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Research pieces ancient ecosystems together to reveal new details about the end-Triassic mass extinction

PALEONTOLOGY

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09/12/2023

Research pieces ancient ecosystems together to reveal new details about the end-Triassic mass extinction

Startling new insights into the catastrophic impact of one of the most devastating events in Earth’s history have been revealed by a team led by researchers with the USC Dornsife College of Letters, Arts and Sciences. More than deepening our understanding of the end-Triassic mass extinction, their findings offer critical lessons for today’s environmental challenges.

About 200 million years ago, Earth experienced its fourth major mass extinction event. Triggered by a dramatic rise in greenhouse gases due to volcanic activity, the event led to rapid global warming and a significant shift in the planet’s biosphere, ending the Triassic period and launching the Jurassic. Many scientists now believe Earth is in the midst of another mass extinction, driven in large part by similar climate changes.

Earth scientists at USC Dornsife took a unique approach to analyzing the impact of this extinction event on both ocean and land ecosystems, using a novel “ecospace framework” method that categorizes animals beyond just their species. It accounts for ecological roles and behaviors—from flying or swimming predators to grazing herbivores and from ocean seafloor invertebrates to soil-dwelling animals on land.

“We wanted to understand not just who survived and who didn’t, but how the roles that different species played in the ecosystem changed,” said David Bottjer, professor of Earth sciences, biological sciences and environmental studies at USC Dornsife and a study senior author. “This approach helps us see the broader, interconnected ecological picture.”

The study, a collaboration between students and faculty at USC Dornsife and the Natural History Museum of Los Angeles County, was published in Proceedings of Royal Society B.

Sea life suffered, but not as much as land animals

The research revealed a stark difference in the impact on marine and terrestrial ecosystems. While both realms suffered greatly, the findings suggest that land-based ecosystems were hit harder and experienced more prolonged instability.

In the oceans, nearly 71% of categories of species, called genera, vanished. Surprisingly, despite this massive loss, the overall structure of marine ecosystems showed resilience. Predators like sharks, mollusks known as ammonites and filter feeders like sponges and brachiopods, though severely affected, eventually bounced back.

Mysteries of Earth's ancient mass extinction event revealed — Reconstruction of a Late Triassic ecosystem from Ghost Ranch, New Mexico. Published specimens and species preserved at Ghost Ranch were incorporated into the research team’s global ecological dataset. Credit: Viktor O. Leshyk/Natural History Museum of Los Angeles County

On land, the scenario proved much bleaker. A staggering 96% of terrestrial genera went extinct, dramatically reshaping the landscape of life on Earth. Large herbivores like early dinosaurs and various small predators suffered greatly, with significant changes in their populations and roles within the ecosystem.

“This contrast between land and sea tells us about the different ways ecosystems respond to catastrophic events,” said co-lead author Alison Cribb, who earned her Ph.D. in geological sciences at USC Dornsife this year and is now at University of Southampton in the U.K. “It also raises important questions about the interplay of biodiversity and ecological resilience.”

Climate change clues from ancient catastrophe

The study’s findings spark more than just historical interest—they carry significant implications for our current environmental challenges. “Understanding past mass extinctions helps us to predict and possibly soften the impacts of current and future environmental crises,” said co-lead author Kiersten Formoso, who is finishing her doctoral studies in vertebrate paleobiology at USC Dornsife and will soon move to a position at Rutgers University.

The parallels between the rapid global warming of the end-Triassic and today’s climate change are particularly striking. “We’re seeing similar patterns now—rapid climate change, loss of biodiversity. Learning how ecosystems responded in the past can inform our conservation efforts today,” Bottjer said.

The research also provides a rare window into the world as it existed over 200 million years ago, he added. “It’s like a time machine, giving us a glimpse of life during a period of profound change.”

The study’s ecospace framework, with its focus on functional roles, offers a fresh perspective on ancient life, according to Frank Corsetti, professor of Earth sciences and chair of USC Dornsife’s Department of Earth Sciences. “It’s not just about identifying fossils,” he said. “It’s about piecing together the puzzle of ancient ecosystems and how they functioned.”

Future ventures will delve into the past’s lessons

As they plan further research, the scientists aim to explore how different species and ecosystems recovered after the extinction, and how these ancient events can parallel current biodiversity loss due to climate change.

Future studies are also planned to examine changes in ecospace dynamics across other periods of profound environmental change in deep time.

“We’ve just scratched the surface,” said Cribb. “There’s so much more to learn about how life on Earth responds to extreme changes, and this new ecospace framework offers great potential for helping us do that.”

Pandemic sparks unique, collaborative project

The study was conceived, and much of the work done, during the COVID-19 pandemic, when restrictions on many other types of research were in place, said Bottjer. “This produced unique conditions that fostered and led to development and completion of this research involving individuals with expertise across a broad variety of paleobiological fields, from microbes to invertebrates to vertebrates, in marine and terrestrial environments, with everyone working together towards one goal,” he said.

Bottjer said Cribb and Formoso initially devised the collaboration with his and Corsetti’s supervision and essential contributions from the study’s other co-authors.

More information: Alison T. Cribb et al, Contrasting terrestrial and marine ecospace dynamics after the end-Triassic mass extinction event, Proceedings of the Royal Society B: Biological Sciences (2023). DOI: 10.1098/rspb.2023.2232

Journal information: Proceedings of the Royal Society B

Provided by University of Southern California

‘Appetite for drumsticks’: First prey found in a tyrannosaur stomach

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09/12/2023

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‘Appetite for drumsticks’: First prey found in a tyrannosaur stomach

Prey has been discovered inside the stomach of a tyrannosaur skeleton for the first time, scientists said Friday, revealing that the mighty dinosaurs had an “appetite for drumsticks” when they were young.

The skeleton of the Gorgosaurus, a member of the tyrannosaurid family that also includes the T-Rex, sheds light on how these dinosaurs grew from fairly slender juveniles into gigantic, bone-crushing, apex-predator adults, they added.

The Gorgosaurus—which means “dreadful lizard”—was around six years old when it died more than 75 million years ago, according to a new study in the journal Science Advances.

The fossil was discovered in 2009 at the Dinosaur Provincial Park, east of the Canadian city of Calgary. But when they got the skeleton back to the lab, the scientists noticed something strange.

The study’s lead author, Francois Therrien of the Royal Tyrrell Museum, told AFP they were amazed to “discover the remains of the last meal of this young tyrannosaur still preserved in place”.

What was most surprising, he added, was that the small leg bones sticking out of the tyrannosaur’s ribcage belonged to two young, bird-like dinosaurs called Citipes.

Citipes are thought to have had feathers, wings and a beak and walk on two feet, somewhat resembling modern-day cassowaries, Therrien said.

They are far smaller than the massive plant-eating dinosaurs that adult tyrannosaurs had been known to eat.

Study co-author Darla Zelenitsky, a paleontologist at the University of Calgary, told AFP that this particular “fussy eater” used its sharp teeth to carve itself only the legs of the two baby Citipes.

“This teenage Gorgosaurus seems to have had an appetite for drumsticks,” she said.

Not always an apex predator

The discovery also offers a rare clue into how tyrannosaurs grew from one-meter-long at birth to some of the biggest predators to have ever walked the Earth.

“This fossil is the first solid evidence that tyrannosaurids drastically changed their diet as they grew from teenagers to adults,” Zelenitsky said.

Young tyrannosaurs had slender heads and legs, sharp knife-like teeth for dissecting carcasses, and could probably run quite fast to catch their turkey-like prey.

These youths probably looked more similar to the velociraptors depicted in the movie “Jurassic Park” than the giant T-Rex, Zelenitsky said.

But at roughly 11 years old, as the tyrannosaurs hit their middle-age, their bodies grew almost ten times in size, ending up weighing more than 3,000 kilograms (6,600 pounds).

Their heads broadened and their teeth thickened into what Therrien called “killer bananas” capable of crunching through huge bones.

This transformation was driven by a change in diet, as the dinosaurs ditched the drumsticks of their youth and started preying on giant plant-eating dinosaurs.

These kind of drastic dietary changes are not necessarily rare in the animal kingdom—crocodiles and Komodo dragons start out eating insects before switching to rodents and eventually large mammals, Therrien said.

The researchers said the Gorgosaurus fossil supports the theory that young tyrannosaurs—including the T-Rex—filled a role in the food chain known as “mesopredators”, before later growing into apex predators.

This change is “probably the reason why tyrannosaurs were so successful and dominated their ecosystems at the end of the Cretaceous in North America and Asia,” Therrien said.

More information: François Therrien et al, Exceptionally preserved stomach contents of a young tyrannosaurid reveal an ontogenetic dietary shift in an iconic extinct predator, Science Advances (2023). DOI: 10.1126/sciadv.adi0505

Journal information: Science Advances

UFOs: How astronomers are searching the sky for alien probes near Earth

ASTRONOMY

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09/12/2023

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UFOs: How astronomers are searching the sky for alien probes near Earth

There has been increased interest in unidentified flying objects (UFOs) ever since the Pentagon’s 2021 report revealed what appears to be anomalous objects in US airspace, dubbed unidentified aerial phenomena (UAP). Fast forward to 2023, and Nasa has already formed a panel to investigate the reports and appointed a director for UAP research.

A newly founded Pentagon desk has also released footage of mysterious metallic orbs. What is perhaps most remarkable is that David Grusch, a former intelligence officer, testified under oath before the US Congress, stating that he had interviewed around 40 people involved in secret programs dealing with crashed UFOs.

I am interested in searching the sky for alien, physical objects which may one day tell us whether we are alone in the galaxy. Consider this: within our own Milky Way galaxy, there are 40 billion Earth-sized, potentially habitable planets.

Human ingenuity has enabled us to engineer and launch probes like Voyager and Pioneer, capable of reaching the closest stars. We’ve initiated efforts such as the Breakthrough Starshot program which aims to reach nearby star Alpha Centauri in just a few decades by exploring innovative propulsion methods. Sending a probe may be more economical than sending out radio or laser communication if there is no need to hurry.

If humans can send a probe to another star, why couldn’t another civilization send a probe to our solar system? Such a probe could make it to the main asteroid belt and lurk on an asteroid.

Or, it could make its way to the Earth, entering our atmosphere. If observed, it would be branded as a “UFO.” A civilization capable of producing and sending probes could dispatch millions of them on exploratory missions throughout our galaxy.

Some may argue that such probes could only exist if they adhere to the laws of physics and engineering as we understand them today. However, humanity is a relatively young civilization, and our knowledge is constantly evolving.

While humans have dreamt of flying for millennia as we gazed at the skies, it has only been 120 years since the Wright brothers achieved the first powered flight. That’s about as long ago as Albert Einstein published his theory of special relativity.

Is it really so difficult to imagine that a civilization that is hundreds of thousands years older than ours might have learned more about the laws of physics or developed a few more engineering tricks?

If a civilization were to evolve into artificial intelligence (AI), it might survive for millions of years. This could mean it would casually regard slow to a neighboring star as nothing more than a leisurely stroll.

That said, few astronomers felt impressed by the US Navy videos or government reports. We need significantly better evidence and data than what has been presented so far.

Unveiling UFOs

How can we test whether there are extra terrestrial probes near Earth, and whether they can be tied to the possible UFO phenomenon? There are many options. Analyzing materials from potentially crashed UFOs could give irrefutable proof. This would require state-of-the-art techniques to determine if these wrecks exhibit exotic or distinctly different characteristics of manufacture.

Obtaining such exotic samples, if they indeed exist, may prove challenging—they are rumored to be in the hands of private companies. But newly proposed legislation might offer a solution to that problem in United States by mandating that all artificial materials from any non-human intelligence be surrendered to the US government.

In the projects I lead, we are searching for artificial non-human objects by looking for short light flashes in the night sky. Short flashes typically occur when a flat, highly reflective surface—such as a mirror or glass—reflects sunlight. It could, however, also result from an artificial object emitting its own internal light.

Such short light flashes sometimes repeat and follow a straight line as the object tumbles in space during its orbit around the Earth. This is why satellites often appear as repeating light flashes in images.

Historical photographic plates taken before the launch of Sputnik 1 in 1957 have revealed the presence of nine light sources (transients) that appear and vanish within an hour in a small image, defying astronomical explanations. In some cases, the transient light sources are even aligned, just like when short flashes come from moving objects.

The most recent finding of this kind shows three bright stars in an image dated July 19, 1952 (coincidentally, the same time as the famous Washington UFO flyovers). The three stars were never seen again.

Searching for alien probes in the modern night sky presents a serious but necessary challenge. A new research program, known as ExoProbe, searches for short light flashes from potential alien objects with the help of multiple telescopes.

To verify the authenticity of each flash, it must be observed in at least two different telescopes. Since these telescopes are separated by hundreds of kilometers, any light flash caused by an object within the inner solar system enables the measurement of parallax—the apparent shift in the position of an object as seen from two different points—and the calculation of the distance to the object.

The ExoProbe project also uses its own methods to filter out light flashes from the millions of space debris fragments and thousands of satellites cluttering the sky. By adding a telescope taking real-time spectra (the wavelength distributions of the light) of the objects in a wide field, you can analyze the transients before they vanish into nothingness.

Finally, increasing the number of telescopes further enhances accuracy in measuring parallax and determining the actual three dimensional location of the object. Ultimately, the goal is to identify any potential alien object and bring it back to Earth for further study.

Some 60 years of searches for extraterrestrial civilizations in the radio frequencies have yielded no candidates whatsoever. We find ourselves at a moment in time when new paths must be explored. That means we can finally focus our attention closer to home. Regardless of the outcome, this journey is certainly an homage to our insatiable curiosity.

Provided by The Conversation

This article is republished from The Conversation under a Creative Commons license. Read the original article.

The longstanding mystery of Mars’ moons—and the mission that could solve it

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09/12/2023

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The longstanding mystery of Mars’ moons—and the mission that could solve it

The two small moons of Mars, Phobos (about 22km in diameter) and Deimos (about 13km in diameter), have been puzzling scientists for decades, with their origin remaining a matter of debate. Some have proposed that they may be made up of residual debris produced from a planet or large asteroid smashing into the surface of Mars (#TeamImpact).

An opposing hypothesis (#TeamCapture), however, suggests the moons are asteroids that were captured by Mars’s gravitational pull and were trapped in orbit.

To solve the mystery, we’ll need material from the moons’ surfaces for analytical analyses on Earth. Luckily, the Japan Aerospace Exploration Agency (Jaxa) will launch a mission, named “Martian Moon eXploration” (MMX), to Phobos and Deimos in September 2024. The mission will be carried by a newly designed rocket, the H-3, which is still under development.

The spacecraft is expected to reach Martian orbit in 2025, after which it will orbit Phobos and finally collect material from its surface before returning to Earth by 2029.

This will make it the next in a series of recent missions bringing material from space back to Earth, following on from Jaxa’s successful mission to asteroid Ryugu (Hayabusa2), as well as Nasa’s Osiris-Rex mission to asteroid Bennu and the Chinese Space Agency’s Chang’e 5 mission to the Moon.

Giveaways

If an impact origin did indeed occur, we would expect to find similar material on Phobos to that which is found on Mars. While we do not have any material returned directly from Mars (yet), we are lucky enough to have rock that has been ejected off its surface which eventually found its way to Earth.

These meteorites may therefore be similar to the material returned from Phobos, providing a fantastic comparison.

In the case of a captured asteroid origin, however, we are more likely to find material on Phobos that is found on other asteroids in our solar system. The prevailing hypothesis in the #TeamCapture group is that the moons are made up of the same rock as meteorites, called carbonaceous chondrite. Thankfully, we have plenty of such meteorites and samples that we could compare with the Phobos material.

Comparing meteorites and material brought back from Phobos will be a fantastic tool for helping us understand the origin of the two moons. Once we have material in the laboratory, rigorous analytical techniques can be applied to the samples.

One such technique is oxygen isotope analysis. Isotopes are versions of elements whose nuclei have more or fewer particles called neutrons. Oxygen, for example, has three stable isotopes, with atomic masses of 16, 17 and 18.

The sum of the isotopic ratios of oxygen-17/oxygen-16 and oxygen-18/oxygen-16 is denoted as Δ¹⁷O, and is characteristic of specific parent objects. Depending on where in the solar system a rocky body is formed, a distinct oxygen composition is acquired and retained in the rocks. For example, rocks from Earth have Δ¹⁷O of around 0, while meteorites from Mars have Δ¹⁷O of around ~0.3. Therefore, rocks from Earth and Martian meteorites can be readily separated from one another.

If Phobos formed in the same or at least similar location in the solar system to Mars, we would expect the composition of the material brought back by MMX also to have Δ¹⁷O of around 0.3.

As mentioned previously, #TeamCapture suggest a carbonaceous chondrite-like origin for Phobos. All known carbonaceous chondrites studied by scientists have revealed negative isotopic Δ¹⁷O, ranging from -0.5 all the way down to -4. Oxygen can therefore be an extremely powerful tool in deciphering the origin of the moons of Mars, and should be a high priority for the mission once material is returned to Earth.

If Phobos does indeed represent an ancient fragment of Mars, it could comprise the most primitive of Martian material. Mars has experienced a wide range of processes that have altered the rocks on its surface, including wind erosion and water alteration. Based on features such as dry river beds observed from orbiters such as Viking, it is clear that water on Mars once existed.

This water likely originated from a mix of asteroids and comets, and volcanic activity. Mars also retained a thick atmosphere, which allowed water to be present as a liquid on the planet’s surface.

Phobos, on the other hand, has remained an airless body where processes such as contamination from water have not occurred (though minor impact events may have taken place). This means that samples returned from Phobos could provide extremely important insights into the original water content of Mars, and a window to processes that occurred in the early solar system.

MMX is one of the most exciting planned missions in space exploration. With less than a year to go, our fingers are already firmly crossed for a successful launch, sample acquisition, and sample return. Many scientists including myself would absolutely love the possibility of one day studying those samples.

Provided by The Conversation

This article is republished from The Conversation under a Creative Commons license. Read the original article.

New technique enhances imaging of fluid-filled rocks, finds connection to microearthquakes

EARTHQUAKES

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08/12/2023

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New technique enhances imaging of fluid-filled rocks, finds connection to microearthquakes

An international team of scientists led by Dr. Xin Liu, Assistant Professor of the Department of Earth Sciences, The University of Hong Kong (HKU), along with seismologists from the U.S. and China, has recently introduced a new method called ambient noise differential adjoint tomography, which allows researchers to better visualize rocks with fluids.

This could lead to potential advancements in the discovery of water and oil resources, as well as applications in urban geologic hazard and early warning systems for tsunamis and the understanding of the water cycle. Their findings have been published in Nature Communications.

The method utilizes a portable instrument called a seismometer to record the Earths natural vibrations, making it a cost-effective and easy way to study areas in cities and oceans. Seismometers record ground motion in three dimensions: up–down, north–south, and east–west. In the study, 42 seismometers were placed along a line across the Los Angeles basin from Long Beach to Whittier Narrows.

Researchers found that rocks about 1–2 km beneath the surface near the Newport-Inglewood Fault, a fault that causes earthquakes, contain a significant amount of fluids. These rocks have tiny holes filled with fluids, which may explain the occurrence of small earthquakes in Long Beach, California. The abundance of fluids within these tiny holes reduces friction along the fault plane, allowing the two rock blocks on either side to slide past each other more easily and generate small earthquakes.

The paper suggests that ambient noise differential adjoint tomography can be used to find water and oil resources without the need for expensive drilling. This novel method generates images of the ground covered by seismometers, revealing how fast seismic waves travel in soils and rocks. In some locations, the seismic wave travels much slower compared to other regions at the same depth, indicating the presence of fluid. As water and oil are fluids in rocks, this method can identify rocks containing such fluids.

“Previously, groundwater aquifers or deep fluid reservoirs were difficult to find without drilling multiple expensive wells or costly seismic surveys with loud artificial sound that are not environmentally friendly on land or ocean. Using just weak seismic noise recordings by two dozen seismometers on land or seafloor, our new technique can create images containing fluid information within rocks, and pinpoint the location and depth of fluid-rich rocks,” said Dr. Liu, who is also the first author of the journal paper.

Additionally, this innovative method can be used to create detailed images of the ground in urban areas and the deep ocean, serving various purposes such as assessing urban geologic hazards, implementing early warning systems for tsunamis and enhancing our understanding of the water cycle under the seafloor.

In urban settings, a series of land seismometers can be deployed over the area of interest. In the ocean, a line of Ocean Bottom Seismometers (OBS) can be installed on the seafloor to record background vibrations.

In both cases, a detailed image is created right underneath the line of seismometers, providing information about the locations of loose soil/sediments and fluid-bearing rocks that directly relate to regions with slow seismic wave velocity.

“In conclusion, this innovative method has the potential to revolutionize our approach to discovering and utilizing water and oil resources, enhancing urban safety measures, and deepening our understanding of the environment. Its direct impact on our daily lives spans from efficient resource exploration to effective disaster preparedness and promoting sustainable environmental management practices. This scientific breakthrough holds excellent promise in shaping a better future for us all,” Dr. Liu added.

More information: Xin Liu et al, Ambient noise differential adjoint tomography reveals fluid-bearing rocks near active faults in Los Angeles, Nature Communications (2023). DOI: 10.1038/s41467-023-42536-4

Journal information: Nature Communications

Provided by The University of Hong Kong

The eruption of the Marapi volcano, the death toll rises to 22

VOLCANOES

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05/12/2023

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The eruption of the Marapi volcano, the death toll rises to 22

At least 22 people have lost their lives as a result of the eruption of the Marapi volcano in Indonesia, while the search for a missing person continues.

Hundreds of rescuers have mobilized for the search, which continues in difficult conditions due to bad weather and ash that continues to flow from the volcano.

Indonesia’s Mt. Merapi erupted with ash plumes on December 3, spreading volcanic ash over several villages and causing the death of 11 hikers out of 50 blocked non the volcano by the event.pic.twitter.com/UWyYZ4uBlm

— Massimo (@Rainmaker1973) December 4, 2023

At least 22 people have lost their lives as a result of the eruption of the Marapi volcano in Indonesia, while the search for a missing person continues.

Massive explosion at Merapi volcano in the Stratovolcano of the Indonesia 🇮🇩 (03.12.2023)
pic.twitter.com/ask2AtdGVv

— #كابتن_غازي_عبداللطيف (@CaptainGhazi) December 4, 2023

Indonesia’s Marapi volcano erupts, killing 11 climbers; 12 missing

VOLCANOES

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04/12/2023

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Indonesia’s Marapi volcano erupts, killing 11 climbers; 12 missing

Eleven climbers were found dead in Indonesia on Monday and 12 were missing after the Marapi volcano erupted in West Sumatra, a rescue official said, as search operations – which were halted temporarily over safety concerns – resumed.

Three survivors were found on Monday along with the bodies of the 11 climbers, out of 75 who were in the area at the time of Sunday’s eruption, said Jodi Haryawan, spokesperson for the search and rescue team, adding they were all local climbers.

“We have continued to search for the 12 missing climbers until this evening. We have not decided when we are going to stop the operation,” Jodi said in a phone call, adding they would continue evacuating the three survivors and bodies of climbers.

There were 49 climbers evacuated from the area earlier on Monday and many were being treated for burns, Jodi said.

It took around four to six hours to evacuate one dead body from the volcano, Jodi said, adding: “It’s very difficult.”

New unified theory shows how past landscapes drove the evolution of Earth’s rich diversity of life

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04/12/2023

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New unified theory shows how past landscapes drove the evolution of Earth’s rich diversity of life

Earth’s surface is the living skin of our planet—it connects the physical, chemical and biological systems.

Over geological time, this surface evolves. Rivers fragment the landscape into an environmentally diverse range of habitats. These rivers also transfer sediments from the mountains to the continental plains and ultimately the oceans.

The idea that landscapes have influenced the trajectory of life on our planet has a long history, dating back to the early 19th century scientific narratives of German polymath Alexander von Humboldt. While we’ve learnt more since then, many aspects of biodiversity evolution remain enigmatic. For example, it’s still unclear why there is a 100-million-year gap between the explosion of marine life and the development of plants on continents.

In research published in Nature today, we propose a new theory that relates the evolution of biodiversity over the past 540 million years to sediment “pulses” controlled by past landscapes.

10 years of computational time

Our simulations are based on an open-source code released as part of a Science paper published earlier this year.

To drive the evolution of the landscape through space and time in our computer model, we used a series of reconstructions for what the climate and tectonics were like in the past.

We then compared the results of our global simulations with reconstructions of marine and continental biodiversity over the past 540 million years.

To perform our computer simulations, we took advantage of Australia’s National Computational Infrastructure running on several hundreds of processors. The combined simulations presented in our study are equivalent to ten years of computational time.

Marine life and river sediment were closely linked

In our model, we discovered that the more sediment rivers carried into the oceans, the more the sea life diversified (a positive correlation). You can see this tracked by the red line in the chart below.

https://youtube.com/watch?v=Uxutnt44NKU%3Fcolor%3Dwhite

As the continents weather, rivers don’t just carry sediment into the oceans, they also bring a large quantity of nutrients. These nutrients, such as carbon, nitrogen and phosphorus, are essential to the biological cycles that move vital elements through all living things.

This is why we think rivers delivering more or less nutrients to the ocean—on a geological timescale of millions of years—is related to the diversification of marine life.

Perhaps even more surprisingly, we found that episodes of mass extinctions in the oceans happened shortly after significant decreases in sedimentary flow. This suggests that a lack or deficiency of nutrients can destabilize biodiversity and make it vulnerable to catastrophic events (like asteroid impacts or volcanic eruptions).

Landscapes also drove the diversity of plants

On the continents, we designed a variable that integrates sediment cover and landscape ruggedness to describe the continents’ capacity to host diverse species.

Here we also found a striking correlation (see below) between our variable and plant diversification for the past 400 million years. This highlights how changes in landscape also have a strong influence on species diversifying on land.

We hypothesize that as Earth’s surface was gradually covered with thicker soil, richer in nutrients deposited by rivers, plants could develop and diversify with more elaborate root systems.

As plants slowly expanded across the land, the planet ended up hosting varied environments and habitats with favorable conditions for plant evolution, such as the emergence of flowering plants some 100 million years ago.

A living planet

Overall, our findings suggest the diversity of life on our planet is strongly influenced by landscape dynamics. At any given moment, Earth’s landscapes determine the maximum number of different species continents and oceans can support.

This shows it’s not just tectonics or climates, but their interactions that determine the long-term evolution of biodiversity. They do this through sediment flows and changes to the landscapes at large.

Our findings also show that biodiversity has always evolved at the pace of plate tectonics. That’s a pace incomparably slower than the current rate of extinction caused by human activity.

More information: Tristan Salles et al, Landscape dynamics and the Phanerozoic diversification of the biosphere, Nature (2023). DOI: 10.1038/s41586-023-06777-z

Journal information: Nature , Science

Provided by The Conversation

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Japan issues tsunami alert after M7.7 quake hits off Philippines

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03/12/2023

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Japan issues tsunami alert after M7.7 quake hits off Philippines

Japan’s weather agency issued a tsunami alert late Saturday for wide areas facing the Pacific including the prefectures of Chiba, Shizuoka and Kagoshima, after an earthquake with a preliminary magnitude of 7.7 hit off the southern Philippine island of Mindanao.

In the Philippines’ Davao, an 8-centimeter tsunami was observed following the quake, which struck at 11:37 p.m., Japan time, an official of the Japan Meteorological Agency said at a press conference early Sunday in Tokyo.

A tsunami warning was also issued for the coastal areas of Surigao del Sur and Davao Oriental provinces, said the Philippine Institute of Volcanology and Seismology. Locals in the areas were told to evacuate to higher ground.

As for Japan, a tsunami of 1 meter high may reach Miyako Island and the vicinity in Okinawa as well as other prefectures, also including Aichi, Mie, Wakayama, Tokushima, Kochi and Miyazaki, early Sunday, the agency said.

There were no immediate reports of injuries or damage in the two countries.

While the institute put the quake at a magnitude of 6.9, it warned that “destructive tsunami is expected with life threatening wave heights.”

The quake, which struck off the eastern coast of Mindanao, occurred at a depth of 32.8 kilometers, according to the U.S. Geological Survey.

The Japanese agency said other areas covered by the alert included the Izu island chain near Tokyo and the Ogasawara Islands in the Pacific Ocean, south of the Japanese capital.

Authorities in Japan and the Philippines warned the public to stay away from the coast until after the tsunami alerts are lifted.

The ocean’s first large swimming apex predators had exceptionally rapid growth, fossil study finds

PALEONTOLOGY

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03/12/2023

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The ocean’s first large swimming apex predators had exceptionally rapid growth, fossil study finds

The rapid diversification of animals over 500 million years ago—often referred to as the Cambrian Explosion—saw the appearance of the first large swimming predators in our oceans. Amplectobelua symbrachiata, a member of the group Radiodonta, which are relatives of modern arthropods, was the largest of these, reaching nearly one meter in length, and can be easily recognized by their fearsome spiny feeding appendages.

However, despite recent studies revealing a huge diversity of radiodonts, our understanding of how these animals grew and their changing ecological role throughout their life has been distinctly lacking. That is, until now.

Hundreds of fossil specimens of the feeding appendages of Amplectobelua symbrachiata (ranging from less than 1 cm to more than 10 cm in length) collected from the famous fossil deposits of Chengjiang in China were carefully studied and statistically analyzed by an international team of researchers based at Northwest University, China, Cambridge University, UK, and University of British Columbia, Canada.

Combining statistical methods with growth modeling methods commonly used in modern fisheries analyses, the team determined both how the relative proportions of parts of the feeding appendages changed with size and quantified the growth rates in these animals for the first time. All analyses revealed that Amplectobelua symbrachiata displayed an unusual and rapid growth strategy when compared to its modern arthropod relatives.

The ocean's first large swimming apex predators had exceptionally rapid growth — Boxplots show comparisons of maximum, minimum and mean growth ratio between stages in total group euarthropods (data gathered from literature). Note how A. symbrachiata displays among the highest maximum growth ratios of any euarthropod in the literature (except for chironomid Chironomus, coenagrionid Ischnura cruzi, and lycaenid Maculinea arion). The diagram is collated from various body parts of large number of modern and extinct euarthropods. Credit: Science China Press

Amplectobelua symbrachiata appendages display isometric growth—the proportions in the shape of individual podomeres and the relative length of spines to the appendage length and height were the same for small juveniles as for large adults. This implies that the overall function of the appendage was similar for the animal’s whole life. However, the greater size of adult A. symbrachiata appendages would have made new food sources available. “The larger size of

adult appendages, alongside faster swimming speeds, would have allowed larger prey to be captured and subdued. Similarity in form must be placed in the context of the scaling up of muscle power and forces with size,” said Dr. Yu Wu, one of the leaders from Northwest University, Xi’an.

Growth and mortality parameters for Amplectobelua symbrachiata were estimated using ELEFAN—a model based on size-frequency distributions commonly used in studies of modern arthropods and fish.

“These results show that Amplectobelua symbrachiata were extremely active animals in Cambrian ecosystems and had exceptionally rapid growth when compared to modern marine arthropods,” said Prof. Pauly, British Columbia University, who led the ELEFAN analyses. consideration of peaks in size-frequency data suggests that this rapid growth might have been achieved over very few growth stages.

The large growth ratio may have been facilitated by the unique body plan of radiodonts such as Amplectobelua symbrachiata—the body was soft and not fully arthrodized, with the most toughened part of the skeleton represented by the feeding appendages.

The unique position of A. symbrachiata, as a large, active apex predator in ecosystems with large amounts of predation, without a fully arthropodized or sclerotized body, appears to have facilitated an active, rapid-growing life history strategy.

“The Cambrian is thought to have been a time with high predation pressure, which may have provided a benefit for rapid growth to a large size. Simultaneously, rapid growth to become one of the largest animals in the ecosystem would have also provided benefits in terms of prey capture, making more prey items available,” said Dr. Stephen Pates of Cambridge University, UK, who co-led the study.

“This unexpected life history strategy might have been shaped by the escalatory ‘arms race’ that has been hypothesized to shape the Cambrian Explosion,” explained Prof. Fu, one of the corresponding authors of this study. “Only through study and analyses of hundreds of fossil specimens are we able to reveal not just what these animals looked like, but also how—and how quickly—they grew.”

Taken together, these results show that the animals in today’s oceans provide a single snapshot of what evolution can produce—and that the different ecological, environmental, and evolutionary pressures and histories present over the last half a billion years have led to disparate morphologies, body plans and life history strategies that data-rich interdisciplinary studies such as this can reveal.

The work is published in the journal National Science Review.

More information: Yu Wu et al, Rapid growth in a large Cambrian apex predator, National Science Review (2023). DOI: 10.1093/nsr/nwad284

Provided by Science China Press