Hexbyte Glen Cove Zinc isotopes of arc-related lavas reveal recycling of forearc serpentinites into subarc mantle

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Credit: Unsplash/CC0 Public Domain

Serpentinite, formed by low-temperature hydrothermal alteration of mantle peridotite, is distributed in the lithospheric mantle at the bottom of the subduction slab (slab-serpentinite) and forearc mantle wedge above the subduction slab (mantle wedge serpentinite) in the subduction zone. 

Since they usually contain a large amount of water, fluid-mobile elements (Cs, Rb, Sr, Ba, Pb, Li, etc.), and heavy B isotopes, using traditional geochemical means to distinguish the two different sources of serpentinite-derived fluids in the genesis of arc magmas is challenging.

A research team led by Zeng Zhigang from the Institute of Oceanology of the Chinese Academy of Sciences (IOCAS), in collaboration Prof. Chen Jiubin from Tianjin University, investigated zinc isotopes of subduction-related lavas from the Western Pacific and implications for crust-mantle recycling.

Their study, published in Journal of Geophysical Research: Solid Earth, provided an effective means to distinguish the contributions of slab and mantle wedge serpentinite-derived fluids to arc magmas, which is significant to understand the role of serpentinite in material recycling in subduction zones.

The researchers found that the arc-related lavas had lower δ66Zn values than those of the mid-ocean ridge basalts (MORB), whereas back-arc lavas displayed MORB-like δ66Zn values. Moreover, δ66Zn has a good correlation with proxies for fluid addition (87Sr/86Sr and Ba/La) and slab depths. 

Since mantle melting and magmatic differentiation induces heavy Zn isotope enrichment in primary and evolved magmas, respectively, while melt extraction yields the limited Zn isotope fractionation in the mantle, lavas with low δ66Zn values thus potentially indicate the involvement of isotopically light fluids in their mantle sources.

In contrast to the heavy Zn isotope of the slab serpentinites, the forearc serpentinites are typically characterized by extremely light Zn isotope. Correspondingly, fluids released by forearc serpentinite dehydration have a significantly lower Zn isotopic composition relative to the mantle wedge.

Therefore, such forearc materials were likely dragged downward to subarc depths and released isotopically light Zn in fluids to modify the overlying mantle wedge, thereby producing low δ66Zn values in arc-related magmas. Beyond subarc depths, forearc serpentinites were broken down completely, so light Zn isotope fluids were absent.

Accordingly, the lavas from the back-arc basin displayed MORB-like δ66Zn values. It provided conclusive evidence for the hypothesis that forearc mantle wedge serpentinites could be involved in the subduction channel and transported into the subarc depth, and then dehydrate and modify the subarc mantle wedge.

More information:
Zuxing Chen et al, Zinc Isotopes of the Mariana and Ryukyu Arc‐Related Lavas Reveal Recycling of Forearc Serpentinites Into the Subarc Mantle, Journal of Geophysical Research: Solid Earth (2021). DOI: 10.1029/2021JB022261

Zinc isotopes of arc-related lavas reveal recycling of forearc serpentinites into subarc mantle (2021, December 23)
retrieved 25 December 2021

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Hexbyte Glen Cove Bringing space inside the lab: Researchers replicate the climates of exoplanets to help find extraterrestrial life

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The high-temperature and high-pressure conditions found on exoplanets can be recreated inside this instrument. Credit: University of Colorado at Boulder

Scientists do not need to travel light-years away to chart the atmospheres of exoplanets, thanks to research happening in the Paul M. Rady Department of Mechanical Engineering with scientists at the Jet Propulsion Laboratory (JPL).

Ryan Cole (Ph.D.MechEngr’21) has developed an experiment that recreates the actual climate of planets beyond our solar system inside a 2,000 lb. instrument at Professor Greg Rieker’s lab on the University of Colorado Boulder campus. By reaching the same high-temperature and high-pressure conditions found on many exoplanets, the instrument can map the gasses in their atmospheres, which could one day help humanity find life on other planets.

“If we looked at Earth’s atmosphere, we would know that life is here because we see methane, carbon dioxide, all these different markers that say something is living here,” Rieker said. “We can look at the chemical signatures of exoplanets as well. If we see the right combination of gasses, it could be an indicator that something is alive there.”

Rieker and Cole’s work can contribute to exoplanet transit spectroscopy—a research method to observe the composition of an exoplanet’s atmosphere. Scientists use a telescope to look at the light passing through it. As the light interacts with gasses in the atmosphere, those gasses absorb the photons as they move through.

A view of the instrument, built by Ryan Cole (PhDMechEngr’21), as the experiment replicates the conditions on exoplanets, causing the experiment to glow with heat. Credit: University of Colorado at Boulder

“Scientists need a map for how to interpret what the light is telling us when it gets here,” Rieker said. “That is where Ryan’s experiment comes in. As we create this little microcosm of that exoplanet’s atmosphere in our lab, we send in our own characterized light with lasers and study the photons that come out. We can measure the changes and map how the light is absorbed.”

In collaboration with scientists at JPL, Cole and Rieker’s experiment combines sensor measurements with computational models to help detect the different gasses on exoplanets. While Cole built the instrument that replicates the exoplanets’ climates and measures how light is being absorbed at those exotic conditions, JPL’s Deputy Section Manager Brian Drouin’s lab supplied the tool that interprets the measurements.

Their research could optimize telescopes like the James Webb Space Telescope, which as of mid-December, is set to launch Dec. 24 from the European Space Agency’s site in French Guiana.

“The James Webb Space Telescope and others like Hubble are looking at the ultimate horizon of what humans can see,” Cole said. “Greg and I are trying to make their visions a little clearer. Our laboratory measurements can help to interpret the telescopes’ observations of distant planetary atmospheres.”

There are endless expanses of the universe for these telescopes to explore—more than 4,800 confirmed exoplanets and about 7,900 more that NASA says could be planets. With Rieker and Cole’s experiment factored into the expedition, our understanding of exoplanets and the gasses in their atmospheres can be improved—and therefore, it also advances the search for extraterrestrial life.

How the instrument works

“There really are not many systems out there that can reach the high-temperature, high-pressure conditions that we reach,” Cole said. “Not only do we need to reach those conditions, we also need the temperature and pressure to be extremely uniform and well-known. Achieving these criteria is one of the most unique aspects of our experiment.”

The size and scope of the instrument Cole developed is what allows them to reach the high-temperatures and high-pressures that are seen on exoplanets. The experiment inside the piece of equipment can get up to 1,000 degrees Kelvin, which is about 1,340 degrees Fahrenheit.

The 2,000 lb. instrument also has thick steel walls that are designed to reach 100 atmospheres. To put that into context, Earth’s mean pressure at sea level is one atmosphere.

Starting in 2016, when he joined Rieker’s lab, Cole had to work through about five iterations of the high-temperature, high-pressure cell before getting it right.

“Ryan is the first one to do it,” Rieker said. “He has created datasets that are really close to perfect.”

Once the conditions are reached inside Cole’s instrument, the team sends light through the experiment from frequency comb lasers, a technology that was the basis of Nobel-Prize winning research at the University of Colorado Boulder and the National Institute of Standards and Technology. The laser has hundreds of thousands of wavelengths of light that are very well-behaved, making it an ideal tool to study light-matter interactions.

“We pass the laser through this environment and in doing so, we record how the laser light interacts with the gas that we have confined in the core of this unique experiment,” Cole said. “We measure how the light has been absorbed at different frequencies, which can be used to interpret observations of actual exoplanetary atmospheres.”

Those measurements then go through JPL’s interpretation tool. That computational model extracts the fundamental quantum parameters that enable the team to map how the atmosphere’s gas molecules will interact with light at any condition.

Rieker compared the relationship between the measurements they attain and the parameters that JPL supplies to a JPEG, the standard format for image data. While we see the photo, the JPEG data is the code, or set of instructions, for the image.

In this case, the equipment in Rieker’s lab provides the photo—the exoplanet conditions and light passing through its atmosphere. The JPL tool provides the JPEG code—the data that describes how the light is interacting with gasses in the atmosphere.

Looking inside the instrument when the experiment reaches high-temperatures and high-pressures. Credit: University of Colorado at Boulder

Applications for sustainability on Earth

Rieker’s work did not start with the goal of mapping exoplanet’s atmospheres. The original objective was to understand the combustion inside a rocket or . He had set out to chart the emissions coming from those engines, which can help society find more efficient ways to burn fuel.

“I think it is interesting that you can tie the applications of the instrument from a jet engine at the Denver International Airport to the atmosphere of a distant an exoplanet far from Earth,” Cole said.

The range of the technology’s function still allows the team to mimic the inside of a jet engine and map the gasses being emitted, but while building the equipment, Cole recognized that the conditions inside the simulated engine were very similar to conditions on the surface of Venus—high-temperature and high-pressure.

“Venus is a really interesting planet because physically, Venus and Earth are very similar in terms of size and density,” Cole said. “There is an ongoing question in the planetary science community that says you can draw an interesting comparison between Venus and Earth. Does Venus give us another data point for how Earth-like planets evolve?”

Venus has an atmosphere that is almost 860 degrees Fahrenheit and is 95-times the pressure of Earth’s atmosphere. The planet is completely inhospitable largely due to a runaway greenhouse effect driven by the high amount of carbon dioxide in the atmosphere. The potent greenhouse gas traps heat in Venus’s atmosphere, leading to extremely high surface temperatures.

While Earth’s atmosphere is nowhere near the levels of carbon dioxide found on Venus, studies of Venus’s atmosphere could advance climate change research.

“Our equipment can help scientists better understand Venus and the evolution of atmospheres that are increasingly burdened with carbon dioxide,” Cole said. “The experiment can help our understanding of the atmospheres of Earth-like planets with a sample size of two planets, instead of just one.”

From the inside of an engine to the surface of Venus and distant exoplanets, the fundamental goal of Rieker and Cole’s work is to understand how light interacts with gas molecules. However, no matter the scope, the applications of Rieker and Cole’s research all have the same theme—to promote life. One day soon, that might include life elsewhere, not just on Earth.

Bringing space inside the lab: Researchers replicate the climates of exoplanets to help find extraterrestrial life (2021, December 23)
retrieved 25 December 2021
from https://phys.org/news/2021-12-space-lab-replicate-climates-exoplanets.html

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Hexbyte Glen Cove Consumer confidence: Omicron plays holiday Grinch

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Credit: CC0 Public Domain

Although consumers were slightly more optimistic about economic conditions in the December survey, nearly all the data were collected prior to the rapid spread of Omicron in the U.S., according to the University of Michigan Surveys of Consumers.

While it is likely that confidence will decline in the month ahead, it is simply too early to judge the eventual impact of Omicron on prices, incomes and employment, said U-M economist Richard Curtin, director of the surveys. The most positive change recorded in December was that the gain was entirely due to rising optimism among households in the bottom third of the income distribution.

Their renewed optimism was due to higher expected income gains during 2022, Curtin said. Those anticipated gains may be vulnerable to the impact of the rapidly spreading Omicron variant on hours worked, he said.

Moreover, inflation has already eroded living standards, with lower income households suffering the biggest relative setbacks. Declining inflation-adjusted incomes, lower savings balances and potential post-holiday spending cutbacks are likely to slow the pace of growth in the overall economy in the first half of 2022, according to Curtin.

“The best news was the anticipated growth in incomes among households in the bottom third of the distribution,” he said. “It was due to a 5.9% boost in 2022 Social Security payments as well as higher expected income gains among the youngest workers.

“Unfortunately, the extremely regressive nature of inflation has also meant that even these gains will leave these households without inflation-adjusted income gains. Moreover, Omicron is likely to continue to put upward pressure on prices as well as weaken the pace of economic growth. The Fed must rebalance policies to both reduce inflationary pressures and to counter any overall weakness in the economy.”

Larger income gains expected by bottom third

Incomes among the bottom third were expected to rise by 2.8% in 2022, up from 1.8% last December, and the highest level since 2.9% was recorded in 1999. There have only been five surveys in the past half century that income expectations among low-income households have exceeded the December level.

The announced increase in Social Security payments of 5.9% in 2022 was partly responsible for the gain as well as the expected wage increases among the youngest workers of 5.0%, Curtin said. Unfortunately, he said, these gains will be offset by inflation.

Inflation more serious than unemployment

When asked whether inflation or unemployment was the more serious problem facing the nation, three-quarters of all consumers picked inflation. Just 15% of all consumers anticipated that their household’s income would rise faster than inflation in the year-end survey. This was the lowest figure recorded in eight years.

Complaints that rising prices had lowered their living standards were voiced by 27% of households, the highest in nine years.

Consumer Sentiment Index

The Consumer Sentiment Index rose to 70.6 in the December 2021 survey, up slightly from last month’s 67.4, but substantially below last year’s 80.7. The Expectations Index rose to 68.3, up from last month’s 63.5, and well below last year’s 74.6. The Current Conditions Index rose to 74.2, up from last month’s 73.6, and significantly below last year’s 90.0.

About the surveys

The Surveys of Consumers is a rotating panel based on a nationally representative sample that gives each household in the coterminous U.S. an equal probability of being selected. Interviews are conducted throughout the month by telephone. The minimum monthly change required for significance at the 95% level in the Sentiment Index is 4.8 points; for the Current and Expectations Index, the minimum is 6 points.

More information:
Surveys: www.sca.isr.umich.edu/

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Hexbyte Glen Cove The fate of Latin American forests in a warming world

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Credit: CC0 Public Domain

Latin American forests—one of the world’s greatest assets in the fight against climate change—will likely continue to shrink in size and economic clout, but not necessarily in their ability to help fight global warming, according to new research from Georgia Tech’s School of Public Policy (SPP).

The study led by environmental economist Alice Favero evaluated different socioeconomic and scenarios to assess what the market and forests will look like in the future. Favero and her colleagues found that in a future with minimal warming, Latin American forests likely will continue to lose ground to agricultural uses. In a more dire climate scenario, forested areas still shrink. Still, the ability of the smaller forests to capture and hold carbon is projected to suffer less as increased atmospheric carbon boosts tree growth.

In both scenarios, Favero’s research suggests the Latin American timber industry will lose ground economically over the next 80 years. But the economic losses will be most significant under the more dire climate scenario. This is the result of climate-change effects on other regions, such as Canada, that will increase the productivity of forests in those areas. That competition will suppress demand for Latin American timber, which currently accounts for 15% to 20% of the global supply. In turn, that could potentially drive more deforestation as forests lose economic value relative to other land uses.

“I think the most interesting part about this research for an economist such as myself is that it not only considers the effects of climate change on forests and the timber market in Latin America, it also takes into account the indirect effects of climate on other regions and corresponding implications on the market and management decisions in the region,” said Favero, an academic professional who studies the economics of climate change on global timber.

Impact of climate change and timber demand

For their study—the first disaggregated assessment of the effects of climate on Latin American forests—Favero and her colleagues, Ph.D. student W. Parker Hamilton and Professor Brent Sohngen of Ohio State University, turned to the Global Timber Model. The tool includes 250 different land classes, from fast-growing to unmanaged forests. It analyzes how land-use, management, and marketplace factors respond to various policy interventions under different climate conditions. Specifically, they also included inputs from a vegetation model that predicts the effects of changes in temperature, precipitation, and greenhouse gases on vegetation growth and surviving conditions.

Finally, their modeling was based on four “shared socioeconomic pathways,” or SSPs. These are models of potential climate futures that go beyond forecast carbon emission predictions to examine cultural, political, and economic changes that could serve to accelerate, or put the brakes on, climate change.

While timber are expected to rise across most of the scenarios simulated in the study, the increase is not enough to stave off the continued loss of forestland to agricultural and other uses, according to the study. Total forestland is predicted to decline by between 97 million and 160 million hectares, or about 375,000 square miles to 618,000 square miles, through 2100. Those effects are most pronounced in the scenarios with the lowest and least demand for timber.

However, increased demand for timber in some scenarios would likely result in additional planting on timber plantations, resulting in up to 16 million hectares (about 62,000 square miles) of new managed forests across the region. Combined with the carbon storage gained from more robust tree growth due to climate change, these new managed forests could help offset the potential damages of climate change in terms of tree migration and increase in dieback rate. That is, the amount of carbon sequestered per hectare of forests in Latin America will increase under climate change, according to the research.

“This is an important finding for this region that has a large portion of natural forests that remains one of the planet’s most important safeguards against carbon emissions and source of other ecosystem services,” the researchers wrote in their paper.

Across the socioeconomic scenarios modeled, natural and unmanaged forests also could decline by 20% relative to current levels without additional forest conservation policies, according to the study.

The changes vary from country to country. For instance, more severe climate change could result in Brazil losing a significant portion of its remaining temperate forests while its tropical forests could grow. But the effects are milder in the rest of South America and Central America. In terms of timber production, the research suggests only Argentina would increase its output under modest and more severe warming models.

Importance of public policy in slowing climate change

The findings are particularly important for public officials, timber companies, and land managers across Latin America, where land management decisions in coming decades could have a tangible impact on global climate.

In the paper, the researchers include a call for forest management policies that will help Latin American forests retain their position as an important element in the fight against climate change.

Similar to how “market and institutional factors have contributed to second-growth forests in plantations, and more enforcement of property rights and community forest management have reduced the negative effects of deforestation on carbon stock, forward-looking management decisions, and conservation policies to preserve in forests could mitigate the adverse effects of climate change in the future,” the researchers wrote in their paper.

More information:
Alice Favero et al, Climate change and timber in Latin America: Will the forestry sector flourish under climate change?, Forest Policy and Economics (2021). DOI: 10.1016/j.forpol.2021.102657

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Hexbyte Glen Cove Research team creates the world’s lightest isotope of magnesium to date

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Image representing new isotope magnesium-18. Credit:S. M. Wang / Fudan University and Facility for Rare Isotope Beams

In collaboration with an international team of researchers, Michigan State University (MSU) has helped create the world’s lightest version—or isotope—of magnesium to date.

Forged at the National Superconducting Cyclotron Laboratory at MSU, or NSCL, this isotope is so unstable that it falls apart before scientists can measure it directly. Yet this isotope that isn’t keen on existing can help researchers better understand how the atoms that define our existence are made.

Led by researchers from Peking University in China, the team included scientists from Washington University in St. Louis, MSU, and other institutions.

“One of the big questions I’m interested in is where do the universe’s elements come from,” said Kyle Brown, an assistant professor of chemistry at the Facility for Rare Isotope Beams, or FRIB. Brown was one of the leaders of the new study, published online Dec. 22 by the journal Physical Review Letters.

“How are these elements made? How do these processes happen?” asked Brown.

The new isotope won’t answer those questions by itself, but it can help refine the theories and models scientists develop to account for such mysteries.

Earth is full of natural , forged long ago in the stars, that has since become a key component of our diets and minerals in the planet’s crust. But this magnesium is stable. Its atomic core, or nucleus, doesn’t fall apart.

The new magnesium isotope, however, is far too unstable to be found in nature. But by using particle accelerators to make increasingly exotic like this one, scientists can push the limits of models that help explain how all nuclei are built and stay together.

This, in turn, helps predict what happens in extreme cosmic environments that we may never be able to directly mimic on or measure from Earth.

“By testing these models and making them better and better, we can extrapolate out to how things work where we can’t measure them,” Brown said. “We’re measuring the things we can measure to predict the things we can’t.”

NSCL has been helping scientists worldwide further humanity’s understanding of the universe since 1982. FRIB will continue that tradition when experiments begin in 2022. FRIB is a U.S. Department of Energy Office of Science (DOE-SC) user facility, supporting the mission of the DOE-SC Office of Nuclear Physics.

“FRIB is going to measure a lot of things we haven’t been able to measure in the past,” Brown said. “We actually have an approved experiment set to run at FRIB. And we should be able to create another nucleus that hasn’t been made before.”

Heading into that future experiment, Brown has been involved with four different projects that have made new isotopes. That includes the newest, which is known as magnesium-18.

All magnesium atoms have 12 protons inside their nuclei. Previously, the lightest version of magnesium had 7 neutrons, giving it a total of 19 protons and neutrons—hence its designation as magnesium-19.

Image representing new isotope magnesium-18. Credit: S. M. Wang / Fudan University and Facility for Rare Isotope Beams

To make magnesium-18, which is lighter by one neutron, the team started with a stable version of magnesium, magnesium-24. The cyclotron at NSCL accelerated a beam of magnesium-24 nuclei to about half the speed of light and sent that beam barreling into a target, which is a metal foil made from the element beryllium. And that was just the first step.

“That collision gives you a bunch of different isotopes lighter than magnesium-24,” Brown said. “But from that soup, we can select out the isotope we want.”

In this case, that isotope is magnesium-20. This version is unstable, meaning it decays, usually within tenths of a second. So the team is on a clock to get that magnesium-20 to collide with another beryllium target about 30 meters, or 100 feet, away.

“But it’s traveling at half the speed of light,” Brown said. “It gets there pretty quickly.”

It’s that next collision that creates magnesium-18, which has a lifetime somewhere in the ballpark of a sextillionth of a second. That’s such a short time that magnesium-18 doesn’t cloak itself with electrons to become a full-fledged atom before falling apart. It exists only as a naked nucleus.

In fact, it’s such a short time that magnesium-18 never leaves the beryllium target. The new isotope decays inside the target.

This means scientists can’t examine the isotope directly, but they can characterize telltale signs of its decay. Magnesium-18 first ejects two protons from its nucleus to become neon-16, which then ejects two more protons to become oxygen-14. By analyzing the protons and oxygen that do escape the target, the team can deduce properties of magnesium-18.

“This was a team effort. Everyone worked really hard on this project,” Brown said. “It’s pretty exciting. It’s not every day people discover a new isotope.”

That said, scientists are adding new entries every year to the list of known isotopes, which number in the thousands.

“We’re adding drops to a bucket, but they’re important drops,” Brown said. “We can put our names on this one, the whole team can. And I can tell my parents that I helped discover this that nobody else has seen before.”

More information:
Y. Jin et al, First Observation of the Four-Proton Unbound Nucleus Mg18, Physical Review Letters (2021). DOI: 10.1103/PhysRevLett.127.262502

Research team creates the world’s lightest isotope of magnesium to date (2021, December 23)
retrieved 24 December 2021
from https://phys.org/news/2021-12-team-world-lightest-isotope-magnesium.html

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Hexbyte Glen Cove Earth’s first-known giant was as big as a sperm whale

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The skull of the first giant creature to ever inhabit the Earth, the ichthyosaur Cymbospondylus youngorum, currently on display at the Natural History Museum of Los Angeles County. Credit: Natalja Kent / Natural History Museum of Los Angeles County

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 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.”

A life recreation of C. youngorum stalking the Nevadan oceans of the Late Triassic 246 million years ago. Credit: Stephanie Abramowicz / Natural History Museum of Los Angeles County

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 reaching epic proportions. As big as a large 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.

Owing to their remote location, fossils have only recently been discovered in the Augusta Mountains. An international team of scientists led by Dr. Sander began collecting on public lands there 30 years ago, with fossil finds being accessioned to the Natural History Museum of Los Angeles County since 2008. Credit: Lars Schmitz

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 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.”

Natural History Museum of Los Angeles County Dinosaur Institute volunteer Viji Shook lying next to the skull of Cymbospondylus youngorum for scale, during the preparation of the specimen. Credit: Martin Sander / Natural History Museum of Los Angeles County

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.”

An ichthyosaur fossil surrounded by the shells of ammonites, the food source that possibly fueled their growth to huge. Credit: Georg Oleschinski / University of Bonn, Germany.

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.

A figure from the text comparing C. youngorum to a modern sperm whale as well as rates of body size evolution over time between ichthyosaurs and cetaceans. The lines trending towards the top indicate larger body sizes whereas those towards the bottom are smaller sizes. Time is displayed as starting from the point of origin of the group until their extinction (for ichthyosaurs) or present (for whales). Credit: Stephanie Abramowicz / Natural History Museum of Los Angeles County

“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.

More information:
P. Martin Sander et al, Early giant reveals faster evolution of large size in ichthyosaurs than in cetaceans, Science (2021). DOI: 10.1126/science.abf5787

Lene Liebe Delsett et al, Early and fast rise of Mesozoic ocean giants, Science (2021). DOI: 10.1126/science.abm3751 , www.science.org/doi/10.1126/science.abm3751

Earth’s first-known giant was as big as a sperm whale (2021, December 23)
retrieved 24 December 2021
from https://phys.org/news/2021-12-earth-first-known-giant-big-sperm.html

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