In the evolution of walking, the hip bone connected to the rib bones

April 13, 2024

New reconstruction of the skeleton of the 375-million-year-old fossil fish, Tiktaalik roseae. In a new study, researchers used Micro-CT to reveal vertebrae and ribs of the fish that were previously hidden beneath rock. The new reconstruction shows that the fish’s ribs likely attached to its pelvis, an innovation thought to be crucial to supporting the body and for the eventual evolution of walking. Credit: Thomas Stewart, Penn State

Before the evolution of legs from fins, the axial skeleton — including the bones of the head, neck, back and ribs — was already going through changes that would eventually help our ancestors support their bodies to walk on land. A research team including a Penn State biologist completed a new reconstruction of the skeleton of Tiktaalik, the 375-million-year-old fossil fish that is one of the closest relatives to limbed vertebrates. The new reconstruction shows that the fish’s ribs likely attached to its pelvis, an innovation thought to be crucial to supporting the body and for the eventual evolution of walking.

A paper describing the new reconstruction, which used microcomputed tomography (micro-CT) to scan the fossil and reveal vertebrae and ribs of the fish that were previously hidden beneath rock, appeared April 2 in the journal Proceedings of the National Academy of Sciences.

“Tiktaalik was discovered in 2004, but key parts of its skeleton were unknown,” said Tom Stewart, assistant professor of biology in the Eberly College of Science at Penn State and one of the leaders of the research team. “These new high-resolution micro-CT scans show us the vertebrae and ribs of Tiktaalik and allow us to make a full reconstruction of its skeleton, which is vital to understanding how it moved through the world.”

Unlike most fish, which have vertebrae and ribs that are the same along the length of the trunk, the axial skeletons of limbed vertebrates show dramatic differences in the vertebrae and ribs from the head region to the tail region. The evolution of this regionalization allowed the performance of specialized functions, one of which was a mechanical linkage between ribs in the sacral region to the pelvis that enabled support of the body by the hind limbs.

The pelvic fins of fish are evolutionarily related to hind limbs in tetrapods — four-limbed vertebrates, including humans. In fish, the pelvic fins and bones of the pelvic girdle are relatively small and float freely in the body. For the evolution of walking, the researchers explained, the hind limbs and pelvis became much larger and formed a connection to the vertebral column as a way of bracing the forces related to supporting the body.

“Tiktaalik is remarkable because it gives us glimpses into this major evolutionary transition,” Stewart said. “Across its whole skeleton, we see a combination of traits that are typical of fish and life in water as well as traits that are seen in land-dwelling animals.”

The original description of Tiktaalik focused on the front portion of the skeleton. Fossils were meticulously prepared to remove the surrounding matrix of rock and expose the skull, shoulder girdle and pectoral fins. The ribs in this area were large and expanded, suggesting that they may have supported the body in some way, but it was unclear exactly how they would have functioned. In 2014, the fish’s pelvis, discovered in the same location as the rest of the skeleton, was also cleaned of matrix and described.

“From past studies, we knew that the pelvis was large, and we had a sense that the hind fins were large too, but until now couldn’t say if or how the pelvis interacted with the axial skeleton,” Stewart said. “This reconstruction shows, for the first-time, how it all fit together and gives us clues about how walking might have first evolved.”

The researchers explained that, unlike our own hips where our bones fit tightly together, the connection between the pelvis and axial skeleton of Tiktaalik was likely a soft-tissue connection made of ligaments.

“Tiktaalik had specialized ribs that would have connected to the pelvis by a ligament,” Stewart said. “It’s astonishing really. This creature has so many traits — large pair of hind appendages, large pelvis, and connection between the pelvis and axial skeleton — that were key to the origin of walking. And while Tiktaalik probably wasn’t walking across land, it was definitely doing something new. This was a fish that could likely prop itself up and push with its hind fin.”

The new reconstruction of the skeleton also sheds light on specializations for head mobility in Tiktaalik and new details of the fish’s pelvic fin anatomy.

“It’s incredible to see the skeleton of Tiktaalik captured in such vivid detail,” said Neil Shubin, Robert R. Bensley Distinguished Service Professor of Organismal Biology and Anatomy at the University of Chicago and one of the authors of the paper. “This study sets the stage for ones that explore how the animal moved about and interacted with its environment 375 million years ago.”

In addition to Stewart and Shubin, the research team includes Justin B. Lemberg, Emily J. Hillan, and Isaac Magallanes at The University of Chicago, and Edward B. Daeschler at Academy of Natural Sciences of Drexel University.

Support from the Brinson Foundation, the Biological Sciences Division of The University of Chicago, an anonymous donor to the Academy of Natural Sciences of Drexel University, and the U.S. National Science Foundation funded this research. Fieldwork was made possible by the Polar Continental Shelf Project of Natural Resources, Canada; the Department of Heritage and Culture, Nunavut; the hamlets of Resolute Bay and Grise Fiord of Nunavut; and the Iviq Hunters and Trappers of Grise Fiord.

Reference:
Thomas A. Stewart, Justin B. Lemberg, Emily J. Hillan, Isaac Magallanes, Edward B. Daeschler, Neil H. Shubin. The axial skeleton of Tiktaalik roseae. Proceedings of the National Academy of Sciences, 2024; 121 (15) DOI: 10.1073/pnas.2316106121

Note: The above post is reprinted from materials provided by Penn State. Original written by Sam Sholtis.

Fault maturity or orientation: Which matters more for quakes?

April 13, 2024

Researchers used unmanned aerial vehicle images superimposed on centimeter-resolution topography to study the surface rupture of the 2021 magnitude 7.4 Maduo earthquake in China. This image shows the fault scarp, tensional cracks on the hanging wall, and the left-laterally offset channel. Credit: Yanxiu Shao

In the early morning of 22 May 2021, a magnitude 7.4 quake rattled China’s remote Maduo County on the Tibetan Plateau. It was the most recent in a series of nine earthquakes with a magnitude of 7 or greater since 1997, and its surface rupture was twice as long as the global average for similarly sized quakes. The tremor occurred on the eastern part of the relatively immature left-lateral Jiangcuo fault system, which slips slowly, about 1 millimeter per year, and was unmapped before the quake.

Uncovering the geological dynamics of this disaster could help inform future efforts to assess seismic hazards in the region and around the world. In a new report published in AGU Advances, Jing Liu-Zeng and colleagues analyze the Maduo quake to probe the relationship between fault structure and earthquake dynamics.

To do so, the researchers combined field observations with satellite images taken prequake and postquake as well as with centimeter-resolution photos taken of the fault system by an unmanned aerial vehicle. These remote sensing techniques enabled them to analyze fractures that would otherwise be inaccessible because of their high altitude and harsh surrounding environment.

The research team assessed changes to Earth’s surface both on and near the fault segments involved in the quake. The segments had varying orientations with respect to the overall regional patterns of seismic stress, as well as varying degrees of maturity. Maturity is not necessarily synonymous with age; rather, it indicates the degree of a segment’s development, or how much it has changed with time and activity.

Prior research has highlighted the importance of fault maturity in earthquake dynamics. However, in the case of the Maduo quake, the researchers found that the faults’ orientations played a larger role in the magnitude and the degree of localization of surface deformation than their maturity levels. These findings suggest that future seismic hazard assessments might be enhanced by more thoroughly accounting for fault segment orientation in the context of regional stress conditions.

Reference:
Jing Liu‐Zeng et al, Fault Orientation Trumps Fault Maturity in Controlling Coseismic Rupture Characteristics of the 2021 Maduo Earthquake, AGU Advances (2024). DOI: 10.1029/2023AV001134

Note: The above post is reprinted from materials provided by Sarah Stanley, American Geophysical Union.

Alaska dinosaur tracks reveal a lush, wet environment

March 16, 2024

A theropod track lies in rock near the west bank of the Kukpowruk River. Photo courtesy of Anthony Fiorillo

Table of Contents

A large find of dinosaur tracks and fossilized plants and tree stumps in far northwestern Alaska provides new information about the climate and movement of animals near the time when they began traveling between the Asian and North American continents roughly 100 million years ago.

The findings by an international team of scientists led by paleontologist Anthony Fiorillo were published Jan. 30 in the journal Geosciences. Fiorillo researched in Alaska while at Southern Methodist University. He is now executive director of the New Mexico Museum of Natural History and Science.

University of Alaska Fairbanks geology professor Paul McCarthy, with the UAF Geophysical Institute and UAF College of Natural Science and Mathematics, was a leading contributor to the research. He and UAF graduate student Eric Orphys are among the eight co-authors.

Fiorillo and McCarthy are longtime collaborators.

“We’ve had projects for the last 20 years in Alaska trying to integrate sedimentology, dinosaur paleontology and the paleoclimate indicators,” McCarthy said. “We’ve done work in three other formations — in Denali, on the North Slope and in Southwest Alaska — and they’re about 70 million years old.”

“This new one is in a formation that’s about 90 to 100 million years old,” he said.

Fiorillo said the additional age is notable.

“What interested us about looking at rocks of this age is this is roughly the time that people think of as the beginning of the Bering Land Bridge — the connection between Asia and North America,” he said. “We want to know who was using it, how they were using it and what the conditions were like.”

Research into the paleoclimate can help scientists understand the warming world of today, the authors write.

“The mid-Cretaceous was the hottest point in the Cretaceous,” said McCarthy, a sedimentologist and fossil soils specialist. “The Nanushuk Formation gives us a snapshot of what a high-latitude ecosystem looks like on a warmer Earth.”

A rich find of evidence

The Nanushuk Formation is an outcropped layer of sedimentary rock 800 to 5,000 feet thick across the central and western North Slope. It dates to roughly 94 million to 113 million years ago in the mid-Cretaceous Period and about when the Bering Land Bridge began.

The fieldwork occurred in 2015-2017 and centered on Coke Basin, a circular geologic feature of the Nanushuk Formation. The basin is in the DeLong Mountains foothills along the Kukpowruk River, about 60 miles south of Point Lay and 20 miles inland from the Chukchi Sea.

In the area, Fiorillo and McCarthy found approximately 75 fossil tracks and other indicators attributed to dinosaurs living in a riverine or delta setting.

“This place was just crazy rich with dinosaur footprints,” Fiorillo said.

One site stands out, Fiorillo said.

“We were at a spot where we eventually realized that for at least 400 yards we were walking on an ancient landscape,” he said. “On that landscape we found large upright trees with little trees in between and leaves on the ground. We had tracks on the ground and fossilized feces.”

They found numerous fossilized tree stumps, some 2 feet in diameter.

“It was just like we were walking through the woods of millions of years ago,” he said.

The Nanushuk Formation encompasses rock of marine and non-marine characteristics and composition, but the authors’ research focuses primarily on the non-marine sediments exposed along the upper Kukpowruk River.

“One of the things we did in our paper was look at the relative frequencies of the different kinds of dinosaurs,” Fiorillo said. “What was interesting to us was that the bipedal plant eaters were clearly the most abundant.”

Two-legged plant eaters accounted for 59% of the total tracks discovered. Four-legged plant eaters accounted for 17%, with birds accounting for 15% and non-avian, mostly carnivorous, bipedal dinosaurs at 9%.

“One of the things that was interesting is the relative frequency of bird tracks,” Fiorillo said.

The authors point out that nearly half of North America’s shorebirds breed in the warm months of today’s Arctic. They suggest that the high number of fossil bird tracks along the Kukpowruk River indicates the warm paleoclimate was a similar driver for Cretaceous Period birds.

A wet and warm place

Carbon isotope analysis of wood samples led to a determination that the region received about 70 inches of precipitation annually. This record of increased precipitation during the mid-Cretaceous provides new data that supports global precipitation patterns associated with the Cretaceous Thermal Maximum, the authors write.

The Cretaceous Thermal Maximum was a long-term trend approximately 90 million years ago in which average global temperatures were significantly higher than those of today.

“The temperature was much warmer than it is today, and what’s possibly more interesting is that it rained a lot,” Fiorillo said. “The samples we analyzed indicate it was roughly equivalent to modern-day Miami. That’s pretty substantial.”

Of note is that the Alaska site investigated by Fiorillo and McCarthy was about 10 to 15 degrees latitude farther north in the mid-Cretaceous than it is today.

McCarthy’s role as a fossil soils expert was to analyze old rocks and sediments to interpret the type of environment that existed at the time.

“We can say here’s a river channel, here’s a flood deposit, here’s a levee, here’s the floodplain, here’s a swamp,” he said. “And so if we’re able to find tracks in that section, then you can sometimes say that a group of dinosaurs seems to have really liked being here as opposed to there.”

Fiorillo said the site indicates there’s much more work to be done.

“This puts a new dot on the map and tells us there’s a lot here, and it fits into the bigger picture,” he said. “The big picture is we’re trying to get better resolution on what life was like in the high latitudes back at the time the dinosaurs were roaming around.”

Reference:
Anthony R. Fiorillo, Paul J. McCarthy, Grant Shimer, Marina B. Suarez, Ryuji Takasaki, Tsogtbaatar Chinzorig, Yoshitsugu Kobayashi, Paul O’Sullivan, Eric Orphys. New Dinosaur Ichnological, Sedimentological, and Geochemical Data from a Cretaceous High-Latitude Terrestrial Greenhouse Ecosystem, Nanushuk Formation, North Slope, Alaska. Geosciences, 2024; 14 (2): 36 DOI: 10.3390/geosciences14020036

Note: The above post is reprinted from materials provided by University of Alaska Fairbanks. Original written by Rod Boyce.

Higher carnivorous dinosaur biodiversity of famous Kem Kem beds, Morocco

March 16, 2024

The most common tooth type, of the famous Spinosaurus, with characteristic sail on its back. Images all from article discussed.

Table of Contents

An international team of palaeontologists from The Netherlands, the UK, Argentina, Germany and Belgium applied recently developed methods to measure theropod (carnivorous) dinosaur species diversity. The newly applied method uses both traditional phylogenetic analysis, discriminant analysis as well as machine learning. This new combination of analyses was performed on teeth of carnivorous dinosaurs, named theropods, from a set of isolated teeth from the famous Cretaceous (~100million years old) Kem Kem beds of Morocco. It turned out to reveal a theropod species previously not found in this area.

Fossilized remains from this site very often comprise teeth, whereas very few dinosaur bones preserve well, leaving scientists often guessing which dinosaur left these teeth behind.

Amongst the study specimens were teeth from the famous Spinosaurus and Carcharodontosaurus, known from movies such as the Jurassic Park franchise.

Next to these easily recogniseable tooth morphotypes, some ‘mystery teeth’ were also analysed.

These teeth were previously classified as belonging to the dromaeosaurid family of Velociraptor fame.

Brand new insights

Simon Wills, a scientific associate at the Natural History Museum who led the research, says, ‘the use of machine learning to identify theropod teeth has thrown the doors wide open to the ecosystem of the dinosaurs that roamed the Kem Kem 100 million years ago.

It was fascinating to see how the powerful tool accurately identified the specimens when combined with traditional methods.

The process highlights how embracing methods old and new can uncover brand new insights into relatively well-explored areas.

I believe we’ll see advances beyond what we thought possible in the coming years as our datasets grow meaning machine learning can reveal more about palaeodiversity and ecosystems from even the smallest remains — such as teeth!’

Close fit

Using the novel technique, the research team tried to determine the closest fit of the teeth’s appearance to other dinosaurs with well-known dentition.

The team from Utrecht University, the Natural History Museum, London, Instituto Miguel Lillo in Tucuman, Argentina, the Palaeontological Museum Munich, and VU Brussels then found that the two mystery tooth morphotypes were not the Jurassic Park raptor’s cousins, but rather, belonged to Abelisauridae, a distant cousin of Tyrannosaurus (including the big head and tiny arms), and a clade called Noasauridae, the latter being very rare in Morocco.

‘These teeth had been in museum collections for decades, but this new combination of techniques brought them to life again, and more importantly, confirms the presence of noasaurids in the Kem Kem, thanks to this international team effort,’ says Dr Femke Holwerda of Utrecht University.

Future work

Noasaurids are peculiar small theropods with long necks, and there are only a few hints of isolated bones known from them from the Kem Kem.

Traditional methods alone did not find this elusive little theropod amongst the tooth sample.

This shows that the new combination of methods is promising for future work on other dinosaurs, such as long-necked dinosaurs, even more rarely found in the Kem Kem.

Kem Kem

The Kem Kem is an Early Cretaceous (roughly 100 million years old) highly fossiliferous site on the border between Morocco and Algeria. It is one of few places in the world that preserves a fairly complete Early Cretaceous dinosaur-dominated ecosystem. Next to a plethora of theropods, sauropod (long-necked) dinosaurs, and one other type of herbivore existed in the area. The ecosystem was riverine, which might be why so many carnivorous animals were supported.

Reference:
Christophe Hendrickx, Thomas H. Trapman, Simon Wills, Femke M. Holwerda, Koen H. W. Stein, Oliver W. M. Rauhut, Roland R. Melzer, Jeroen Van Woensel, Jelle W. F. Reumer. A combined approach to identify isolated theropod teeth from the Cenomanian Kem Kem Group of Morocco: cladistic, discriminant, and machine learning analysesCitation for this article: Hendrickx, C., Trapman, T. H., Wills, S., Holwerda, F. M., Stein, K. H. . Journal of Vertebrate Paleontology, 2024; DOI: 10.1080/02724634.2024.2311791

Note: The above post is reprinted from materials provided by Utrecht University.

Fossils of giant sea lizard with dagger-like teeth show how our oceans have fundamentally changed since the dinosaur era

March 16, 2024

Khinjaria acuta was around the length of an orca, (7-8 metres). (Credit: Andrey Atuchin)

Paleontologists have discovered a strange new species of marine lizard with dagger-like teeth that lived near the end of the age of dinosaurs. Their findings, published in Cretaceous Research, show a dramatically different ocean ecosystem to what we see today, with numerous giant top predators eating large prey, unlike modern ecosystems where a few apex predators — such as great white sharks, orca and leopard seals — dominate.

Khinjaria acuta was a member of the family Mosasauridae, or mosasaurs. Mosasaurs weren’t dinosaurs, but giant marine lizards, relatives of today’s Komodo dragons and anacondas, which ruled the oceans 66 million years ago, during the era of Tyrannosaurus and Triceratops.

Khinjaria had powerful jaws and long, dagger-like teeth to seize prey, giving it a nightmarish appearance. It was part of an extraordinarily diverse fauna of predators that inhabited the Atlantic Ocean off the coast of Morocco, just before the dinosaurs went extinct.

The study is based on a skull and parts of the skeleton collected from a phosphate mine southeast of Casablanca. The study involved researchers from the University of Bath in the UK, the Marrakech Museum of Natural History, the Museum National d’ Histoire Naturelle (NMNH) in Paris (France), Southern Methodist University in Texas (USA), and the University of the Basque Country (Bilbao).

“What’s remarkable here is the sheer diversity of top predators,” said Dr Nick Longrich of the Department of Life Sciences and the Milner Centre for Evolution at the University of Bath, who led the study. “We have multiple species growing larger than a great white shark, and they’re top predators, but they all have different teeth, suggesting they’re hunting in different ways.

“Some mosasaurs had teeth to pierce prey, others to cut, tear, or crush. Now we have Khinjaria, with a short face full of huge, dagger-shaped teeth. This is one of the most diverse marine faunas seen anywhere, at any time in history, and it existed just before the marine reptiles and the dinosaurs went extinct.”

Morocco’s diverse marine reptiles lived just before an asteroid struck the Yucatan Peninsula in Mexico. Dust and fine particles shot into the high atmosphere blocked out the sun for months, causing darkness and cooling, which drove most of the planet’s species to extinction.

Dinosaurs were wiped out on land, and a handful of surviving species of mammals, birds, and lizards diversified to take their place. Meanwhile, the same happened in the oceans.

Mosasaurs, plesiosaurs and giant sea turtles disappeared, along with entire families of fish. This opened the way for whales and seals, and fish like swordfish and tuna appeared. However, the ecosystem that evolved after the impact was different.

“There seems to have been a huge change in the ecosystem structure in the past 66 million years,” said Longrich. “This incredible diversity of top predators in the Late Cretaceous is unusual, and we don’t see that in modern marine communities.”

Modern marine food chains have just a few large apex predators, animals like orcas, white sharks, and leopard seals. The Cretaceous had a whole host of top predators.

Dr Longrich said: “It’s not just that we’re getting rid of the old actors and recasting new ones into the same roles. The story has changed dramatically.

“Modern ecosystems have predators like baleen whales and dolphins that eat small prey, and not many things eating large prey. The Cretaceous has a huge number of marine reptile species that take large prey. Whether there’s something about marine reptiles that caused the ecosystem to be different, or the prey, or perhaps the environment, we don’t know. But this was an incredibly dangerous time to be a fish, a sea turtle, or even a marine reptile.”

Professor Nathalie Bardet, from the NMNH, said: “The Phosphates of Morocco deposit in a shallow and warm epicontinental sea, under a system of upwellings; these zones are caused by currents of deep, cold, nutrient-rich waters rising towards the surface, providing food for large numbers of sea creatures and, as a result, supporting a lot of predators. This is probably one of the explanations for this extraordinary paleobiodiversity observed in Morocco at the end of the Cretaceous.”

“The phosphates of Morocco immerse us in the Upper Cretaceous seas during the latest geological times of the dinosaurs’ age. No deposit has provided so many fossils and so many species from this period,” said Professor NE. Jalil of NMNH. “After the’ titan of the seas’, Thalassotitan, the ‘saw-toothed’ mosasaur Xenodens, the ‘star-toothed’ mosasaur, Stelladens and many others, now there is Khinjaria, a new mosasaur with dagger-like teeth.

“The elongation of the posterior part of the skull which accommodated the jaw musculature suggests a terrible biting force.”

Reference:
Nicholas R. Longrich, Michael J. Polcyn, Nour-Eddine Jalil, Xabier Pereda-Suberbiola, Nathalie Bardet. A bizarre new plioplatecarpine mosasaurid from the Maastrichtian of Morocco. Cretaceous Research, 2024; 105870 DOI: 10.1016/j.cretres.2024.105870

Note: The above post is reprinted from materials provided by University of Bath.

Fossil named ‘Attenborough’s strange bird’ was the first in its kind without teeth

March 16, 2024

Illustration showing the fossil skeleton of Imparavis attenboroughi, alongside a reconstruction of the bird in life. © Ville Sinkkonen.

A new fossil, named “Attenborough’s strange bird” after naturalist and documentarian Sir David Attenborough, is the first of its kind to evolve a toothless beak. It’s from a branch of the bird family tree that went extinct in the mass extinction 66 million years ago, and this strange bird is another puzzle piece that helps explain why some birds — and their fellow dinosaurs — went extinct, and others survived to today.

No birds alive today have teeth. But that wasn’t always the case — many early fossil birds had beaks full of sharp, tiny teeth. In a paper in the journal Cretaceous Research, scientists have described a new species of fossil bird that was the first of its kind to evolve toothless-ness; its name, in honor of naturalist Sir David Attenborough, means “Attenborough’s strange bird.”

“It is a great honour to have one’s name attached to a fossil, particularly one as spectacular and important as this. It seems the history of birds is more complex than we knew,” says Sir David Attenborough.

All birds are dinosaurs, but not all dinosaurs fall into the specialized type of dinosaurs known as birds, sort of like how all squares are rectangles, but not all rectangles are squares. The newly described Imparavis attenboroughi is a bird, and therefore, also a dinosaur.

Imparavis attenboroughi was a member of a group of birds called enantiornithines, or “opposite birds,” named for a feature in their shoulder joints that is “opposite” from what’s seen in modern birds. Enantiornithines were once the most diverse group of birds, but they went extinct 66 million years ago following the meteor impact that killed most of the dinosaurs. Scientists are still working to figure out why the enantiornithines went extinct and the ornithuromorphs, the group that gave rise to modern birds, survived.

“Enantiornithines are very weird. Most of them had teeth and still had clawed digits. If you were to go back in time 120 million years in northeastern China and walk around, you might have seen something that looked like a robin or a cardinal, but then it would open its mouth, and it would be filled with teeth, and it would raise its wing, and you would realize that it had little fingers,” says Alex Clark, a PhD student at the University of Chicago and the Field Museum and the paper’s corresponding author.

But “Attenborough’s strange bird” bucked this trend. “Scientists previously thought that the first record of toothlessness in this group was about 72 million years ago, in the late Cretaceous. This little guy, Imparavis, pushes that back by about 48 to 50 million years. So toothlessness, or edentulism, evolved much earlier in this group than we thought,” says Clark.

The specimen was found by an amateur fossil collector near the village of Toudaoyingzi in northeastern China and donated to the Shandong Tianyu Museum of Nature. Clark’s advisor and co-author on the paper, Field Museum associate curator of fossil reptiles Jingmai O’Connor, first noticed something unusual about this fossil several years ago, when she was visiting the Shandong Tianyu Museum’s collections.

“I think what drew me to the specimen wasn’t its lack of teeth — it was its forelimbs,” says O’Connor. “It had a giant bicipital crest — a bony process jutting out at the top of the upper arm bone, where muscles attach. I’d seen crests like that in Late Cretaceous birds, but not in the Early Cretaceous like this one. That’s when I first suspected it might be a new species.”

O’Connor, Clark, and their coauthors in China, Xiaoli Wang, Xiangyu Zhang, Xing Wang, Xiaoting Zheng, and Zhonghe Zhou, undertook further study of the specimen and determined that it did indeed represent an animal new to science.

The unusual wing bones could have allowed for muscle attachments that let this bird flap its wings with extra power. “We’re potentially looking at really strong wing beats. Some features of the bones resemble those of modern birds like puffins or murres, which can flap crazy fast, or quails and pheasants, which are stout little birds but produce enough power to launch nearly vertically at a moment’s notice when threatened,” says Clark.

Meanwhile, the bird’s toothless beak doesn’t necessarily tell scientists what it was eating, since modern toothless birds have a wide variety of diets. Like its fellow enantiornithines, and unlike modern birds, it does not appear to have a digestive organ called a gizzard, or gastric mill, that helped it crush up its food.

While Clark notes that “an animal is more than the sum of its parts, and we can’t fully know what an animal’s life was like just by looking at single components of its body,” he and his coauthors have been able to hypothesize about some of Imparavis’s behavior and ecology, based on the details of its wings, feet, and beak together. “I like to think of these guys kind of acting like modern robins. They can perch in trees just fine, but for the most part, you see them foraging on the ground, hopping around and walking,” says Clark.

“It seems like most enantiornithines were pretty arboreal, but the differences in the forelimb structure of Imparavis suggests that even though it’s still probably lived in the trees, it maybe ventured down to the ground to feed, and that might mean it had a unique diet compared to other enantiornithines, which also might explain why it lost its teeth,” says O’Connor.

In the paper, the researchers also revisited a previously described fossil bird, Chiappeavis (which O’Connor named eight years ago after her PhD advisor), and suggest that it too was an early toothless enantiornithine. This finding, along with Imparavis, indicates that toothlessness may not have been quite as unique in Early Cretaceous enantiornithines as previously thought.

Clark said that nature documentaries by Sir David Attenborough, in which the renowned British naturalist narrates the behavior of different animals, were pivotal to his own interest in science. “I most likely wouldn’t be in the natural sciences if it weren’t for David Attenborough’s documentaries,” says Clark, explaining why he chose to name the new fossil after Attenborough.

Clark and O’Connor noted the importance of Attenborough’s messaging that not only celebrates life on earth, but also warns against the mass extinction the planet is undergoing due to human-caused climate change and habitat destruction.

“Learning about enantiornithines like Imparavis attenboroughi helps us understand why they went extinct and why modern birds survived, which is really important for understanding the sixth mass extinction that we’re in now,” says O’Connor. “The biggest crisis humanity is facing is the sixth mass extinction, and paleontology provides the only evidence we have for how organisms respond to environmental changes and how animals respond to the stress of other organisms going extinct.”

Reference:
Xiaoli Wang, Alexander D. Clark, Jingmai K. O’Connor, Xiangyu Zhang, Xing Wang, Xiaoting Zheng, Zhonghe Zhou. First Edentulous Enantiornithine (Aves: Ornithothoraces) from the Lower Cretaceous Jehol Avifauna. Cretaceous Research, 2024; 159: 105867 DOI: 10.1016/j.cretres.2024.105867

Note: The above post is reprinted from materials provided by Field Museum.

Earth’s earliest forest revealed in Somerset fossils

March 16, 2024

Fossilised trackways of small arthropods

The oldest fossilised forest known on Earth — dating from 390 million years ago — has been found in the high sandstone cliffs along the Devon and Somerset coast of South West England.

The fossils, discovered and identified by researchers from the Universities of Cambridge and Cardiff, are the oldest fossilised trees ever found in Britain, and the oldest known fossil forest on Earth. This fossil forest is roughly four million years older than the previous record holder, which was found in New York State.

The fossils were found near Minehead, on the south bank of the Bristol Channel, near what is now a Butlin’s holiday camp. The fossilised trees, known as Calamophyton, at first glance resemble palm trees, but they were a ‘prototype’ of the kinds of trees we are familiar with today. Rather than solid wood, their trunks were thin and hollow in the centre. They also lacked leaves, and their branches were covered in hundreds of twig-like structures.

These trees were also much shorter than their descendants: the largest were between two and four metres tall. As the trees grew, they shed their branches, dropping lots of vegetation litter, which supported invertebrates on the forest floor.

Scientists had previously assumed this stretch of the English coast did not contain significant plant fossils, but this particular fossil find, in addition to its age, also shows how early trees helped shape landscapes and stabilise riverbanks and coastlines hundreds of millions of years ago. The results are reported in the Journal of the Geological Society.

The forest dates to the Devonian Period, between 419 million and 358 million years ago, when life started its first big expansion onto land: by the end of the period, the first seed-bearing plants appeared and the earliest land animals, mostly arthropods, were well-established.

“The Devonian period fundamentally changed life on Earth,” said Professor Neil Davies from Cambridge’s Department of Earth Sciences, the study’s first author. “It also changed how water and land interacted with each other, since trees and other plants helped stabilise sediment through their root systems, but little is known about the very earliest forests.”

The fossil forest identified by the researchers was found in the Hangman Sandstone Formation, along the north Devon and west Somerset coasts. During the Devonian period, this region was not attached to the rest of England, but instead lay further south, connected to parts of Germany and Belgium, where similar Devonian fossils have been found.

“When I first saw pictures of the tree trunks I immediately knew what they were, based on 30 years of studying this type of tree worldwide” said co-author Dr Christopher Berry from Cardiff’s School of Earth and Environmental Sciences. “It was amazing to see them so near to home. But the most revealing insight comes from seeing, for the first time, these trees in the positions where they grew. It is our first opportunity to look directly at the ecology of this earliest type of forest, to interpret the environment in which Calamophyton trees were growing, and to evaluate their impact on the sedimentary system.”

The fieldwork was undertaken along the highest sea-cliffs in England, some of which are only accessible by boat, and revealed that this sandstone formation is in fact rich with plant fossil material from the Devonian period. The researchers identified fossilised plants and plant debris, fossilised tree logs, traces of roots and sedimentary structures, preserved within the sandstone. During the Devonian, the site was a semi-arid plain, criss-crossed by small river channels spilling out from mountains to the northwest.

“This was a pretty weird forest — not like any forest you would see today,” said Davies. “There wasn’t any undergrowth to speak of and grass hadn’t yet appeared, but there were lots of twigs dropped by these densely-packed trees, which had a big effect on the landscape.”

This period marked the first time that tightly-packed plants were able to grow on land, and the sheer abundance of debris shed by the Calamophyton trees built up within layers of sediment. The sediment affected the way that the rivers flowed across the landscape, the first time that the course of rivers could be affected in this way.

“The evidence contained in these fossils preserves a key stage in Earth’s development, when rivers started to operate in a fundamentally different way than they had before, becoming the great erosive force they are today,” said Davies. “People sometimes think that British rocks have been looked at enough, but this shows that revisiting them can yield important new discoveries.”

The research was supported in part by the Natural Environment Research Council (NERC), part of UK Research and Innovation (UKRI). Neil Davies is a Fellow of Churchill College, Cambridge.

Reference:
Neil S. Davies, William J. McMahon and Christopher M. Berry. Earth’s earliest forest: fossilized trees and vegetation-induced sedimentary structures from the Middle Devonian (Eifelian) Hangman Sandstone Formation, Somerset and Devon, SW England. Journal of the Geological Society, 2024 DOI: 10.1144/jgs2023-204

Note: The above post is reprinted from materials provided by University of Cambridge. Original written by Sarah Collins. The original text of this story is licensed under a Creative Commons License.

Biggest Holocene volcano eruption found by seabed survey

March 16, 2024

The eruption and volcanic material sedimentation processes of giant caldera eruptions are not well understood, making it also difficult to estimate their size. Kobe University researchers used seismic reflection surveys to visualize the sedimentary structure and analyzed collected sediment samples, enabling them to obtain important information on the distribution, volume, and transport mechanisms of the ejecta. © SHIMIZU Satoshi (CC BY)

A detailed survey of the volcanic underwater deposits around the Kikai caldera in Japan clarified the deposition mechanisms as well as the event’s magnitude. As a result, the Kobe University research team found that the event 7,300 years ago was the largest volcanic eruption in the Holocene by far.

In addition to lava, volcanos eject large amounts of pumice, ashes and gases as a fast-moving flow, known as “pyroclastic flow,” and its sediments are a valuable data source on past eruptions. For volcanoes on land, geologists understand the sedimentation mechanism of pyroclastic flows well, but the sediments themselves get lost easily due to erosion. On the other hand, for volcanoes on oceanic islands or near the coast, the pyroclastic flow deposition process is largely unclear, both because the interaction with water is less well understood and because reliable data is difficult to obtain and therefore sparse. For these reasons, it is difficult to estimate the impact of many past eruptions on the climate and on history.

A Kobe University research team around SEAMA Nobukazu and SHIMIZU Satoshi took to the seas on the Kobe University-owned training vessel Fukae Maru (since replaced by the newly built Kaijin Maru) and conducted seismic imaging as well as sediment sampling around the Kikai caldera, off the south coast of Japan’s Ky?sh? island. The outstanding detail of the seismic reflection data revealed the sedimentary structure with a vertical resolution of 3 meters and down to a depth of several hundred meters below the seafloor. Shimizu explains: “Due to the fact that volcanic ejecta deposited in the sea preserve well, they record a lot of information at the time of eruption. By using seismic reflection surveys optimized for this target and by identifying the collected sediments, we were able to obtain important information on the distribution, volume, and transport mechanisms of the ejecta.”

In their article published in the Journal of Volcanology and Geothermal Research, the geoscientists report that an eruption that happened 7,300 years ago ejected a large amount of volcanic products (ash, pumice, etc.) that settled in an area measuring more than 4,500 square kilometers around the eruption site. With a dense-rock equivalent volume of between 133 and 183 cubic kilometers, the event was the largest volcanic eruption to have taken place within the Holocene (the most recent 11,700 years of Earth’s history following the end of the last ice age) known to science.

In the process of their analysis, the research team confirmed that the sedimentations on the ocean floor and those deposited on nearby islands have the same origin and from their distribution around the eruption site they could clarify the interaction between the pyroclastic flow and water. They noticed that the underwater portion of the flow could travel vast distances even uphill.

Their findings yield new insights into the elusive dynamics of volcanic mega events that may prove useful in identifying the remains of other events as well as in estimating their size. Seama explains, “Large volcanic eruptions such as those yet to be experienced by modern civilization rely on sedimentary records, but it has been difficult to estimate eruptive volumes with high precision because many of the volcanic ejecta deposited on land have been lost due to erosion. But giant caldera eruptions are an important phenomenon in geoscience, and because we also know that they influenced the global climate and thus human history in the past, understanding this phenomenon has also social significance.” In this light, it is fascinating to think that the event that created a caldera about the size of a modern capital city was in fact the largest volcanic event since humans have spread all over the globe.

This research was funded by the Ministry of Education, Culture, Sports, Science and Technology Japan under The Second Earthquake and Volcano Hazards Observation and Research Program (Earthquake and Volcano Hazard Reduction Research) and the Japan Society for the Promotion of Science (grant 20H00199).

Reference:
Satoshi Shimizu, Reina Nakaoka, Nobukazu Seama, Keiko Suzuki-Kamata, Katsuya Kaneko, Koji Kiyosugi, Hikaru Iwamaru, Mamoru Sano, Tetsuo Matsuno, Hiroko Sugioka, Yoshiyuki Tatsumi. Submarine pyroclastic deposits from 7.3 ka caldera-forming Kikai-Akahoya eruption. Journal of Volcanology and Geothermal Research, 2024; 108017 DOI: 10.1016/j.jvolgeores.2024.108017

Note: The above post is reprinted from materials provided by Kobe University.

New theory explains sand ripples on Mars and on Earth

March 16, 2024

Photo caption: Waves received in the wind tunnel of Ben Gurion University of the Negev with glass balls with a diameter of 90 microns. Two scales of waves can be seen in the image.

Sand ripples are fascinating. They are symmetrical, yet wind — which causes them — is very much not. Furthermore, they can be found on Mars and on Earth. They would be even more fascinating if the same effect found on Mars could be found here on Earth as well. What if one unified theory could explain their formation on two different planets of our solar system?

That is what Ben-Gurion University of the Negev physicist Prof.

Hezi Yizhaq and Prof. Itzhak Katra and their colleagues from Denmark, Germany, Italy, China, and the US contend in a cover article published in Nature Geoscience.

Sand ripples photographed on Mars by NASA’s Curiosity rover in 2015 showed two distinct patterns — large ripples (meter scale) and a shorter “impact” ripples pattern (decimeter scale). The prevailing theory proposed since then argues that the smaller scale ripples are produced by the impact mechanism of the particles transported by the wind like normal ripples on Earth and the larger ripples form due to hydrodynamic instability like subaqueous ripples.

Furthermore, it was believed that the physical conditions that produced them on Mars could not produce them on Earth.

However, Prof. Yizhaq and Prof. Katra have proven experimentally using Ben-Gurion University’s wind tunnel and Aarhus University’s Mars tunnel that such a phenomenon could exist on Earth — we just haven’t noticed it yet because we didn’t know we should be looking for it.

Imitating Martian sand was not easy because it’s finer than sand here on Earth, explains Prof.

Yizhaq, but the breakthrough occurred when they decided to try tiny glass balls to represent fine grains of sand.

Furthermore, the international research team has proposed a unified theoretical framework that would explain sand ripples on Mars and on Earth.

At its most basic level, sand ripples on Mars caused by wind look like sand ripples on Earth caused by water.

“There is much more research, both fieldwork and experimentally, needed to prove our theory, but it is amazing to propose something so radically new in a field I have been studying for over 20 years. It is exciting to go out and try to find on Earth what can clearly be seen on Mars,” says Prof. Yizhaq.

Prof. Yizhaq is a member of the Department of Solar Energy and Environmental Physics.

Prof. Itzhak Katra is a member of the Department of Environmental, Geoinformatics and Urban Planning Sciences.

The research was supported by the Israel Science Foundation (Grant no. 1270/20), the German-Israel Foundation for Scientific Research and Development (GIF) (Grant no. 155-301.10/2018), the National Natural Science Foundation of China, Texas A&M Engineering Experiment Station, Europlanet grant no. 871149, and the Horizon 2020 Research and Innovation Program.

Reference:
Hezi Yizhaq, Katharina Tholen, Lior Saban, Nitzan Swet, Conner Lester, Simone Silvestro, Keld R. Rasmussen, Jonathan P. Merrison, Jens J. Iversen, Gabriele Franzese, Klaus Kroy, Thomas Pähtz, Orencio Durán, Itzhak Katra. Coevolving aerodynamic and impact ripples on Earth. Nature Geoscience, 2024; 17 (1): 66 DOI: 10.1038/s41561-023-01348-3

Note: The above post is reprinted from materials provided by Ben-Gurion University of the Negev.

Rock weathering and climate: Low-relief mountain ranges are largest carbon sinks

March 16, 2024

Aaron Bufe investigates the weathering of rocks. | © C. Trepmann

For many hundreds of millions of years, the average temperature at the surface of the Earth has varied by not much more than 20° Celsius, facilitating life on our planet. To maintain such stable temperatures, Earth appears to have a ‘thermostat’ that regulates the concentration of atmospheric carbon dioxide over geological timescales, influencing global temperatures. The erosion and weathering of rocks are important parts of this ‘thermostat.’ A team led by LMU geologist Aaron Bufe and Niels Hovius from the German Research Centre for Geosciences has now modeled the influence of these processes on carbon in the atmosphere. Their surprising result: CO2 capture through weathering reactions is highest in low-relief mountain ranges with moderate erosion rates and not where erosion rates are fastest.

Weathering occurs where rock is exposed to water and wind. “When silicates weather, carbon is removed from the atmosphere and later precipitated as calcium carbonate. By contrast, weathering of other phases — such as carbonates and sulfides or organic carbon contained in rocks — releases CO2. These reactions are typically much faster than silicate weathering,” says Hovius.

“As a consequence, the impact of mountain building on the carbon cycle is complex.”

Weathering model shows common mechanisms

To address this complexity, the researchers used a weathering model to analyze fluxes of sulfide, carbonate, and silicate weathering in a number of targeted study regions — such as Taiwan and New Zealand — with large ranges in erosion rates.

“We discovered similar behaviors in all locations, pointing to common mechanisms,” says Bufe.

Further modelling showed that the relationship between erosion and CO2-fluxes is not linear, but that CO2 capture from weathering peaks at an erosion rate of approximately 0.1 millimeters per year.

When rates are lower or higher, less CO2 is sequestered and CO2 may even be released into the atmosphere.

“High erosion rates like in Taiwan or the Himalayas push weathering into being a CO2 source, because silicate weathering stops increasing with erosion rates at some point, whereas the weathering of carbonates and sulfides increases further,” explains Bufe.

In landscapes with moderate erosion rates of around 0.1 millimeters per year, the rapidly weathering carbonates and sulfides are largely depleted, whereas silicate minerals are abundant and weather efficiently. Where erosion is even slower than 0.1 millimeters per year, only few minerals are left to weather. The biggest CO2 sinks are therefore low-relief mountain ranges such as the Black Forest or the Oregon Coast Range, where erosion rates approach the optimum. “Over geological timescales, the temperature to which Earth’s ‘thermostat’ is set therefore depends strongly on the global distribution of erosion rates,” says Bufe. To understand the effects of erosion on Earth’s climate system in greater detail, Bufe thinks that future studies should additionally consider organic carbon sinks and weathering in floodplains.

Reference:
Aaron Bufe, Jeremy K. C. Rugenstein, Niels Hovius. CO 2 drawdown from weathering is maximized at moderate erosion rates. Science, 2024; 383 (6687): 1075 DOI: 10.1126/science.adk0957

Note: The above post is reprinted from materials provided by Ludwig-Maximilians-Universität München.

Surprising insights about debris flows on Mars

March 16, 2024

Satellite image of gully landscapes on Mars, taken by HiRISE (High Resolution Imaging Experiment), a camera on board the Mars Reconnaissance Orbiter (photo no.: ESP_039114_1115). The white CO2 ice is visible on the sides of the gullies.

Table of Contents

The period that liquid water was present on the surface of Mars may have been shorter than previously thought. Channel landforms called gullies, previously thought to be formed exclusively by liquid water, can also be formed by the action of evaporating CO2 ice. That is the conclusion of a new study by Lonneke Roelofs, a planetary researcher at Utrecht University. “This influences our ideas about water on Mars in general, and therefore our search for life on the planet.” The results of the study are published this week in the journal Communications Earth and Environment.

“The Martian atmosphere is 95% CO2,” Lonneke Roelofs explains.

“In winter, air temperatures drop below -120 degrees Celsius, which is cold enough for CO2 in the atmosphere to freeze.” In the process of freezing, CO2 gas can change directly to CO2 ice, skipping the liquid phase.

The process is similar to frost on Earth, where water vapour forms ice crystals and blankets the landscape in a white film.

Warmer spring temperatures, combined with the thin Martian atmosphere, causes CO2 ice to evaporate directly back to gas, again skipping the liquid phase.

“We call that ‘sublimation’. The process is extremely explosive due to Mars’ low air pressure. The created gas pressure pushes sediment grains apart causing the material to flow, similar to debris flows in mountainous areas on Earth. These flows can reshape the Martian landscape — even in the absence of water.”

Scientists have long hypothesised that CO2 ice could be a driving force behind these Martian landscape structures.

“But those hypotheses were mainly based on models or satellite studies,” Roelofs explains.

“With our experiments in a so-called ‘Mars chamber’, we were able to simulate this process under Martian conditions. Using this specialised lab equipment we could directly study this process with our own eyes. We even observed that debris flows driven by CO2 ice under Martian conditions flow just as efficiently as the debris flows driven by water on Earth.”

Extraterrestrial life

“We know for sure that there was once water on the surface of Mars. This study does not prove the contrary,” Roelofs says.

“But the emergence of life likely needs a long period where liquid water was present. Previously, we thought that these landscape structures were formed by debris flows driven by water, because of their similarity to debris flow systems on Earth. My research now shows that, in addition to debris flows powered by water, the sublimation of frozen CO2 can also serve as a driving force behind the formation of these Martian gully landscapes. That pushes the presence of water on Mars further into the past, making the chance of life on Mars smaller.” And that makes us even more unique than we thought.

Why Mars?

But what makes someone interested in landscapes 330 million km away? “Mars is our closest neighbour. It’s the only other rocky planet close to our solar system’s ‘green zone’. The zone is precisely far enough from the sun to allow for liquid water to exist, a prerequisite for life. So Mars is a place where we possibly can find answers to questions about how life developed, including potential extraterrestrial life,” answers Roelofs. “Plus, studying the formation of landscape structures on other planets is a way for us to step outside our Earthly context. You ask different questions, which leads to new insights on processes here on Earth. For example, we can also observe the process of gas-driven debris flows in pyroclastic flows around volcanoes, here on Earth. So this research could contribute to a better understanding of terrestrial volcanic hazards.”

Reference:
Lonneke Roelofs, Susan J. Conway, Tjalling de Haas, Colin Dundas, Stephen R. Lewis, Jim McElwaine, Kelly Pasquon, Jan Raack, Matthew Sylvest, Manish R. Patel. How, when and where current mass flows in Martian gullies are driven by CO2 sublimation. Communications Earth & Environment, 2024; 5 (1) DOI: 10.1038/s43247-024-01298-7

Note: The above post is reprinted from materials provided by Utrecht University.

Sulfur and the origin of life

March 16, 2024

Grand Prismatic Spring in Yellowstone National Park, seen here from an aerial photo, provides a modern-day glimpse into the types of environments where sulfites may have accumulated and possibly played a role in kick-starting the earliest life on Earth.

Many artists have tried to depict what Earth might have looked like billions of years ago, before life made its appearance. Many scenes trade snow-covered mountains for lava-gushing volcanoes and blue skies for lightning bolts pummeling what’s below from a hazy sky.

But what did early Earth actually look like? This question has been the subject of intense scientific research for decades.

A publication led by Sukrit Ranjan, an assistant professor in the University of Arizona’s Lunar and Planetary Laboratory, shines a spotlight on sulfur, a chemical element that, while all familiar, has proved surprisingly resistant to scientific efforts in probing its role in the origin of life.

“Our picture of early Earth is pretty fuzzy,” said Ranjan, who explores sulfur concentrations in early Earth’s waters and atmosphere. The same processes that make our planet habitable — liquid water and plate tectonics — constantly destroy the rocks that hold Earth’s geologic record, he argues. “It’s great for us because it recycles nutrients that would otherwise be locked up in Earth’s crust, but it’s terrible for geologists in the sense that it removes the messengers.”

Published in the journal AGU Advances in December, Ranjan’s paper was selected as an editor’s highlight, in recognition of “experiments that were extremely difficult to perform but provide constraints for ongoing laboratory prebiotic chemistry experiments.”

At the core of efforts to pull back the curtain on the emergence of life on Earth has been a concept known as the “RNA world,” Ranjan said, referring to ribonucleic acid, a class of molecules that are present in every living cell and crucial to life as we know it.

The RNA world hypothesis is based on an interesting feature of modern biology, which is that of the four major categories of biomolecules — amino acids, carbohydrates, lipids and nucleic acids — RNA is the only one that can perform the role of an enzyme and the storage and replication of genetic information, by making copies of itself, all by itself. There’s just one problem: It’s really hard to make.

“For about 50 years, people have tried to figure out how to make RNA without enzymes, which is how biology does it,” Ranjan said, explaining that it wasn’t until the last five years that researchers figured out non-enzymatic pathways to make RNA.

“If we can get RNA, then on the far horizon we see a pathway to get everything else going,” he said. “And this begs the question: Was this molecule actually available earlier in any quantities whatsoever? And this is actually a major open question.”

Recently, scientists have completed a half-century quest to make RNA molecules without biological enzymes, a huge step forward to demonstrating the RNA world. However, these chemical pathways all rely on a critical sulfur molecule, called sulfite. By studying rock samples from some of Earth’s oldest rocks, scientists know there was plenty of sulfur to go around on the early, prebiotic Earth. But how much of it was in the atmosphere? How much of it ended up in water? And how much of it ended up as RNA-producing sulfite? Those are the questions Ranjan and his team set out to answer.

“Once it’s in the water, what happens to it? Does it stick around for a long time, or does it go away quickly?” he said. “For modern Earth we know the answer — sulfite loves to oxidize, or react with oxygen, so it’ll go away super-fast.”

By contrast, as geological evidence indicates, there was very little oxygen in early Earth’s atmosphere, which could have allowed sulfite to accumulate and last much longer. However, even in the absence of oxygen, sulfite is very reactive, and many reactions could have scrubbed it from the early Earth environment.

One such reaction is known as disproportionation, a process by which several sulfites react with each other, turning them into sulfate, and elemental sulfur, which are not useful for origin-of-life chemistry. But how fast is this process? Would it have allowed for sufficient quantities of sulfites to build up to kickstart life?

“No one has actually looked into this in depth outside of other contexts, mainly wastewater management,” Ranjan said.

His team then set out to investigate this problem under various conditions, an effort that took five years from designing the experiments to publishing the results.

“Of all the atoms that stock the prebiotic shipyard, including carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur, sulfur is perhaps the thorniest,” wrote Sonny Harman of NASA’s Ames Research Center, in a viewpoint article accompanying the publication. Because of its eagerness to enter into chemical reactions, “sulfur compounds tend to be more unstable, posing hazards to lab personnel and equipment, clogging up instrumentation and gumming up experiments.”

A lab tech’s nightmare

In their setup, Ranjan and his co-authors dissolved sulfite in water at various levels of acidity or alkalinity, locked it into a container under an oxygen-free atmosphere and let it “age,” as Ranjan put it. Every week, the team measured the concentrations of various sulfites with ultraviolet light. At the end of the experiment, they subjected them to a suite of analyses, all geared toward answering a relatively simple question, he said: “Just how much of this original molecule is left, and what did it turn into?”

Sulfites, it turned out, disproportionate much slower than what conventional wisdom held. Earlier studies, for example, had floated the idea of a sulfur haze engulfing the early Earth, but Ranjan’s team found that sulfites break down under ultraviolet light more quickly than expected. In the absence of an ozone layer during Earth’s early days, this process, known as photolysis, would have quickly purged sulfur compounds from the atmosphere and the water, albeit not quite as efficiently as the abundant oxygen in today’s world.

While it’s plausible that slow disproportionation could have allowed sulfites to accumulate, photolysis would have made that very unlikely except in certain environments such as shallow water pools, shaded from UV radiation, particularly if fed by surface runoff to provide mineral shields. Examples include underground pools or closed basin carbonate lakes, drainage-less depressions where sediments accumulate but water can only leave by evaporation.

“Think bodies of water like the Great Salt Lake in Utah or Mono Lake in California,” Ranjan said, adding that hydrothermal environments are emerging as hot candidates for life’s first appearance. Here, groundwater carrying dissolved minerals comes into contact with heat from volcanic activity, creating unique micro-environments that offer “safe spaces” for chemical process that could not occur elsewhere.

Such places can be found at mid-ocean ridges in the deep sea, but also on land, Ranjan said.

“A modern-day example of this is Yellowstone National Park, where we find pools that accumulate lots of sulfite, despite the oxygen,” he said, “and that can happen just because the sulfite is continually being replenished by volcanic outgassing.”

The study provides opportunities to test the hypothesis of sulfite availability in the evolution of the first molecules of life experimentally, the authors point out. Ranjan said one field of research in particular has him excited — phylogenetic microbiology, which uses genome analysis to reconstruct the blueprints of sulfur-using microorganisms believed to represent the oldest phyla on Earth.

There is evidence that these bacteria gain energy by reducing highly oxidized forms of sulfur to less oxidized ones. Intriguingly, Ranjan pointed out, they depend on a fairly complex enzyme machinery for the first step, reducing sulfate, sulfur’s abundant “modern” form, to sulfite, suggesting these enzymes are the product of a long evolutionary process. In contrast, only one enzyme is involved in the conversion from sulfite — the proposed key ingredient in “prebiotic puddle environments” — to sulfide.

“If true, this implies that sulfite was present in the natural environment in at least some water bodies, similar to what we argue here,” he said. “Geologists are just now turning to this. Can we use ancient rocks to test if they’re rich in sulfite? We don’t know the answer yet. This is still cutting-edge science.”

References:

Sukrit Ranjan, Khaled Abdelazim, Gabriella G. Lozano, Sangita Mandal, Cindy Y. Zhou, Corinna L. Kufner, Zoe R. Todd, Nita Sahai, Dimitar D. Sasselov. Geochemical and Photochemical Constraints on S[IV] Concentrations in Natural Waters on Prebiotic Earth. AGU Advances, 2023; 4 (6) DOI: 10.1029/2023AV000926
Sonny Harman. The Search for Slow Sulfur Sinks. AGU Advances, 2023; 4 (6) DOI: 10.1029/2023AV001064

Note: The above post is reprinted from materials provided by University of Arizona. Original written by Daniel Stolte.

Mercury rising: Study sheds new light on ancient volcanoes’ environmental impact

March 16, 2024

Scientists analyzed mercury levels from core samples from the Mochras Farm (Llanbedr) borehole in Wales to estimate how much and how rapidly carbon was released during ancient volcano events in Earth's history Credit: Stephen Hesselbo. All Rights Reserved. — Scientists analyzed mercury levels from core samples from the Mochras Farm (Llanbedr) borehole in Wales to estimate how much and how rapidly carbon was released during ancient volcano events in Earth’s history Credit: Stephen Hesselbo. All Rights Reserved.

Massive volcanic events in Earth’s history that released large amounts of carbon into the atmosphere frequently correlate with periods of severe environmental change and mass extinctions. A new method to estimate how much and how rapidly carbon was released by the volcanoes could improve our understanding of the climate response, according to an international team led by researchers from Penn State and the University of Oxford.

The scientists reported this week (Feb. 26) in the journal Nature Geosciences that they have developed a new technique to estimate excess mercury left behind in the rock record due to ancient volcanic activity. The technique can estimate carbon emissions from large igneous provinces (LIPs), volcanic events that can last millions of years and produce magma that reaches Earth’s surface and forms lava flows hundreds of miles long.

“Large igneous provinces are often used as an analog for human-caused climate change because they occur relatively rapidly geologically and release a lot of carbon dioxide,” said Isabel Fendley, assistant research professor of geosciences at Penn State and lead author of the study. “But one big challenge we address with this study is that to date, it has been really difficult to figure out exactly how much carbon was released by these volcanoes.”

The researchers analyzed core samples that capture a 20-million-year record of the early Jurassic period and found mercury levels increased during the peak activity of the Karoo-Ferrar large igneous province and the associated Toarcian Oceanic Anoxic Event, a period of extensive environmental and climate change some 185 million years ago.

However, the total estimated carbon emissions using the mercury records were significantly lower than what carbon-cycle models had predicted would be necessary to cause the observed environmental changes.

The findings suggest the volcanism triggered positive Earth system feedbacks — climate and environmental responses to the initial warming that in turn produced more warming. These positive feedbacks may be as important as the primary emissions in these large carbon emission scenarios, and current carbon cycle models may be underestimating the effects of a given amount of emissions, the scientists said.

‘What this shows us is that there are Earth system responses that exacerbate the effects of the carbon the volcanoes emitted,” Fendley said. “And based on our results, these feedback processes are actually quite important but not well understood.”

Accurate estimates of LIP carbon emissions are important for understanding the impacts of positive and negative carbon-cycle feedback processes on future climate projections, the scientists said.

“In addition to historical climate change and understanding the history of life, it’s also relevant for how we understand Earth’s climate and how we investigate what happens to the environment after you release large amounts of carbon dioxide into the atmosphere,” Fendley said.

Estimating the quantity of carbon emissions associated with LIPs has been a challenge in part because scientists have an incomplete record of how much lava erupted. The Karoo-Ferrar LIP, for example, occurred on the former supercontinent Gondwana, and that material is now spread out across the southern hemisphere, spanning modern-day Southern Africa, Antarctica and Tasmania, the scientists said.

The researchers instead turned to mercury, which is released as a gas during volcanic eruptions but was otherwise rarely found in high concentrations in the environment prior to human activity. Looking at the chemistry of rocks in the core samples, the scientists were able to determine how much mercury would be expected based on environmental conditions and how much extra was present caused by the volcanoes.

They developed a method to convert the measured changes in mercury concentrations to the volume of mercury gas emissions. Using the ratio of mercury gas emissions to carbon emissions in modern volcanoes, they estimated how much carbon the ancient volcanoes released.

The researchers said the core samples, from the Mochras borehole in Wales, U.K., provided a unique opportunity to conduct this research. The long record showed the first clear evidence that there were significantly larger volcanic eruptions during this time period compared to the preceding 15 million years, the scientists said.

“The large amount of existing geochemical data from the Mochras Farm (Llanbedr) borehole in Wales, drilled by the British Geological Survey, plus the very well-constrained chronology, provided a unique opportunity that enabled this analysis,” Fendley said. “The decades-worth of previous work on the Mochras core enabled us to reconstruct original gas fluxes over millions of years, for periods that are traditional targets for paleo-environmental studies as well as the background state.”

Other researchers on this project were Joost Frieling, postdoctoral research assistant, and Tamsin Mather and Hugh Jenkyns, professors, at the University of Oxford; Michael Ruhl, assistant professor at Trinity College Dublin; and Stephen Hesselbo, professor at the University of Exeter.

European Research Council and the Natural Environment Research Council provided funding for this work.

Reference:
Isabel M. Fendley, Joost Frieling, Tamsin A. Mather, Micha Ruhl, Stephen P. Hesselbo, Hugh C. Jenkyns. Early Jurassic large igneous province carbon emissions constrained by sedimentary mercury. Nature Geoscience, 2024; DOI: 10.1038/s41561-024-01378-5

Note: The above post is reprinted from materials provided by Penn State. Original written by Matthew Carroll.

Which Dinosaurs Could Fly?

February 24, 2024

Left: The flight feathers of Temminck's Lark. Right: The wing of a fossil bird, Confuciusornis. Photos by Yosef Kiat. — Left: The flight feathers of Temminck’s Lark. Right: The wing of a fossil bird, Confuciusornis. Photos by Yosef Kiat.

Birds can fly — at least, most of them can. Flightless birds like penguins and ostriches have evolved lifestyles that don’t require flight. However, there’s a lot that scientists don’t know about how the wings and feathers of flightless birds differ from their airborne cousins. In a new study in the journal PNAS, scientists examined hundreds of birds in museum collections and discovered a suite of feather characteristics that all flying birds have in common. These “rules” provide clues as to how the dinosaur ancestors of modern birds first evolved the ability to fly, and which dinosaurs were capable of flight.

Not all dinosaurs evolved into birds, but all living birds are dinosaurs. Birds are members of the group of dinosaurs that survived when an asteroid hit the Earth 66 million years ago. Long before the asteroid hit, some of the members of a group of dinosaurs called Penneraptorans began to evolve feathers and the ability to fly.

Members of the Penneraptoran group began to develop feathers before they were able to fly; the original purpose of feathers might have been for insulation or to attract mates. For instance, Velocirpator had feathers, but it couldn’t fly.

Of course, scientists can’t hop in a time machine to the Cretaceous Period to see whether Velociraptors could fly. Instead, paleontologists rely on clues in the animals’ fossilized skeletons, like the size and shape of arm/wing bones and wishbones, along with the shape of any preserved feathers, to determine which species were capable of true, powered flight. For instance, the long primary feathers along the tips of birds’ wings are asymmetrical in birds that can fly, but symmetrical in birds that can’t.

The quest for clues about dinosaur flight led to a collaboration between Jingmai O’Connor, a paleontologist at the Field Museum in Chicago, and Yosef Kiat, a postdoctoral researcher at the Field.

“Yosef, an ornithologist, was investigating traits like the number of different types of wing feathers in relation to the length of arm bone they attach to, and the degree of asymmetry in birds’ flight feathers,” said O’Connor, the museum’s associate curator of fossil reptiles, who specializes in early birds. “Through our collaboration, Yosef is able track these traits in fossils that are 160-120 million years old, and therefore study the early evolutionary history of feathers.”

Kiat undertook a study of the feathers of every order of living birds, examining specimens from 346 different species preserved in museums around the world. As he looked at the wings and feathers from hummingbirds and hawks, penguins and pelicans, he noticed a number of consistent traits among species that can fly. For instance, in addition to asymmetrical feathers, all the flighted birds had between 9 and 11 primary feathers. In flightless birds, the number varies widely — penguins have more than 40, while emus have none. It’s a deceptively simple rule that’s seemingly gone unnoticed by scientists.

“It’s really surprising, that with so many styles of flight we can find in modern birds, they all share this trait of having between 9 and 11 primary feathers,” says Kiat. “And I was surprised that no one seems to have found this before.”

By applying the information about the number of primary feathers to the overall bird family tree, Kiat and O’Connor also found that it takes a long time for birds to evolve a different number of primary feathers. “This trait only changes after really long periods of geologic time,” says O’Connor. “It takes a very long time for evolution to act on this trait and change it.”

In addition to modern birds, the researchers also examined 65 fossil specimens representing 35 different species of feathered dinosaurs and extinct birds. By applying the findings from modern birds, the researchers were able to extrapolate information about the fossils. “You can basically look at the overlap of the number of primary feathers and the shape of those feathers to determine if a fossil bird could fly, and whether its ancestors could,” says O’Connor.

For instance, the researchers looked at the feathered dinosaur Caudipteryx. Caudipteryx had 9 primary feathers, but those feathers are almost symmetrical, and the proportions of its wings would have made flight impossible. The researchers said it’s possible that Caudipteryx had an ancestor that was capable of flight, but that trait was lost by the time Caudipteryx arrived on the scene. Since it takes a long time for the number of primary feathers to change, the flightless Caudipteryx retained its 9 primaries. Meanwhile, other feathered fossils’ wings seemed flight-ready — including those of the earliest known bird, Archaeopteryx, and Microraptor, a tiny, four-winged dinosaur that isn’t a direct ancestor of modern birds.

Taken a step further, these data may inform the conversation among scientists about the origins of dinosaurian flight. “It was only recently that scientists realized that birds are not the only flying dinosaurs,” says O’Connor. “And there have been debates about whether flight evolved in dinosaurs just once, or multiple separate times. Our results here seem to suggest that flight only evolved once in dinosaurs, but we have to really recognize that our understanding of flight in dinosaurs is just beginning, and we’re likely still missing some of the earliest stages of feathered wing evolution.”

“Our study, which combines paleontological data based on fossils of extinct species with information from birds that live today, provides interesting insights into feathers and plumage — one of the most interesting evolutionary novelties among vertebrates. Thus, it helps us learn about the evolution of these dinosaurs and highlights the importance of integrating knowledge from different sources for an improved understanding of evolutionary processes,” says Kiat.

“Theropod dinosaurs, including birds, are one of the most successful vertebrate lineages on our planet,” says O’Connor. “One of the reasons that they’re so successful is their flight. One of the other reasons is probably their feathers, because there’s such versatile structures. So any information that can help us understand how these two important features co-evolved that led to this enormous success is really important.”

Reference:
Yosef Kiat, Jingmai K. O’Connor. Functional constraints on the number and shape of flight feathers. Proceedings of the National Academy of Sciences, 2024; 121 (8) DOI: 10.1073/pnas.2306639121

Note: The above post is reprinted from materials provided by Field Museum

New fossil site of worldwide importance uncovered in southern France

February 24, 2024

mollusc from the Cabrières Biota. Credit: Farid Saleh - UNIL — mollusc from the Cabrières Biota. Credit: Farid Saleh – UNIL

Nearly 400 exceptionally well-preserved fossils dating back 470 million years have been discovered in the south of France by two amateur paleontologists. This new fossil site of worldwide importance has been analyzed by scientists from the University of Lausanne, in collaboration with the CNRS and international teams. This discovery provides unprecedented information on the polar ecosystems of the Ordovician period.

Paleontology enthusiasts have unearthed one of the world’s richest and most diverse fossil sites from the Lower Ordovician period (around 470 million years ago). Located in Montagne Noire, in the Hérault department of France, this deposit of over 400 fossils is distinguished by an exceptionally well-preserved fauna.

In addition to shelly components, it contains extremely rare soft elements such as digestive systems and cuticles, in a remarkable state of preservation.

Moreover, this biota was once located very close to the South Pole, revealing the composition of Ordovician southernmost ecosystems.

At the Faculty of Geosciences and Environment at the University of Lausanne (UNIL), scientists have collaborated with the CNRS and international teams to carry out the first analyses of this deposit, known as the Cabrières Biota.

The results are published in Nature Ecology & Evolution.

Ordovician climate refugia

Analyses of the new biota reveal the presence of arthropods (a group that includes millipedes and shrimps) and cnidarians (a group that includes jellyfish and corals), as well as a large number of algae and sponges.

The site’s high biodiversity suggests that this area served as a refuge for species that had escaped the high temperatures prevailing further north at the time.

“At this time of intense global warming, animals were indeed living in high latitude refugia, escaping extreme equatorial temperatures,” points out Farid Saleh, researcher at the University of Lausanne, and first author of the study.

“The distant past gives us a glimpse of our possible near future,” adds Jonathan Antcliffe, researcher at the University of Lausanne and co-author of the study.

For their part, Eric Monceret and Sylvie Monceret-Goujon, the amateurs who discovered the site, add with enthusiasm: “We’ve been prospecting and searching for fossils since the age of twenty,” says Eric Monceret.

“When we came across this amazing biota, we understood the importance of the discovery and went from amazement to excitement,” adds Sylvie Monceret-Goujon.

This first publication marks the start of a long research program involving large-scale excavations and in-depth fossil analyses. Using innovative methods and techniques, the aim is to reveal the internal and external anatomy of the organisms, as well as to deduce their phylogenetic relationships and modes of life.

Reference:
Farid Saleh, Lorenzo Lustri, Pierre Gueriau, Gaëtan J.-M. Potin, Francesc Pérez-Peris, Lukáš Laibl, Valentin Jamart, Antoine Vite, Jonathan B. Antcliffe, Allison C. Daley, Martina Nohejlová, Christophe Dupichaud, Sebastian Schöder, Emilie Bérard, Sinéad Lynch, Harriet B. Drage, Romain Vaucher, Muriel Vidal, Eric Monceret, Sylvie Monceret, Bertrand Lefebvre. The Cabrières Biota (France) provides insights into Ordovician polar ecosystems. Nature Ecology & Evolution, 2024; DOI: 10.1038/s41559-024-02331-w

Note: The above post is reprinted from materials provided by University of Lausanne.

Mystery solved: The oldest fossil reptile from the alps is an historical forgery

February 24, 2024

Tridentinosaurus antiquus was discovered in the Italian alps in 1931 and was thought to be an important specimen for understanding early reptile evolution – but has now been found to be, in part a forgery. Its body outline, appearing dark against the surrounding rock, was initially interpreted as preserved soft tissues but is now known to be paint.

A 280-million-year-old fossil that has baffled researchers for decades has been shown to be, in part, a forgery following new examination of the remnants.

The discovery has led the team led by Dr Valentina Rossi of University College Cork, Ireland (UCC) to urge caution in how the fossil is used in future research.

Tridentinosaurus antiquus was discovered in the Italian alps in 1931 and was thought to be an important specimen for understanding early reptile evolution.

Its body outline, appearing dark against the surrounding rock, was initially interpreted as preserved soft tissues.

This led to its classification as a member of the reptile group Protorosauria.

However, this new research, published in the scientific journal Palaeontology, reveals that the fossil renowned for its remarkable preservation is mostly just black paint on a carved lizard-shaped rock surface.

The purported fossilised skin had been celebrated in articles and books but never studied in detail.

The somewhat strange preservation of the fossil had left many experts uncertain about what group of reptiles this strange lizard-like animal belonged to and more generally its geological history.

Dr Rossi, of UCC’s School of Biological, Earth and Environmental Sciences, said:

“Fossil soft tissues are rare, but when found in a fossil they can reveal important biological information, for instance, the external colouration, internal anatomy and physiology.

“The answer to all our questions was right in front of us, we had to study this fossil specimen in details to reveal its secrets — even those that perhaps we did not want to know.”

The microscopic analysis showed that the texture and composition of the material did not match that of genuine fossilised soft tissues.

Preliminary investigation using UV photography revealed that the entirety of the specimen was treated with some sort of coating material.

Coating fossils with varnishes and/or lacquers was the norm in the past and sometimes is still necessary to preserve a fossil specimen in museum cabinets and exhibits.

The team was hoping that beneath the coating layer, the original soft tissues were still in good condition to extract meaningful palaeobiological information.

The findings indicate that the body outline of Tridentinosaurus antiquus was artificially created, likely to enhance the appearance of the fossil.

This deception misled previous researchers, and now caution is being urged when using this specimen in future studies.

The team behind this research includes contributors based in Italy at the University of Padua, Museum of Nature South Tyrol, and the Museo delle Scienze in Trento.

Co-author Prof Evelyn Kustatscher, coordinator of the project “Living with the supervolcano,” funded by the Autonomous Province of Bolzano said:

“The peculiar preservation of Tridentinosaurus had puzzled experts for decades. Now, it all makes sense. What it was described as carbonized skin, is just paint.”

However all not all is lost, and the fossil is not a complete fake.

The bones of the hindlimbs, in particular, the femurs seem genuine, although poorly preserved.

Moreover, the new analyses have shown the presence of tiny bony scales called osteoderms — like the scales of crocodiles — on what perhaps was the back of the animal.

This study is an example of how modern analytical palaeontology and rigorous scientific methods can resolve an almost century-old palaeontological enigma.

Reference:
Valentina Rossi, Massimo Bernardi, Mariagabriella Fornasiero, Fabrizio Nestola, Richard Unitt, Stefano Castelli, Evelyn Kustatscher. Forged soft tissues revealed in the oldest fossil reptile from the early Permian of the Alps. Palaeontology, 2024; 67 (1) DOI: 10.1111/pala.12690

Note: The above post is reprinted from materials provided by University College Cork.

Early-stage subduction invasion

February 23, 2024

Maps showing the evolution of the Gibraltar subduction zone from 30 million years ago to 50 million years into the future. From Duarte et al., 2024.

Our planet’s lithosphere is broken into several tectonic plates. Their configuration is ever-shifting, as supercontinents are assembled and broken up, and oceans form, grow, and then start to close in what is known as the Wilson cycle.

In the Wilson cycle, when a supercontinent like Pangea is broken up, an interior ocean is formed.

In the case of Pangea, the interior ocean is the Atlantic. This ocean has a rift in the middle, and passive margins on the side, which means no seismic or volcanic activity occurs along its shores.

Destined to keep expanding, an Atlantic-type ocean will eventually become the exterior ocean of the next supercontinent.

Currently, Earth’s exterior ocean is the Pacific. The Pacific also has a rift in the middle, but it is bounded by subduction zones and thus will eventually close.

Along its margins, earthquakes and eruptions abound — a pattern known as the ring of fire.

The ocean-closing phase of each Wilson cycle requires the transition from passive to active (subducting) margins at the edges of the interior ocean.

The oceanic crust along the coast of the Atlantic is old and heavy, so it is primed to subduct, but before it can do so, it must break and bend.

The only force in nature that can break oceanic plates like these is slab pull from another subduction zone.

But this doesn’t happen spontaneously. So how does subduction initiate around interior oceans?

There currently are two subduction zones in the Atlantic: the Lesser Antilles and Scotia.

But neither of them formed spontaneously in the Atlantic; they were forced by subduction zones in the Pacific during the Cretaceous and then propagated along transform margins, where the continent is narrow and there is barely a land bridge.

They jumped oceans.

Today, on the eastern shore of the Atlantic, in Gibraltar, we have the opportunity to observe the very earliest stages of this process, known as subduction invasion, while the jump occurs from a different basin — in this case, the Mediterranean.

This is an incredibly valuable opportunity because the chances of observing the very start of any given tectonic process are limited.

And subduction initiation is difficult to observe because it leaves almost no traces behind.

Once subduction starts, it erases the record of its initial stages; the subducted plate ends up in the mantle, never to be exposed at the surface again (except in the rare case of ophiolites).

The activity of the Gibraltar subduction zone in the Mediterranean has been hotly debated.

The Gibraltar arc formed in the Oligocene as a part of the Western Mediterranean subduction zones.

While we can see a subducted plate in the mantle underneath it, almost no further movement is currently happening.

A new paper by Duarte et al., just published in Geology, suggests that Gibraltar is active — it is just currently experiencing a slow movement phase because the subducting slab is very narrow, and it is trying to pull down the entire Atlantic plate.

“[These are] some of the oldest pieces of crust on Earth, super strong and rigid — if it were any younger, the subducting plate would just break off and subduction would come to a halt,” explains Duarte.

“Still, it is just barely strong enough to make it, and thus moves very slowly.”

A new computational, gravity-driven 3-D model, developed by the authors, shows that this slow phase will last for another 20 million years.

After that, the Gibraltar subduction zone will invade the Atlantic Ocean and accelerate.

That will be the beginning of the recycling of crust on the eastern side of the Atlantic, and might be the start of the Atlantic itself beginning to close, initiating a new phase in the Wilson cycle.

Broadly, this study shows that subduction invasion, the process whereby a new subduction zone forms in an exterior ocean and then migrates to an interior ocean, is likely a common mechanism of subduction initiation in Atlantic-type oceans, and thus plays a key role in the geological evolution of our planet.

Locally, the finding that the Gibraltar subduction is still currently active has important implications for seismic activity in the area.

Recurrence intervals are expected to be very long during this slow phase, but the potential for high-magnitude events, such as the 1755 Lisbon earthquake, remains and requires preparedness.

Much remains to be figured out about the future of the Gibraltar arc. One of the next aspects that Duarte will focus on is determining the exact geometry of the subduction, which will require assessing the relative strength of the nearby continental margins.

Reference:
João C. Duarte, Nicolas Riel, Filipe M. Rosas, Anton Popov, Christian Schuler, Boris J.P. Kaus. Gibraltar subduction zone is invading the Atlantic. Geology, 2024; DOI: 10.1130/G51654.1

Note: The above post is reprinted from materials provided by Geological Society of America.

Researchers studying ocean transform faults, describe a previously unknown part of the geological carbon cycle

February 23, 2024

A cut slice of altered mantle rock. (Photo by: Solvin Zankl)

Studying a rock is like reading a book. The rock has a story to tell, says Frieder Klein, an associate scientist in the Marine Chemistry & Geochemistry Department at the Woods Hole Oceanographic Institution (WHOI).

The rocks that Klein and his colleagues analyzed from the submerged flanks of the St. Peter and St. Paul Archipelago in the St. Paul’s oceanic transform fault, about 500 km off the coast of Brazil, tells a fascinating and previously unknown story about parts of the geological carbon cycle.

Transform faults, where tectonic plates move past each other, are one of three main plate boundaries on Earth and about 48,000 km in length globally, with the others being the global mid-ocean ridge system (about 65,000 km) and subduction zones (about 55,000 km).

Carbon cycling at mid-ocean ridges and subduction zones has been studied for decades. In contrast, scientists have paid relatively scant attention to CO2 in oceanic transform faults. The transform faults were considered “somewhat boring” places for quite some time because of the low magmatic activity there, says Klein. “What we have now pieced together is that the mantle rocks that are exposed along these ocean transform faults represent a potentially vast sink for CO.,” he says. Partial melting of the mantle releases CO2 that becomes entrained in hydrothermal fluid, reacts with the mantle closer to the seafloor, and is captured there. This is a part of the geological carbon cycle that was not known before,” says Klein, lead author of a new journal study “Mineral Carbonation of Peridotite Fueled by Magmatic Degassing and Melt Impregnation in an Oceanic Transform Fault,” published inthe Proceedings of the National Academy of Sciences (PNAS).Because transform faults have not been accounted for in previous estimates of global geological CO2 fluxes, the mass transfer of magmatic CO2 to the altered oceanic mantle and seawater may be larger than previously thought.”

“The amount of CO2 emitted at the transform faults is negligible compared to the amount of anthropogenic — or human driven — CO2,” says Klein. “However, on geological timescales and before humans emitted so much CO2, geological emissions from Earth’s mantle — including from transform faults — were a major driving force of Earth’s climate.”

As the paper states, “global anthropogenic CO2 emissions are estimated to be on the order of 36 gigatons (Gt) per year, dwarfing estimates of average geological emissions (0.26 Gt per year) to the atmosphere and hydrosphere. Yet, over geological timescales, emissions of CO2 sourced from Earth’s mantle have been pivotal in regulating Earth’s climate and habitability, as well as the C [carbon]-concentration in surface reservoirs, including the oceans, atmosphere, and lithosphere.” Klein adds that “this is before anthropogenic combustion of fossil fuels, of course.”

“In order to fully understand modern human-caused climate change, we need to understand natural climate fluctuations in Earth’s deep past, which are tied to perturbations in Earth’s natural carbon cycle. Our work provides insights into long-timescale fluxes of carbon between Earth’s mantle and the ocean/atmosphere system,” says co-author Tim Schroeder, member of the faculty at Bennington College, Vermont. “Large changes in such carbon fluxes over millions of years have caused Earth’s climate to be much warmer or colder than it is today.”

To better understand carbon cycling between Earth’s mantle and the ocean, Klein, Schroeder, and colleagues studied the formation of soapstone “and other magnesite-bearing assemblages during mineral carbonation of mantle peridotite” in the St. Paul’s transform fault, the paper notes. “Fueled by magmatism in or below the root zone of the transform fault and subsequent degassing, the fault constitutes a conduit for CO2-rich hydrothermal fluids, while carbonation of peridotite represents a potentially vast sink for the emitted CO2.”

The researchers argue in the paper that “the combination of low extents of melting, which generates melts enriched in incompatible elements, volatiles and particularly CO2, and the presence of peridotite at oceanic transform faults creates conditions conducive to extensive mineral carbonation.”

The rocks were collected using human-occupied vehicles during a 2017 cruise to the area.

Finding and analyzing these rocks “was a dream come true. We had predicted the presence of carbonate-altered oceanic mantle rocks 12 years ago, but we couldn’t find them anywhere,” says Klein. “We went to the archipelago to explore for low-temperature hydrothermal activity, and we failed miserably in finding any such activity there. It was unbelievable that we were able to find these rocks in a transform fault, because we found them by chance while looking for something else.”

Funding for this research was provided by the Dalio Ocean Initiative, the Independent Research & Development Program at WHOI, and the National Science Foundation.

Reference:
Frieder Klein, Timothy Schroeder, Cédric M. John, Simon Davis, Susan E. Humphris, Jeffrey S. Seewald, Susanna Sichel, Wolfgang Bach, Daniele Brunelli. Mineral carbonation of peridotite fueled by magmatic degassing and melt impregnation in an oceanic transform fault. Proceedings of the National Academy of Sciences, 2024; 121 (8) DOI: 10.1073/pnas.2315662121

Note: The above post is reprinted from materials provided by Woods Hole Oceanographic Institution.

High resolution techniques reveal clues in 3.5 billion-year-old biomass

February 23, 2024

Rocks made of barium sulphate (known as barite rocks) from the from the Pilbara Craton in Western Australia. Credit: Gerhard Hundertmark

To learn about the first organisms on our planet, researchers have to analyze the rocks of the early Earth. These can only be found in a few places on the surface of Earth. The Pilbara Craton in Western Australia is one of these rare sites; there are rocks there that are around 3.5 billion years old containing traces of the microorganisms that lived at that time.

A research team led by the University of Göttingen has now found new clues about the formation and composition of this ancient biomass, providing insights into the earliest ecosystems on Earth. The results are published in the journal Precambrian Research.

Using high-resolution techniques such as nuclear magnetic resonance spectroscopy (NMR) and near-edge X-ray Absorption Fine Structure (NEXAFS), the researchers analyzed carbonaceous particles found in rocks made of barium sulfate. This enabled scientists to obtain important information about the structure of microscopically small particles and show that they are of biological origin. It is likely that the particles were deposited as sediment in the body of water of a “caldera”—a large cauldron-shaped hollow that forms after volcanic activity.

In addition, some of the particles must have been transported and changed by hydrothermal waters just beneath the surface of the volcano. This indicates a turbulent history of sediment deposits. By analyzing various carbon isotopes, the researchers concluded that different types of microorganisms were already living in the vicinity of the volcanic activity, similar to those found today at Icelandic geysers or at hot springs in Yellowstone National Park.

The study not only sheds light on the Earth’s past, but is also interesting from a methodological point of view. First author Lena Weimann, Göttingen University’s Geosciences Centre, explains, “It was very exciting to be able to combine a range of high-resolution techniques, which enabled us to derive information about the history of how the organic particles were deposited and their origin. As our findings show, original traces of the first organisms can still be found even from extremely old material.”

Reference:
L. Weimann et al, Carbonaceous matter in ∼ 3.5 Ga black bedded barite from the Dresser Formation (Pilbara Craton, Western Australia)—Insights into organic cycling on the juvenile Earth, Precambrian Research (2024). DOI: 10.1016/j.precamres.2024.107321

Note: The above post is reprinted from materials provided by University of Göttingen.

Dinosaurs’ success helped by specialized stance and gait, study finds

February 12, 2024

A typical early dinosaur, Eoraptor from the Late Triassic of Argentina. Photo Copyright: Nobu Tamura, Wikimedia

Dinosaurs’ range of locomotion made them incredibly adaptable, University of Bristol researchers have found.

In a new study, published today in Royal Society Open Science, findings show that the first dinosaurs were simply faster and more dynamic than their competitors and why they were able to dominate the Earth for 160 million years.

The researchers compared the limb proportions of a broad array of reptiles from the Triassic, the period of time from 252 to 201 million years ago, when dinosaurs first appeared and rose to prominence.

They identified which of these ancient beasts was quadrupedal (four-footed) or bipedal (two-footed), and also looked at their cursoriality index, a measure of their running ability.

They found that, from the beginning, not only were the dinosaurs and their close relatives bipedal and cursorial — which meant they had limbs adapted for running, they also showed a much wider range of running styles than some of their close competitors, called the Pseudosuchia.

The pseudosuchians included the ancestors of modern crocodiles.

Some were small insect-eating bipeds, but most were medium-to-large-sized carnivores and herbivores and they were diverse throughout the Triassic.

The team found that dinosaurs and their kin, the Avemetatarsalia, maintained a higher range of locomotory modes throughout this period.

MSc Palaeobiology student Amy Shipley led the study.

“At that time, climates went from wet to dry, and there was severe pressure for food. Somehow the dinosaurs, which had been around in low numbers already for 20 million years, took off and the pseudosuchians did not.

“It’s likely the early dinosaurs were good at water conservation, as many modern reptiles and birds are today. But our evidence shows that their greater adaptability in walking and running played a key part.”

“After the end of the Triassic, when there was a mass extinction, the dinosaurs expanded again,” said Professor Mike Benton.

“Most of the pseudosuchians were wiped out by the mass extinction, except for the ancestors of crocodiles, and we found that these surviving dinosaurs expanded their range of locomotion again, taking over many of the empty niches.”

Co-author Dr Armin Elsler explained: “When we looked at evolutionary rates, we found that in fact dinosaurs were not evolving particularly fast.

“This was a surprise because we expected to see fast evolution in avemetatarsalians and slower evolution in pseudosuchians. What this means is that the locomotion style of dinosaurs was advantageous to them, but it was not an engine of intense evolutionary selection. In other words, when crises happened, they were well placed to take advantage of opportunities after the crisis.”

“We always think of dinosaurs as huge and lumbering,” says Dr Tom Stubbs, another collaborator.

“The first dinosaurs were only a metre long, up high on their legs, and bipedal. Their leg posture meant they could move fast and catch their prey while escaping larger predators.”

Co-author Dr Suresh Singh concluded: “And of course, their diversity of posture and focus on fast running meant that dinosaurs could diversify when they had the chance.

“After the end-Triassic mass extinction, we get truly huge dinosaurs, over ten metres long, some with armour, many quadrupedal, but many still bipedal like their ancestors. The diversity of their posture and gait meant they were immensely adaptable, and this ensured strong success on Earth for so long.”

Reference:
Amy E. Shipley, Armin Elsler, Suresh A. Singh, Thomas L. Stubbs, Michael J. Benton. Locomotion and the early Mesozoic success of Archosauromorpha. Royal Society Open Science, 2024; 11 (2) DOI: 10.1098/rsos.231495

Note: The above post is reprinted from materials provided by University of Bristol.

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