It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Tuesday, December 13, 2022
Fossil site reveals giant arthropods dominated the seas 470 million years ago
IMAGE: FOSSILS FROM THE FEZOUATA SHALE. FROM LEFT TO RIGHT, A NON-MINERALIZED ARTHROPOD (MARRELLOMORPHA), A PALAEOSCOLECID WORM AND A TRILOBITESview more
CREDIT: EMMANUEL MARTIN
Discoveries at a major new fossil site in Morocco suggest giant arthropods – relatives of modern creatures including shrimps, insects and spiders – dominated the seas 470 million years ago.
Early evidence from the site at Taichoute, once undersea but now a desert, records numerous large “free-swimming” arthropods.
More research is needed to analyse these fragments, but based on previously described specimens, the giant arthropods could be up to 2m long.
An international research team say the site and its fossil record are very different from other previously described and studied Fezouata Shale sites from 80km away.
They say Taichoute (considered part of the wider “Fezouata Biota”) opens new avenues for paleontological and ecological research.
“Everything is new about this locality – its sedimentology, paleontology, and even the preservation of fossils – further highlighting the importance of the Fezouata Biota in completing our understanding of past life on Earth,” said lead author Dr Farid Saleh, from the University of Lausanne and and Yunnan University.
Dr Xiaoya Ma, from the University of Exeter and Yunnan University, added: “While the giant arthropods we discovered have not yet been fully identified, some may belong to previously described species of the Fezouata Biota, and some will certainly be new species.
“Nevertheless, their large size and free-swimming lifestyle suggest they played a unique role in these ecosystems.”
The Fezouata Shale was recently selected as one of the 100 most important geological sites worldwide because of its importance for understanding the evolution during the Early Ordovician period, about 470 million years ago.
Fossils discovered in these rocks include mineralised elements (eg shells), but some also show exceptional preservation of soft parts such as internal organs, allowing scientists to investigate the anatomy of early animal life on Earth.
Animals of the Fezouata Shale, in Morocco’s Zagora region, lived in a shallow sea that experienced repeated storm and wave activities, which buried the animal communities and preserved them in place as exceptional fossils.
However, nektonic (or free-swimming) animals remain a relatively minor component overall in the Fezouata Biota.
The new study reports the discovery of the Taichoute fossils, preserved in sediments that are a few million years younger than those from the Zagora area and are dominated by fragments of giant arthropods.
“Carcasses were transported to a relatively deep marine environment by underwater landslides, which contrasts with previous discoveries of carcass preservation in shallower settings, which were buried in place by storm deposits,” said Dr Romain Vaucher, from the University of Lausanne.
Professor Allison Daley, also from the University of Lausanne, added: “Animals such as brachiopods are found attached to some arthropod fragments, indicating that these large carapaces acted as nutrient stores for the seafloor dwelling community once they were dead and lying on the seafloor.”
Dr Lukáš Laibl, from the Czech Academy of Sciences, who had the opportunity to participate in the initial fieldwork, said: “Taichoute is not only important due to the dominance of large nektonic arthropods.
“Even when it comes to trilobites, new species so far unknown from the Fezouata Biota are found in Taichoute.”
Dr Bertrand Lefebvre, from the University of Lyon, who is the senior author on the paper, and who has been working on the Fezouata Biota for the past two decades, concluded: “The Fezouata Biota keeps surprising us with new unexpected discoveries”.
The paper, published in the journal Scientific Reports, is entitled: “New fossil assemblages from the Early Ordovician Fezouata Biota.”
IMAGE: ECOLOGICAL RESTORATION OF SINGING KATYDIDS FROM THE MIDDLE JURASSIC DAOHUGOU KONSERVAT-LAGERSTÄTTE OF CHINAview more
CREDIT: NIGPAS
Acoustic communication has played a key role in the evolution of animals especially vertebrates and insects, ranging from mating to warning calls and even social learning. The reconstruction of ancient acoustic signals is challenging, however, due to the extreme rarity of fossilized organs.
Insects were the first terrestrial animals to use airborne sound signals for long-distance communication. Among acoustically signaling insects, katydids stand out as an ideal source for investigating the evolution of acoustic organs and behavior.
Recently, Ph.D. student XU Chunpeng, under the supervision of Profs. WANG Bo and ZHANG Haichun from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences (NIGPAS), working with an international team of paleoentomologists, carried out a detailed and global investigation of fossil katydids from the Mesozoic Era (commonly referred to as the age of the dinosaurs).
The study provides novel insights on acoustic evolution of Mesozoic katydids and evolution of the Mesozoic soundscape. It was published in PNAS on Dec. 12.
The research team reported the earliest tympanal ears and sound-producing system (stridulatory apparatus) in exceptionally preserved Mesozoic katydids.
"The newly found tympanal ears in prophalangopsid katydids from the Middle Jurassic Daohugou Konservat-Lagerstätte represent the earliest-known insect ears, extending the age range of the modern-type auditory tympana by 100 million years to the Middle Jurassic, some 160 million years ago," said XU.
The reconstruction of singing frequencies of Mesozoic katydids and oldest tympanal ears demonstrate that katydids had evolved complex acoustic communication, including mating signals, inter-male communication, and directional hearing, at least by the Middle Jurassic.
Also, katydids had evolved a high diversity of singing frequencies, including high-frequency musical calls, accompanied by acoustic niche partitioning, all at least by the Late Triassic (200 million years ago). This suggests that acoustic communication already could have been an important evolutionary driver in the early radiation of terrestrial insects after the Permo-Triassic mass extinction.
The Early and Middle Jurassic katydid transition from extinct haglid- to extant prophalangopsid-dominated insect faunas coincided with the diversification of derived mammalian groups (clades) and improvement of hearing in early mammals, supporting the hypothesis of acoustic co-evolution of mammals and katydids. The high-frequency songs of Mesozoic katydids could even have driven the evolution of intricate hearing systems in early mammals, and conversely, mammals with progressive hearing ability could have exerted selective pressure on the evolution of katydids, including faunal turnover.
These findings demonstrate that insects, especially katydids, dominated choruses during the Triassic—a situation different from the modern soundscape. After the appearance of birds and frogs in the Jurassic, the forest soundscape became almost the same as the modern one in the Cretaceous, except lacking the sound of cicadas (which have fewer musical calls). These results also highlight the ecological significance of insects in the Mesozoic soundscape, which has hitherto been largely unknown in the palaeontological record.
This research was supported by the National Natural Science Foundation of China, the Strategic Priority Research Program of the Chinese Academy of Sciences, and the Deep-time Digital Earth (DDE) Big Science Program.
Stridulatory files of Triassic katydids (A–C) and tympanal ears of Jurassic katydids (D–E)
Frequency range of hearing in vertebrates (above) and frequency range of tones used by extant crickets and fossil katydids (below)
IMAGE: RISING SUN VIEWED FROM THE STONE CAUSEWAY OF THE SOLAR OBSERVATORY ON MOUNT TLALOC, MEXICO. THE VIEW ALIGNS WITH THE RISING SUN ON FEBRUARY 24, COINCIDING WITH THE MEXICA CALENDAR'S NEW YEAR.view more
CREDIT: BEN MEISSNER
Without clocks or modern tools, ancient Mexicans watched the sun to maintain a farming calendar that precisely tracked seasons and even adjusted for leap years.
Before the Spanish arrival in 1519, the Basin of Mexico’s agricultural system fed a population that was extraordinarily large for the time. Whereas Seville, the largest urban center in Spain, had a population of fewer than 50,000, the Basin, now known as Mexico City, was home to as many as 3 million people.
To feed so many people in a region with a dry spring and summer monsoons required advanced understanding of when seasonal variations in weather would arrive. Planting too early, or too late, could have proved disastrous. The failure of any calendar to adjust for leap-year fluctuations could also have led to crop failure.
Though colonial chroniclers documented the use of a calendar, it was not previously understood how the Mexica, or Aztecs, were able to achieve such accuracy. New UC Riverside research demonstrates how they did it. They used the mountains of the Basin as a solar observatory, keeping track of the sunrise against the peaks of the Sierra Nevada mountains.
“We concluded they must have stood at a single spot, looking eastwards from one day to another, to tell the time of year by watching the rising sun,” said Exequiel Ezcurra, distinguished UCR professor of ecology who led the research.
To find that spot, the researchers studied Mexica manuscripts. These ancient texts referred to Mount Tlaloc, which lies east of the Basin. The research team explored the high mountains around the Basin and a temple at the mountain’s summit. Using astronomical computer models, they confirmed that a long causeway structure at the temple aligns with the rising sun on Feb. 24, the first day of the Aztec new year.
“Our hypothesis is that they used the whole Valley of Mexico. Their working instrument was the Basin itself. When the sun rose at a landmark point behind the Sierras, they knew it was time to start planting,” Ezcurra said.
The sun, as viewed from a fixed point on Earth, does not follow the same trajectory every day. In winter, it runs south of the celestial equator and rises toward the southeast. As summer approaches, because of the Earth’s tilt, sunrise moves northeast, a phenomenon called solar declination.
This study may be the first to demonstrate how the Mexica were able to keep time using this principle, the sun, and the mountains as guiding landmarks. Though some may be familiar with the “Aztec calendar,” that is an incorrect name given to the Sun Stone, arguably the most famous work of Aztec sculpture used solely for ritual and ceremonial purposes.
“It did not have any practical use as a celestial observatory. Think of it as a monument, like Nelson’s Column in Trafalgar Square or Lincoln’s Memorial in Washington, D.C.,” Ezcurra said.
Learning about Aztec tools that did have practical use offers a lesson about the importance of using a variety of methods to solve questions about the natural world.
“The same goals can be achieved in different ways. It can be difficult to see that sometimes. We don’t always need to rely solely on modern technology,” Ezcurra said. “The Aztecs were just as good or better as the Europeans at keeping time, using their own methods.”
The Aztec observatory could also have a more modern function, according to Ezcurra. Comparing old images of the Basin of Mexico to current ones shows how the forest is slowly climbing up Mount Tlaloc, likely as a result of an increase in average temperatures at lower elevation.
“In the 1940s the tree line was way below the summit. Now there are trees growing in the summit itself,” Ezcurra said. “What was an observatory for the ancients could also be an observatory for the 21st century, to understand global climate changes.”
Solar observatory in Mount Tlaloc, Mexico. The inclined causeway aligns with the rising sun on February 23–24, in coincidence with the Mexica calendar's new year.
Ancient inhabitants of the Basin of Mexico kept an accurate agricultural calendar using sunrise observatories and mountain alignments
ARTICLE PUBLICATION DATE
12-Dec-2022
Transplants can save dying coral reefs, but genetically diverse donors are key, say researchers
Scientists aiming to save failing reefs by transplanting healthy coral reveal that success lies with genetic diversity — and not a single, coveted “super coral.”
IMAGE: A TRANSPLANTED STAGHORN CORAL (ACROPORA CERVICORNIS) COLONY GROWS ON A REEF.view more
CREDIT: WYATT MILLION/USC DORNSIFE COLLEGE OF LETTERS, ARTS AND SCIENCES
Key points:
Climate change is decimating the worlds’ reefs.
Transplanting healthy coral onto dying reefs may save them.
Some transplanted corals seem to thrive while others fail, but researchers weren’t sure why.
A new study led by USC Dornsife scientists solves the mystery, revealing a path to successful transplants and rejuvenated reefs.
As the health of coral reefs continues to decline under the stress of climate change, researchers aim to rejuvenate failing reefs by transplanting healthy coral. Unfortunately, they’ve found mixed results, as some transplanted coral wither and die while others take root and thrive.
Why some transplanted coral, called “outplants,” flourish and others struggle or perish has remained a mystery, until now. A new study led by researchers at the USC Dornsife College of Letters, Arts and Sciences and published in the Proceedings of the National Academy of Sciences reveals the key to successful coral transplantation.
Solving the mystery is critical to restoring dying reefs with transplanted coral, says Carly Kenkel, Gabilan Assistant Professor of Biological Sciences at USC Dornsife and a corresponding author on the study. And saving reefs remains a global imperative.
According to a 2021 study, Earth has lost half of its coral reefs since 1950. This global devastation holds tragic potential: A billion people benefit from reef ecosystems, and the U.S. economy alone gains $3.4 billion per year from them through industries like fishing and tourism, according to the National Oceanic and Atmospheric Administration.
Is it the one or the many?
Kenkel’s transplant research centers on the critically endangered Caribbean staghorn coral, Acropora cervicornis.
Before the current study, scientists used different individual staghorn coral at various transplant sites and found some outplants fared better at some locations than others. But because they used different coral at different sites, they were unable to narrow down the reason for success or failure: Was it the environment, the coral or a combination of both?
“We didn’t know if the coral were performing poorly at some sites because the environment was poor, because the individual coral were poor performers, or because those individual coral just happened to be poor performers in that particular environment,” said Kenkel.
To find the answer, Kenkel and Wyatt Million, formerly a PhD student in Kenkel’s lab at USC Dornsife and first author on the study, reduced the number of variables involved. They used clones of just 10 staghorn individuals and transplanted specimens of each at nine well-understood reef sites in the Florida Keys. They then tracked the outplants’ survival, growth, shape and size at each location.
They found that both the coral and the environment mattered. No single clone proved strong across all environments; each site saw a different clone step up and adapt for success.
“This is very important information for reef restoration,” said Kenkel. “It means that the genetic diversity of coral transplants is going to be important for hedging our bets.” As researchers aim to restore reefs, they’ll want to use a variety of individuals to ensure at least one can adapt to the new home.
She likened the idea to investing: “Diversifying your portfolio is safer than betting big on one particular company because even if some companies lose money, others will win.”
Maximizing genetic diversity — rather than looking for one standout coral to save the day, as has been the trend among researchers — is a wiser approach, she said.
“On these reefs, diversifying coral outplants is safer than betting on one ’super coral’ to succeed. There will be winners and losers in every environment. And reefs are really dynamic; each environment can be really different from a coral’s perspective, and they’re going to be even more different as the climate continues to change.”
“Plastic coral”
The findings also mean scientists will want to focus on how adaptable individual coral can be to various environments, meaning how much an individual can change its shape, size and other characteristics in response to changing environmental factors on the reef.
This “plasticity” could affect the chances of long-term success of outplants over many generations as climate change continues.
“We found that some coral were more plastic than others, and the most plastic coral — those that were able to grow biggest when it made sense to be big at a particular site or stay smallest when that was a benefit — were actually the ones who survived the best on average,” Kenkel said.
Study first author Wyatt Million — formerly a PhD student in Kenkel’s lab and now a postdoc at Germany’s Justus Liebig University Giessen — warns that coral plasticity isn’t a substitute for addressing climate change at its roots, however.
“I’d like to emphasize that adaptive plasticity is not a magic bullet for coral and cannot replace the goal of reversing the effects of climate change if we hope to ensure the ultimate persistence of coral,” he said.
What’s next?
Kenkel’s team now aims to dig deeper into what gives coral its plasticity and how it might affect future transplant efforts.
“We’re going to be asking questions like, ‘Are there any downsides to a coral being more plastic?’ Maybe it doesn’t show up in their lifetime — maybe it affects their offspring or their ability to produce offspring,” Kenkel said.
They’ll also study how coral plasticity impacts the function of the whole reef as well as what’s happening at a cellular and molecular level to enable the coral to grow, an avenue Million finds particularly interesting.
“Perhaps the most pertinent next steps include identifying the genetic basis of this plasticity and whether it belongs to the animal host or the algal symbiont,” he said.
Coral have microscopic algae living within them in a relationship known as “symbiosis.” The algae provide the coral with food and other benefits in exchange for nutrients and a safe place to live.
Understanding the genetics of both organisms will help scientists predict how a coral’s plasticity might evolve over generations with changing climate conditions.
About the study
In addition to Kenkel and Million, researchers on the study include Maria Ruggeri and Sibelle O’Donnell of USC Dornsife; Erich Bartels of Mote Marine Laboratory; Trinity Conn of The Pennsylvania State University; and Cory Krediet of Eckerd College.
This research was supported by NOAA Coral Reef Conservation Program grant NA17NOS4820084 and private funding from the Alfred P. Sloan Foundation and Rose Hills Foundation.
Evidence for adaptive morphological plasticity in the Caribbean coral, Acropora cervicornis
Report provides guide to funding for coral reef restoration projects
Multi-agency working group’s report supports communities seeking funding for projects to reduce flood risks by restoring coral reefs for storm hazard mitigation and climate adaptation
IMAGE: THE NEW REPORT PROVIDES GUIDANCE ON THE DEVELOPMENT OF CORAL REEF RESTORATION PROPOSALS FOR FEDERAL HAZARD MITIGATION FUNDING.view more
CREDIT: PHOTO CREDIT: CURT STORLAZZI, USGS
UC Santa Cruz played a leading role in a multi-agency group working for the U.S. Coral Reef Task Force to provide guidance on the development of coral reef restoration proposals for federal hazard mitigation funding.
Austen Stovall, the report's lead author, worked on the project as a graduate student in the Coastal Science and Policy Program at UC Santa Cruz.
“We developed this guide to help local project champions to apply for funding from FEMA and USACE to reduce coastal flooding by restoring coral reefs,” Stovall said.
Research Professor Michael Beck, who holds the AXA Chair in Coastal Resilience and directs the Center for Coastal Climate Resilience at UC Santa Cruz, noted that billions of dollars in federal funding are available for hazard mitigation and disaster recovery projects.
“Under the Biden administration, FEMA wants to fund nature-based projects. Unfortunately, communities have not had the tools to be successful in winning funds for habitat restoration for coastal protection; we are solving that problem with this report,” Beck said.
Coral reef restoration for risk reduction (CR4) projects are different from solely ecological coral restoration projects in that CR4 projects aim to meet two different management objectives—environmental conservation and hazard mitigation. They often will require more specific placement and planning, detailed hydrodynamic analyses, and larger project scales to meet both objectives.
FEMA provides billions of dollars in hazard mitigation assistance to communities each year to reduce or eliminate long-term disaster risks. For example, in July 2022, President Biden announced that $2.3 billion would be available in the current fiscal year for pre-disaster hazard mitigation projects through FEMA’s Building Resilient Infrastructure and Communities (BRIC) Program. According to Stovall, this large amount of funding available through federal hazard mitigation sources could significantly increase the scale at which coral restoration can be implemented, as long as projects also meet hazard mitigation objectives.
Because this is a relatively new approach, many stakeholders, including community leaders, natural resource managers, and government entities, may not know when and where it can be used for flood risk reduction nor how to apply for funding for CR4 projects from agencies that provide funds for hazard mitigation or disaster recovery.
Beck's Coastal Resilience Lab at UCSC is involved in a variety of projects related to coral reef restoration, including work with the USGS and the Nature Conservancy to advance CR4 efforts in the U.S. Virgin Islands, with funding from FEMA. His group is also part of a collaborative coral reef restoration project focused on protecting vulnerable coastal regions in Florida and the Caribbean and funded by the U.S. Defense Advanced Research Projects Agency (DARPA) as part of its nationwide Reefense research program.
Coral reefs are highly diverse and biologically complex ecosystems that provide a range of key ecosystem services for people. The total economic value of coral reefs in the United States—based on their contributions to tourism, fisheries, and coastal protection—is estimated at $3.4 billion.
Coral reefs offer coastal protection by reducing flooding and erosion through wave breaking and friction. On average, coral reefs dissipate 97% of wave energy before it reaches coastlines. According to Stovall, coral reefs protect from flooding more than 18,000 people, $825 million in coastal infrastructure, and $700 million in economic activity annually in the United States.
Beck's group has been at the forefront of making the case for the value of nature-based solutions in coastal protection and adaptation to climate change. He and his team have worked with federal agencies and the insurance industry on a variety of projects to demonstrate the value of coastal wetlands, coral reefs, and mangroves for coastal defense.
Beck noted that the approaches outlined in the CR4 guidance document can also be used to support many other nature-based projects and proposals beyond reef restoration for federal hazard mitigation funding.
The United States Coral Reef Task Force (USCRTF) was established in 1998 by Presidential Executive Order to lead U.S. efforts to preserve and protect coral reef ecosystems. The USCRTF includes leaders of Federal agencies, U.S. States, territories, commonwealths, and Freely Associated States. The USCRTF helps build partnerships, strategies, and support for on-the-ground action to conserve coral reefs.
CENTER FOR HIGH PRESSURE SCIENCE & TECHNOLOGY ADVANCED RESEARCH
IMAGE: IRON-RICH FE–O COMPOUNDS AT EARTH’S CORE PRESSURESview more
CREDIT: JIN LIU
Oxygen is the key substance for life and one of the most abundant elements in the Earth. However, it’s still unknown whether oxygen is present and in which form in the inner core with extreme high pressure and temperature conditions, and almost composed of pure iron. Scientists co-led by Dr. Jin Liu from HPSTAR (the Center for High Pressure Science &Technology Advanced Research) and Dr. Yang Sun from Columbia University reveal that Fe-rich Fe-O alloys are stable at extreme pressures of nearly 300 GPa and high temperatures of more than 3,000 K. The results published in the journal of The Innovation prove that oxygen can exist in the solid inner core, which provides key constraints for further understanding of the formation process and evolution history of the Earth's core.
The Earth’s solid inner core, as one of the most mysterious places on the planet, is in the most extreme temperature and pressure environment on Earth, with a pressure of more than 3 million atmospheres and a temperature close to the surface of the Sun, about 6000 K. Because the inner core is far beyond the reach of humans, we can only infer its density and chemical composition from the seismic signals generated by earthquakes. At present, it is believed that light elements exist in the inner core, but the type and content are still debated. Cosmochemical and geochemical evidence suggests that it should contain sulfur, silicon, carbon, and hydrogen. Experiments and calculations also confirmed that these elements mix with pure iron to form various Fe alloys under high temperatures and high-pressure conditions of the deep Earth.
However, oxygen, which is closely related to us, is usually excluded from the inner core. This is mainly because Fe-O alloys with iron-rich compositions have never been found in the surface or mantle environments. The oxygen content in all known iron oxides is greater than or equal to 50 atomic percent. Although people have been trying to synthesize iron oxide compounds with iron-rich compositions, such substances have never been found yet. Is the Earth's inner core so "anoxic"? To answer this question, a series of experiments and theoretical calculations were carried out in this study.
To be close to the temperature and pressure of Earth's core, pure iron and iron oxide were placed on the tips of two diamond anvils and heated with a high-energy laser beam. After many attempts, it was found that a chemical reaction between iron and iron oxide occurs above 220-260 GPa and 3000 K. The XRD results reveal that the reaction product is different from the common high-temperature and high-pressure structure of pure iron and iron oxide. Theoretical crystal structure search using a genetic algorithm proved that the iron-rich Fe-O alloy could exist stably at approximately 200 GPa. Under such conditions, the new Fe-rich Fe-O alloys form a hexagonal close-packed structure, where the oxygen layers are arranged in between Fe layers to stabilize the structure. Such a mechanism produces many close-packed arrangements forming a large family of Fe-rich Fe-O compounds with large configurational entropy. Based on this theoretical information, an atomic configuration of Fe28O14 was found to match the experimentally measured XRD pattern. Further calculations showed that Fe-rich Fe-O phases are metallic, in contrast with common iron oxides at low pressures. The electronic structure depends on O concentration and the Fe and O layer arrangements. The mechanical properties and thermal properties of the alloy need to be further studied in the future.
Nearly two years after Japanese mission Hayabusa2 returned to Earth, samples from asteroid Ryugu continue to reveal valuable information about the history of the early solar system. A study by scientists from the Institut de Physique du Globe de Paris, Université Paris Cité and CNRS1, as part of an international consortium, reveals the isotopic composition of zinc and copper of asteroid Ryugu. The isotopic signatures show that Ryugu’s composition is close to Ivuna-like carbonaceous chondrites, and that Ryugu-like material from the outer solar system accounts for ~5-6% of Earth's mass. These results are published on 12 December 2022 in the journal Nature Astronomy.
Meteorites found on Earth give scientists access to samples representing the first moments of the solar system. However, the return to Earth in December 2020 of the Hayabusa2 mission, operated by the Japanese space agency JAXA and bringing back 5 grams of fragments from the asteroid Ryugu, marks a major step forward by offering the possibility of analyzing samples unaltered by their arrival and stay on Earth. The first analyses, carried out by an international team, including researchers from the Institut de physique du globe de Paris, Université Paris Cité and the CNRS, have shown that the composition of the asteroid Ryugu is close to that of Ivuna-like carbonaceous chondrites (CI) - the most chemically primitive meteorites, and considered to have the composition closest to the Sun. However, some isotopic signatures (e.g., titanium and chromium) overlap with other groups of carbonaceous chondrites, so the details of the link between Ryugu and CI chondrites are not yet fully understood.
Zinc and copper are two moderately volatile elements, and are key elements to study the processes of accretion of volatiles during the formation of telluric planets. The different groups of carbonaceous chondrites show distinct zinc and copper isotopic compositions, with the CI chondrites being the more enriched in volatile elements. By carrying out additional analyzes of the zinc and copper isotopic composition of Ryugu, the scientists had access to a crucial tool for studying the origin of the asteroid.
The international team showed, in a study published on December 12th, 2022 in the journal Nature Astronomy and led by Marine Paquet and Frédéric Moynier, cosmochemists at the IPGP, that the isotopic ratios of copper and zinc in the samples from Ryugu were identical to CI chondrites but different from all other types of meteorites. By finally confirming the similarity between Ryugu and CI chondrites, this study establishes that these primitive samples from Ryugu represent the best estimate of the solar composition to date for copper and zinc.
Finally, the zinc isotopic composition of Ryugu can also be used to study the accretional history of moderately volatile elements on Earth, which are essential for the development of planetary habitability. The study also demonstrates that the contribution of Ryugu-like material represents about 5% of the Earth’s mass.
> Contribution of Ryugu-like material to Earth’s volatile inventory by Cu and Zn isotopic analysis, Marine Paquet, Frederic Moynier, Tetsuya Yokoyama et al., Nature Astronomy, 2022, DOI : 10.1038/s41550-022-01846-1
