areas — makes the predictions worthwhile, said Lin.
“I think the practical goal would be if your ability to model tsunamis is so improved, … you could come up with much better predictions of what areas might need to be warned [and] how badly it might hit certain places,” Schnepf said.
Reference:
Zhiheng Lin, Hiroaki Toh, Takuto Minami. Direct Comparison of the Tsunami‐Generated Magnetic Field With Sea Level Change for the 2009 Samoa and 2010 Chile Tsunamis. Journal of Geophysical Research: Solid Earth, 2021; 126 (11) DOI: 10.1029/2021JB022760
On September 29, 2009, a tsunami caused substantial damage and loss of life in American Samoa, Samoa, and Tonga. The tsunami was generated by a large earthquake in the Southern Pacific Ocean. Credit: NOAA
Earthquakes of similar magnitude can cause tsunamis of greatly varying sizes. This commonly observed, but not well-understood phenomenon has hindered reliable warnings of local tsunamis.
Research led by University of Hawai’i (UH) at Manoa scientists provides new insight that connects the characteristics of earthquakes — magnitude, depth where two tectonic plates slip past each other and the rigidity of the plates involved — with the potential size of a resulting tsunami.
Previous researchers identified a special class of events known as tsunami earthquakes, which produce disproportionately large tsunamis for their magnitude. Kwok Fai Cheung, professor of Ocean and Resources Engineering in the UH Manoa School of Ocean and Earth Science and Technology (SOEST), Thorne Lay from the University of California — Santa Cruz and co-authors discovered a straightforward explanation for this conundrum. Their findings were published recently in Nature Geoscience.
Using computer models, the team incorporated physical processes that produce earthquakes and tsunamis with a wide range of observations of real-world events, including those classified as tsunami earthquakes. The model results demonstrated that for a given earthquake magnitude, if the rupture extends to shallow depth in the less rigid part of the plate, the resulting tsunami is larger than if the rupture is deeper.
“In a subduction zone, the upper plate is thinner and less rigid than the underthrusting plate near the trench,” explained Cheung. “A concentrated near-trench or shallow rupture produces relatively weak ground shaking as recorded by seismometers, but the displaced water in the overlying deep ocean has enhanced energy and produces shorter tsunami waves that amplify at a high rate as they move toward the shore.”
“Earthquake and tsunamigenic processes are complex, involving many factors that vary from one event to another,” said Lay, professor of Earth and Planetary Sciences at UC Santa Cruz. “We utilized a simplified numerical model to isolate key earthquake parameters and evaluate their importance in defining tsunami size.”
Having verified that the presence of shallow earthquake rupture can be a more significant factor than the earthquake magnitude for the resulting tsunami size led the researchers to an important question: Can earthquake magnitude continue to be used as the primary indication of potential tsunami impacts?
“The practice of using earthquake magnitude to estimate potential tsunami threat has led to poor predictive capability for tsunami impacts, and more information about the source is required to do better,” said Cheung.
An important aspect of this interdisciplinary research is the synergy of expertise in seismology, with Lay, and tsunamis, with Cheung’s research group, applied to a large set of observations. This study motivates development of new seismological and seafloor geodesy research that can rapidly detect occurrence of shallow rupture in order to achieve more reliable tsunami warning.
While shorelines throughout the Pacific Ocean and along the “Ring of Fire” are vulnerable to tsunamis, the situation is most critical for coastal communities near the earthquake, where the tsunami arrives quickly — when detailed information about the earthquake is not yet available.
Cheung and Lay continue their collaboration to investigate prehistorical, historical, and future tsunami events to better understand the hazards posed to coastal communities and enable more accurate warning systems.
Reference:
Kwok Fai Cheung, Thorne Lay, Lin Sun, Yoshiki Yamazaki. Tsunami size variability with rupture depth. Nature Geoscience, 2021; DOI: 10.1038/s41561-021-00869-z
Stick-slip events in the earth cause damage like this, but limited data from these relatively rare earthquakes makes them difficult to model with machine learning. Transfer learning may provide a path to understanding when such deep faults slip. Credit: Dreamstime
A machine-learning approach developed for sparse data reliably predicts fault slip in laboratory earthquakes and could be key to predicting fault slip and potentially earthquakes in the field. The research by a Los Alamos National Laboratory team builds on their previous success using data-driven approaches that worked for slow-slip events in earth but came up short on large-scale stick-slip faults that generate relatively little data — but big quakes.
“The very long timescale between major earthquakes limits the data sets, since major faults may slip only once in 50 to 100 years or longer, meaning seismologists have had little opportunity to collect the vast amounts of observational data needed for machine learning,” said Paul Johnson, a geophysicist at Los Alamos and a co-author on a new paper, “Predicting Fault Slip via Transfer Learning,” in Nature Communications.
To compensate for limited data, Johnson said, the team trained a convolutional neural network on the output of numerical simulations of laboratory quakes as well as on a small set of data from lab experiments. Then they were able to predict fault slips in the remaining unseen lab data.
This research was the first application of transfer learning to numerical simulations for predicting fault slip in lab experiments, Johnson said, and no one has applied it to earth observations.
With transfer learning, researchers can generalize from one model to another as a way of overcoming data sparsity. The approach allowed the Laboratory team to build on their earlier data-driven machine learning experiments successfully predicting slip in laboratory quakes and apply it to sparse data from the simulations. Specifically, in this case, transfer learning refers to training the neural network on one type of data — simulation output — and applying it to another — experimental data — with the additional step of training on a small subset of experimental data, as well.
“Our aha moment came when I realized we can take this approach to earth,” Johnson said. “We can simulate a seismogenic fault in earth, then incorporate data from the actual fault during a portion of the slip cycle through the same kind of cross training.” The aim would be to predict fault movement in a seismogenic fault such as the San Andreas, where data is limited by infrequent earthquakes.
The team first ran numerical simulations of the lab quakes. These simulations involve building a mathematical grid and plugging in values to simulate fault behavior, which are sometimes just good guesses.
For this paper, the convolutional neural network comprised an encoder that boils down the output of the simulation to its key features, which are encoded in the model’s hidden, or latent space, between the encoder and decoder. Those features are the essence of the input data that can predict fault-slip behavior.
The neural network decoded the simplified features to estimate the friction on the fault at any given time. In a further refinement of this method, the model’s latent space was additionally trained on a small slice of experimental data. Armed with this “cross-training,” the neural network predicted fault-slip events accurately when fed unseen data from a different experiment.
Reference:
Kun Wang, Christopher W. Johnson, Kane C. Bennett, Paul A. Johnson. Predicting fault slip via transfer learning. Nature Communications, 2021; 12 (1) DOI: 10.1038/s41467-021-27553-5
The asteroid belt between Jupiter and Mars is the main source of extraterrestrial material that lands on Earth. (Illustration: ESA/ATG Medialab)
A new University of Liverpool study has found that the minerology of the rocks that a meteorite hits, rather than the size of the impact, determines how deadly an impact it will have.
The earth has been bombarded by meteorites throughout its long history. Meteorite impacts generate atmospheric dust and cover the Earth’s surface with debris and have long been considered as a trigger of mass extinctions through Earth’s history.
A multidisciplinary research team from the University of Liverpool and the Instituto Tecnológico y de Energías Renovables, Tenerife with expertise in palaeontology, asteroid stratigraphy, mineralogy, cloud microphysics and climate modelling, sought to explore why some meteorites have caused mass extinctions, for example the K/Pg Chixulclub impact that killed off dinosaurs, yet many which are larger in size have not.
They analysed 44 impacts over the past 600 million years using a new method: assessing the mineral content of the dust ejected into the atmosphere upon impact.
Their findings, published in the Journal of the Geological Society of London, reveal that meteorites that hit rocks rich in potassium feldspar (a common and rather benign mineral) always correspond with a mass extinction episode, irrespective of size.
Potassium feldspar is non-toxic. However, it is a powerful ice-nucleating mineral aerosol that strongly affects cloud dynamics, which makes them let through more solar radiation. This in turn warms up the planet and changes the climate. The atmosphere also becomes more sensitive to warming from greenhouse gas emissions, such as large volcanic eruptions.
Liverpool sedimentologist, Dr Chris Stevenson, from the University’s school of Earth, Ocean and Ecological Sciences co-authored the study.
He said: “For decades scientists have puzzled over why some meteorites cause mass extinctions, and others, even really big ones, don’t.
“It’s surprising when we put together the data: life carried on as normal during the 4th largest impact with a crater diameter of ~48 km, whereas an impact half the size was associated with a mass extinction only 5 million years ago.
“Many kill mechanisms have been proposed, such as large volcanic eruptions, but just like meteorites, these don’t always correlate with mass extinctions.
“Using this new method for assessing the mineral content of the meteorite ejecta blankets, we show that every time a meteorite, big or small, hits rocks rich in potassium feldspar it correlates with a mass extinction event.
This opens up a whole new avenue of research: what exactly kills off life during these episodes, and how long do the potassium feldspar effects last? Until now, only meteorites have changed the aerosol regime of the climate. However, present day human activities represent a similar mechanism with increasing emissions of mineral aerosols into the atmosphere.”
Reference:
M.J. Pankhurst, C.J. Stevenson, B.C. Coldwell. Meteorites that produce K-feldspar-rich ejecta blankets correspond to mass extinctions. Journal of the Geological Society, 2021; jgs2021-055 DOI: 10.1144/jgs2021-055
Dinosaur egg and embryo reconstruction (Julius Csotonyi)
A 72 to 66-million-year-old embryo found inside a fossilised dinosaur egg sheds new light on the link between the behaviour of modern birds and dinosaurs, according to a new study.
The embryo, dubbed ‘Baby Yingliang’, was discovered in the Late Cretaceous rocks of Ganzhou, southern China and belongs to a toothless theropod dinosaur, or oviraptorosaur. Among the most complete dinosaur embryos ever found, the fossil suggests that these dinosaurs developed bird-like postures close to hatching.
Scientists found the posture of ‘Baby Yingliang’ unique among known dinosaur embryos — its head lies below the body, with the feet on either side and the back curled along the blunt end of the egg. Previously unrecognised in dinosaurs, this posture is similar to that of modern bird embryos.
In modern birds, such postures are related to ‘tucking’ — a behaviour controlled by the central nervous system and critical for hatching success. After studying egg and embryo, researchers believe that such pre-hatching behaviour, previously considered unique to birds, may have originated among non-avian theropods.
Led by scientists from the University of Birmingham and China University of Geosciences (Beijing), the research team from institutions in China, UK and Canada today published its findings in iScience.
Life reconstruction of a close-to-hatching oviraptorosaur dinosaur embryo, based on the new specimen “Baby Yingliang.” Credit: Lida Xing
The embryo is articulated in its life position without much disruption from fossilisation. Estimated to be 27 cm long from head to tail, the creature lies inside a 17-cm-long elongatoolithid egg. The specimen is housed in Yingliang Stone Nature History Museum.
Fion Waisum Ma, joint first author and PhD researcher at the University of Birmingham, said: “Dinosaur embryos are some of the rarest fossils and most of them are incomplete with the bones dislocated. We are very excited about the discovery of ‘Baby Yingliang’ — it is preserved in a great condition and helps us answer a lot of questions about dinosaur growth and reproduction with it.
“It is interesting to see this dinosaur embryo and a chicken embryo pose in a similar way inside the egg, which possibly indicates similar prehatching behaviours.”
‘Baby Yingliang’ was identified as an oviraptorosaur based on its deep, toothless skull. Oviraptorosaurs are a group of feathered theropod dinosaurs, closely related to modern-day birds, known from the Cretaceous of Asia and North America. Their variable beak shapes and body sizes are likely to have allowed them to adopt a wide range of diets, including herbivory, omnivory and carnivory.
Birds are known to develop a series of tucking postures, in which they bend their body and bring their head under their wing, soon before hatching. Embryos that fail to attain such postures have a higher chance of death due to unsuccessful hatching.
By comparing ‘Baby Yingliang’ with the embryos of other theropods, long-necked sauropod dinosaurs and birds, the team proposed that tucking behaviour, which was considered unique to birds, first evolved in theropod dinosaurs many tens or hundreds of millions of years ago. Additional discoveries of embryo fossils would be invaluable to further test this hypothesis.
Professor Lida Xing from China University of Geosciences (Beijing), joint first author of the study, said: “This dinosaur embryo was acquired by the director of Yingliang Group, Mr Liang Liu, as suspected egg fossils around the 2000. During the construction of Yingliang Stone Nature History Museum in 2010s, museum staff sorted through the storage and discovered the specimens.
“These specimens were identified as dinosaur egg fossils. Fossil preparation was conducted and eventually unveiled the embryo hidden inside the egg. This is how ‘Baby Yingliang’ was brought to light.”
Professor Steve Brusatte from the University of Edinburgh, part of the research team, said: “This dinosaur embryo inside its egg is one of the most beautiful fossils I have ever seen. This little prenatal dinosaur looks just like a baby bird curled in its egg, which is yet more evidence that many features characteristic of today’s birds first evolved in their dinosaur ancestors.”
Reference:
Lida Xing, Kecheng Niu, Waisum Ma, Darla K. Zelenitsky, Tzu-Ruei Yang, Stephen L. Brusatte. An exquisitely preserved in-ovo theropod dinosaur embryo sheds light on avian-like prehatching postures. iScience, 2021; 103516 DOI: 10.1016/j.isci.2021.103516
