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Sulfur and the origin of life

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.
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

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?

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

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

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.
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

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.
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

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

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

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

Surprisingly vibrant color of 12-million-year-old snail shells

Coloured fossil snail shells (left) and a snail shell from modern times (large specimen on the right)Photo: Klaus Wolkenstein
Coloured fossil snail shells (left) and a snail shell from modern times (large specimen on the right)
Photo: Klaus Wolkenstein

Snail shells are often colourful and strikingly patterned. This is due to pigments that are produced in special cells of the snail and stored in the shell in varying concentrations. Fossil shells, on the other hand, are usually pale and inconspicuous because the pigments are very sensitive and have already decomposed. Residues of ancient colour patterns are therefore very rare. This makes this new discovery by researchers from the University of Göttingen and the Natural History Museum Vienna (NHMW) all the more astonishing: they found pigments in twelve-million-year-old fossilised snail shells. These are the world’s first pigments from the chemical group of polyenes that have been preserved almost unchanged and found in fossils. The study was published in the journal Palaeontology.

Palaeontologists from the NHMW found snail shells of the superfamily Cerithioidea in Burgenland, Austria.

The snails lived there twelve million years ago on the shores of a tropical sea.

Professor Mathias Harzhauser at NHMW, who was involved in the discovery, explains: “It was unclear whether the patterns of reddish colour were from the original shell or were formed by later processes in the sediment.” Researchers at Göttingen University’s Geoscience Center solved the mystery.

They analysed the pigments using Raman spectroscopy. This involves irradiating samples with laser light.

The scattered light reflected from the sample can be used to clearly identify chemical compounds.

They detected pigments in the fossilised shells that belong to the polyene group of chemicals.

These are organic compounds that include the well-known “carotenoids,” which are responsible for producing the vibrant red, orange and yellow colours seen in birds’ feathers, carrots and egg yolks, for instance.

Dr Klaus Wolkenstein, who led the study and has been researching the chemistry of fossil pigments at Göttingen University for many years, explains: “Normally, after such a long period of time, the best we can hope for is that there are traces of degradation products of these chemicals. If degraded, however, these compounds would be devoid of colour. So, it was really surprising to discover these pigments, preserved almost intact, in fossils that are twelve million years old.”

Reference:
Klaus Wolkenstein, Burkhard C. Schmidt, Mathias Harzhauser. Detection of intact polyene pigments in Miocene gastropod shells. Palaeontology, 2024; 67 (1) DOI: 10.1111/pala.12691

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

A new origin story for deadly Seattle fault

The modern Seattle fault zone cuts directly through the densely populated Puget lowlands, including Seattle and its metro area. Fifty million years ago, the continent tore in two here, setting the geologic stage for the modern faults, according to a new Tectonics study. Credit: Washington Geological Survey.
The modern Seattle fault zone cuts directly through the densely populated Puget lowlands, including Seattle and its metro area. Fifty million years ago, the continent tore in two here, setting the geologic stage for the modern faults, according to a new Tectonics study. Credit: Washington Geological Survey.

The Seattle fault zone is a network of shallow faults slicing through the lowlands of Puget Sound, threatening to create damaging earthquakes for the more than four million people who live there. A new origin story, proposed in a new study, could explain the fault system’s earliest history and help scientists improve hazard modeling for the densely populated region. The study was published in Tectonics, AGU’s journal for research exploring the evolution, structure and change of Earth’s crust and upper mantle.

The Seattle fault is active today because of forces exerted on the region from ongoing tectonic deformation both to the west and south, but that was not always the case. Washington in the Eocene looked different from today, with a coastline well east of where Seattle sits today and a chain of volcanic islands dotting the horizon offshore.

The study suggests that around 55 million years ago, that island chain was pulled toward the continent. As it ran into the North American plate, part of it went up and over the crust while the rest was sucked under it. Between these two parts, the crust would have been under great strain and torn. That ancient tear zone set the geologic stage for the modern Seattle fault, the study authors posit.

“It was a total surprise,” said Megan Anderson, a geophysicist with the Washington Geological Survey and lead author of the study. “It wasn’t something we were going for originally, but our results predict a major ancient fault where the Seattle fault is today.”

A massive mystery

The Pacific Northwest lies just inland from the Cascadia subduction zone, where dense oceanic crust gets pulled under the continent. In 1700, a roughly 1000-kilometer (620-mile) rupture of the subduction zone created a massive quake between magnitude 8.7 and 9.2; smaller quakes shook the region throughout the 1900s and, most recently, during the 2001 Nisqually earthquake. The Seattle fault ruptured notably in 923-924 AD, based on local Indigenous oral traditions and geologic evidence along the Puget Sound shoreline.

Despite the region’s seismic activity, scientists didn’t begin to study the Seattle fault zone in earnest until the 1990s.

“There’s a lot more uncertainty about the Seattle fault than, for example, the San Andreas fault,” Anderson said. “The Seattle fault could generate something like a magnitude 7.2 earthquake, and we want to be prepared for it. There’s still a lot to learn so that engineering geologists can do better simulations for earthquakes and understand the potential risks to our communities.”

Previous work to determine the geometry of the Seattle fault at depth relied primarily on seismic data, which are sound waves traveling through and being reflected by underground layers of rock. The data revealed faults and geologic structures that seismologists and geologists interpreted differently. They knew the region hosted a major fault zone, but scientists had proposed different ways parts of the fault are connected, how deep it extends, and how steeply it cuts through the bedrock.

Anderson and her co-authors set out to test the existing hypotheses of the fault zone’s geometry by mapping kilometers-deep bedrock across western Washington and building a more complete picture of the region’s geologic structure. Gravity and magnetic fields vary across Earth’s surface based on rocks’ density and composition, so Anderson compiled those data for western Washington and paired them with seismic data. The researchers also collected rock samples from geologic formations that correspond to different parts of the ancient fault and mountain system.

The researchers used computer models to see which, if any, of the hypotheses matched up with the gravity, magnetic and seismic data. The gravity data did not show a complex pattern, but the magnetic data revealed a key secret seismic data missed: deep in the crust, the bedrock consistently alternates between being more and less magnetic, suggesting slanted layers of changing rock type. And in map view, features on either side of the Seattle fault zone angle away from each other; north of the Seattle fault zone, structures are angled north-northwest, while in the south, they’re oriented north-northeast.

Those wonky orientations gave Anderson pause; they hinted at an ancient mountain range, but to check that, Anderson needed to match up the map-view data with deeper rocks. To connect the map view with known, deeper bedrock geology, Anderson modeled a vertical profile of rocks underground and found some of those structures dip at different orientations underground, too.

“These are all very different orientations,” Anderson said. “It’s very hard to do that unless there’s a place where the structures get disconnected from each other and then restart.”

Anderson had stumbled upon a new possible explanation for the Seattle fault zone’s early history and why it’s reactivated today.

A tear in the crustal continuum

The data suggested that about 55 million years ago, as the subduction zone pulled in a string of oceanic islands, the northern half of the island chain was subducted, but the southern half was added to the top of the crust, or obducted. Over a couple million years, as the islands were obducted, they crumpled into a fold-and-thrust mountain belt with topography similar to the Blue Ridge Mountains of Appalachia today.

The zone where the islands switched from being subducted to being accreted would have been under incredible strain and been ripped apart.

“It would have been this slow, ongoing tear, almost like the crust unzipping itself,” Anderson said. “As this progressed, the tear fault got longer and longer.”

And that “torn” region overlaps perfectly with the modern Seattle fault zone.

The intense tearing would have stopped after the islands were crunched into the continent, but the damage was done. The zone of intense tearing created fragmented, weakened crust, setting the geologic stage for the modern Seattle fault zone.

Beyond offering a possible explanation for why the fault zone exists, the study’s results about the geometry of Washington’s more ancient faults and geologic structures provide valuable details about the bedrock under and within the Seattle basin. This basin is filled with kilometers of looser sedimentary rock which make seismic ground shaking stronger, and the new data can help scientists make more accurate models of future ground shaking in the area.

Anderson is excited to use her findings to study western Washington’s active faults next.

“This buried tectonic story was so much fun to discover, and now it will provide a great basis for getting back to answering our original questions about active fault geometry for the Seattle fault and other faults in western Washington,” Anderson said.

Reference:
M. L. Anderson, R. J. Blakely, R. E. Wells, J. D. Dragovich. Deep Structure of Siletzia in the Puget Lowland: Imaging an Obducted Plateau and Accretionary Thrust Belt With Potential Fields. Tectonics, 2024 DOI: 10.1029/2022TC007720

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

Researchers uncover source rocks of the first real continents

Three types of granitoid rocks—tonalite, trondhjemite and granodiorite (TTG).
Three types of granitoid rocks—tonalite, trondhjemite and granodiorite (TTG).

Geoscientists have uncovered a missing link in the enigmatic story of how the continents developed — a revised origin story that doesn’t require the start of plate tectonics or any external factor to explain their formation. Instead, the findings published last week in Nature Communications, rely solely on internal geological forces that occurred within oceanic plateaus that formed during the first few hundred million years of Earth’s history.

A major hurdle in understanding how the continents formed during the Archean Eon (four to 2.5 billion years ago) has been identifying the building blocks of Earth’s early crust.

Much of the “new” Archean crust formed during this period comprised a very distinct association of three types of granitoid rocks — tonalite, trondhjemite and granodiorite (TTG).

Understanding what went into making TTGs and the magmas they formed from has been difficult, because so many geological processes occurred between their initial melting and ultimate crystallization.

Earlier researchers focused on the trace element composition of these rocks, hoping to find clues about TTG magmas and their source.

“We tracked a specific set of trace elements that aren’t affected by alteration and pristinely preserve signatures from the original magma that made new TTG crust,” said Dr. Matthijs Smit, associate professor and Canada Research Chair at the University of British Columbia’s (UBC) Department of Earth, Ocean and Atmospheric Sciences.

“These elements allowed us to look back through the chemical changes that TTG magmas go through and trace the melt compositions back to their initial state and source — most likely a sort of gabbro.”

“Funnily enough, many people have varieties of this type of rock as a kitchen countertop,” Dr. Smit says.

“In a way, many people are preparing their dinner on the type of rock that was responsible for making our modern continents.”

The Archean TTG crust is still part of the continents today.

For instance, in North America they make up much of the Canadian Interior between the Cordillera mountain belt in the west and the Grenville and Appalachian mountain belts in the east.

The majority of Ontario, Quebec, Manitoba, Saskatchewan, Northwest Territories and Nunavut is made up of Archean crustal fragments that are dominated by TTGs and their slightly younger and more evolved granite counterparts.

“All of these rocks — and especially their combination — can be explained by the model we present,” said Dr. Smit.

“Ours is a simple model in which TTGs, as well as the younger rocks that TTGs are typically associated with, resulted from the slow burial, thickening and melting of precursor crust that likely resembled oceanic plateaus. The continental crust was destined to develop the way it did, because it kept getting buried further and the rocks at its base had no choice but to melt. In doing so, they made the TTGs that proved a winning recipe for continental survival and growth.”

The UBC researchers’ discovery of a stand-alone “intra-crustal” mechanism to make TTGs dispels the long-standing theory that Archean TTGs are formed in Earth’s first subduction zones and mark the start of plate tectonics.

“There’s always been a ‘chicken-and-egg’ question of which came first — the start of plate tectonics or TTG magmatism to make new continental crust,” says Dr. Smit.

“We show that these things may actually not be directly related. The recognition of the type of source rock makes this leap possible and also takes away the need to have other mechanisms, such as meteorite impact, explain the growth of the first real continents.”

The study by Dr. Smit and his UBC-based team used data from all the TTG samples ever analyzed — samples from Archean cratonic fragments exposed worldwide scrutinized by researchers over the past 30 years. This allowed Dr. Smit and his team to filter out local anomalies and analytical issues, and get at the actual trends in composition that the rocks capture. The study used a huge volume of data, now available in the open-source Geochemistry of Rocks of the Oceans and Continents geochemical data repository hosted by the Georg-August-Universität, Göttingen.

Reference:
Matthijs A. Smit, Kira A. Musiyachenko, Jeroen Goumans. Archaean continental crust formed from mafic cumulates. Nature Communications, 2024; 15 (1) DOI: 10.1038/s41467-024-44849-4

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

Ancient rocks improve understanding of tectonic activity between earthquakes

Shears — or breaks caused by strain — in rock outcrops like the one pictured here could shed new light on tectonics that occur between major earthquakes in the subduction zone, according to new research. A camera lens shows the scale of the features of the rock. Credit: Provided by Donald Fisher . All Rights Reserved.
Shears — or breaks caused by strain — in rock outcrops like the one pictured here could shed new light on tectonics that occur between major earthquakes in the subduction zone, according to new research. A camera lens shows the scale of the features of the rock. Credit: Provided by Donald Fisher . All Rights Reserved.

Rocks once buried deep in ancient subduction zones — where tectonic plates collide — could help scientists make better predictions of how these zones behave during the years between major earthquakes, according to a research team from Penn State and Brown University.

Clues from rock formations in Alaska and Japan allowed the scientists to develop a new model to predict the pressure solution activity in subduction zones, the researchers reported in the journal Science Advances. Sedimentary rocks comprise grains surrounded by water-containing pores.

When rocks are squeezed together under great pressure, the grains dissolve at their boundaries into the water present in pores, forming pressure solution.

This allows the rocks to deform, or change shape, influencing how the tectonic plates slide past each other.

“It’s like when you go ice skating — the blade on the surface ends up melting the ice, which allows you to glide along,” said corresponding author Donald Fisher, professor of geosciences at Penn State.

“In rocks, what happens is quartz grains dissolve at stressed contacts and the dissolved material moves to cracks where it precipitates.”

The world’s most powerful earthquakes happen in subduction zones, where one tectonic plate slides beneath the other.

When these plates become stuck together, stress builds in the crust of the Earth — like a rubber band being stretched.

When enough stress builds up to overcome the friction holding the plates together — like a rubber band snapping — an earthquake occurs.

“We’ve shown that pressure solution is a fundamental process during the interseismic period in subduction zones,” Fisher said.

“The occurrence of this pressure solution can really affect the amount of elastic strain that accumulates in different parts of the seismogenic zone.”

Pressure solution is difficult to explore in the laboratory because it typically occurs very slowly over thousands to millions of years, Fisher said.

Speeding up the process in the lab requires higher temperatures, which produces other changes in rocks that impact the experiments.

The scientists instead turned to rocks that once experienced these tectonic pressures and were later brought to the surface by geological processes.

The rocks show microscopic shears — or breaks caused by strain — that contain textures that provide evidence for pressure solution, the scientists said.

“This work allows us to test a flow law, or model, that describes the rate of pressure solution in ancient rocks that were once down at the plate boundary and have been exhumed to the surface,” Fisher said.

“And we can apply this to active margins that are moving today.”

A previous study by another team of scientists linked stress the rocks experienced and strain rate — or how much they deformed.

In the new work, Fisher and his colleague, Greg Hirth, professor at Brown University, created a more detailed model that considers factors like the rocks’ grain size and solubility, or how much of the rock material can dissolve into liquid.

“We were able to parameterize the solubility as a function of temperature and pressure, in a practical way that hadn’t been done before,” Fisher said.

“So now we can plug in numbers — different grain sizes, different temperatures, different pressures and get the strain rate out of that.”

The results can help reveal where in the seismogenic layer — the range of depths at which most earthquakes occur — that strain is occurring.

The researchers applied their model to the Cascadia Subduction Zone, an active fault that runs from northern California to Canada and by major cities like Portland, Oregon, Seattle and Vancouver, British Columbia.

The temperature along the plate boundary and the amount of strain built up is well studied there, and the results of their model match crustal movements based on satellite observations, the scientists said.

“Cascadia is a great example because it’s late in the interseismic period — it’s been 300 years since the last major earthquake,” Fisher said.

“We may experience one in our lifetime, which would be the biggest natural disaster that North America can anticipate in terms of the potential for shaking and resulting tsunami.”

The National Science Foundation supported this work.

Reference:
Donald M. Fisher, Greg Hirth. A pressure solution flow law for the seismogenic zone: Application to Cascadia. Science Advances, 2024; 10 (4) DOI: 10.1126/sciadv.adi7279

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

Rare 3D fossils show that some early trees had forms unlike any you’ve ever seen

Sanfordiacaulis densifolia fossil (Scale is 1 m). Credit: Matthew Stimson
Sanfordiacaulis densifolia fossil (Scale is 1 m). Credit: Matthew Stimson

In the fossil record, trees typically are preserved with only their trunks. They don’t usually include any leaves to show what their canopies and overall forms may have looked like. But now, researchers reporting in the journal Current Biology on February 2 describe fossilized trees from New Brunswick, Canada with a surprising and unique three-dimensional crown shape.

“The way in which this tree produced hugely long leaves around its spindly trunk, and the sheer number over a short length of trunk, is startling,” says Robert Gastaldo of Colby College in Waterville, Maine.

The forms taken by these 350-million-year-old trees look something like a fern or palm, even though palms didn’t arise until 300 million years later, he explains.

However, the functional leaves in ferns or palm trees cluster at the top and are relatively few.

“In contrast, Sanfordiacaulis preserves more than 250 leavesaround its trunk, with each partially preserved leaf extending 1.75 meters from it,” Gastaldo says.

“We estimate that each leaf grew at least another meter before terminating. This means that the ‘bottle brush’ had a dense canopy of leaves that extended at least 5.5 meters (or 18 feet) around a trunk that was non-woody and only 16 centimeters (or 0.5 feet) in diameter. Startling to say the least.”

This work was made possible by a long-term international collaboration with Matthew Stimson and Olivia King of the New Brunswick Museum, Saint John, and Saint Mary’s University in Halifax.

The researchers’ findings offer important insights into the evolution of plants and arborescence, meaning plants that grow to a tree height, or at least 15 feet at maturity.

They’re also a reminder that over the history of life on Earth, there have existed trees that look unlike any we’ve ever seen before and some that look as though they may come from the imagination of Dr. Seuss, the researchers say.

“We all have a mental concept of what a tree looks like, depending on where we live on the planet, and we have a vision of what is familiar,” Gastaldo says.

The fossils in question were preserved by earthquake-induced, catastrophic burial of trees and other vegetation along the margin of a rift lake.

The first fossil tree was unearthed about 7 years ago from a quarry, but it only included one partial sample.

It took several years for another four specimens of the same plant, in close spatial proximity, to also be found, Gastaldo says.

One of the specimens revealed how the leaves departed from the top of the tree, which makes it “absolutely unique.” It’s one of only a few in a fossil record spanning more than 400 million years in which a trunk is preserved around which the crown leaves are still attached, the researchers say.

“Any fossil tree with an intact crown is a rarity in the history of life,” Gastaldo says.

“Having the crown leaves attached to a trunk, by itself, begs the questions what kind of plant is it, how is that plant organized, And is it some form that continues to the present, or is it outside of the ‘normal’ concept of a tree? All of these questions, and more, led to this multi-year endeavor.”

The researchers report that the tree likely relied on its unusual growth form to maximize the amount of light it could capture and reduce its competition with other plants on the ground.

They suggest that the tree now represents the earliest evidence of smaller trees growing beneath a taller forest canopy.

It means that plant life in the Early Carboniferous period was more complex than expected, suggesting Sanfordiacaulis lived at a time when plants were “experimenting” with a variety of possible forms or architectures.

“The history of life on land consists of plants and animals that are unlike any of those that live at the present,” Gastaldo says. “Evolutionary mechanisms operating in the deep past resulted in organisms that successfully lived over long periods of time, but their shapes, forms, growth architectures, and life histories undertook different trajectories and strategies. Rare and unusual fossils, such as the New Brunswick tree, is but one example of what colonized our planet but was an unsuccessful experiment.”

Reference:
Robert A. Gastaldo, Patricia G. Gensel, Ian J. Glasspool, Steven J. Hinds, Olivia A. King, Duncan McLean, Adrian F. Park, Matthew R. Stimson, Timothy Stonesifer. Enigmatic fossil plants with three-dimensional, arborescent-growth architecture from the earliest Carboniferous of New Brunswick, Canada. Current Biology, 2024; DOI: 10.1016/j.cub.2024.01.011

Note: The above post is reprinted from materials provided by Cell Press.

Student discovers 200-million-year-old flying reptile in Somerset

Showing partial skeleton of gliding reptile Kuehneosaurus on rock from Emborough. Image credit: David Whiteside
Showing partial skeleton of gliding reptile Kuehneosaurus on rock from Emborough. Image credit: David Whiteside

Gliding winged-reptiles were amongst the ancient crocodile residents of the Mendip Hills in Somerset, researchers at the University of Bristol have revealed.

Kuehneosaurs looked like lizards, but were more closely related to the ancestors of crocodilians and dinosaurs.

They were small animals, which could fit neatly on the palm of a hand, and there were two species, one with extensive wings, the other with shorter wings, made from a layer of skin stretched over their elongated side ribs, which allowed them to swoop from tree to tree.

Like the modern flying lizard Draco from southeast Asia, they most likely wandered about on the ground and climbed trees in search of insect prey.

When startled, or if they spotted a tasty insect flying by, they could launch themselves into the air, and land safely 10m away.

The discovery was made by University of Bristol Masters student Mike Cawthorne, researching numerous reptile fossils from limestone quarries, which formed the biggest sub-tropical island at the time, called the Mendip Palaeo-island.

The study, published today in Proceedings of the Geologists’ Association, also records the presence of reptiles with complex teeth, the trilophosaur Variodens and the aquatic Pachystropheus that probably lived a bit like a modern-day otter likely eating shrimps and small fish.

The animals either fell or their bones were washed into caves and cracks in the limestone.

“All the beasts were small,” said Mike.

“The collections I studied had been made in the 1940s and 1950s when the quarries were still active, and palaeontologists were able to visit and see fresh rock faces and speak to the quarrymen.”

Professor Mike Benton Bristol’s School of Earth Sciences explained: “It took a lot of work identifying the fossil bones, most of which were separate and not in a skeleton.

“However, we have a lot of comparative material, and Mike Cawthorne was able to compare the isolated jaws and other bones with more complete specimens from the other sites around Bristol.

“He has shown that the Mendip Palaeo-island, which extended from Frome in the east to Weston-super-Mare in the west, nearly 30 km long, was home to diverse small reptiles feeding on the plants and insects.

“He didn’t find any dinosaur bones, but it’s likely that they were there because we have found dinosaur bones in other locations of the same geological age around Bristol.”

The area around Bristol 200 million years ago in the Late Triassic was an archipelago of small islands set in a warm sub-tropical sea.

Bristol’s Dr David Whiteside added: “The bones were collected by some great fossil finders in the 1940s and 1950s including Tom Fry, an amateur collector working for Bristol University and who generally cycled to the quarries and returned laden with heavy bags of rocks.

“The other collectors were the gifted researchers Walter Kühne, a German who was imprisoned in Great Britain in the 2nd world war, and Pamela L. Robinson from University College London. They gave their specimens to the Natural History Museum in London and the Geological collections of the University of Bristol.”

Reference:
Michael Cawthorne, David I. Whiteside, Michael J. Benton. Latest Triassic terrestrial microvertebrate assemblages from caves on the Mendip palaeoisland, S.W. England, at Emborough, Batscombe and Highcroft Quarries. Proceedings of the Geologists’ Association, 2024; DOI: 10.1016/j.pgeola.2023.12.003

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

The megalodon was less mega than previously believed

Study sheds new light on the body form of the Megalodon, and its role in shaping ancient marine life. (DePaul University/Kenshu Shimada)
Study sheds new light on the body form of the Megalodon, and its role in shaping ancient marine life. (DePaul University/Kenshu Shimada)

A new study shows the Megalodon, a gigantic shark that went extinct 3.6 million years ago, was more slender than earlier studies suggested. This finding changes scientists’ understanding of Megalodon behavior, ancient ocean life, and why the sharks went extinct.

The Megalodon or megatooth shark is typically portrayed as a super-sized monster in popular culture, with recent examples in the sci-fi films “The Meg” (2018) and “Meg 2: The Trench” (2023). Previous studies assume that the shark likely reached lengths of at least 50 feet and possibly as much as 65 feet.

However, the Megalodon is largely known only from its teeth and vertebrae in the fossil record — a rather incomplete set of data from which to draw assumptions.

Thus, the modern great white shark was traditionally used as a model for Megalodon bodies in previous studies.

That model led researchers to conclude that the shark was round and stocky like great whites.

“Our team reexamined the fossil record, and discovered the Megalodon was more slender and possibly even longer than we thought. Therefore, a better model might be the modern mako shark,” said UCR biologist and paper first author Phillip Sternes.

“It still would have been a formidable predator at the top of the ancient marine food chain, but it would have behaved differently based on this new understanding of its body.”

For the new study published in the journal Palaeontologia Electronica, a team of 26 scientists from around the world, co-led by Sternes and DePaul University paleobiology professor Kenshu Shimada, was inspired by differences in previously estimated body lengths for the Megalodon.

“It was a ‘eureka-moment’ when our research team realized the discrepancy between two previously published lengths for the same Megalodon specimen,” said Shimada.

The team then weighed in on a new comparison of Megalodon vertebra fossils to those of living lamniform shark relatives.

“We measured the whole vertebral skeleton of a living great white shark with a CT scanner and compared that to the previous reconstruction of the Megalodon vertebral column,” Sternes said.

“It was still a giant, predatory shark. But the results strongly suggest that the Megalodon was not merely a larger version of the modern great white shark.”

A revised understanding of the Megalodon body type would in turn affect scientists’ understanding not only of the giant shark itself, but also of its impact on the ecology and evolution of marine ecosystems that shaped the present-day oceans.

There is no doubt the Megalodon is one of the largest marine predators ever to have lived.

But a slimmer and more elongated body would suggest the Megalodon also had a longer digestive canal.

Sternes explained that in this case, the sharks might have enjoyed enhanced absorption of nutrients, and may not have had to eat as often as previously believed.

“With increased ability to digest its food, it could have gone for longer without needing to hunt. This means less predation pressure on other marine creatures,” Sternes said.

“If I only have to eat one whale every so often, whale populations would remain more stable over time.”

Some shark scientists have theorized that a natural decrease in prey led to the extinction of Megalodons.

However, Sternes has another theory, in part supported by the revised understanding of its shape.

“I believe there were a combination of factors that led to the extinction, but one of them may have been the emergence of the great white shark, which was possibly more agile, making it an even better predator than the Megalodon,” Sternes said.

“That competition for food may have been a major factor in its demise.”

The research team of shark experts from the U.S., UK, Austria, France, Japan, Mexico, Brazil, and Australia all feel that a revised understanding of ancient marine life would have a cascading effect on the oceans that are still visible today.

“Now that we know it was a thinner shark, we need to reinvestigate its lifestyle, how it really lived, and what caused it to die,” Sternes said. “This study represents a major stepping stone for others to follow up on.”

Reference:
Phillip C. Sternes, Patrick L. Jambura, Julia Türtscher, Jürgen Kriwet, Mikael Siversson, Iris Feichtinger, Gavin J.P. Naylor, Adam P. Summers, John G. Maisey, Taketeru Tomita, Joshua K. Moyer, Timothy E. Higham, João Paulo C.B. da Silva, Hugo Bornatowski, Douglas J. Long, Victor J. Perez, Alberto Collareta, Charlie Underwood, David J. Ward, Romain Vullo, Gerardo González-Barba, Harry M. Maisch IV, Michael L. Griffiths, Martin A. Becker, Jake J. Wood, and Kenshu Shimada. White shark comparison reveals a slender body for the extinct megatooth shark, Otodus megalodon (Lamniformes: Otodontidae). Palaeontologia Electronica, 2024 DOI: 10.26879/1345

Note: The above post is reprinted from materials provided by University of California – Riverside. Original written by Jules Bernstein.

Woolly mammoth movements tied to earliest Alaska hunting camps

Woolly mammoth illustration Mauricio Antón © 2008 Public Library of Science
Woolly mammoth illustration Mauricio Antón © 2008 Public Library of Science

Researchers have linked the travels of a 14,000-year-old woolly mammoth with the oldest known human settlements in Alaska, providing clues about the relationship between the iconic species and some of the earliest people to travel across the Bering Land Bridge.

Scientists made those connections by using isotope analysis to study the life of a female mammoth, named Élmayųujey’eh, by the Healy Lake Village Council.

A tusk from Elma was discovered at the Swan Point archaeological site in Interior Alaska.

Samples from the tusk revealed details about Elma and the roughly 1,000-kilometer journey she took through Alaska and northwestern Canada during her lifetime.

Isotopic data, along with DNA from other mammoths at the site and archaeological evidence, indicates that early Alaskans likely structured their settlements to overlap with areas where mammoths congregated.

Those findings, highlighted in the new issue of the journal Science Advances, provide evidence that mammoths and early hunter-gatherers shared habitat in the region.

The long-term predictable presence of woolly mammoths would have attracted humans to the area.

“She wandered around the densest region of archaeological sites in Alaska,” said Audrey Rowe, a University of Alaska Fairbanks Ph.D. student and lead author of the paper.

“It looks like these early people were establishing hunting camps in areas that were frequented by mammoths.”

The mammoth tusk was excavated and identified in 2009 by Charles Holmes, affiliate research professor of anthropology at UAF, and François Lanoë, research associate in archaeology at the University of Alaska Museum of the North.

They found Elma’s tusk and the remains of two related juvenile mammoths, along with evidence of campfires, the use of stone tools, and butchered remains of other game.

All of this “indicates a pattern consistent with human hunting of mammoths,” said Ben Potter, an archaeologist and professor of anthropology at UAF.

Researchers at UAF’s Alaska Stable Isotope Facility then analyzed thousands of samples from Elma’s tusk to recreate her life and travels.

Isotopes provide chemical markers of an animal’s diet and location.

The markers are then recorded in the bones and tissues of animals and remain even after they die.

Mammoth tusks are well-suited to isotopic study because they grew throughout the ancient animals’ lives, with clearly visible layers appearing when split lengthwise.

Those growth bands give researchers a way to collect a chronological record of a mammoth’s life by studying isotopes in samples along the tusk.

Much of Elma’s journey overlapped with that of a previously studied male mammoth who lived 3,000 years earlier, demonstrating long-term movement patterns by mammoths over several millennia.

In Elma’s case, they also indicated she was a healthy 20-year-old female.

“She was a young adult in the prime of life. Her isotopes showed she was not malnourished and that she died in the same season as the seasonal hunting camp at Swan Point where her tusk was found,” said senior author Matthew Wooller, who is director of the Alaska Stable Isotope Facility and a professor at UAF’s College of Fisheries and Ocean Sciences.

The era in which Elma lived may have compounded the challenges posed by the relatively recent appearance of humans.

The grass- and shrub-dominated steppe landscape that had been common in Interior Alaska was beginning to shift toward more forested terrain.

“Climate change at the end of the ice age fragmented mammoths’ preferred open habitat, potentially decreasing movement and making them more vulnerable to human predation,” Potter said.

Other contributors to the study included the University of Alaska Anchorage, University of Ottawa, McMaster University, University of Alaska Museum of the North, University of Michigan Museum of Paleontology, Adelphi University, University of Arizona, Hakai Institute and the Healy Lake Village Council.

Reference:
Audrey G. Rowe, Clement P. Bataille, Sina Baleka, Evelynn A. Combs, Barbara A. Crass, Daniel C. Fisher, Sambit Ghosh, Charles E. Holmes, Kathryn E. Krasinski, François Lanoë, Tyler J. Murchie, Hendrik Poinar, Ben Potter, Jeffrey T. Rasic, Joshua Reuther, Gerad M. Smith, Karen J. Spaleta, Brian T. Wygal, Matthew J. Wooller. A female woolly mammoth’s lifetime movements end in an ancient Alaskan hunter-gatherer camp. Science Advances, 2024; 10 (3) DOI: 10.1126/sciadv.adk0818

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

Key moment in the evolution of life on Earth captured in fossils

Earth
Earth

Curtin-led research has for the first time precisely dated some of the oldest fossils of complex multicellular life in the world, helping to track a pivotal moment in the history of Earth when the seas began teeming with new lifeforms — after four billion years of containing only single-celled microbes.

Lead author PhD student Anthony Clarke, from the Timescales of Mineral Systems Group within Curtin’s School of Earth and Planetary Sciences, said to determine the age of the fossils, researchers used volcanic ash layers like bookmarks in the geological sequence.

“Located in the Coed Cochion Quarry in Wales, which contains the richest occurrence of shallow marine life in Britain, we used outfall from an ancient volcano that blanketed the animals as a time marker to accurately date the fossils to 565 million years, accurate down to 0.1 per cent,” Mr Clarke said.

“With similar Ediacaran fossils found at sites around the world including in Australia, dating the fossils identifies them as being part of an ancient living community that developed as Earth thawed out from a global ice age.

“These creatures would in some ways resemble modern day marine species such as jellyfish, yet in other ways be bizarre and unfamiliar. Some appear fern-like, others like cabbages, whereas others resembled sea pens.”

Study co-author Professor Chris Kirkland, also from the Timescales of Mineral Systems Group at Curtin, said the fossils are named after the Ediacara Hills in South Australia’s Flinders Ranges, where they were first discovered, leading to the first new geological period established in over a century.

“These Welsh fossils appear directly comparable to the famous fossils of Ediacara in South Australia,” Professor Kirkland said.

“The fossils, including creatures like the disc-shaped Aspidella terranovica, showcase some of the earliest evidence of large-scale multicellular organisms, marking a transformative moment in Earth’s biological history.

“Ediacaran fossils record the response of life to the thaw out from a global glaciation, which shows the deep connection between geological processes and biology.

“Our study underscores the importance of understanding these ancient ecosystems in order to unravel the mysteries of Earth’s past and shape our comprehension of life’s evolution.”

Reference:
Anthony J. I. Clarke, Christopher L. Kirkland, Latha R. Menon, Daniel J. Condon, John C. W. Cope, Richard E. Bevins, Stijn Glorie. U–Pb zircon–rutile dating of the Llangynog Inlier, Wales: constraints on an Ediacaran shallow-marine fossil assemblage from East Avalonia. Journal of the Geological Society, 2024; 181 (1) DOI: 10.1144/jgs2023-081

Note: The above post is reprinted from materials provided by Curtin University. Original written by Lucien Wilkinson.

‘Juvenile T. rex’ fossils are a distinct species of small tyrannosaur

For decades, paleontologists have debated whether Nanotyrannus is a separate species or simply a juvenile T. rex. (Credit Raul Martin)
For decades, paleontologists have debated whether Nanotyrannus is a separate species or simply a juvenile T. rex. (Credit Raul Martin)

A new analysis of fossils believed to be juveniles of T. rex now shows they were adults of a small tyrannosaur, with narrower jaws, longer legs, and bigger arms than T. rex. The species, Nanotyrannus lancensis, was first named decades ago but later reinterpreted as a young T. rex.

The first skull of Nanotyrannus was found in Montana in 1942, but for decades, paleontologists have gone back and forth on whether it was a separate species, or simply a juvenile of the much larger T. rex.

Dr Nick Longrich, from the Milner Centre for Evolution at the University of Bath (UK), and Dr Evan Saitta, from the University of Chicago (USA) re-analysed the fossils, looking at growth rings, the anatomy of Nanotyrannus, and a previously unrecognized fossil of a young T. rex.

Measuring the growth rings in Nanotyrannus bones, they showed that they became more closely packed towards the outside of the bone — its growth was slowing. It suggests these animals were nearly full size; not fast-growing juveniles.

Modelling the growth of the fossils showed the animals would have reached a maximum of around 900-1500 kilograms and five metres — about 15 per cent of the size of the giant T. rex, which grew to 8,000 kilograms and nine metres or more.

The researchers have published their findings in Fossil Studies.

“When I saw these results I was pretty blown away,” said Longrich. “I didn’t expect it to be quite so conclusive.

“If they were young T. rex they should be growing like crazy, putting on hundreds of kilograms a year, but we’re not seeing that.

“We tried modeling the data in a lot of different ways and we kept getting low growth rates. This is looking like the end for the hypothesis that these animals are young T. rex.”

Supporting the existence of distinct species, the researchers found no evidence of fossils combining features of both the Nanotyrannus and T. rex – which would exist if the one turned into the other. Every fossil they examined could be confidently identified as one species or the other.

Neither did the patterns of growth in other tyrannosaurs fit with the hypothesis that these were young T. rex.

Dr Longrich said: “If you look at juveniles of other tyrannosaurs, they show many of the distinctive features of the adults. A very young Tarbosaurus – a close relative of T. rex – shows distinctive features of the adults.

“In the same way that kittens look like cats and puppies look like dogs, the juveniles of different tyrannosaurs are distinctive. And Nanotyrannus just doesn’t look anything like a T. rex.

“It could be growing in a way that’s completely unlike any other tyrannosaur, or any other dinosaur- but it’s more likely it’s just not a T. rex.”

But that raises a mystery — if Nanotyrannus isn’t a juvenile Tyrannosaurus, then why hasn’t anyone ever found a young T. rex?

“That’s always been one of the big questions. Well, it turns out we actually had found one,” said Longrich. “But the fossil was collected years ago, stuck in a box of unidentified bones in a museum drawer, and then forgotten.”

The research led Longrich and co-author Evan Saitta to a previous fossil discovery, stored in a museum in San Francisco which they identified as a juvenile Tyrannosaurus.

That young T. rex is represented by a skull bone — the frontal bone — with distinctive features that ally it with Tyrannosaurus, but which aren’t seen in Nanotyrannus. It comes from a small animal, one with a skull about 45 cm long and a body length of around 5 metres.

Dr Longrich said: “Yes, it’s just one specimen, and just one bone, but it only takes one. T. rex skull bones are very distinctive, nothing else looks like it. Young T. rex exist, they’re just incredibly rare, like juveniles of most dinosaurs.”

The researchers argue these findings are strong evidence that Nanotyrannus is a separate species, one not closely related to Tyrannosaurus. It was more lightly-built and long-limbed than its thick-set relative. It also had larger arms, unlike the famously short-armed T. rex.

“The arms are actually longer than those of T. rex. Even the biggest T. rex, has shorter arms and smaller claws than in these little Nanotyrannus. This was an animal where the arms were actually pretty formidable weapons. It’s really just a completely different animal — small, fast, agile.

“T. rex relied on size and strength, but this animal relied on speed.”

The long arms and other features suggest it was only distantly related to T. rex – and may have sat outside the family Tyrannosauridae, which T. rex is part of, in its own family of predatory dinosaurs.

The new study is the latest in a series of publications on the problem, going back decades.

Longrich said: “Nanotyrannus is highly controversial in paleontology. Not long ago, it seemed like we’d finally settled this problem, and it was a young T. rex.

“I was very skeptical about Nanotyrannus myself until about six years ago when I took a close look at the fossils and was surprised to realise we’d gotten it wrong all these years.”

The authors suggest that, given how difficult it is to tell dinosaurs apart based on their often-incomplete skeletons, we may be underestimating the diversity of dinosaurs, and other fossil species.

Longrich said: “It’s amazing to think how much we still don’t know about the most famous of all the dinosaurs. It makes you wonder what else we’ve gotten wrong.”

Reference:
Nicholas R. Longrich, Evan T. Saitta. Taxonomic Status of Nanotyrannus lancensis (Dinosauria: Tyrannosauroidea)—A Distinct Taxon of Small-Bodied Tyrannosaur. Fossil Studies, 2024; 2 (1): 1 DOI: 10.3390/fossils2010001

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

This Japanese ‘dragon’ terrorized ancient seas

A mosasaur discovered in Japan was the most complete skeleton ever found in Japan or the northwestern Pacific. Graphic/Takuya Konishi
A mosasaur discovered in Japan was the most complete skeleton ever found in Japan or the northwestern Pacific. Graphic/Takuya Konishi

Researchers have described a Japanese mosasaur the size of a great white shark that terrorized Pacific seas 72 million years ago.

Extra-long rear flippers might have aided propulsion in concert with its long finned tail.

And unlike other mosasaurs, or large extinct marine reptiles, it had a dorsal fin like a shark’s that would have helped it turn quickly and with precision in the water.

University of Cincinnati Associate Professor Takuya Konishi and his international co-authors described the mosasaur and placed it in a taxonomic context in the Journal of Systematic Palaeontology.

The mosasaur was named for the place where it was found, Wakayama Prefecture.

Researchers call it the Wakayama Soryu, which means blue dragon.

Dragons are creatures of legend in Japanese folklore, Konishi said.

“In China, dragons make thunder and live in the sky. They became aquatic in Japanese mythology,” he said.

The specimen was discovered along the Aridagawa River in Wakayama by co-author Akihiro Misaki in 2006.

The specimen is the most complete skeleton of a mosasaur ever found in Japan or the northwestern Pacific, Konishi said.

“In this case, it was nearly the entire specimen, which was astounding,” Konishi said.

He has dedicated his career to studying these ancient marine reptiles.

But the Japanese specimen has unique features that defies simple classification, he said.

Its rear flippers are longer than its front ones. These enormous flippers are even longer than its crocodile-like head, which is unique among mosasaurs.

“I thought I knew them quite well by now,” Konishi said. “Immediately it was something I had never seen before.”

Mosasaurs were apex predators in prehistoric oceans from about 100 million years ago to 66 million years ago.

They were contemporaries of Tyrannosaurus rex and other late Cretaceous dinosaurs that ruled the Earth.

Mosasaurs were victims of the same mass extinction that killed off nearly all dinosaurs when an asteroid struck what is now the Gulf of Mexico.

Researchers placed the specimen in the subfamily Mosasaurinae and named it Megapterygius wakayamaensis to recognize where it was found.

Megapterygius means “large winged” in keeping with the mosasaur’s enormous flippers.

Konishi said those big paddle-shaped flippers might have been used for locomotion.

But that type of swimming would be extraordinary not only among mosasaurs but among virtually all other animals.

“We lack any modern analog that has this kind of body morphology — from fish to penguins to sea turtles,” he said.

“None has four large flippers they use in conjunction with a tail fin.”

Researchers speculated that the large front fins might have helped with rapid maneuvering while its large rear fins might have provided pitch to dive or surface.

And presumably like other mosasaurs, its tail would have generated powerful and fast acceleration as it hunted fish.

“It opens a whole can of worms that challenges our understanding of how mosasaurs swim,” Konishi said.

Reference:
Takuya Konishi, Masaaki Ohara, Akihiro Misaki, Hiroshige Matsuoka, Hallie P. Street, Michael W. Caldwell. A new derived mosasaurine (Squamata: Mosasaurinae) from south-western Japan reveals unexpected postcranial diversity among hydropedal mosasaurs. Journal of Systematic Palaeontology, 2023; 21 (1) DOI: 10.1080/14772019.2023.2277921

Note: The above post is reprinted from materials provided by University of Cincinnati. Original written by Michael Miller.

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