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Plant-eating dinosaurs evolved backup teeth to eat tough food, research reveals

The teeth of Iguanodon weren't as adapted for chewing, and formed much more slowly, than those of their later relatives. Credit: The Trustees of the Natural History Museum, London
The teeth of Iguanodon weren’t as adapted for chewing, and formed much more slowly, than those of their later relatives. Credit: The Trustees of the Natural History Museum, London

At the end of the Cretaceous, the duck-billed hadrosaurs were the most advanced herbivores on Earth. New research has revealed just how voracious these dinosaurs were, with their average tooth worn away in less than two months as they consumed enormous amounts of plants. Some of Earth’s most successful herbivores may have had hundreds of thousands of teeth in their lifetime.

The ornithopods are a group of dinosaurs that include Iguanodon, Hypsilophodon and their relatives, including the rare rhabdodontids. Ornithopods first appeared in the Middle Jurassic but were most prominent in the Cretaceous, when they became the dominant herbivores across large parts of the world.

This journey took them from small generalists to becoming large and specialized “plant-eating machines” which rival modern cows and sheep. The research, led by Dr. Attila Ősi from Eötvös Loránd University in Hungary, shows that the dinosaurs achieved this following the evolution of vast numbers of replacement teeth, which allowed them to eat even the toughest of plants in large quantities.

“The teeth and jaws of the ornithopods changed drastically during their evolution,” Attila says. “Earlier members of the group, like Iguanodon, took more than 200 days to form their teeth and at least that long to wear them down by chewing. But by the end of the Cretaceous, hadrosaurs would wear through their teeth in as little as 50 days.”

“We think this is because the later ornithopods must have been feeding on tough plants that rapidly eroded their teeth. As they wore away at a huge rate, these dinosaurs would have needed to build up banks of teeth in their skulls to stop themselves from starving.”

The findings of the study are published in the journal Nature Communications.

Becoming the top dinosaur herbivores

While herbivory is one of the most common ways of life for animals, it’s surprisingly difficult to eat plants. Unlike meat, which is easily broken down in the gut, plants are generally made up of tough fibers and complex carbohydrates which are hard to digest.

Teeth are on the front line of this dietary battle, breaking open plants and cutting them into smaller pieces so that gut bacteria can break them down more efficiently. However, as co-author Professor Paul Barrett explains, this takes its toll on the teeth.

“Across a herbivore’s life, its teeth gradually wear down,” Paul says. “This puts an upper limit on the life of some mammals, like elephants or cows. Once their teeth are gone, the animal can no longer feed, and so it dies.”

“This isn’t a problem for reptiles. They are able to continually make new teeth, with a replacement ready to surface from beneath as soon as its predecessor wears out. As a result, dinosaur teeth are common fossils, making them a valuable way to investigate how these animals evolved.”

The team were particularly interested in investigating the teeth and jaws of the ornithopods, which eventually became some of the most advanced herbivores to have ever lived on our planet. By examining well-preserved skulls, they were able to track how the dinosaurs’ skulls developed into increasingly complex forms that were better suited to eating plants.

“We can see a sequential increase in the complexity of their adaptations for herbivory as they evolve,” Paul explains. “At the start, they had single rows of fairly simple teeth with limited wear, probably because these dinosaurs focused on fruits and softer plants.”

“By the time the hadrosaurs evolved, they had vastly more teeth which developed a large blade-like edge on one side and a series of ridges behind it. This structure is unique to these dinosaurs, and kept the upper and lower teeth sharp as they ground against each other.”

Later ornithopods also moved their jaws in new ways, being able to slide them back and forth and side to side, allowing them to grind plants down even further. Their bodies also grew much bigger, allowing them to accommodate larger guts that can more effectively release the nutrients inside plants.

Different dinosaurs took different approaches to herbivory. But the team noticed that a few groups of ornithopods, like the tenontosaurids and their more advanced iguanodontian relatives, all follow a strikingly similar evolutionary path. They believe this is an example of convergent evolution.

“About 110 million years ago, these ornithopods rapidly evolved a series of similar characteristics,” Paul explains. “Their teeth increase in number, their jaws interlock more tightly and they build up more replacement teeth, making them more effective herbivores.”

“We also see this happen in the horned dinosaurs, which include species like Triceratops. It’s tempting to speculate that these changes happened for similar reasons.”

Could flowers be responsible?

While the evidence that the environment changed in the Early Cretaceous is strong, finding out exactly what happened is challenging. To try and reveal potential causes, the team examined worn areas of dinosaur teeth, known as wear facets, for signs of microscopic changes.

“Before the Early Cretaceous, ornithopod teeth had a lot of large pits,” Attila says. “This suggests that they were eating a large amount of plant seeds, as well as potentially consuming a lot of dust and soil by feeding close to the ground.”

“Later forms have fewer pits, with many more scratches instead. This suggests that they were now eating harder plants, or feeding in a different way.”

Rather than the dinosaurs actively changing what they ate, one possible explanation could be that certain plants became more common. It’s possible that the rise of flowers could be responsible, but it doesn’t quite fit the available evidence.

“While it is suspicious that the flowering plants start to diversify around this time, they were still pretty uncommon at the time,” Paul says. “In fact, until the Late Cretaceous, horsetails, ferns and conifers would be much more common for dinosaurs looking for something to eat.”

“As it’s very difficult to disentangle the plant and dinosaur fossil records, it’s unlikely we’ll ever have enough detailed evidence to prove there is a link, even if it is a very interesting idea.”

Having finished their work on the ornithopods, the team hope to gradually widen their research to other herbivorous dinosaurs, like the ankylosaurs or the horned dinosaurs. This could give us a better idea of why these reptiles were so successful, and how evolution shaped the diet of the different groups.

“We’d like to be able to sample other dinosaurs to see if the trend of increasing body size, tooth number and the change in teeth wear we found in the ornithopods is more widespread,” Attila says. “If we can find out what changes herbivores were going through at the time, it will give us a much better chance of understanding the place of these dinosaurs in the ecosystems of the Mesozoic Era.”

Reference:
Attila Ősi et al, Trophic evolution in ornithopod dinosaurs revealed by dental wear, Nature Communications (2024). DOI: 10.1038/s41467-024-51697-9

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

Some Pterosaurs Would Flap, Others Would Soar

Inabtanin alarabia, left, and Arambourgiania philadelphiae, right. With flying styles also demonstrated. ©Terryl Whitlatch
Inabtanin alarabia, left, and Arambourgiania philadelphiae, right. With flying styles also demonstrated. ©Terryl Whitlatch

Some species of pterosaurs flew by flapping their wings while others soared like vultures, demonstrates a new study published in the peer-reviewed Journal of Vertebrate Paleontology.

It has long been debated whether the largest pterosaurs could fly at all.

However, “remarkable” and “rare” three-dimensional fossils of two different large-bodied azhdarchoid pterosaur species — including one new-to-science — have enabled scientists to hypothesize that not only could the largest pterosaurs take to the air, but their flight styles could differ too.

The new findings are led by experts from the University of Michigan, in the US, the Natural Resources Authority and Yarmouk University, in Jordan, and the Saudi Geological Survey, in Saudi Arabia.

Their paper details how these fossils — which date back to the latest Cretaceous period (approximately 72 to 66 million years ago) — were remarkably three-dimensionally preserved within the two different sites that preserve a nearshore environment on the margin of Afro-Arabia, an ancient landmass that included both Africa and the Arabian Peninsula. The research team used high-resolution computed tomography (CT) scans to then analyze the internal structure of the wing bones.

“The dig team was extremely surprised to find three-dimensionally preserved pterosaur bones, this is a very rare occurrence,” explains lead author Dr Kierstin Rosenbach, from the Department of Earth and Environmental Sciences of the University of Michigan.

“Since pterosaur bones are hollow, they are very fragile and are more likely to be found flattened like a pancake, if they are preserved at all.

“With 3D preservation being so rare, we do not have a lot of information about what pterosaur bones look like on the inside, so I wanted to CT scan them.

“It was entirely possible that nothing was preserved inside, or that CT scanners were not sensitive enough to differentiate fossil bone tissue from the surrounding matrix.”

Luckily, though, what the team uncovered was “remarkable,” via “exciting internal structures not only preserved, but visible in the CT scanner.”

CT scans reveal one soars; one flaps!

Newly collected specimens of the already-known giant pterosaur, Arambourgiania philadelphiae, confirm its 10-meter wingspan and provide the first details of its bone structure. CT images revealed that the interior of its humerus, which is hollow, contains a series of ridges that spiral up and down the bone.

This resembles structures in the interior of wing bones of vultures. The spiral ridges are hypothesized to resist the torsional loadings associated with soaring (sustained powered flight that requires launch and maintenance flapping).

The other specimen analyzed was the new-to-science Inabtanin alarabia, which had a five-meter wingspan. The team named it after the place where it was excavated — near a large grape-colored hill, called Tal Inab. The generic name combines the Arabic words “inab,” for grape, and “tanin” for dragon. ‘Alarabia’ refers to the Arabian Peninsula.

Inabtanin is one of the most complete pterosaurs ever recovered from Afro-Arabia, and the CT scans revealed the structure of its flight bones was completely different from that of Arambourgiania.

The interior of the flight bones were crisscrossed by arrangement with struts that match those found in the wing bones of modern flapping birds.

This indicates it was adapted to resist bending loads associated with flapping flight, and so it is likely that Inabtanin flew this way — although this does not preclude occasional use of other flight styles too.

“The struts found in Inabtanin were cool to see, though not unusual,” says Dr Rosenbach.

“The ridges in Arambourgiania were completely unexpected, we weren’t sure what we were seeing at first!

“Being able to see the full 3D model of Arambourgiania’s humerus lined with helical ridges was just so exciting.”

What explains this difference?

The discovery of diverse flight styles in differently-sized pterosaurs is “exciting,” the experts state, because it opens a window into how these animals lived. It also poses interesting questions, like to what extent flight style is correlated with body size and which flight style is more common among pterosaurs.

“There is such limited information on the internal bone structure of pterosaurs across time, it is difficult to say with certainty which flight style came first,” Dr Rosenbach adds.

“If we look to other flying vertebrate groups, birds and bats, we can see that flapping is by far the most common flight behavior.

“Even birds that soar or glide require some flapping to get in the air and maintain flight.

“This leads me to believe that flapping flight is the default condition, and that the behavior of soaring would perhaps evolve later if it were advantageous for the pterosaur population in a specific environment; in this case the open ocean.”

Co-author Professor Jeff Wilson Mantilla, Curator at Michigan’s Museum of Paleontology, and Dr Iyad Zalmout, from the Saudi Geological Survey, found these specimens in 2007 at sites in the north and south of Jordan.

Professor Jeff Wilson Mantilla says the “variations likely reflect responses to mechanical forces applied on the pterosaurs’ wings during flight.”

Enabling further study of vertebrate flight

Concluding, Dr Rosenbach states: “Pterosaurs were the earliest and largest vertebrates to evolve powered flight, but they are the only major volant group that has gone extinct.

“Attempts to-date to understand their flight mechanics have relied on aerodynamic principles and analogy with extant birds and bats.

“This study provides a framework for further investigation of the correlation between internal bone structure and flight capacity and behavior, and will hopefully lead to broader sampling of flight bone structure in pterosaur specimens.”

Journal Reference:
Kierstin L. Rosenbach, Danielle M. Goodvin, Mohammed G. Albshysh, Hassan A. Azzam, Ahmad A. Smadi, Hakam A. Mustafa, Iyad S. A. Zalmout, Jeffrey A. Wilson Mantilla. New pterosaur remains from the Late Cretaceous of Afro-Arabia provide insight into flight capacity of large pterosaurs. Journal of Vertebrate Paleontology, 2024; DOI: 10.1080/02724634.2024.2385068

Note: The above post is reprinted from materials provided by Taylor & Francis Group.

Chemists explain why dinosaur collagen may have survived for millions of years

A new study from MIT offers an explanation for how dinosaur collagen survived for so much longer than expected.Credits:Credit: MIT News, iStock
A new study from MIT offers an explanation for how dinosaur collagen survived for so much longer than expected.
Credits:Credit: MIT News, iStock

Collagen, a protein found in bones and connective tissue, has been found in dinosaur fossils as old as 195 million years. That far exceeds the normal half-life of the peptide bonds that hold proteins together, which is about 500 years.

A new study from MIT offers an explanation for how collagen can survive for so much longer than expected. The research team found that a special atomic-level interaction defends collagen from attack by water molecules. This barricade prevents water from breaking the peptide bonds through a process called hydrolysis.

“We provide evidence that that interaction prevents water from attacking the peptide bonds and cleaving them. That just flies in the face of what happens with a normal peptide bond, which has a half-life of only 500 years,” says Ron Raines, the Firmenich Professor of Chemistry at MIT.

Raines is the senior author of the new study, which will appear in ACS Central Science. MIT postdoc Jinyi Yang PhD ’24 is the lead author of the paper. MIT postdoc Volga Kojasoy and graduate student Gerard Porter are also authors of the study.

Water-resistant

Collagen is the most abundant protein in animals, and it is found in not only bones but also skin, muscles, and ligaments. It’s made from long strands of protein that intertwine to form a tough triple helix.

“Collagen is the scaffold that holds us together,” Raines says. “What makes the collagen protein so stable, and such a good choice for this scaffold, is that unlike most proteins, it’s fibrous.”

In the past decade, paleobiologists have found evidence of collagen preserved in dinosaur fossils, including an 80-million-year-old Tyrannosaurus rex fossil, and a sauropodomorph fossil that is nearly 200 million years old.

Over the past 25 years, Raines’ lab has been studying collagen and how its structure enables its function. In the new study, they revealed why the peptide bonds that hold collagen together are so resistant to being broken down by water.

Peptide bonds are formed between a carbon atom from one amino acid and a nitrogen atom of the adjacent amino acid. The carbon atom also forms a double bond with an oxygen atom, forming a molecular structure called a carbonyl group. This carbonyl oxygen has a pair of electrons that don’t form bonds with any other atoms. Those electrons, the researchers found, can be shared with the carbonyl group of a neighboring peptide bond.

Because this pair of electrons is being inserted into those peptide bonds, water molecules can’t also get into the structure to disrupt the bond.

To demonstrate this, Raines and his colleagues created two interconverting mimics of collagen — the one that usually forms a triple helix, which is known as trans, and another in which the angles of the peptide bonds are rotated into a different form, known as cis. They found that the trans form of collagen did not allow water to attack and hydrolyze the bond. In the cis form, water got in and the bonds were broken.

“A peptide bond is either cis or trans, and we can change the cis to trans ratio. By doing that, we can mimic the natural state of collagen or create an unprotected peptide bond. And we saw that when it was unprotected, it was not long for the world,” Raines says.

“No weak link”

This sharing of electrons has also been seen in protein structures known as alpha helices, which are found in many proteins. These helices may also be protected from water, but the helices are always connected by protein sequences that are more exposed, which are still susceptible to hydrolysis.

“Collagen is all triple helices, from one end to the other,” Raines says. “There’s no weak link, and that’s why I think it has survived.”

Previously, some scientists have suggested other explanations for why collagen might be preserved for millions of years, including the possibility that the bones were so dehydrated that no water could reach the peptide bonds.

“I can’t discount the contributions from other factors, but 200 million years is a long time, and I think you need something at the molecular level, at the atomic level in order to explain it,” Raines says.

The research was funded by the National Institutes of Health and the National Science Foundation.

Journal Reference:
Jinyi Yang, Volga Kojasoy, Gerard J. Porter, Ronald T. Raines. Pauli Exclusion by n→π* Interactions: Implications for Paleobiology. ACS Central Science, 2024; DOI: 10.1021/acscentsci.4c00971

Note: The above post is reprinted from materials provided by Massachusetts Institute of Technology. Original written by Anne Trafton

What microscopic fossilized shells tell us about ancient climate change

Images of forams created by a scanning electronic microscope. Credit: Dustin Harper
Images of forams created by a scanning electronic microscope. Credit: Dustin Harper

At the end of the Paleocene and beginning of the Eocene epochs, between 59 to 51 million years ago, Earth experienced dramatic warming periods, both gradual periods stretching millions of years and sudden warming events known as hyperthermals.

Driving this planetary heat up were massive emissions of carbon dioxide (CO2) and other greenhouse gases, but other factors like tectonic activity may have also been at play.

New research led by University of Utah geoscientists pairs sea surface temperatures with levels of atmospheric CO2 during this period, showing the two were closely linked. The findings also provide case studies to test carbon cycle feedback mechanisms and sensitivities critical for predicting anthropogenic climate change as we continue pouring greenhouse gases into the atmosphere on an unprecedented scale in the planet’s history.

“The main reason we are interested in these global carbon release events is because they can provide analogs for future change,” said lead author Dustin Harper, a postdoctoral researcher in the Department of Geology & Geophysics. “We really don’t have a perfect analog event with the exact same background conditions and rate of carbon release.”

But the study published Monday in the Proceedings of the National Academy of Sciences, or PNAS, suggests emissions during two ancient “thermal maxima” are similar enough with today’s anthropogenic climate change to help scientists forecast its consequences.

The research team analyzed microscopic fossils — recovered in drilling cores taken from an undersea plateau in the Pacific — to characterize surface ocean chemistry at the time the shelled creatures were alive. Using a sophisticated statistical model, they reconstructed sea surface temperatures and atmospheric CO2 levels over a 6-million-year period that covered two hyperthermals, the Paleocene-Eocene Thermal Maximum, or PETM, 56 million years ago and Eocene Thermal Maximum 2, ETM-2, 54 million years ago.

The findings indicate that as atmospheric levels of CO2 rose, so too did global temperatures.

“We have multiple ways that our planet, that our atmosphere is being influenced by CO2 additions, but in each case, regardless of the source of CO2, we’re seeing similar impacts on the climate system,” said co-author Gabriel Bowen, a U professor of geology & geophysics.

“We’re interested in how sensitive the climate system was to these changes in CO2. And what we see in this study is that there’s some variation, maybe a little lower sensitivity, a lower warming associated with a given amount of CO2 change when we look at these very long-term shifts. But that overall, we see a common range of climate sensitivities.”

Today, human activities associated with fossil fuels are releasing carbon 4 to 10 times more rapidly than occurred during these ancient hyperthermal events. However, the total amount of carbon released during the ancient events is similar to the range projected for human emissions, potentially giving researchers a glimpse of what could be in store for us and future generations.

First scientists must determine what happened to the climate and oceans during these episodes of planetary heating more than 50 million years ago.

“These events might represent a mid- to worst-case scenario kind of case study,” Harper said. “We can investigate them to answer what’s the environmental change that happens due to this carbon release?”

Earth was very warm during the PETM. No ice sheets covered the poles and ocean temperatures in the mid-90s degrees Fahrenheit.

To determine oceanic CO2 levels the researchers turned to fossilized remains of foraminifera, a shelled single-cell organism akin to plankton. The research team based the study on cores previously extracted by the International Ocean Discovery Program at two locations in Pacific.

The foram shells accumulate small amounts of boron, the isotopes of which are a proxy reflecting CO2 concentrations in the ocean at the time the shells formed, according to Harper.

“We measured the boron chemistry of the shells, and we’re able to translate those values using modern observations to past seawater conditions. We can get at seawater CO2 and translate that into atmospheric CO2,” Harper said. “The goal of the target study interval was to establish some new CO2 and temperature records for the PETM and ETM-2, which represent two of the best analogs in terms of modern change, and also provide a longer-term background assessment of the climate system to better contextualize those events.”

The cores Harper studied were extracted from Shatsky Rise in the subtropical North Pacific, which is an ideal location for recovering ocean-bottom sediments that reflect conditions in the ancient past.

Carbonate shells dissolve if they settle into deep ocean, so scientists must look to underwater plateaus like Shatsky Rise, where the water depths are relatively shallow. While their inhabitants were living millions of years ago, the foraminifera shells record the sea surface conditions.

“Then they die and sink to the sea floor, and they’re deposited in about two kilometers of water depth,” Harper said. “We’re able to retrieve the complete sequence of the dead fossils. At these places in the middle of the ocean, you really don’t have a lot of sediment supply from continents, so it is predominantly these fossils and that’s all. It makes for a really good archive for what we want to do.”

Journal Reference:
Dustin T. Harper, Bärbel Hönisch, Gabriel J. Bowen, Richard E. Zeebe, Laura L. Haynes, Donald E. Penman, James C. Zachos. Long- and short-term coupling of sea surface temperature and atmospheric CO 2 during the late Paleocene and early Eocene. Proceedings of the National Academy of Sciences, 2024; 121 (36) DOI: 10.1073/pnas.2318779121

Note: The above post is reprinted from materials provided by University of Utah. Original written by Brian Maffly.

Matching dinosaur footprints found on opposite sides of the Atlantic Ocean

L. Theropod footprint from Sousa Basin, Lower Cretaceous of Northeastern Brazil. Credit: Ismar de Souza Carvalho. R. Theropod tracks from the Koum Basin in Cameroon. Credit: SMU.
L. Theropod footprint from Sousa Basin, Lower Cretaceous of Northeastern Brazil. Credit: Ismar de Souza Carvalho. R. Theropod tracks from the Koum Basin in Cameroon. Credit: SMU.

An international team of researchers led by SMU paleontologist Louis L. Jacobs has found matching sets of Early Cretaceous dinosaur footprints on what are now two different continents.

More than 260 footprints were discovered in Brazil and in Cameroon, showing where land-dwelling dinosaurs were last able to freely cross between South America and Africa millions of years ago before the two continents split apart.

“We determined that in terms of age, these footprints were similar,” Jacobs said. “In their geological and plate tectonic contexts, they were also similar. In terms of their shapes, they are almost identical.”

The footprints, impressed into mud and silt along ancient rivers and lakes, were found more than 3,700 miles, or 6,000 kilometers, away from each other. Dinosaurs made the tracks 120 million years ago on a single supercontinent known as Gondwana — which broke off from the larger landmass of Pangea, Jacobs said.

“One of the youngest and narrowest geological connections between Africa and South America was the elbow of northeastern Brazil nestled against what is now the coast of Cameroon along the Gulf of Guinea,” Jacobs explained. “The two continents were continuous along that narrow stretch, so that animals on either side of that connection could potentially move across it.”

Most of the dinosaur fossils were created by three-toed theropod dinosaurs.. A few were also likely made by sauropods or ornithischians, said Diana P. Vineyard, who is a research associate at SMU and co-author of the study.

Other co-authors of the study were Lawrence J. Flynn in the Department of Human Evolutionary Biology at Harvard University, Christopher R. Scotese in the Department of Earth and Planetary Sciences at Northwestern University and Ismar de Souza Carvalho at the Universidade Federal do Rio de Janeiro and Centro de Geociências.

The study was published by New Mexico Museum of Natural History & Science in a tribute to the late paleontologist Martin Lockley, who spent much of his career studying dinosaurs tracks and footprints.

Dinosaur footprints tell the whole story

Africa and South America started to split around 140 million years ago, causing gashes in Earth’s crust called rifts to open up along pre-existing weaknesses. As the tectonic plates beneath South America and Africa moved apart, magma from the Earth’s mantle rose to the surface, creating new oceanic crust as the continents moved away from each other. And eventually, the South Atlantic Ocean filled the void between these two newly-shaped continents.

Signs of some of those major events were evident between both locations where the dinosaur footprints were found — at the Borborema region in the northeast part of Brazil and the Koum Basin in northern Cameroon. Half-graben basins — geologic structures formed during rifting as the Earth’s crust pulls apart and faults form — are found in both areas and contain ancient river and lake sediments. Along with dinosaur tracks, these sediments contain fossil pollen that indicate an age of 120 million years.

Before the continental connection between Africa and South America was severed, “rivers flowed and lakes formed in the basins” Jacobs said. “Plants fed the herbivores and supported a food chain. Muddy sediments left by the rivers and lakes contain dinosaur footprints, including those of meat-eaters, documenting that these river valleys could provide specific avenues for life to travel across the continents 120 million years ago.”

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

Tracking down the asteroid that sealed the fate of the dinosaurs

Illustrated scene of dinosaurs and asteroid.
Illustrated scene of dinosaurs and asteroid. (© stock.adobe.com)

Geoscientists from the University of Cologne have led an international study to determine the origin of the huge piece of rock that hit the Earth around 66 million years ago and permanently changed the climate. The scientists analysed samples of the rock layer that marks the boundary between the Cretaceous and Paleogene periods. This period also saw the last major mass extinction event on Earth, in which around 70 percent of all animal species became extinct. The results of the study published in Science indicate that the asteroid formed outside Jupiter’s orbit during the early development of our solar system.

According to a widely accepted theory, the mass extinction at the Cretaceous-Paleogene boundary was triggered by the impact of an asteroid at least 10 kilometres in diameter near Chicxulub on the Yucatán Peninsula in Mexico.

On impact, the asteroid and large quantities of earth rock vaporized.

Fine dust particles spread into the stratosphere and obscured the sun.

This led to dramatic changes in the living conditions on the planet and brought photosynthetic activity to a halt for several years.

The dust particles released by the impact formed a layer of sediment around the entire globe.

This is why the Cretaceous-Paleogene boundary can be identified and sampled in many places on Earth.

It contains high concentrations of platinum-group metals, which come from the asteroid and are otherwise extremely rare in the rock that forms the Earth’s crust.

By analysing the isotopic composition of the platinum metal ruthenium in the cleanroom laboratory of the University of Cologne’s Institute of Geology and Mineralogy, the scientists discovered that the asteroid originally came from the outer solar system.

“The asteroid’s composition is consistent with that of carbonaceous asteroids that formed outside of Jupiter’s orbit during the formation of the solar system,” said Dr Mario Fischer-Gödde, first author of the study.

The ruthenium isotope compositions were also determined for other craters and impact structures of different ages on Earth for comparison. This data shows that within the last 500 million years, almost exclusively fragments of S-type asteroids have hit the Earth. In contrast to the impact at the Cretaceous-Paleogene boundary, these asteroids originate from the inner solar system. Well over 80 percent of all asteroid fragments that hit the Earth in the form of meteorites come from the inner solar system. Professor Dr Carsten Münker, co-author of the study, added: “We found that the impact of an asteroid like the one at Chicxulub is a very rare and unique event in geological time. The fate of the dinosaurs and many other species was sealed by this projectile from the outer reaches of the solar system.”

Reference:
Mario Fischer-Gödde, Jonas Tusch, Steven Goderis, Alessandro Bragagni, Tanja Mohr-Westheide, Nils Messling, Bo-Magnus Elfers, Birger Schmitz, Wolf U. Reimold, Wolfgang D. Maier, Philippe Claeys, Christian Koeberl, François L. H. Tissot, Martin Bizzarro, Carsten Münker. Ruthenium isotopes show the Chicxulub impactor was a carbonaceous-type asteroid. Science, 2024; 385 (6710): 752 DOI: 10.1126/science.adk4868

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

Decoding mysterious seismic signals

Earth’s interior. Credit: Michael Thorne
Earth’s interior. Credit: Michael Thorne

For the decades since their discovery, seismic signals known as PKP precursors have challenged scientists. Regions of Earth’s lower mantle scatter incoming seismic waves, which return to the surface as PKP waves at differing speeds.

The origin the precursor signals, which arrive ahead of the main seismic waves that travel through Earth’s core, has remained unclear, but research led by University of Utah geophysicists sheds new light on this mysterious seismic energy.

PKP precursors appear to propagate from places deep below North America and the western Pacific and possibly bear an association with “ultra-low velocity zones,” thin layers in the mantle where seismic waves significantly slow down, according to research published in AGU Advances, the American Geophysical Union’s lead journal. (The AGU highlighted the research in its magazine Eos.)

“These are some of the most extreme features discovered on the planet. We legitimately do not know what they are,” said lead author Michael Thorne, a U associate professor of geology and geophysics. “But one thing we know is they seem to end up accumulating underneath hotspot volcanoes. They seem like they may be the root of whole mantle plumes giving rise to hotspot volcanoes.”

These plumes are responsible for the volcanism observed at Yellowstone, the Hawaiian Islands, Samoa, Iceland and the Galapagos Islands.

“These really, really big volcanoes seem to persist for hundreds of millions of years in roughly the same spot,” Thorne said. In previous work, he also found one of the world’s largest known ultra-low velocity zones.

“It sits right beneath Samoa, and Samoa is one of the biggest hotspot volcanoes,” Thorne noted.

For nearly a century, geoscientists have used seismic waves to probe Earth’s interior, leading to numerous discoveries that would not be otherwise possible. Other researchers at the U, for example, have characterized the structure of Earth’s solid inner core and tracked its movement by analyzing seismic waves.

When an earthquake rattles Earth’s surface, seismic waves shoot through the mantle — the 2,900-kilometer-thick dynamic layer of hot rock between Earth’s crust and metal core. Thorne’s team is interested in those that get “scattered” when they pass through irregular features that pose changes in material composition in the mantle. Some of those scattered waves become PKP precursors.

Thorne sought to determine exactly where this scattering happens, especially since the waves travel through Earth’s mantle twice, that is, before and after passing through Earth’s liquid outer core. Because of that double journey through the mantle, it has been nearly impossible to distinguish whether the precursors originated on the source-side or receiver-side of the ray path.

Thorne’s team, which included research assistant professor Surya Pachhai, devised a way to model waveforms to detect crucial effects that previously went unnoticed.

Using a cutting-edge seismic array method and new theoretical observations from earthquake simulations, the researchers developed, they analyzed data from 58 earthquakes that occurred around New Guinea and were recorded in North America after passing through the planet.

“I can put virtual receivers anywhere on the surface of the earth, and this tells me what the seismogram should look like from an earthquake at that location. And we can compare that to the real recordings that we have,” Thorne said. “We’re able to now back project where this energy’s coming from.”

Their new method allowed them to pinpoint where the scattering occurred along the boundary between the liquid metal outer core and the mantle, known as the core-mantle boundary, located 2,900 kilometers below Earth’s surface.

Their findings indicate that the PKP precursors likely come from regions that are home to ultra-low velocity zones. Thorne suspects these layers, which are only 20 to 40 kilometers thick, are formed where subducted tectonic plates impinge on the core-mantle boundary in oceanic crust.

“What we’ve now found is that these ultra-low velocity zones do not just exist beneath the hotspots. They’re spread out all across the core-mantle boundary beneath North America,” Thorne said. “It really looks like these ULVZs are getting actively generated. We don’t know how. But because we’re seeing them near subduction, we think mid-ocean ridge basalts are getting melted, and that is how it’s getting generated. And then the dynamics is pushing these things all across Earth, and ultimately they’re going to accumulate beneath the hotspots.”

“What we’ve now found is that these ultra-low velocity zones do not just exist beneath the hotspots. They’re spread out all across the core-mantle boundary beneath North America,” Thorne said. “It really looks like these ULVZs are getting actively generated. We don’t know how. But because we’re seeing them near subduction, we think mid-ocean ridge basalts are getting melted, and that may be how they’re getting generated.”

The dynamics is pushing these things all across Earth, and ultimately, they’re going to accumulate against the boundaries of Large Low Velocity Provinces, which are compositionally distinct continent scale features beneath the Pacific and Africa, according to Thorne.

“They may additionally accumulate beneath the hotspots, but it is unclear if these ULVZs are generated by the same process,” he said. Determining the consequences of such a process will have to wait for future research.

Reference:
Michael S. Thorne, Surya Pachhai, Mingming Li, Jamie Ward, Sebastian Rost. Investigating Ultra‐Low Velocity Zones as Sources of PKP Scattering Beneath North America and the Western Pacific Ocean: Potential Links to Subducted Oceanic Crust. AGU Advances, 2024; 5 (4) DOI: 10.1029/2024AV001265

Note: The above post is reprinted from materials provided by University of Utah. Original written by Brian Maffly.

Scottish and Irish rocks confirmed as rare record of ‘snowball Earth’

An outcrop called ‘the Bubble’ on Eileach an Naoimh (Holy Isle). It shows a huge white rock fragment, tens of metres across, which was originally part of the underlying rock sequence. The layering in the carbonate rock has been squeezed tightly under immense pressure and transported by thick ice sheets to its final resting as one of many different rock fragments within a moraine. Credit: Graham Shields
An outcrop called ‘the Bubble’ on Eileach an Naoimh (Holy Isle). It shows a huge white rock fragment, tens of metres across, which was originally part of the underlying rock sequence. The layering in the carbonate rock has been squeezed tightly under immense pressure and transported by thick ice sheets to its final resting as one of many different rock fragments within a moraine. Credit: Graham Shields

A rock formation spanning Ireland and Scotland may be the world’s most complete record of “snowball Earth,” a crucial moment in planetary history when the globe was covered in ice, finds a new study led by UCL (University College London) researchers.

The study, published in the Journal of the Geological Society of London, found that the Port Askaig Formation, composed of layers of rock up to 1.1km thick, was likely laid down between 662 to 720 million years ago during the Sturtian glaciation — the first of two global freezes thought to have triggered the development of complex, multicellular life.

One exposed outcrop of the formation, found on Scottish islands called the Garvellachs, is unique as it shows the transition into “snowball Earth” from a previously warm, tropical environment.

Other rocks that formed at a similar time, for instance in North America and Namibia, are missing this transition.

Senior author Professor Graham Shields, of UCL Earth Sciences, said: “These rocks record a time when Earth was covered in ice. All complex, multicellular life, such as animals, arose out of this deep freeze, with the first evidence in the fossil record appearing shortly after the planet thawed.”

First author Elias Rugen, a PhD candidate at UCL Earth Sciences, said: “Our study provides the first conclusive age constraints for these Scottish and Irish rocks, confirming their global significance.

“The layers of rock exposed on the Garvellachs are globally unique. Underneath the rocks laid down during the unimaginable cold of the Sturtian glaciation are 70 metres of older carbonate rocks formed in tropical waters. These layers record a tropical marine environment with flourishing cyanobacterial life that gradually became cooler, marking the end of a billion years or so of a temperate climate on Earth.

“Most areas of the world are missing this remarkable transition because the ancient glaciers scraped and eroded away the rocks underneath, but in Scotland by some miracle the transition can be seen.”

The Sturtian glaciation lasted approximately 60 million years and was one of two big freezes that occurred during the Cryogenian Period (between 635 and 720 million years ago). For billions of years prior to this period, life consisted only of single-celled organisms and algae.

After this period, complex life emerged rapidly, in geologic terms, with most animals today similar in fundamental ways to the types of life forms that evolved more than 500 million years ago.

One theory is that the hostile nature of the extreme cold may have prompted the emergence of altruism, with single-celled organisms learning to co-operate with each other, forming multicellular life.

The advance and retreat of the ice across the planet was thought to have happened relatively quickly, over thousands of years, because of the albedo effect — that is, the more ice there is, the more sunlight is reflected back into space, and vice versa.

Professor Shields explained: “The retreat of the ice would have been catastrophic. Life had been used to tens of millions of years of deep freeze. As soon as the world warmed up, all of life would have had to compete in an arms race to adapt. Whatever survived were the ancestors of all animals.”

For the new study, the research team collected samples of sandstone from the 1.1km-thick Port Askaig Formation as well as from the older, 70-metre thick Garbh Eileach Formation underneath.

They analysed tiny, extremely durable minerals in the rock called zircons. These can be precisely dated as they contain the radioactive element uranium, which converts (decays) to lead at a steady rate. The zircons together with other geochemical evidence suggest the rocks were deposited between 662 and 720 million years ago.

The researchers said the new age constraints for the rocks may provide the evidence needed for the site to be declared as a marker for the start of the Cryogenian Period.

This marker, known as a Global Boundary Stratotype Section and Point (GSSP), is sometimes referred to as a golden spike, as a gold spike is driven into the rock to mark the boundary.

GSSPs attract visitors from around the world and in some cases museums have been established at the sites.

A group from the International Commission on Stratigraphy, a part of the International Union of Geological Sciences, visited the Garvellachs in July to assess the case for a golden spike on the archipelago. Currently, the islands are only accessible by chartering a boat or by sailing or kayaking to them.

The study involved researchers from UCL, the University of Milano-Bicocca, Italy, and Birkbeck University of London. The work was funded by the Natural Environment Research Council (NERC).

Reference:
Elias J. Rugen, Guido Pastore, Pieter Vermeesch, Anthony M. Spencer, David Webster, Adam G. G. Smith, Andrew Carter, Graham A. Shields. Glacially influenced provenance and Sturtian affinity revealed by detrital zircon U–Pb ages from sandstones in the Port Askaig Formation, Dalradian Supergroup. Journal of the Geological Society, 2024; 181 (5) DOI: 10.1144/jgs2024-029

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

Researchers unveil mysteries of ancient Earth

Structure layers of the earth.
Structure layers of the earth.

A team of researchers has made strides in understanding the formation of massif-type anorthosites, enigmatic rocks that only formed during the middle part of Earth’s history. These plagioclase-rich igneous rock formations, which can cover areas as large as 42,000 square kilometers and host titanium ore deposits, have puzzled scientists for decades due to conflicting theories about their origins.

A new study published in Science Advances on Aug. 14 highlights the intricate connections between Earth’s evolving mantle and crust and the tectonic forces that have shaped the planet throughout its history. It also provides new ways to explore when plate tectonics began, how subduction dynamics operated billions of years ago and the evolution of Earth’s crust.

The research team, led by Rice’s Duncan Keller and Cin-Ty Lee, studied massif-type anorthosites to test ideas about the magmas that formed them. The research focused on the Marcy and Morin anorthosites, classic examples from North America’s Grenville orogen that are about 1.1 billion years old.

By analyzing the isotopes of boron, oxygen, neodymium and strontium in the rocks as well as conducting petrogenetic modeling, the researchers discovered that the magmas that formed these anorthosites were rich in melts derived from oceanic crust altered by seawater at low temperatures. They also found isotopic signatures corresponding to other subduction zone rocks such as abyssal serpentinite.

“Our research indicates that these giant anorthosites likely originated from the extensive melting of subducted oceanic crust beneath convergent continental margins,” said Keller, the Clever Planets Postdoctoral Research Associate, Earth, Environmental and Planetary Sciences and the study’s lead author. “Because the mantle was hotter in the past, this process directly connects the formation of massif-type anorthosites to Earth’s thermal and tectonic evolution.”

The study, which combines classical methods with the novel application of boron isotopic analysis to massif-type anorthosites, suggests that these rocks formed during very hot subduction that may have been prevalent billions of years ago.

Because massif-type anorthosites don’t form on Earth today, the new evidence linking these rocks to very hot subduction on the early Earth opens new interdisciplinary approaches for understanding how these rocks chronicle the physical evolution of our planet.

“This research advances our understanding of ancient rock formations and sheds light on the broader implications for Earth’s tectonic and thermal history,” said Lee, the Harry Carothers Wiess Professor of Geology, professor of Earth, environmental and planetary sciences and study co-author.

The study’s other co-authors include William Peck of the Department of Earth and Environmental Geosciences at Colgate University; Brian Monteleone of the Department of Geology and Geophysics at Woods Hole Oceanographic Institution; Céline Martin of the Department of Earth and Planetary Sciences at the American Museum of Natural History; Jeffrey Vervoort of the School of the Environment at Washington State University; and Louise Bolge of the Lamont-Doherty Earth Observatory at Columbia University.

This study was supported by NASA and the U.S. National Science Foundation.

Reference:
Duncan S. Keller, Cin-Ty A. Lee, William H. Peck, Brian D. Monteleone, Céline Martin, Jeffrey D. Vervoort, Louise Bolge. Mafic slab melt contributions to Proterozoic massif-type anorthosites. Science Advances, 2024; 10 (33) DOI: 10.1126/sciadv.adn3976

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

Water delivered to the mantle by aluminum enriched hydrated slabs?

Effect of Al + H incorporation on the sound velocities of superhydrous phase BSchematic representation of the incorporation of aluminum together with water (as Al + H) in the crystal structure of superhydrous phase B. credit : Geodynamics Research Center, Ehime University
Effect of Al + H incorporation on the sound velocities of superhydrous phase B
Schematic representation of the incorporation of aluminum together with water (as Al + H) in the crystal structure of superhydrous phase B.
credit : Geodynamics Research Center, Ehime University

Researchers at the Geodynamics Research Center (GRC), Ehime University, found a notable effect of aluminum on the sound velocities of superhydrous phase B, a dense hydrous magnesium silicate and potential host of water in the deep Earth. Their results, which employed X-ray synchrotron radiation and ultrasonic measurements in a large volume press apparatus, suggest that aluminous phase B could explain seismic velocity anomalies in the Earth’s mantle transition region and uppermost lower mantle.

Dense Hydrous Magnesium Silicates (DHMSs) are generally considered as primary water carriers from the shallow lithosphere to the deep mantle transition region (MTR; 410-660 km in depth). Among DHMSs, Superhydrous phase B (hereafter, SuB) holds the chemical formula, Mg10Si3H3O18. This phase is believed to hold a large amount of water and thus may have an important role in the water storage capacity of the MTR and the transportation of water to the deeper parts of the Earth’s interior; but because of its relative instability against the high temperature of the Earth’s mantle, SuB is generally associated with cold regions, such as the inner parts of the subducted slab.

A recent experimental study conducted at Ehime University, however, showed that when aluminum incorporates SuB, its stability against temperature is drastically improved (Kakizawa et al., AmMin 2018), allowing this mineral to remain stable at pressure and temperature conditions matching those of the Earth’s lower mantle.

In 2022, the same Ehime University research team reported the longitudinal (VP) and shear (VS) velocities of SuB (Xu et al., GRL 2022) using the X-ray and ultrasonic techniques implemented in a multi-anvil apparatus at the beamline BL04B1, located at the synchrotron facility, SPring-8, in Japan.

The results showed that the presence of SuB could be correlated with the low seismic velocities observed in subducted slab regions.

This time, they carried out similar high pressure and high temperature measurements on SuB samples doped with aluminum.

Their new data suggest that incorporation of aluminum in SuB promotes unusual variations of velocities with an increase in water content compared to the velocities of SuB without aluminum.

This new finding, in addition to the knowledge that the stability against temperature and capacity to store water of SuB are improved when aluminum is present in its structure, suggests that the Al-bearing SuB may account for seismically visible anomalies at the bottom of the MTR and beneath subduction zones in the uppermost lower mantle. These results should greatly contribute to tracing the existence and recycling of the former hydrated lithospheric crust in the Earth’s lower mantle and interpreting seismic velocities in terms of mantle composition, and estimate the amount of water that could be passed down to the deep mantle.

Reference:
Chaowen Xu, Steeve Gréaux, Ying Li, Fengxia Sun, Jing Gao, Fei Qin, Toru Inoue. Effect of Al‐Incorporation on the Sound Velocities of Superhydrous Phase B at High Pressure and High Temperature. Geophysical Research Letters, 2024; 51 (12) DOI: 10.1029/2023GL107818

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

Scientists uncover hidden forces causing continents to rise

Satellite image of the Great Escarpment in southern Africa from the Sentinel Hub Earth Observation Browser. Taken using the Sentinel-2 L1C dataset, in May 2020. Credit: Prof Tom Gernon, University of Southampton.
Satellite image of the Great Escarpment in southern Africa from the Sentinel Hub Earth Observation Browser. Taken using the Sentinel-2 L1C dataset, in May 2020. Credit: Prof Tom Gernon, University of Southampton.

Scientists at the University of Southampton have answered one of the most puzzling questions in plate tectonics: how and why ‘stable’ parts of continents gradually rise to form some of the planet’s greatest topographic features.

They have found that when tectonic plates break apart, powerful waves are triggered deep within the Earth that can cause continental surfaces to rise by over a kilometre.

Their findings help resolve a long-standing mystery about the dynamic forces that shape and connect some of the Earth’s most dramatic landforms — expansive topographic features called ‘escarpments’ and ‘plateaus’ that profoundly influence climate and biology.

The new research, led by the University of Southampton, examined the effects of global tectonic forces on landscape evolution over hundreds of millions of years. The findings are published today (07/08/2024) in the journal Nature.

Tom Gernon, Professor of Earth Science at the University of Southampton and lead author of the study said: “Scientists have long suspected that steep kilometre-high topographic features called Great Escarpments — like the classic example encircling South Africa — are formed when continents rift and eventually split apart. However, explaining why the inner parts of continents, far from such escarpments, rise and become eroded has proven much more challenging. Is this process even linked to the formation of these towering escarpments? Put simply, we didn’t know.”

The vertical motions of the stable parts of continents, called cratons, remain one of the least understood aspects of plate tectonics.

The team from the University of Southampton, including Dr Thea Hincks, Dr Derek Keir, and Alice Cunningham, collaborated with colleagues from the Helmholtz Centre Potsdam — GFZ German Research Centre for Geosciences and the University of Birmingham to address this fundamental question.

Their results help explain why parts of the continents previously thought of as ‘stable’ experience substantial uplift and erosion, and how such processes can migrate hundreds or even thousands of kilometres inland, forming sweeping elevated regions known as plateaus, like the Central Plateau of South Africa.

Linking diamonds with landscape evolution

Building on their study linking diamond eruptions to continental breakup, published last year in Nature, the team used advanced computer models and statistical methods to interrogate how the Earth’s surface has responded to the breakup of continental plates through time.

They discovered that when continents split apart, the stretching of the continental crust causes stirring movements in Earth’s mantle (the voluminous layer between the crust and the core).

Professor Sascha Brune, who leads the Geodynamic Modelling Section at GFZ Potsdam, said: “This process can be compared to a sweeping motion that moves towards the continents and disturbs their deep foundations.”

Professor Brune and Dr Anne Glerum, also based at Potsdam, ran simulations to investigate how this process unfolds. The team noticed an interesting pattern: the speed of the mantle ‘waves’ moving under the continents in their simulations closely match the speed of major erosion events that swept across the landscape in Southern Africa following the breakup of the ancient supercontinent Gondwana.

The scientists pieced together evidence to propose that the Great Escarpments originate at the edges of ancient rift valleys, much like the steep walls seen at the margins of the East African Rift today. Meanwhile, the rifting event also sets about a ‘deep mantle wave’ that travels along the continent’s base at about 15-20 kilometres per million years.

They believe that this wave convectively removes layers of rock from the continental roots.

“Much like how a hot-air balloon sheds weight to rise higher, this loss of continental material causes the continents to rise — a process called isostasy,” said Professor Brune.

Building on this, the team modelled how landscapes respond to this mantle-driven uplift. They found that migrating mantle instabilities give rise to a wave of surface erosion that lasts tens of millions of years and moves across the continent at a similar speed. This intense erosion removes a huge weight of rock that causes the land surface to rise further, forming elevated plateaus.

“Our landscape evolution models show how a sequence of events linked to rifting can result in an escarpment as well as a stable, flat plateau, even though a layer of several thousands of meters of rocks has been eroded away,” explained Jean Braun, Professor of Earth Surface Process Modelling at GFZ Potsdam, also based at the University of Potsdam.

The team’s study provides a new explanation for the puzzling vertical movements of cratons far from the edges of continents, where uplift is more common.

Dr Steve Jones, Associate Professor in Earth Systems at the University of Birmingham, added: “What we have here is a compelling argument that rifting can, in certain circumstances, directly generate long-lived continental scale upper mantle convection cells, and these rift-initiated convective systems have a profound effect on Earth’s surface topography, erosion, sedimentation and the distribution of natural resources.”

The team has concluded that the same chain of mantle disturbances that trigger diamonds to quickly rise from Earth’s deep interior also fundamentally shape continental landscapes, influencing a host of factors from regional climates and biodiversity to human settlement patterns.

Professor Gernon, who was awarded a major philanthropic grant from the WoodNext Foundation, administered by Greater Houston Community Foundation, to study global cooling, explained that continental breakup disturbs not only the deep layers of the Earth but also has effects that reverberate across the surface of the continents, previously thought to be stable.

“Destabilising the cores of the continents must have impacted ancient climates too,” concluded Professor Gernon.

Reference:
Thomas M. Gernon, Thea K. Hincks, Sascha Brune, Jean Braun, Stephen M. Jones, Derek Keir, Alice Cunningham, Anne Glerum. Coevolution of craton margins and interiors during continental break-up. Nature, 2024; 632 (8024): 327 DOI: 10.1038/s41586-024-07717-1

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

Millions of years for plants to recover from global warming

Drone imagery of April 2024 eruption at Sundhnúkur, Iceland. Photo: Geoffrey Cook/Scripps Oceanography
Drone imagery of April 2024 eruption at Sundhnúkur, Iceland. Photo: Geoffrey Cook/Scripps Oceanography

Scientists often seek answers to humanity’s most pressing challenges in nature. When it comes to global warming, geological history offers a unique, long-term perspective. Earth’s geological history is spiked by periods of catastrophic volcanic eruptions that released vast amounts of carbon into the atmosphere and oceans. The increased carbon triggered rapid climate warming that resulted in mass extinctions on land and in marine ecosystems. These periods of volcanism may also have disrupted carbon-climate regulation systems for millions of years.

Ecological imbalance

Earth and environmental scientists at ETH Zurich led an international team of researchers from the University of Arizona, University of Leeds, CNRS Toulouse, and the Swiss Federal Institute for Forest Snow and Landscape Research (WSL) in a study on how vegetation responds and evolves in response to major climatic shifts and how such shifts affect Earth’s natural carbon-climate regulation system.

Drawing on geochemical analyses of isotopes in sediments, the research team compared the data with a specially designed model, which included a representation of vegetation and its role in regulating the geological climate system.

They used the model to test how the Earth system responds to the intense release of carbon from volcanic activity in different scenarios.

They studied three significant climatic shifts in geological history, including the Siberian Traps event that caused the Permian-Triassic mass extinction about 252 million years ago.

ETH Zurich professor, Taras Gerya points out, “The Siberian Traps event released some 40,000 gigatons (Gt) of carbon over 200,000 years. The resulting increase in global average temperatures between 5 — 10°C caused Earth’s most severe extinction event in the geologic record.”

Move, adapt, or perish

“The recovery of vegetation from the Siberian Traps event took several millions of years and during this time Earth’s carbon-climate regulation system would have been weak and inefficient resulting in long-term climate warming,” explains lead author, Julian Rogger, ETH Zurich.

Researchers found that the severity of such events is determined by how fast emitted carbon can be returned to Earth’s interior — sequestered through silicate mineral weathering or organic carbon production, removing carbon from Earth’s atmosphere.

They also found that the time it takes for the climate to reach a new state of equilibrium depended on how fast vegetation adapted to increasing temperatures.

Some species adapted by evolving and others by migrating geographically to cooler regions.

However, some geological events were so catastrophic that plant species simply did not have enough time to migrate or adapt to the sustained increase in temperature.

The consequences of which left its geochemical mark on climate evolution for thousands, possibly millions, of years.

Today’s human-induced climate crisis

What does this mean for human induced climate change? The study found that a disruption of vegetation increased the duration and severity of climate warming in the geologic past.

In some cases, it may have taken millions of years to reach a new stable climatic equilibrium due to a reduced capacity of vegetation to regulate Earth’s carbon cycle.

“Today, we find ourselves in a major global bioclimatic crisis,” comments Loïc Pellissier, Professor of Ecosystems and Landscape Evolution at ETH Zurich and WSL. “Our study demonstrates the role of a functioning of vegetation to recover from abrupt climatic changes. We are currently releasing greenhouse gases at a faster rate than any previous volcanic event. We are also the primary cause of global deforestation, which strongly reduces the ability of natural ecosystems to regulate the climate. This study, in my perspective, serves as ‘wake-up call’ for the global community.”

Reference:
Julian Rogger, Emily J. Judd, Benjamin J. W. Mills, Yves Goddéris, Taras V. Gerya, Loïc Pellissier. Biogeographic climate sensitivity controls Earth system response to large igneous province carbon degassing. Science, 2024; 385 (6709): 661 DOI: 10.1126/science.adn3450

Note: The above post is reprinted from materials provided by ETH Zurich. Original written by Marianne Lucien.

Fossil shows how penguins’ wings evolved

A reconstructed image of Pakudyptes at a New Zealand coast. PHOTO: Tatsuya Shinmura & Ashoro Museum of Paleontology
A reconstructed image of Pakudyptes at a New Zealand coast. PHOTO: Tatsuya Shinmura & Ashoro Museum of Paleontology

A tiny fossil penguin plays a huge role in the evolutionary history of the bird, an international study shows.

Published in the Journal of the Royal Society of New Zealand, the study describes a new species of fossil penguin which lived in Otago about 24 million years ago.

Named Pakudyptes hakataramea, the penguin was very small — about the same size as the little blue penguin, the smallest in the world — with anatomical adaptations that allowed it to dive.

Lead author Dr Tatsuro Ando, formerly a PhD candidate at the University of Otago — Ōtākou Whakaihu Waka and now at the Ashoro Museum of Palentology in Japan, collaborated with researchers from Otago, Okayama University of Science and Osaka University.

Dr Ando’s inspiration for the paper came from discussions with the late Professor Ewan Fordyce, his supervisor and mentor at Otago.

Researchers analysed three bones — a humerus, femur and ulna — found by Professor Fordyce in the Hakataramea Valley, South Canterbury.

Dr Ando says Pakudyptes fills a morphological gap between modern and fossil penguins.

“In particular, the shape of the wing bones differed greatly, and the process by which penguin wings came to have their present form and function remained unclear,” he says.

The humerus and ulna highlight how penguins’ wings have evolved.

“Surprisingly, while the shoulder joints of the wing of Pakudyptes were very close to the condition of the present-day penguin, the elbow joints were very similar to those of older types of fossil penguins.

“Pakudyptes is the first fossil penguin ever found with this combination, and it is the ‘key’ fossil to unlocking the evolution of penguin wings.”

Co-author Dr Carolina Loch, from Otago’s Faculty of Dentistry, says analysis of the internal bone structure conducted at the Faculty of Dentistry, with comparison with data on living penguins provided from the Okayama University of Science, shows these penguins had microanatomical features suggestive of diving.

Modern penguins have excellent swimming abilities, largely due to their dense, thick bones that contribute to buoyancy during diving.

In Pakudyptes, the bone cortex was reasonably thick although the medullary cavity, which contains bone marrow, was open, similar to what we see in the modern little blue penguin, which tends to swim in shallow waters.

The ability for Pakudyptes to dive and swim comes down to the distinctive combination of its bones.

Bones such as the humerus and ulna show areas for attachment of muscles and ligaments which reveal how the wings were being used to swim and manoeuvre under water.

Dr Loch says fossil penguins were usually large, about 1m in height.

“Penguins evolved rapidly from the Late Oligocene to Early Miocene and Pakudyptes is an important fossil from this period. Its small size and unique combination of bones may have contributed to the ecological diversity of modern penguins.”

Reference:
Tatsuro Ando, Jeffrey Robinson, Carolina Loch, Tamon Nakahara, Shoji Hayashi, Marcus D. Richards, Robert Ewan Fordyce. A new tiny fossil penguin from the Late Oligocene of New Zealand and the morphofunctional transition of the penguin wing. Journal of the Royal Society of New Zealand, 2024; 1 DOI: 10.1080/03036758.2024.2362283

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

Scientists assess how large dinosaurs could really get

Skeleton of the largest-known T. rex (foreground) and silhouette of the largest possible giant T. rex. Credit: Mark Witton.
Skeleton of the largest-known T. rex (foreground) and silhouette of the largest possible giant T. rex. Credit: Mark Witton.

A new study published today in the scientific journal Ecology and Evoiution looks at the maximum possible sizes of dinosaurs, using the carnivore, Tyrannosaurus rex, as an example. Using computer modelling, Dr. Jordan Mallon of the Canadian Museum of Nature and Dr. David Hone of Queen Mary University of London, produced estimates that T. Rex might have been 70% heavier than what the fossil evidence suggests.

The researchers assert that the huge sizes attained by many dinosaurs make them a source of endless fascination, raising the question as to how these animals evolved to be so big. There are perennial claims and counter-claims about which dinosaur species was the largest of its group or even the largest ever.

Most dinosaur species are known from only one or a handful of specimens, so it’s extraordinarily unlikely that their size ranges will include the largest individuals that ever existed. The question remains: how big were the largest individuals, and are we likely to find them?

To address this question, Mallon and Hone used computer modelling to assess a population of T. rex. They factored in variables such as population size, growth rate, lifespan, the incompleteness of the fossil record, and more.

T. rex was chosen for the model because it is a familiar dinosaur for which many of these details are already well estimated. Body-size variance at adulthood, which is still poorly known in T. rex, was modelled with and without sex differences, and is based on examples of living alligators, chosen for their large size and close kinship with the dinosaurs.

The palaeontologists found that the largest known T. rex fossils probably fall in the 99th percentile, representing the top 1% of body size, but to find an animal in the top 99.99% (a one-in-ten-thousand individual) scientists would need to excavate fossils at the current rate for another 1,000 years.

The computer models suggest that the largest individual that could have existed (one in 2.5 billion animals) may have been 70% more massive than the current largest-known T. rex specimens (an estimated 15 tonnes vs 8.8 tonnes) and 25% longer (15 metres vs 12 metres).

The values are estimates based on the model, but patterns of discovery of giants of modern species tell us there must have been larger dinosaurs out there that have not yet been found. “Some isolated bones and pieces certainly hint at still larger individuals than for which we currently have skeletons,” says Hone.

This study adds to the debates about the largest fossil animals. Many of the largest dinosaurs in various groups are known from a single good specimen, so it’s impossible to know if that one animal was a big or small example of the species. An apparently large species might be based on a single giant individual, and a small species based on a particularly tiny individual — neither of which reflect the average size of their respective species.

The chances that palaeontologists will find the largest ever individuals for a given species are incredibly small. So, despite the giant skeletons that can be seen in museums around the world, the very largest individuals of these species were likely even larger than those on display.

Dr. Jordan Mallon, from the Canadian Museum of Nature, said: “Our study suggests that, for big fossil animals like T. rex, we really have no idea from the fossil record about the absolute sizes they might have reached. It’s fun to think about a 15 tonne T. rex, but the implications are also interesting from a biomechanical or ecological perspective.”

Reference:
Jordan C. Mallon, David W. E. Hone. Estimation of maximum body size in fossil species: A case study using Tyrannosaurus rex. Ecology and Evolution, 2024; 14 (7) DOI: 10.1002/ece3.11658

Note: The above post is reprinted from materials provided by Canadian Museum of Nature.

Research tracks 66 million years of mammalian diversity

The Syndyoceras existed for 4.2 million years during the Cenozoic era on the North American continent. This skeletal display can be found in the University of Nebraska State Museum–Morill Hall.
The Syndyoceras existed for 4.2 million years during the Cenozoic era on the North American continent. This skeletal display can be found in the University of Nebraska State Museum–Morill Hall.

When trying to understand the present, it’s helpful to look to history. New research from the University of Nebraska-Lincoln examined the fossil record going back 66 million years and tracked changes to mammalian ecosystems and species diversity on the North American continent.

The study, led by Alex Shupinski, who earned her doctorate in May, and co-authored by Kate Lyons, associate professor in the School of Biological Sciences, provides a large-scale view of how species diversity changed over the first 65 million years of the Cenozoic era — up until the arrival of humans — and how climate and other environmental factors, including changing landscapes, affected animal life on the continent.

The findings published in Proceedings of the Royal Society B also provide a glimpse into how mammals rebounded following the last mass extinction event — the eradication of non-avian dinosaurs.

“Beginning 66 million years ago, we go from a completely sub-tropical environment across North America to grasslands to a frozen savanna, and finally, reaching the Ice Age,” Shupinski said. “It’s showing how species changed through time, through many ecological, environmental and climatic changes and it allows us to compare across those events and at different spatial scales.”

The researchers sliced the fossil record of the Cenozoic era into million-year increments and used three indices of functional diversity — which quantifies changes in community structures using mammalian traits — to examine mammalian communities on both a local and continental scale.

For most of the Cenozoic era, local and continental measures of functional diversity differed, but surprisingly, during the first 10 million years of the era, immediately following the extinction of non-avian dinosaurs, all measures of functional diversity, both locally and across the continent, increased.

“That was fascinating to see, that for most of the Cenozoic, functional diversity was uncoupled across time and spatial scales, except this one time,” Shupinski said. “For 10 million years, all the measures are changing in the same way. Then, around 56 million years ago, we get this massive immigration of mammals into North America from other continents, and at that point, we see a divergence of functional diversity.

“Communities are changing at different times, at different rates and in different directions,” she said. “We might see locally, the diversity of roles increasing, but continentally, they’re decreasing.”

Lyons said that some of the changes among mammalian species can be explained by environmental changes, including cooling and warming periods or when heavily forested areas were usurped by grasslands, but that the large-scale environmental changes did not rise to the level of disruption caused by the mass extinction of dinosaurs.

“That is why this could potentially be a way to pinpoint areas of the globe or communities that are under particular stress,” Lyons said. “We may be entering a sixth mass extinction event, and if so, we might expect to see communities that are on the vanguard of that extinction respond in a similar way, based on the patterns we see after the extinction of the non-avian dinosaurs.”

In the field of conservation paleobiology, tracking past changes in ecosystems over long periods of time helps scientists and the public better understand biodiversity crises happening today, and this current study offers a thorough analysis of the age of mammals and hints at what may come next.

“If we are looking at the modern (crises) and we see a similar response in the functional diversity of modern community structures, it may be a conservation tool as we can highlight some of these communities that are experiencing the most disturbance and that are at highest risk of change and disturbance in their ecological services and function,” Shupinski said.

Additional authors on the study are Peter Wagner, professor of Earth and atmospheric sciences at Nebraska, and Felisa Smith of the University of New Mexico, Albuquerque.

Reference:
Alex B. Shupinski, Peter J. Wagner, Felisa A. Smith, S. Kathleen Lyons. Unique functional diversity during early Cenozoic mammal radiation of North America. Proceedings of the Royal Society B: Biological Sciences, 2024; 291 (2026) DOI: 10.1098/rspb.2024.0778

Note: The above post is reprinted from materials provided by University of Nebraska-Lincoln. Original written by Deann Gayman.

Komodo dragons have iron-coated teeth to rip apart their prey

Komodo dragon. Credit: Charlotte Ellis, Zoological Society of London
Komodo dragon. Credit: Charlotte Ellis, Zoological Society of London

Scientists have discovered that the serrated edges of Komodo dragons’ teeth are tipped with iron.

Led by researchers from King’s College London, the study gives new insight into how Komodo dragons keep their teeth razor-sharp and may provide clues to how dinosaurs like Tyrannosaurus rex killed and ate their prey.

Native to Indonesia, Komodo dragons are the largest living species of monitor lizard, averaging around 80kg. Deadly predators, Komodos have sharp, curved teeth similar to many carnivorous dinosaurs. They eat almost any kind of meat, from smaller reptiles and birds to deer, horses or water buffalo, pulling and tearing at their prey to rip flesh apart.

The researchers discovered that many reptiles have some iron in their teeth, but Komodo dragons have concentrated the iron along the cutting edges and tips of their teeth, staining them orange. Crocodiles and other monitor lizards, by comparison, have so little that the iron is often invisible.

To understand the chemical and structural make-up of Komodo dragon’s teeth, scientists scoured museums for skulls and teeth of Komodo dragons and studied the teeth of Ganas, the 15-year-old Komodo dragon who had lived at ZSL conservation zoo, London Zoo.

Through advanced imaging and chemical analysis, the team was able to observe that the iron in Komodo dragons’ enamel is concentrated into a thin coating on top of their tooth serrations and tips. This protective layer keeps the serrated edges of their teeth sharp and ready to be used at a moment’s notice.

The research, published today in Nature Ecology & Evolution, leads to new questions and avenues for research into how extinct species such as dinosaurs lived and ate.

Dr Aaron LeBlanc, lecturer in Dental Biosciences at King’s College London and the study’s lead author said: “Komodo dragons have curved, serrated teeth to rip and tear their prey just like those of meat-eating dinosaurs. We want to use this similarity to learn more about how carnivorous dinosaurs might have ate and if they used iron in their teeth the same way as the Komodo dragon.

“Unfortunately, using the technology we have at the moment, we can’t see whether fossilised dinosaur teeth had high levels of iron or not. We think that the chemical changes which take place during the fossilisation process obscure how much iron was present to start with.

“What we did find, though, was that larger meat-eating dinosaurs, like tyrannosaurs, did change the structure of the enamel itself on the cutting edges of their teeth. So, while Komodo dragons have altered the chemistry of their teeth, some dinosaurs altered the structure of their dental enamel to maintain a sharp cutting edge.

“With further analysis of the Komodo teeth we may be able to find other markers in the iron coating that aren’t changed during fossilisation. With markers like that we would know with certainty whether dinosaurs also had iron-coated teeth and have a greater understanding of these ferocious predators.”

Dr Benjamin Tapley, Curator of Reptiles and Amphibians at ZSL and co-author on the study said: “As the world’s largest lizards, Komodo dragons are inarguably impressive animals. Having worked with them for 12 years at London Zoo, I continue to be fascinated by them and these findings further emphasise just how incredible they are.

“Komodo dragons are sadly endangered, so in addition to strengthening our understanding of how iconic dinosaurs might have lived, this discovery also helps us build a deeper understanding of these amazing reptiles as we work to protect them.”

Reference:
Aaron R. H. LeBlanc, Alexander P. Morrell, Slobodan Sirovica, Maisoon Al-Jawad, David Labonte, Domenic C. D’Amore, Christofer Clemente, Siyang Wang, Finn Giuliani, Catriona M. McGilvery, Michael Pittman, Thomas G. Kaye, Colin Stevenson, Joe Capon, Benjamin Tapley, Simon Spiro, Owen Addison. Iron-coated Komodo dragon teeth and the complex dental enamel of carnivorous reptiles. Nature Ecology & Evolution, 2024; DOI: 10.1038/s41559-024-02477-7

Note: The above post is reprinted from materials provided by King’s College London.

A new species of extinct crocodile relative rewrites life on the Triassic coastline

Benggwigwishingasuchus eremicarminis on the Panthalassan Ocean coast artwork by Jorge Gonzalez
Benggwigwishingasuchus eremicarminis on the Panthalassan Ocean coast
artwork by Jorge Gonzalez

The surprising discovery of a new species of extinct crocodile relative from the Triassic Favret Formation of Nevada, USA, rewrites the story of life along the coasts during the first act of the Age of Dinosaurs. Described in a study published in Biology Letters, the new species Benggwigwishingasuchus eremicarminis reveals that while giant ichthyosaurs ruled the oceans, the ancient crocodile kin known as pseudosuchian archosaurs ruled the shores across the Middle Triassic globe between 247.2 and 237 million years ago.

“This exciting new species demonstrates that pseudosuchians were occupying coastal habitats on a global basis during the Middle Triassic,” said Dr. Nate Smith, lead author of the paper, and Gretchen Augustyn Director and Curator of the Dinosaur Institute at the Natural History Museum of Los Angeles County.

Capturing fossil life from the eastern Panthalassan Ocean of the Triassic, the locality that includes the Favret Formation is known for fossils of sea-going creatures like ammonites along with marine reptiles like the giant ichthyosaur C. youngorum — finding the newly described B. eremicarminis came as a bit of a shock.

“Our first reaction was: What the hell is this?” said co-author Dr. Nicole Klein of the University of Bonn. “We were expecting to find things like marine reptiles. We couldn’t understand how a terrestrial animal could end up so far out in the sea among the ichthyosaurs and ammonites. It wasn’t until seeing the nearly completely prepared specimen in person that I was convinced it really was a terrestrial animal.”

Pseudosuchian archosaurs have been unearthed in fossil beds from the shores of the ancient Tethys Ocean, but this is the first coastal representative from the Panthalassan Ocean and western hemisphere, revealing that these crocodile relatives were present in coastal environments worldwide during the Middle Triassic. Interestingly, these coastal species aren’t all from the same evolutionary group, suggesting that pseudosuchians (and archosauriforms more broadly) were independently adapting to life along the shores.

“Essentially, it looks like you had a bunch of very different archosauriform groups deciding to dip their toes in the water during the Middle Triassic. What’s interesting, is that it doesn’t look like many of these ‘independent experiments’ led to broader radiations of semi-aquatic groups,” said Smith.

During the Triassic, archosaurs, “the ruling reptiles,” arose and split into two groups with two surviving representatives: birds, the descendants of dinosaurs, and crocodilians (alligators, crocodiles, and gharials), the descendants of pseudosuchian archosaurs like B. eremicarminis. While today’s crocodilians are similar enough to be mistaken for one another by most people, their ancient relatives varied wildly in size and lifestyle. The evolutionary relationships of B. eremicarminis and its relatives suggest that pseudosuchians achieved great diversity very quickly following the End-Permian mass extinction — the extent of which is waiting to be discovered in the fossil record.

“A growing number of recent discoveries of Middle Triassic pseudosuchians are hinting that an underappreciated amount of morphological and ecological diversity and experimentation was happening early in the group’s history. While a lot of the public’s fascination with the Triassic focuses on the origin of dinosaurs, it’s really the pseudosuchians that were doing interesting things at the beginning of the Mesozoic,” Smith said.

The new species underlines the multiplicity of these ancient reptiles during the Triassic, from giants like Mambawakale ruhuhu to smaller animals like the newly described B. eremicarminis, which probably reached around 5-6 feet in length. Exactly how long B. eremicarminis was and how it survived along the coasts remains shrouded in the past. Only a few elements of the individual’s skull were found, and any clues to how it fed and hunted are similarly absent. What’s more clear is that B. eremicarminis likely stuck pretty close to the shore. Its well-preserved limbs are well-developed without any of the signs of aquatic living like flippers or altered bone density.

The research team wanted a name that paid respect to the original human inhabitants of the Augusta Mountains where the specimen was found, and so consulted a member of the Fallon Paiute Shoshone Tribe to decide on an appropriate name.”Benggwi-Gwishinga,” a word that means “catching fish” in Shoshone, was combined with the Greek word for Sobek, the Egyptian crocodile-headed god, to coin the new genus, Benggwigwishingasuchus. The specific epithet eremicarminis translates to “desert song,” honoring two supporters of NHMLAC who have a passion for the paleontology and opera of the Southwest. Thus, the full name is meant to translate roughly as “Fisherman Croc’s Desert Song.”

Reference:
Nathan D. Smith, Nicole Klein, P. Martin Sander, Lars Schmitz. A new pseudosuchian from the Favret Formation of Nevada reveals that archosauriforms occupied coastal regions globally during the Middle Triassic. Biology Letters, 2024; 20 (7) DOI: 10.1098/rsbl.2024.0136

Note: The above post is reprinted from materials provided by Natural History Museum of Los Angeles County.

New model refutes leading theory on how Earth’s continents formed

Continental plates around Greenland.
This is a visualization of the continental plates around Greenland. Credit: NASA’s Goddard Space Flight Center

The formation of Earth’s continents billions of years ago set the stage for life to thrive. But scientists disagree over how those land masses formed and if it was through geological processes we still see today.

A recent paper from the University of Illinois Chicago’s David Hernández Uribe in Nature Geoscience adds new information to that debate, poking holes in the leading theory of continent formation.

Hernández Uribe used computer models to study the formation of magmas thought to hold clues to the origin of continents.

Magma is the molten substance that, when it cools, forms rocks and minerals.

Hernández Uribe looked for magmas that match the compositional signature of rare mineral deposits called zircons that date back to the Archaean period of 2.5 to 4 billion years ago, when scientists believed that continents first formed.

Last year, scientists from China and Australia published a paper arguing that Archaean zircons could only be formed by subduction — when two tectonic plates collide underwater, pushing land mass to the surface.

That process still happens today, causing earthquakes and volcanic eruptions and reshaping the coasts of continents.

But Hernández Uribe, assistant professor of earth and environmental sciences, found that subduction was not necessary to create Archaean zircons.

Instead, he found that the minerals could form through high pressure and temperatures associated with the melting of the Earth’s thick primordial crust.

“Using my calculations and models, you can get the same signatures for zircons and even provide a better match through the partial melting of the bottom of the crust,” Hernández Uribe said.

“So based on these results, we still do not have enough evidence to say which process formed the continents.”

The results also raise uncertainty about when plate tectonics started on Earth.

If Earth’s first continents formed by subduction, that meant that continents started moving between 3.6 to 4 billion years ago — as little as 500 million years into the planet’s existence.

But the alternative theory of melting crust forming the first continents means that subduction and tectonics could have started much later.

“Our planet is the only planet in the solar system that has active plate tectonics as we know it,” Hernández Uribe said. “And this relates to the origin of life, because how the first continents moved controlled the weather, it controlled the chemistry of the oceans, and all that is related to life.”

Reference:
David Hernández-Uribe. Generation of Archaean oxidizing and wet magmas from mafic crustal overthickening. Nature Geoscience, 2024; DOI: 10.1038/s41561-024-01489-z

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

Greenland fossil discovery reveals increased risk of sea-level catastrophe

A rocky landscape with tundra plants near the eastern coast of Greenland, similar to what the interior of the island may have looked like when its massive ice sheet melted away. (Photo: Joshua Brown)
A rocky landscape with tundra plants near the eastern coast of Greenland, similar to what the interior of the island may have looked like when its massive ice sheet melted away. (Photo: Joshua Brown)

The story of Greenland keeps getting greener — and scarier.

A new studyprovides the first direct evidence that the center — not just the edges — of Greenland’s ice sheet melted away in the recent geological past and the now-ice-covered island was then home to a green, tundra landscape.

A team of scientists re-examined a few inches of sediment from the bottom of a two-mile-deep ice core extracted at the very center of Greenland in 1993 — and held for 30 years in a Colorado storage facility. They were amazed to discover soil that contained willow wood, insect parts, fungi, and a poppy seed in pristine condition.

“These fossils are beautiful,” says Paul Bierman, a scientist at the University of Vermont who co-led the new study with UVM graduate student Halley Mastro and nine other researchers, “but, yes, we go from bad to worse,” in what this implies about the impact of human-caused climate change on the melting of the Greenland ice sheet.

The study, published in the Proceedings of the National Academy of Sciences on August 5th, confirms that Greenland’s ice melted and the island greened during a prior warm period likely within the last million years — suggesting that the giant ice sheet is more fragile than scientists had realized until the last few years.

If the ice covering the center of the island was melted, then most of the rest of it had to be melted too. “And probably for many thousands of years,” Bierman said, enough time for soil to form and an ecosystem to take root.

“This new study confirms and extends that a lot of sea-level rise occurred at a time when causes of warming were not especially extreme,” said Richard Alley, a leading climate scientist at Penn State who reviewed the new research, “providing a warning of what damages we might cause if we continue to warm the climate.”

Sea level today is rising more than an inch each decade. “And it’s getting faster and faster,” said Bierman. It is likely to be several feet higher by the end of this century, when today’s children are grandparents. And if the release of greenhouse gases — from burning fossil fuels — is not radically reduced, he said, the near complete melting of Greenland’s ice over the next centuries to a few millennia would lead to some 23 feet of sea level rise.

“Look at Boston, New York, Miami, Mumbai or pick your coastal city around the world, and add twenty plus feet of sea level,” said Bierman. “It goes underwater. Don’t buy a beach house.”

Core Assumptions

In 2016, Joerg Schaefer at Columbia University and colleagues tested rock from the bottom of the same 1993 ice core (called GISP2) and published a then-controversial study suggesting that the current Greenland ice sheet could be no more than 1.1 million years old; that there were extended ice-free periods during the Pleistocene (the geological period that began 2.7 million years ago); and that if the ice was melted at the GISP2 site then 90% of the rest of Greenland would be melted also. This was a major step toward overturning the longstanding story that Greenland is an implacable fortress of ice, frozen solid for millions of years.

Then, in 2019, UVM’s Paul Bierman and an international team reexamined another ice core, this one extracted at Camp Century near the coast of Greenland in the 1960s. They were stunned to discover twigs, seeds, and insect parts at the bottom of that core — revealing that the ice there had melted within the last 416,000 years. In other words, the walls of the ice fortress had failed much more recently than had been previously imagined possible.

“Once we made the discovery at Camp Century, we thought, ‘Hey, what’s at the bottom of GISP2?'” said Bierman, a professor in UVM’s Rubenstein School of Environment and Natural Resources and fellow in the Gund Institute for Environment. Though the ice and rock in that core had been studied extensively, “no one’s looked at the 3 inches of till to see if it’s soil and if it contains plant or insect remains,” he said. So he and his colleagues requested a sample from the bottom of the GISP2 core held at the National Science Foundation Ice Core Facility in Lakewood, Colorado.

Now this new study in PNAS, with support from the U.S. National Science Foundation, provides confirmation that the 2016 “fragile Greenland” hypothesis is right. And it deepens the reasons for concern, showing that the island was warm enough, for long enough, that an entire tundra ecosystem, perhaps with stunted trees, established itself where today ice is two miles deep.

“We now have direct evidence that not only was the ice gone, but that plants and insects were living there,” said Bierman. “And that’s unassailable. You don’t have to rely on calculations or models.”

From Flowers

The initial discovery that there was intact biological material — not just gravel and rock — in the bottom of the ice core was made by geoscientist Andrew Christ who completed his PhD working at UVM and was a post-doctoral associate in Bierman’s lab. Then Halley Mastro picked up the case and began to study the material closely.

“It was amazing,” she said. Under the microscope, what had looked like no more than specks floating on the surface of the melted core sample, was, in fact, a window into a tundra landscape. Working with Dorothy Peteet, an expert on macrofossils at the Lamont-Doherty Earth Observatory and co-author on the new study, Mastro was able to identify spores from spikemoss, the bud scale of a young willow, the compound eye of an insect, “and then we found Arctic poppy, just one seed of that,” she said. “That is a tiny flower that’s really good at adapting to the cold.”

But not that good. “It lets us know that Greenland’s ice melted and there was soil,” said Mastro, “because poppies don’t grow on top of miles of ice.”

Reference:
Paul R. Bierman, Halley M. Mastro, Dorothy M. Peteet, Lee B. Corbett, Eric J. Steig, Chris T. Halsted, Marc M. Caffee, Alan J. Hidy, Greg Balco, Ole Bennike, Barry Rock. Plant, insect, and fungi fossils under the center of Greenland’s ice sheet are evidence of ice-free times. Proceedings of the National Academy of Sciences, 2024; 121 (33) DOI: 10.1073/pnas.2407465121

Note: The above post is reprinted from materials provided by University of Vermont. Original written by Joshua Brown.

Research reveals the most complete dinosaur discovered in the UK in a century

An artist’s impression of the dinosaur. Image credit: John Sibbick
An artist’s impression of the dinosaur. Image credit: John Sibbick

The most complete dinosaur discovered in this country in the last 100 years, with a pubic hip bone the size of a ‘dinner plate’, has been described in a new paper published today.

The specimen, which is around 125 million years old, was found in the cliffs of Compton Bay on the Isle of Wight in 2013 by fossil collector Nick Chase, before he tragically died of cancer.

Jeremy Lockwood, a retired GP and University of Portsmouth PhD student, helped with the dinosaur’s excavation and has spent years analysing the 149 different bones that make up the skeleton.

Jeremy determined that the skeleton represented a new genus and species, which he named Comptonatus chasei in tribute to Nick.

Jeremy said: “Nick had a phenomenal nose for finding dinosaur bones — he really was a modern-day Mary Anning. He collected fossils daily in all weathers and donated them to museums. I was hoping we’d spend our dotage collecting together as we were of similar ages, but sadly that wasn’t to be the case.

“Despite his many wonderful discoveries over the years, including the most complete Iguanodon skull ever found in Britain, this is the first dinosaur to be named after him.”

When it was first discovered, the specimen was thought to be a known dinosaur called Mantellisaurus, but Jeremy’s study revealed a lot more dinosaur diversity. Indeed, this is the second new genus to be described by Jeremy.

He said: “I’ve been able to show this dinosaur is different because of certain unique features in its skull, teeth and other parts of its body. For example its lower jaw has a straight bottom edge, whereas most iguanodontians have a jaw that curves downwards. It also has a very large pubic hip bone, which is much bigger than other similar dinosaurs. It’s like a dinner plate!”

Jeremy doesn’t know why the pubic hip bone, which is placed at the base of the abdomen was so big: “It was probably for muscle attachments, which might mean its mode of locomotion was a bit different, or it could have been to support the stomach contents more effectively, or even have been involved in how the animal breathed, but all of these theories are somewhat speculative.”

Jeremy named the dinosaur Comptonatus after Compton Bay where it was found and ‘tonatus’ is a latin word meaning ‘thunderous’.

“This animal would have been around a ton, about as big as a large male American bison. And evidence from fossil footprints found nearby shows it was likely to be a herding animal, so possibly large herds of these heavy dinosaurs may have been thundering around if spooked by predators on the floodplains over 120 million years ago.”

Dr Susannah Maidment, Senior Researcher and palaeontologist at the Natural History Museum and senior author of the paper completed whilst supervising Jeremy’s PhD, commented: “Comptonatus is a fantastic dinosaur specimen: one of the most complete to be found in the UK in a century.

“Its recognition as a new species is due to incredibly detailed work by NHM Scientific Associate Dr Jeremy Lockwood, whose research continues to reveal that the diversity of dinosaurs in southern England in the Early Cretaceous was much greater than previously realised.

“The specimen, which is younger than Brighstoneus but older than Mantellisaurus (two iguandontian dinosaurs closely related to Comptonatus) demonstrate fast rates of evolution in iguandontian dinosaurs during this time period, and could help us understand how ecosystems recovered after a putative extinction event at the end of the Jurassic Period.”

Despite only four new dinosaur species being described on the Isle of Wight in the whole of the 1900s, there have been eight new species named in the last five years.

Jeremy added: “This really is a remarkable find. It helps us understand more about the different types of dinosaurs that lived in England in the Early Cretaceous. This adds to recent research that shows that Wessex was one of the world’s most diverse ecosystems.”

The dinosaur has been added to the collections at the Dinosaur Isle Museum in Sandown on the Isle of Wight. The paper is published today in the Journal of Systematic Palaeontology.

Dr Martin Munt, Dinosaur Isle curator, said: “Ongoing research on the museum collection continues to reveal exciting new discoveries. Most of Nick’s most important finds have remained on the Island, a lasting legacy.

“We can look forward to many more new types of prehistoric creatures being discovered from the Island’s cliffs and collection.”

Mike Greenslade, General Manager for the National Trust on the Isle of Wight, said: “This extraordinary discovery at National Trust’s Compton Bay highlights the rich natural heritage of the Isle of Wight.

“Finding the most complete dinosaur in the UK in a century not only showcases the island’s palaeontological significance but also underscores the importance of preserving our landscapes for future generations to explore and learn from.

“Nick Chase’s remarkable find and Jeremy Lockwood’s dedicated research are a testament to the incredible history waiting to be uncovered here. We are thrilled to be part of this ongoing journey of discovery and scientific advancement.”

Reference:
Jeremy A. F. Lockwood, David M. Martill, Susannah C. R. Maidment. Comptonatus chasei , a new iguanodontian dinosaur from the Lower Cretaceous Wessex Formation of the Isle of Wight, southern England. Journal of Systematic Palaeontology, 2024; 22 (1) DOI: 10.1080/14772019.2024.2346573

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

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