The opening and closing of the Rocas Verdes Basin, a back-arc basin in Patagonia, as described by researchers at The University of Texas at Austin in a study published in Geology. Panels B and C illustrate the basin-closure process, in which an underlying portion of the oceanic crust is thrust into a magma chamber (B) and breaks off ahead of continental crust (C). The last two panels (C and D) show the oceanic plate and continental plate colliding together – squeezing the basin together into the Andes Mountains of Patagonia that we see today. Credit: Fernando Rey et al
Scientists use tiny minerals called zircons as geologic timekeepers. Often no bigger than a grain of sand, these crystals record chemical signatures of the geological environment where they formed. In a new study led by scientists at The University of Texas at Austin, researchers used them to describe what could be an overlooked step in a fundamental tectonic process that raises seafloors into mountains.
In a study published in the journal Geology, the researchers describe zircons from the Andes mountains of Patagonia. Although the zircons formed when tectonic plates were colliding, they have a chemical signature associated with when the plates were moving apart.
The researchers think that the unexpected signature could be explained by the mechanics of underlying tectonic plates that hasn’t yet been described in other models. This missing step involves a sort of geologic juicing in a magma chamber where zircons form before they reach the surface, with oceanic crust entering the chamber ahead of continental crust.
“If you put some oceanic basin below this magma, you have a change in the composition of this magma as it’s incorporated,” said the study’s lead author Fernando Rey, a doctoral student at the UT Jackson School of Geosciences. “This is something that was not documented before this study.”
This theory of oceanic magma mixing is important because it could represent a transitional step in the formation of back arc basins — an important geological structure that shapes landscapes, geologic records and helps regulate the planet’s climate.
These basins form between oceanic and continental tectonic plates, opening up as the plates move apart and closing as they come back together. While the opening of the basin creates oceanic crust, its closing squeezes the crust into mountains — bringing a geologic record of Earth history to the surface where humans can more easily access it, said coauthor Matt Malkowski, an assistant professor at the Jackson School’s Department of Earth and Planetary Sciences. What’s more, the weathering of the ocean crust is a major driver of natural carbon dioxide storage. “This is the Earth’s way of sequestering carbon. Very effective on its own, but it may take hundreds of thousands if not millions of years,” said Malkowski.
Malkowski collected the zircons examined in the study from rock and sediment samples at a field site in Patagonia. The samples captured the entire record of the back arc basin, called the Rocas Verdes Basin, from opening to closing.
When Rey started analyzing the chemical signatures of the zircons, nothing looked out of place at first. The zircons associated with an opening basin had the expected signature. However, when he started examining zircons associated with the closing of the basin, the signature didn’t undergo the expected chemical shift — known to scientists as a “pull down” because of the way data plotting the isotope ratios goes from steadily rising to falling down.
When that pull down signature didn’t show up until 200 million years later, appearing in zircons that formed 30 million years ago when the basin was already well into its closure phase, Rey and his collaborators hypothesized a scenario that could help explain the data.
In their paper, they propose a model where the same tectonic forces that squeeze the oceanic crust into mountains could be underthrusting parts of that crust and pushing it toward the magmatic chamber where the zircons are formed — influencing the chemical signatures recorded in the crystals during the early to middle stages of closure. As the continents continue to squeeze together, the oceanic crust is eventually replaced by continental crust, the source of the pulldown signal.
The researchers think this transitional phase where zircons are juiced by oceanic crust could be part of back arc basins around the world. But there’s a good reason why it hasn’t been observed before, said Rey. Most back arc basins close faster than Patagonia did — in a few million years rather than tens of millions of years — meaning a shorter window of time in which these zircons can form.
Now that scientists have discovered this zircon signal in Patagonia, they can start looking for signs of it in zircons from other places. Rey is currently analyzing zircons from the Sea of Japan — a modern back arc basin that’s in the early stages of closure — to see if there’s signs of oceanic crust influencing the zircon signature.
This research adds to a record of discovery about back arc basins at UT Austin, said Malkowski. Professor Ian Dalziel authored a well-known Nature paper in 1974 that first recognized the Andes of Patagonia as forming due to back arc basin closure.
“Here we are 50 years later, and we’re still learning new things about these rocks,” Malkowski said.
The research was funded by the National Science Foundation and UT Austin.
References:
F.M. Rey, M.A. Malkowski, J.C. Fosdick, S.C. Dobbs, M. Calderón, M.C. Ghiglione, S.A. Graham. Detrital isotopic record of a retreating accretionary orogen: An example from the Patagonian Andes. Geology, 2024; DOI: 10.1130/G51918.1
Ian W. D. Dalziel, Maarten J. de Wit, Keith F. Palmer. Fossil marginal basin in the southern Andes. Nature, 1974; 250 (5464): 291 DOI: 10.1038/250291a0
The zircon crystals we found in river sand and rocks from Finland have signatures that point towards them being much older than anything ever found in Scandinavia, while matching the age of Greenlandic rock samples. Photo: Andreas Petersson.
In a Finnish outcrop nestled between some of Northern Europe’s oldest mountains, researchers have found traces of a previously hidden part of Earth’s crust that points more than three billion years back in time and north towards Greenland.
These traces were found in the mineral zircon, which after chemical analyses, indicated to researchers from the Department of Geosciences and Natural Resource Management that the “foundation” upon which Denmark and Scandinavia rest, was probably ‘born’ from Greenland approximately 3.75 billion years ago.
“Our data suggest that the oldest part of Earth’s crust beneath Scandinavia originates in Greenland and is about 250 million years older than we previously thought,” says Professor Tod Waight, a geologist at the Department of Geosciences and Natural Resource Management.
The researchers’ study of the zircon showed that, in several ways, its chemical fingerprint matches those of some of the oldest rocks on the planet found in West Greenland’s North Atlantic Craton.
“The zircon crystals we found in river sand and rocks from Finland have signatures that point towards them being much older than anything ever found in Scandinavia, while matching the age of Greenlandic rock samples. At the same time, the results of three independent isotope analyses confirm that Scandinavia’s bedrock was most likely linked to Greenland,” says Department of Geosciences and Natural Resource Management researcher Andreas Petersson.
Denmark, Sweden, Norway and Finland rest atop a part of Earth’s crust known as the Fennoscandian Shield, or the Baltic Shield. The researchers believe that it broke away from Greenland as a “seed” and shifted for hundreds of millions of years until it “took root” where Finland is today.
Here, the plate grew as new geological material accumulated around it, until it became Scandinavia. At the time of the crust’s detachment from Greenland, the planet looked very different than today.
“Earth was probably a watery planet, like in the movie Waterworld, but without any oxygen in the atmosphere and without emergent crust. But, because that’s so far back in time, we can’t be really be sure about what it actually looked like,” says Tod Waight.
According to the researchers, the fact that Earth even has a continental crust composed of granite is quite special when they look out into space and compare it with other planets in our galactic neighborhood.
“This is unique in our solar system. And, evidence of liquid water and a granite crust are key factors when trying to identify habitable exoplanets and the possibility of life beyond Earth,” explains Andreas Petersson.
Continents are the key to life
The new study adds pieces to a primordial continental puzzle that began long before life on Earth truly blossomed, but which has largely paved the way for both human and animal life.
“Understanding how continents formed helps us understand why ours is the only planet in the solar system with life on it. Because without fixed continents and water in between them, we wouldn’t be here. Indeed, continents influence both ocean currents and climate, which are crucial for life on Earth,” says Andreas Petersson.
Furthermore, the new study contributes to a growing number of studies which reject the means used thus far to calculate how continents have grown — especially during the first billion years of Earth’s history.
“The most commonly used models assume that Earth’s continental crust began to form when the planet was formed, about 4.6 billion years ago. Instead, our and several other recent studies suggest that the chemical signatures showing growth of the continental crust can only be identified about a billion years later. This means that we may need to revise much of what we thought about how early continents evolved,” says Professor Waight.
At the same time, results of the study add to previous research that found similar “seeds” from ancient crusts in other parts of the world.
“Our study provides us with another important clue in the mystery of how continents formed and spread across Earth — especially in the case of the Fennoscandian Shield. But there is still plenty that we don’t know. In Australia, South Africa and India, for example, similar seeds have been found, but we’re unsure of whether they all come from the same “birthplace,” or whether they originated independently of one another in several places on Earth. This is something that we would like to investigate more using the method we used in this study,” concludes Professor Waight.
About the study
The study demonstrates that the oldest part of Earth’s crust beneath Scandinavia comes from Greenland and is about 250 million years older than once thought.
Therefore, Denmark and Scandinavia’s geologic foundation was most likely connected to Greenland approximately 3.75 billion years ago.
The researchers analysed zircons from modern river sand and rock samples from the remote Pudasjärvi and Suomujärvi regions of Finland, whose geological origins have been little studied.
The zircon crystals found in the Finnish river sand originally crystallized in granitic magmas deep within the crust. These granites were then lifted to the surface and eroded to eventually form sand.
The researchers used isotopic compositions of lead, hafnium and oxygen to trace the chemical fingerprint from the Fennoscandian Shield back to Greenland.
The study has been published in the scientific journal Geology.
Reference:
Andreas Petersson, Tod Waight, Anthony I.S. Kemp, Martin. J. Whitehouse, John W. Valley. An Eoarchean continental nucleus for the Fennoscandian Shield and a link to the North Atlantic craton. Geology, 2023; 52 (3): 171 DOI: 10.1130/G51658.1
This is a mosaic image of Mars created from over 100 images taken by Viking Orbiters in the 1970s. Credit: NASA
Scientists from the Universities of Sydney and Sorbonne University have used the geological record of the deep sea to discover a connection between the orbits of Earth and Mars, past global warming patterns and the speeding up of deep ocean circulation.
They discovered a surprising 2.4-million-year cycle where deep currents wax and wane which, in turn, is linked to periods of increased solar energy and a warmer climate.
The study, published in Nature Communications, tackles the questions of how geological-timescale climate change affects ocean circulation and how this could help scientists to model future climates outcomes. The researchers looked to find if ocean-bottom currents become more vigorous or more sluggish in a warmer climate.
These cycles are not linked to the current rapid global warming caused by human greenhouse gas emissions.
Lead author ARC Future Fellow Dr Adriana Dutkiewicz from the University of Sydney EarthByte Group in the School of Geosciences and co-authors used more than half a century of scientific drilling data from hundreds of sites worldwide to understand the vigour of deep-sea currents through time.
In a collaboration with Professor Dietmar Müller (University of Sydney) and Associate Professor Slah Boulila (Sorbonne), Dr Dutkiewicz used the deep-sea sediment record to check for links between sedimentary shifts and changes in the Earth’s orbit.
They found that the vigour of deep-sea currents shifts in 2.4-million-year cycles.
These cycles are called “astronomical grand cycles,” predicted to occur due to the interactions of Earth and Mars orbits. However, evidence for this is rarely detected in the geological record.
Dr Dutkiewicz said: “We were surprised to find these 2.4-million-year cycles in our deep-sea sedimentary data. There is only one way to explain them: they are linked to cycles in the interactions of Mars and Earth orbiting the Sun.”
Co-author Professor Müller said: “The gravity fields of the planets in the solar system interfere with each other and this interaction, called a resonance, changes planetary eccentricity, a measure of how close to circular their orbits are.”
For the Earth it means periods of higher incoming solar radiation and warmer climate in cycles of 2.4 million years. The researchers found that the warmer cycles correlate with an increased occurrence of breaks in the deep-sea record, related to more vigorous deep ocean circulation.
The study has identified that deep eddies were an important component of earlier warming seas. It is possible these could partly mitigate ocean stagnation some have predicted could follow a faltering AMOC (Atlantic meridional overturning circulation) that drives the Gulf Stream and maintains temperate climates in Europe.
Professor Müller said: “We know there are at least two separate mechanisms that contribute to the vigour of deep-water mixing in the oceans. AMOC is one of them, but deep ocean eddies seem to play an important role in warm climates for keeping the ocean ventilated.
“Of course, this would not have the same effect as AMOC in terms of transporting water masses from low to high latitudes and vice-versa.”
These eddies are like giant whirlpools and often reach the abyssal seafloor, resulting in seafloor erosion and large sediment accumulations called contourites, akin to snowdrifts.
Dr Dutkiewicz said: “Our deep-sea data spanning 65 million years suggest that warmer oceans have more vigorous deep circulation. This will potentially keep the ocean from becoming stagnant even if Atlantic Meridional Overturning Circulation slows or stops altogether.”
How the interplay between different processes driving deep-ocean dynamics and ocean life may play out in the future is still not well known, but the authors hope that their new results will help with building better climate models.
Reference:
Adriana Dutkiewicz, Slah Boulila, R. Dietmar Müller. Deep-sea hiatus record reveals orbital pacing by 2.4 Myr eccentricity grand cycles. Nature Communications, 2024; 15 (1) DOI: 10.1038/s41467-024-46171-5
A reconstruction of a gigantic ichthyosaur – floating dead on the surface of the ocean. Remains of ichthyosaurs have been found in ocean sediment in various places around Europe. Credit: Marcello Perillo/University of Bonn
Several similar large, fossilized bone fragments have been discovered in various regions across Western and Central Europe since the 19th century. The animal group to which they belonged is still the subject of much debate to this day. A study carried out at the University of Bonn could now settle this dispute once and for all: The microstructure of the fossils indicates that they come from the lower jaw of a gigantic ichthyosaur. These animals could reach 25 to 30 meters in length, a similar size to the modern blue whale. The results have now been published in the journal PeerJ.
In 1850, the British naturalist Samuel Stutchbury reported a mysterious find in a scientific journal: A large, cylindrical bone fragment had been discovered at Aust Cliff — a fossil deposit near to Bristol. Similar bone fragments have since been found in various different places around Europe, including Bonenburg in North Rhine-Westphalia and in the Provence region of France. More than 200 million years ago, these areas were submerged beneath a huge ocean that covered vast swathes of Western and Central Europe. Fossil remains from the animal world of that time — including marine and coastal dwellers — have been preserved in the sediment.
There is still some debate to this day about the animal group to which these large, fossilized bones belonged. Stutchbury assumed in his examination of the first finds that they came from a labyrinthodontia, an extinct crocodile-like land creature. However, this hypothesis was questioned by other researchers, who believed instead that the fossils came from long-necked dinosaurs (sauropods), stegosaurs or a still completely unknown group of dinosaurs.
“Already by the beginning of the 20th century, some other researchers had theorized that the fossils could possibly be from a gigantic ichthyosaur,” explains Marcello Perillo. The young researcher has been investigating this theory as part of his Master’s Thesis in the research group headed by Prof. Martin Sander in the Institute of Geosciences at the University of Bonn. As part of his work, he examined the microstructure of the fossilized bone tissue. “Bones of similar species generally have a similar structure,” he says. “Osteohistology — the analysis of bone tissue — can thus be used to draw conclusions about the animal group from which the find originates.”
Perillo first took samples from the bones that have so far not been classified. “I compared specimens from South West England, France and Bonenburg,” he says. “They all displayed a very specific combination of properties. This discovery indicated that they might come from the same animal group.” He then used a special microscope to prove that the bone wall had a very unusual structure: It contained long strands of mineralized collagen, a protein fiber, which were interwoven in a characteristic way that had not yet been found in other bones.
Ichthyosaur bones with a similar structure
Interestingly, fossils from large ichthyosaurs from Canada also have a very similar bone wall structure. “However, this structure is not found in fossil samples from other animal groups that I have studied,” emphasized Perillo. “Therefore, it seems highly probable that the fragments in question also belong to an ichthyosaur and that the findings refute the claim that the bones come from a land-living dinosaur.”
It is likely that the fossils come from the lower jaw of a sea creature. By comparing the size of the fragments with the jaws of other species in this animal group, it is possible to deduce the length of the animals: They could possibly have reached a length of 25 to 30 meters, as proponents of the ichthyosaur theory had originally speculated in an earlier study. “However, this number is only an estimate and far from certain — until, that is, we find more complete fossil remains,” says Perillo. Nevertheless, they were certainly exceptionally large.
The first ichthyosaur lived in the ancient oceans in the early Triassic period around 250 million years ago. Species as big as whales existed early on but the largest creatures only appeared around 215 million years ago. Almost all species of ichthyosaur then died out at the end of the Triassic period more than 200 million years ago.
The unusual structure of their bone walls — which is similar to carbon fiber reinforced materials — probably kept the bone very stable while allowing for fast growth. “These huge jaws would have been exposed to strong shearing forces even when the animal was eating normally,” says Perillo. “It is possible that these animals also used their snouts to ram into their prey, similar to the orcas of today. However, this is still pure speculation at this time.”
Reference:
Marcello Perillo, P Martin Sander. The dinosaurs that weren’t: osteohistology supports giant ichthyosaur affinity of enigmatic large bone segments from the European Rhaetian. PeerJ, 2024; 12: e17060 DOI: 10.7717/peerj.17060
Art by James Havens Nanuqsaurus, standing in the background, and pachyrhinosaurus, skull in the foreground, were among the dinosaur species included in a new study led by scientists at the University of Alaska Fairbanks and the University of Reading that calls into question Bergmann’s rule.
When you throw dinosaurs into the mix, sometimes you find that a rule simply isn’t.
A new study led by scientists at the University of Alaska Fairbanks and the University of Reading calls into question Bergmann’s rule, an 1800s-era scientific principle stating that animals in high-latitude, cooler climates tend to be larger than close relatives living in warmer climates.
The fossil record shows otherwise.
“Our study shows that the evolution of diverse body sizes in dinosaurs and mammals cannot be reduced to simply being a function of latitude or temperature,” said Lauren Wilson, a UAF graduate student and a lead author of a paper published today in the journal Nature Communications.
“We found that Bergmann’s rule is only applicable to a subset of homeothermic animals (those that maintain stable body temperatures), and only when you consider temperature, ignoring all other climatic variables. This suggests that Bergmann’s ‘rule’ is really the exception rather than the rule.”
The study started as a simple question Wilson discussed with her undergraduate advisor: Does Bergmann’s rule apply to dinosaurs?
After evaluating hundreds of data points gleaned from the fossil record, the answer seemed a solid “no.”
The dataset included the northernmost dinosaurs known to scientists, those in Alaska’s Prince Creek Formation.
They experienced freezing temperatures and snowfall. Despite this, the researchers found no notable increase in body size for any of the Arctic dinosaurs.
Next the researchers tried the same evaluation with modern mammals and birds, the descendants of prehistoric mammals and dinosaurs.
The results were largely the same: Latitude was not a predictor of body size in modern bird and mammal species.
There was a small relationship between the body size of modern birds and temperature, but the same was not the case for prehistoric birds.
The researchers say the study is a good example of how scientists can and should use the fossil record to test current-day scientific rules and hypotheses.
“The fossil record provides a window into completely different ecosystems and climate conditions, allowing us to assess the applicability of these ecological rules in a whole new way,” said Jacob Gardner, a postdoctoral researcher at the University of Reading and the other lead author of the paper.
Scientific rules should apply to fossil organisms in the same way they do modern organisms, said Pat Druckenmiller, director of the University of Alaska Museum of the North and one of the co-authors of the paper.
“You can’t understand modern ecosystems if you ignore their evolutionary roots,” he said. “You have to look to the past to understand how things became what they are today.”
Reference:
Lauren N. Wilson, Jacob D. Gardner, John P. Wilson, Alex Farnsworth, Zackary R. Perry, Patrick S. Druckenmiller, Gregory M. Erickson, Chris L. Organ. Global latitudinal gradients and the evolution of body size in dinosaurs and mammals. Nature Communications, 2024; 15 (1) DOI: 10.1038/s41467-024-46843-2
Herrerasaurus ischigualastensis is an early saurischian dinosaur. It shared a bipedal, running anatomy common to large carnivorous dinosaurs that would evolve in the future, but this dinosaur lived at a time when dinosaurs were small-bodied and rare. Credit: Kristina Curry Rogers (illustration by Jordan Harris, CC-BY 4.0 (creativecommons.org/licenses/by/4.0/)
The earliest dinosaurs had rapid growth rates, but so did many of the other animals living alongside them, according to a study published April 3, 2024 in the open-access journal PLOS ONE by Kristina Curry Rogers of Macalester College, Minnesota and colleagues.
Dinosaurs grew up fast, a feature that likely set them apart from many other animals in their Mesozoic (252 to 66 million years ago) ecosystems.
Some researchers have proposed that these elevated growth rates were key to the global success of dinosaurs, but little is known about the growth strategies of the earliest dinosaurs.
In this study, Rogers and colleagues performed histological analysis, examining patterns of bone tissue growth in the fossilized leg bones of an array of animals in one of the earliest known Mesozoic ecosystems.
The studied fossils come from the Ischigualasto Formation of Argentina and date between 231-229 million years old.
Sampled fossils include several of the earliest known dinosaurs as well as several non-dinosaur reptiles and one early relative of mammals.
The analysis found that most of the examined species had elevated growth rates, more similar to some modern-day mammals and birds than to living reptiles.
The early dinosaurs all exhibited particularly fast growth, but they weren’t alone in this, as similar growth rates were seen in several of the non-dinosaur reptiles as well.
These results show that the earliest dinosaurs were already fast growers, supporting the idea that this feature was important to their later success.
But apparently dinosaurs were only one of multiple lineages evolving with elevated growth rates during the Triassic (252-201 million years ago), suggesting that this feature is only part of the story of dinosaurs’ eventual global prosperity.
The authors note that future studies could expand on these preliminary results by sampling a wider variety of ancient animals from additional early Mesozoic fossil sites.
The authors add: “Our sample comes from a time in which dinosaurs were the new kids on the block, restricted to relatively small, basic body plans, and evolving within a world rich with a diverse array of more specialized, non-dinosaur reptiles. We tackled the question of how all of these animals grew, and found that the earliest dinosaurs grew quickly, and that these rapid growth rates probably played a significant role in dinosaurs’ subsequent ascent within Mesozoic ecosystems; but dinosaurs weren’t unique — many of their non-dino sidekicks shared rapid growth 230 million years ago.”
Reference:
Kristina Curry Rogers, Ricardo N. Martínez, Carina Colombi, Raymond R. Rogers, Oscar Alcober. Osteohistological insight into the growth dynamics of early dinosaurs and their contemporaries. PLOS ONE, 2024; 19 (4): e0298242 DOI: 10.1371/journal.pone.0298242
Note: The above post is reprinted from materials provided by PLOS.
Reconstruction of fossil fish. Credit: Richard Dearden
Early jawless fish were likely to have used bony projections surrounding their mouths to modify the mouth’s shape while they collected food.
Experts led by the University of Birmingham have used CT scanning techniques to build up the first 3D pictures of these creatures, which are some of the earliest vertebrates (animals with backbones) in which the mouth is fossilised. Their aim was to answer questions about feeding in early vertebrates without jaws in the early Devonian epoch — sometimes called the Age of Fishes — around 400 million years ago.
Feeding behaviours are commonly used by scientists to help piece together early evolution of vertebrates, and different jaw shapes and constructions can suggest a broad range of feeding strategies. In the absence of jaws, many competing theories have been developed ranging from biting and slicing, to filtering food from sediment or water.
In a new study, published in Proceedings of the Royal Society B, an international team of palaeontologists have been able to visualise the mouth parts of one of these jawless fish, called Rhinopteraspis dunensis, in detail. The images revealed the structure and arrangement of finger-like bones that project from the lower ‘lip’ of the animal’s mouth, which the scientists believe acted to control the mouth’s size and shape as it captured food particles from surrounding water.
Senior author and project lead Dr Ivan Sansom said: “The application of CT scanning techniques to the study of fossil fish is revealing so much new information about these ancient vertebrates and giving us the opportunity to study precious and unique specimens without destructive investigation.”
Lead author Dr Richard Dearden explained: “In this case, these methods have allowed us to fit all of the small bones of this animal’s mouth together, and try and understand how it fed from this integrated system rather than by using isolated bones. Instead of a steady trend towards ‘active food acquisition’ — scavenging or hunting — we see a real diversity and range of feeding behaviours among our earliest vertebrate relatives.”
The reconstruction produced by the team shows that the bony plates around the mouth would have had limited movement, making it unlikely that the animals were hunters capable of ‘biting’. In combination with an elongated snout, they would also have found it difficult to scoop and filter sediment directly from the bottom of the sea. However these plates would have allowed it to control opening of the mouth, and perhaps strain food from water in a way also used by animals such as flamingos or oysters.
The findings offer a new perspective on theories of vertebrate evolution, since current hypotheses argue that long term evolutionary trends move from passive food consumption to increasingly predatory behaviour. In contrast, the work outlined in this paper suggests that in fact, early vertebrates had a broad range of different feeding behaviours long before jawed animals started to appear.
The study was funded by the Leverhulme Trust and is part of a collaborative project between the University of Birmingham, the Natural History Museum, and the University of Bristol, in the UK, and Naturalis Biodiversity Centre, in the Netherlands.
Early jawless fish were likely to have used bony projections surrounding their mouths to modify the mouth’s shape while they collected food.
Experts led by the University of Birmingham have used CT scanning techniques to build up the first 3D pictures of these creatures, which are some of the earliest vertebrates (animals with backbones) in which the mouth is fossilised. Their aim was to answer questions about feeding in early vertebrates without jaws in the early Devonian epoch — sometimes called the Age of Fishes — around 400 million years ago.
Feeding behaviours are commonly used by scientists to help piece together early evolution of vertebrates, and different jaw shapes and constructions can suggest a broad range of feeding strategies. In the absence of jaws, many competing theories have been developed ranging from biting and slicing, to filtering food from sediment or water.
In a new study, published in Proceedings of the Royal Society B, an international team of palaeontologists have been able to visualise the mouth parts of one of these jawless fish, called Rhinopteraspis dunensis, in detail. The images revealed the structure and arrangement of finger-like bones that project from the lower ‘lip’ of the animal’s mouth, which the scientists believe acted to control the mouth’s size and shape as it captured food particles from surrounding water.
Senior author and project lead Dr Ivan Sansom said: “The application of CT scanning techniques to the study of fossil fish is revealing so much new information about these ancient vertebrates and giving us the opportunity to study precious and unique specimens without destructive investigation.”
Lead author Dr Richard Dearden explained: “In this case, these methods have allowed us to fit all of the small bones of this animal’s mouth together, and try and understand how it fed from this integrated system rather than by using isolated bones. Instead of a steady trend towards ‘active food acquisition’ — scavenging or hunti
Senior author and project lead Dr Ivan Sansom said: “The application of CT scanning techniques to the study of fossil fish is revealing so much new information about these ancient vertebrates and giving us the opportunity to study precious and unique specimens without destructive investigation.”
Lead author Dr Richard Dearden explained: “In this case, these methods have allowed us to fit all of the small bones of this animal’s mouth together, and try and understand how it fed from this integrated system rather than by using isolated bones. Instead of a steady trend towards ‘active food acquisition’ — scavenging or hunting — we see a real diversity and range of feeding behaviours among our earliest vertebrate relatives.”
The reconstruction produced by the team shows that the bony plates around the mouth would have had limited movement, making it unlikely that the animals were hunters capable of ‘biting’. In combination with an elongated snout, they would also have found it difficult to scoop and filter sediment directly from the bottom of the sea. However these plates would have allowed it to control opening of the mouth, and perhaps strain food from water in a way also used by animals such as flamingos or oysters.
The findings offer a new perspective on theories of vertebrate evolution, since current hypotheses argue that long term evolutionary trends move from passive food consumption to increasingly predatory behaviour. In contrast, the work outlined in this paper suggests that in fact, early vertebrates had a broad range of different feeding behaviours long before jawed animals started to appear.
The study was funded by the Leverhulme Trust and is part of a collaborative project between the University of Birmingham, the Natural History Museum, and the University of Bristol, in the UK, and Naturalis Biodiversity Centre, in the Netherlands.
Early jawless fish were likely to have used bony projections surrounding their mouths to modify the mouth’s shape while they collected food.
Experts led by the University of Birmingham have used CT scanning techniques to build up the first 3D pictures of these creatures, which are some of the earliest vertebrates (animals with backbones) in which the mouth is fossilised. Their aim was to answer questions about feeding in early vertebrates without jaws in the early Devonian epoch — sometimes called the Age of Fishes — around 400 million years ago.
Feeding behaviours are commonly used by scientists to help piece together early evolution of vertebrates, and different jaw shapes and constructions can suggest a broad range of feeding strategies. In the absence of jaws, many competing theories have been developed ranging from biting and slicing, to filtering food from sediment or water.
In a new study, published in Proceedings of the Royal Society B, an international team of palaeontologists have been able to visualise the mouth parts of one of these jawless fish, called Rhinopteraspis dunensis, in detail. The images revealed the structure and arrangement of finger-like bones that project from the lower ‘lip’ of the animal’s mouth, which the scientists believe acted to control the mouth’s size and shape as it captured food particles from surrounding water.
Senior author and project lead Dr Ivan Sansom said: “The application of CT scanning techniques to the study of fossil fish is revealing so much new information about these ancient vertebrates and giving us the opportunity to study precious and unique specimens without destructive investigation.”
Lead author Dr Richard Dearden explained: “In this case, these methods have allowed us to fit all of the small bones of this animal’s mouth together, and try and understand how it fed from this integrated system rather than by using isolated bones. Instead of a steady trend towards ‘active food acquisition’ — scavenging or hunting — we see a real diversity and range of feeding behaviours among our earliest vertebrate relatives.”
The reconstruction produced by the team shows that the bony plates around the mouth would have had limited movement, making it unlikely that the animals were hunters capable of ‘biting’. In combination with an elongated snout, they would also have found it difficult to scoop and filter sediment directly from the bottom of the sea. However these plates would have allowed it to control opening of the mouth, and perhaps strain food from water in a way also used by animals such as flamingos or oysters.
The findings offer a new perspective on theories of vertebrate evolution, since current hypotheses argue that long term evolutionary trends move from passive food consumption to increasingly predatory behaviour. In contrast, the work outlined in this paper suggests that in fact, early vertebrates had a broad range of different feeding behaviours long before jawed animals started to appear.
The study was funded by the Leverhulme Trust and is part of a collaborative project between the University of Birmingham, the Natural History Museum, and the University of Bristol, in the UK, and Naturalis Biodiversity Centre, in the Netherlands.
Reference:
Richard P. Dearden, Andy S. Jones, Sam Giles, Agnese Lanzetti, Madleen Grohganz, Zerina Johanson, Stephan Lautenschlager, Emma Randle, Philip C. J. Donoghue, Ivan J. Sansom. The three-dimensionally articulated oral apparatus of a Devonian heterostracan sheds light on feeding in Palaeozoic jawless fishes. Proceedings of the Royal Society B: Biological Sciences, 2024; 291 (2019) DOI: 10.1098/rspb.2023.2258
New reconstruction of the skeleton of the 375-million-year-old fossil fish, Tiktaalik roseae. In a new study, researchers used Micro-CT to reveal vertebrae and ribs of the fish that were previously hidden beneath rock. The new reconstruction shows that the fish’s ribs likely attached to its pelvis, an innovation thought to be crucial to supporting the body and for the eventual evolution of walking. Credit: Thomas Stewart, Penn State
Before the evolution of legs from fins, the axial skeleton — including the bones of the head, neck, back and ribs — was already going through changes that would eventually help our ancestors support their bodies to walk on land. A research team including a Penn State biologist completed a new reconstruction of the skeleton of Tiktaalik, the 375-million-year-old fossil fish that is one of the closest relatives to limbed vertebrates. The new reconstruction shows that the fish’s ribs likely attached to its pelvis, an innovation thought to be crucial to supporting the body and for the eventual evolution of walking.
A paper describing the new reconstruction, which used microcomputed tomography (micro-CT) to scan the fossil and reveal vertebrae and ribs of the fish that were previously hidden beneath rock, appeared April 2 in the journal Proceedings of the National Academy of Sciences.
“Tiktaalik was discovered in 2004, but key parts of its skeleton were unknown,” said Tom Stewart, assistant professor of biology in the Eberly College of Science at Penn State and one of the leaders of the research team. “These new high-resolution micro-CT scans show us the vertebrae and ribs of Tiktaalik and allow us to make a full reconstruction of its skeleton, which is vital to understanding how it moved through the world.”
Unlike most fish, which have vertebrae and ribs that are the same along the length of the trunk, the axial skeletons of limbed vertebrates show dramatic differences in the vertebrae and ribs from the head region to the tail region. The evolution of this regionalization allowed the performance of specialized functions, one of which was a mechanical linkage between ribs in the sacral region to the pelvis that enabled support of the body by the hind limbs.
The pelvic fins of fish are evolutionarily related to hind limbs in tetrapods — four-limbed vertebrates, including humans. In fish, the pelvic fins and bones of the pelvic girdle are relatively small and float freely in the body. For the evolution of walking, the researchers explained, the hind limbs and pelvis became much larger and formed a connection to the vertebral column as a way of bracing the forces related to supporting the body.
“Tiktaalik is remarkable because it gives us glimpses into this major evolutionary transition,” Stewart said. “Across its whole skeleton, we see a combination of traits that are typical of fish and life in water as well as traits that are seen in land-dwelling animals.”
The original description of Tiktaalik focused on the front portion of the skeleton. Fossils were meticulously prepared to remove the surrounding matrix of rock and expose the skull, shoulder girdle and pectoral fins. The ribs in this area were large and expanded, suggesting that they may have supported the body in some way, but it was unclear exactly how they would have functioned. In 2014, the fish’s pelvis, discovered in the same location as the rest of the skeleton, was also cleaned of matrix and described.
“From past studies, we knew that the pelvis was large, and we had a sense that the hind fins were large too, but until now couldn’t say if or how the pelvis interacted with the axial skeleton,” Stewart said. “This reconstruction shows, for the first-time, how it all fit together and gives us clues about how walking might have first evolved.”
The researchers explained that, unlike our own hips where our bones fit tightly together, the connection between the pelvis and axial skeleton of Tiktaalik was likely a soft-tissue connection made of ligaments.
“Tiktaalik had specialized ribs that would have connected to the pelvis by a ligament,” Stewart said. “It’s astonishing really. This creature has so many traits — large pair of hind appendages, large pelvis, and connection between the pelvis and axial skeleton — that were key to the origin of walking. And while Tiktaalik probably wasn’t walking across land, it was definitely doing something new. This was a fish that could likely prop itself up and push with its hind fin.”
The new reconstruction of the skeleton also sheds light on specializations for head mobility in Tiktaalik and new details of the fish’s pelvic fin anatomy.
“It’s incredible to see the skeleton of Tiktaalik captured in such vivid detail,” said Neil Shubin, Robert R. Bensley Distinguished Service Professor of Organismal Biology and Anatomy at the University of Chicago and one of the authors of the paper. “This study sets the stage for ones that explore how the animal moved about and interacted with its environment 375 million years ago.”
In addition to Stewart and Shubin, the research team includes Justin B. Lemberg, Emily J. Hillan, and Isaac Magallanes at The University of Chicago, and Edward B. Daeschler at Academy of Natural Sciences of Drexel University.
Support from the Brinson Foundation, the Biological Sciences Division of The University of Chicago, an anonymous donor to the Academy of Natural Sciences of Drexel University, and the U.S. National Science Foundation funded this research. Fieldwork was made possible by the Polar Continental Shelf Project of Natural Resources, Canada; the Department of Heritage and Culture, Nunavut; the hamlets of Resolute Bay and Grise Fiord of Nunavut; and the Iviq Hunters and Trappers of Grise Fiord.
Reference:
Thomas A. Stewart, Justin B. Lemberg, Emily J. Hillan, Isaac Magallanes, Edward B. Daeschler, Neil H. Shubin. The axial skeleton of Tiktaalik roseae. Proceedings of the National Academy of Sciences, 2024; 121 (15) DOI: 10.1073/pnas.2316106121
Note: The above post is reprinted from materials provided by Penn State. Original written by Sam Sholtis.
Researchers used unmanned aerial vehicle images superimposed on centimeter-resolution topography to study the surface rupture of the 2021 magnitude 7.4 Maduo earthquake in China. This image shows the fault scarp, tensional cracks on the hanging wall, and the left-laterally offset channel. Credit: Yanxiu Shao
In the early morning of 22 May 2021, a magnitude 7.4 quake rattled China’s remote Maduo County on the Tibetan Plateau. It was the most recent in a series of nine earthquakes with a magnitude of 7 or greater since 1997, and its surface rupture was twice as long as the global average for similarly sized quakes. The tremor occurred on the eastern part of the relatively immature left-lateral Jiangcuo fault system, which slips slowly, about 1 millimeter per year, and was unmapped before the quake.
Uncovering the geological dynamics of this disaster could help inform future efforts to assess seismic hazards in the region and around the world. In a new report published in AGU Advances, Jing Liu-Zeng and colleagues analyze the Maduo quake to probe the relationship between fault structure and earthquake dynamics.
To do so, the researchers combined field observations with satellite images taken prequake and postquake as well as with centimeter-resolution photos taken of the fault system by an unmanned aerial vehicle. These remote sensing techniques enabled them to analyze fractures that would otherwise be inaccessible because of their high altitude and harsh surrounding environment.
The research team assessed changes to Earth’s surface both on and near the fault segments involved in the quake. The segments had varying orientations with respect to the overall regional patterns of seismic stress, as well as varying degrees of maturity. Maturity is not necessarily synonymous with age; rather, it indicates the degree of a segment’s development, or how much it has changed with time and activity.
Prior research has highlighted the importance of fault maturity in earthquake dynamics. However, in the case of the Maduo quake, the researchers found that the faults’ orientations played a larger role in the magnitude and the degree of localization of surface deformation than their maturity levels. These findings suggest that future seismic hazard assessments might be enhanced by more thoroughly accounting for fault segment orientation in the context of regional stress conditions.
Reference:
Jing Liu‐Zeng et al, Fault Orientation Trumps Fault Maturity in Controlling Coseismic Rupture Characteristics of the 2021 Maduo Earthquake, AGU Advances (2024). DOI: 10.1029/2023AV001134
A theropod track lies in rock near the west bank of the Kukpowruk River. Photo courtesy of Anthony Fiorillo
A large find of dinosaur tracks and fossilized plants and tree stumps in far northwestern Alaska provides new information about the climate and movement of animals near the time when they began traveling between the Asian and North American continents roughly 100 million years ago.
The findings by an international team of scientists led by paleontologist Anthony Fiorillo were published Jan. 30 in the journal Geosciences. Fiorillo researched in Alaska while at Southern Methodist University. He is now executive director of the New Mexico Museum of Natural History and Science.
University of Alaska Fairbanks geology professor Paul McCarthy, with the UAF Geophysical Institute and UAF College of Natural Science and Mathematics, was a leading contributor to the research. He and UAF graduate student Eric Orphys are among the eight co-authors.
Fiorillo and McCarthy are longtime collaborators.
“We’ve had projects for the last 20 years in Alaska trying to integrate sedimentology, dinosaur paleontology and the paleoclimate indicators,” McCarthy said. “We’ve done work in three other formations — in Denali, on the North Slope and in Southwest Alaska — and they’re about 70 million years old.”
“This new one is in a formation that’s about 90 to 100 million years old,” he said.
Fiorillo said the additional age is notable.
“What interested us about looking at rocks of this age is this is roughly the time that people think of as the beginning of the Bering Land Bridge — the connection between Asia and North America,” he said. “We want to know who was using it, how they were using it and what the conditions were like.”
Research into the paleoclimate can help scientists understand the warming world of today, the authors write.
“The mid-Cretaceous was the hottest point in the Cretaceous,” said McCarthy, a sedimentologist and fossil soils specialist. “The Nanushuk Formation gives us a snapshot of what a high-latitude ecosystem looks like on a warmer Earth.”
The Nanushuk Formation is an outcropped layer of sedimentary rock 800 to 5,000 feet thick across the central and western North Slope. It dates to roughly 94 million to 113 million years ago in the mid-Cretaceous Period and about when the Bering Land Bridge began.
The fieldwork occurred in 2015-2017 and centered on Coke Basin, a circular geologic feature of the Nanushuk Formation. The basin is in the DeLong Mountains foothills along the Kukpowruk River, about 60 miles south of Point Lay and 20 miles inland from the Chukchi Sea.
In the area, Fiorillo and McCarthy found approximately 75 fossil tracks and other indicators attributed to dinosaurs living in a riverine or delta setting.
“This place was just crazy rich with dinosaur footprints,” Fiorillo said.
One site stands out, Fiorillo said.
“We were at a spot where we eventually realized that for at least 400 yards we were walking on an ancient landscape,” he said. “On that landscape we found large upright trees with little trees in between and leaves on the ground. We had tracks on the ground and fossilized feces.”
They found numerous fossilized tree stumps, some 2 feet in diameter.
“It was just like we were walking through the woods of millions of years ago,” he said.
The Nanushuk Formation encompasses rock of marine and non-marine characteristics and composition, but the authors’ research focuses primarily on the non-marine sediments exposed along the upper Kukpowruk River.
“One of the things we did in our paper was look at the relative frequencies of the different kinds of dinosaurs,” Fiorillo said. “What was interesting to us was that the bipedal plant eaters were clearly the most abundant.”
Two-legged plant eaters accounted for 59% of the total tracks discovered. Four-legged plant eaters accounted for 17%, with birds accounting for 15% and non-avian, mostly carnivorous, bipedal dinosaurs at 9%.
“One of the things that was interesting is the relative frequency of bird tracks,” Fiorillo said.
The authors point out that nearly half of North America’s shorebirds breed in the warm months of today’s Arctic. They suggest that the high number of fossil bird tracks along the Kukpowruk River indicates the warm paleoclimate was a similar driver for Cretaceous Period birds.
A wet and warm place
Carbon isotope analysis of wood samples led to a determination that the region received about 70 inches of precipitation annually. This record of increased precipitation during the mid-Cretaceous provides new data that supports global precipitation patterns associated with the Cretaceous Thermal Maximum, the authors write.
The Cretaceous Thermal Maximum was a long-term trend approximately 90 million years ago in which average global temperatures were significantly higher than those of today.
“The temperature was much warmer than it is today, and what’s possibly more interesting is that it rained a lot,” Fiorillo said. “The samples we analyzed indicate it was roughly equivalent to modern-day Miami. That’s pretty substantial.”
Of note is that the Alaska site investigated by Fiorillo and McCarthy was about 10 to 15 degrees latitude farther north in the mid-Cretaceous than it is today.
McCarthy’s role as a fossil soils expert was to analyze old rocks and sediments to interpret the type of environment that existed at the time.
“We can say here’s a river channel, here’s a flood deposit, here’s a levee, here’s the floodplain, here’s a swamp,” he said. “And so if we’re able to find tracks in that section, then you can sometimes say that a group of dinosaurs seems to have really liked being here as opposed to there.”
Fiorillo said the site indicates there’s much more work to be done.
“This puts a new dot on the map and tells us there’s a lot here, and it fits into the bigger picture,” he said. “The big picture is we’re trying to get better resolution on what life was like in the high latitudes back at the time the dinosaurs were roaming around.”
Reference:
Anthony R. Fiorillo, Paul J. McCarthy, Grant Shimer, Marina B. Suarez, Ryuji Takasaki, Tsogtbaatar Chinzorig, Yoshitsugu Kobayashi, Paul O’Sullivan, Eric Orphys. New Dinosaur Ichnological, Sedimentological, and Geochemical Data from a Cretaceous High-Latitude Terrestrial Greenhouse Ecosystem, Nanushuk Formation, North Slope, Alaska. Geosciences, 2024; 14 (2): 36 DOI: 10.3390/geosciences14020036
The most common tooth type, of the famous Spinosaurus, with characteristic sail on its back. Images all from article discussed.
An international team of palaeontologists from The Netherlands, the UK, Argentina, Germany and Belgium applied recently developed methods to measure theropod (carnivorous) dinosaur species diversity. The newly applied method uses both traditional phylogenetic analysis, discriminant analysis as well as machine learning. This new combination of analyses was performed on teeth of carnivorous dinosaurs, named theropods, from a set of isolated teeth from the famous Cretaceous (~100million years old) Kem Kem beds of Morocco. It turned out to reveal a theropod species previously not found in this area.
Fossilized remains from this site very often comprise teeth, whereas very few dinosaur bones preserve well, leaving scientists often guessing which dinosaur left these teeth behind.
Amongst the study specimens were teeth from the famous Spinosaurus and Carcharodontosaurus, known from movies such as the Jurassic Park franchise.
Next to these easily recogniseable tooth morphotypes, some ‘mystery teeth’ were also analysed.
These teeth were previously classified as belonging to the dromaeosaurid family of Velociraptor fame.
Simon Wills, a scientific associate at the Natural History Museum who led the research, says, ‘the use of machine learning to identify theropod teeth has thrown the doors wide open to the ecosystem of the dinosaurs that roamed the Kem Kem 100 million years ago.
It was fascinating to see how the powerful tool accurately identified the specimens when combined with traditional methods.
The process highlights how embracing methods old and new can uncover brand new insights into relatively well-explored areas.
I believe we’ll see advances beyond what we thought possible in the coming years as our datasets grow meaning machine learning can reveal more about palaeodiversity and ecosystems from even the smallest remains — such as teeth!’
Close fit
Using the novel technique, the research team tried to determine the closest fit of the teeth’s appearance to other dinosaurs with well-known dentition.
The team from Utrecht University, the Natural History Museum, London, Instituto Miguel Lillo in Tucuman, Argentina, the Palaeontological Museum Munich, and VU Brussels then found that the two mystery tooth morphotypes were not the Jurassic Park raptor’s cousins, but rather, belonged to Abelisauridae, a distant cousin of Tyrannosaurus (including the big head and tiny arms), and a clade called Noasauridae, the latter being very rare in Morocco.
‘These teeth had been in museum collections for decades, but this new combination of techniques brought them to life again, and more importantly, confirms the presence of noasaurids in the Kem Kem, thanks to this international team effort,’ says Dr Femke Holwerda of Utrecht University.
Future work
Noasaurids are peculiar small theropods with long necks, and there are only a few hints of isolated bones known from them from the Kem Kem.
Traditional methods alone did not find this elusive little theropod amongst the tooth sample.
This shows that the new combination of methods is promising for future work on other dinosaurs, such as long-necked dinosaurs, even more rarely found in the Kem Kem.
Kem Kem
The Kem Kem is an Early Cretaceous (roughly 100 million years old) highly fossiliferous site on the border between Morocco and Algeria. It is one of few places in the world that preserves a fairly complete Early Cretaceous dinosaur-dominated ecosystem. Next to a plethora of theropods, sauropod (long-necked) dinosaurs, and one other type of herbivore existed in the area. The ecosystem was riverine, which might be why so many carnivorous animals were supported.
Reference:
Christophe Hendrickx, Thomas H. Trapman, Simon Wills, Femke M. Holwerda, Koen H. W. Stein, Oliver W. M. Rauhut, Roland R. Melzer, Jeroen Van Woensel, Jelle W. F. Reumer. A combined approach to identify isolated theropod teeth from the Cenomanian Kem Kem Group of Morocco: cladistic, discriminant, and machine learning analysesCitation for this article: Hendrickx, C., Trapman, T. H., Wills, S., Holwerda, F. M., Stein, K. H. . Journal of Vertebrate Paleontology, 2024; DOI: 10.1080/02724634.2024.2311791
Khinjaria acuta was around the length of an orca, (7-8 metres). (Credit: Andrey Atuchin)
Paleontologists have discovered a strange new species of marine lizard with dagger-like teeth that lived near the end of the age of dinosaurs. Their findings, published in Cretaceous Research, show a dramatically different ocean ecosystem to what we see today, with numerous giant top predators eating large prey, unlike modern ecosystems where a few apex predators — such as great white sharks, orca and leopard seals — dominate.
Khinjaria acuta was a member of the family Mosasauridae, or mosasaurs. Mosasaurs weren’t dinosaurs, but giant marine lizards, relatives of today’s Komodo dragons and anacondas, which ruled the oceans 66 million years ago, during the era of Tyrannosaurus and Triceratops.
Khinjaria had powerful jaws and long, dagger-like teeth to seize prey, giving it a nightmarish appearance. It was part of an extraordinarily diverse fauna of predators that inhabited the Atlantic Ocean off the coast of Morocco, just before the dinosaurs went extinct.
The study is based on a skull and parts of the skeleton collected from a phosphate mine southeast of Casablanca. The study involved researchers from the University of Bath in the UK, the Marrakech Museum of Natural History, the Museum National d’ Histoire Naturelle (NMNH) in Paris (France), Southern Methodist University in Texas (USA), and the University of the Basque Country (Bilbao).
“What’s remarkable here is the sheer diversity of top predators,” said Dr Nick Longrich of the Department of Life Sciences and the Milner Centre for Evolution at the University of Bath, who led the study. “We have multiple species growing larger than a great white shark, and they’re top predators, but they all have different teeth, suggesting they’re hunting in different ways.
“Some mosasaurs had teeth to pierce prey, others to cut, tear, or crush. Now we have Khinjaria, with a short face full of huge, dagger-shaped teeth. This is one of the most diverse marine faunas seen anywhere, at any time in history, and it existed just before the marine reptiles and the dinosaurs went extinct.”
Morocco’s diverse marine reptiles lived just before an asteroid struck the Yucatan Peninsula in Mexico. Dust and fine particles shot into the high atmosphere blocked out the sun for months, causing darkness and cooling, which drove most of the planet’s species to extinction.
Dinosaurs were wiped out on land, and a handful of surviving species of mammals, birds, and lizards diversified to take their place. Meanwhile, the same happened in the oceans.
Mosasaurs, plesiosaurs and giant sea turtles disappeared, along with entire families of fish. This opened the way for whales and seals, and fish like swordfish and tuna appeared. However, the ecosystem that evolved after the impact was different.
“There seems to have been a huge change in the ecosystem structure in the past 66 million years,” said Longrich. “This incredible diversity of top predators in the Late Cretaceous is unusual, and we don’t see that in modern marine communities.”
Modern marine food chains have just a few large apex predators, animals like orcas, white sharks, and leopard seals. The Cretaceous had a whole host of top predators.
Dr Longrich said: “It’s not just that we’re getting rid of the old actors and recasting new ones into the same roles. The story has changed dramatically.
“Modern ecosystems have predators like baleen whales and dolphins that eat small prey, and not many things eating large prey. The Cretaceous has a huge number of marine reptile species that take large prey. Whether there’s something about marine reptiles that caused the ecosystem to be different, or the prey, or perhaps the environment, we don’t know. But this was an incredibly dangerous time to be a fish, a sea turtle, or even a marine reptile.”
Professor Nathalie Bardet, from the NMNH, said: “The Phosphates of Morocco deposit in a shallow and warm epicontinental sea, under a system of upwellings; these zones are caused by currents of deep, cold, nutrient-rich waters rising towards the surface, providing food for large numbers of sea creatures and, as a result, supporting a lot of predators. This is probably one of the explanations for this extraordinary paleobiodiversity observed in Morocco at the end of the Cretaceous.”
“The phosphates of Morocco immerse us in the Upper Cretaceous seas during the latest geological times of the dinosaurs’ age. No deposit has provided so many fossils and so many species from this period,” said Professor NE. Jalil of NMNH. “After the’ titan of the seas’, Thalassotitan, the ‘saw-toothed’ mosasaur Xenodens, the ‘star-toothed’ mosasaur, Stelladens and many others, now there is Khinjaria, a new mosasaur with dagger-like teeth.
“The elongation of the posterior part of the skull which accommodated the jaw musculature suggests a terrible biting force.”
Reference:
Nicholas R. Longrich, Michael J. Polcyn, Nour-Eddine Jalil, Xabier Pereda-Suberbiola, Nathalie Bardet. A bizarre new plioplatecarpine mosasaurid from the Maastrichtian of Morocco. Cretaceous Research, 2024; 105870 DOI: 10.1016/j.cretres.2024.105870
A new fossil, named “Attenborough’s strange bird” after naturalist and documentarian Sir David Attenborough, is the first of its kind to evolve a toothless beak. It’s from a branch of the bird family tree that went extinct in the mass extinction 66 million years ago, and this strange bird is another puzzle piece that helps explain why some birds — and their fellow dinosaurs — went extinct, and others survived to today.
No birds alive today have teeth. But that wasn’t always the case — many early fossil birds had beaks full of sharp, tiny teeth. In a paper in the journal Cretaceous Research, scientists have described a new species of fossil bird that was the first of its kind to evolve toothless-ness; its name, in honor of naturalist Sir David Attenborough, means “Attenborough’s strange bird.”
“It is a great honour to have one’s name attached to a fossil, particularly one as spectacular and important as this. It seems the history of birds is more complex than we knew,” says Sir David Attenborough.
All birds are dinosaurs, but not all dinosaurs fall into the specialized type of dinosaurs known as birds, sort of like how all squares are rectangles, but not all rectangles are squares. The newly described Imparavis attenboroughi is a bird, and therefore, also a dinosaur.
Imparavis attenboroughi was a member of a group of birds called enantiornithines, or “opposite birds,” named for a feature in their shoulder joints that is “opposite” from what’s seen in modern birds. Enantiornithines were once the most diverse group of birds, but they went extinct 66 million years ago following the meteor impact that killed most of the dinosaurs. Scientists are still working to figure out why the enantiornithines went extinct and the ornithuromorphs, the group that gave rise to modern birds, survived.
“Enantiornithines are very weird. Most of them had teeth and still had clawed digits. If you were to go back in time 120 million years in northeastern China and walk around, you might have seen something that looked like a robin or a cardinal, but then it would open its mouth, and it would be filled with teeth, and it would raise its wing, and you would realize that it had little fingers,” says Alex Clark, a PhD student at the University of Chicago and the Field Museum and the paper’s corresponding author.
But “Attenborough’s strange bird” bucked this trend. “Scientists previously thought that the first record of toothlessness in this group was about 72 million years ago, in the late Cretaceous. This little guy, Imparavis, pushes that back by about 48 to 50 million years. So toothlessness, or edentulism, evolved much earlier in this group than we thought,” says Clark.
The specimen was found by an amateur fossil collector near the village of Toudaoyingzi in northeastern China and donated to the Shandong Tianyu Museum of Nature. Clark’s advisor and co-author on the paper, Field Museum associate curator of fossil reptiles Jingmai O’Connor, first noticed something unusual about this fossil several years ago, when she was visiting the Shandong Tianyu Museum’s collections.
“I think what drew me to the specimen wasn’t its lack of teeth — it was its forelimbs,” says O’Connor. “It had a giant bicipital crest — a bony process jutting out at the top of the upper arm bone, where muscles attach. I’d seen crests like that in Late Cretaceous birds, but not in the Early Cretaceous like this one. That’s when I first suspected it might be a new species.”
O’Connor, Clark, and their coauthors in China, Xiaoli Wang, Xiangyu Zhang, Xing Wang, Xiaoting Zheng, and Zhonghe Zhou, undertook further study of the specimen and determined that it did indeed represent an animal new to science.
The unusual wing bones could have allowed for muscle attachments that let this bird flap its wings with extra power. “We’re potentially looking at really strong wing beats. Some features of the bones resemble those of modern birds like puffins or murres, which can flap crazy fast, or quails and pheasants, which are stout little birds but produce enough power to launch nearly vertically at a moment’s notice when threatened,” says Clark.
Meanwhile, the bird’s toothless beak doesn’t necessarily tell scientists what it was eating, since modern toothless birds have a wide variety of diets. Like its fellow enantiornithines, and unlike modern birds, it does not appear to have a digestive organ called a gizzard, or gastric mill, that helped it crush up its food.
While Clark notes that “an animal is more than the sum of its parts, and we can’t fully know what an animal’s life was like just by looking at single components of its body,” he and his coauthors have been able to hypothesize about some of Imparavis’s behavior and ecology, based on the details of its wings, feet, and beak together. “I like to think of these guys kind of acting like modern robins. They can perch in trees just fine, but for the most part, you see them foraging on the ground, hopping around and walking,” says Clark.
“It seems like most enantiornithines were pretty arboreal, but the differences in the forelimb structure of Imparavis suggests that even though it’s still probably lived in the trees, it maybe ventured down to the ground to feed, and that might mean it had a unique diet compared to other enantiornithines, which also might explain why it lost its teeth,” says O’Connor.
In the paper, the researchers also revisited a previously described fossil bird, Chiappeavis (which O’Connor named eight years ago after her PhD advisor), and suggest that it too was an early toothless enantiornithine. This finding, along with Imparavis, indicates that toothlessness may not have been quite as unique in Early Cretaceous enantiornithines as previously thought.
Clark said that nature documentaries by Sir David Attenborough, in which the renowned British naturalist narrates the behavior of different animals, were pivotal to his own interest in science. “I most likely wouldn’t be in the natural sciences if it weren’t for David Attenborough’s documentaries,” says Clark, explaining why he chose to name the new fossil after Attenborough.
Clark and O’Connor noted the importance of Attenborough’s messaging that not only celebrates life on earth, but also warns against the mass extinction the planet is undergoing due to human-caused climate change and habitat destruction.
“Learning about enantiornithines like Imparavis attenboroughi helps us understand why they went extinct and why modern birds survived, which is really important for understanding the sixth mass extinction that we’re in now,” says O’Connor. “The biggest crisis humanity is facing is the sixth mass extinction, and paleontology provides the only evidence we have for how organisms respond to environmental changes and how animals respond to the stress of other organisms going extinct.”
Reference:
Xiaoli Wang, Alexander D. Clark, Jingmai K. O’Connor, Xiangyu Zhang, Xing Wang, Xiaoting Zheng, Zhonghe Zhou. First Edentulous Enantiornithine (Aves: Ornithothoraces) from the Lower Cretaceous Jehol Avifauna. Cretaceous Research, 2024; 159: 105867 DOI: 10.1016/j.cretres.2024.105867
The oldest fossilised forest known on Earth — dating from 390 million years ago — has been found in the high sandstone cliffs along the Devon and Somerset coast of South West England.
The fossils, discovered and identified by researchers from the Universities of Cambridge and Cardiff, are the oldest fossilised trees ever found in Britain, and the oldest known fossil forest on Earth. This fossil forest is roughly four million years older than the previous record holder, which was found in New York State.
The fossils were found near Minehead, on the south bank of the Bristol Channel, near what is now a Butlin’s holiday camp. The fossilised trees, known as Calamophyton, at first glance resemble palm trees, but they were a ‘prototype’ of the kinds of trees we are familiar with today. Rather than solid wood, their trunks were thin and hollow in the centre. They also lacked leaves, and their branches were covered in hundreds of twig-like structures.
These trees were also much shorter than their descendants: the largest were between two and four metres tall. As the trees grew, they shed their branches, dropping lots of vegetation litter, which supported invertebrates on the forest floor.
Scientists had previously assumed this stretch of the English coast did not contain significant plant fossils, but this particular fossil find, in addition to its age, also shows how early trees helped shape landscapes and stabilise riverbanks and coastlines hundreds of millions of years ago. The results are reported in the Journal of the Geological Society.
The forest dates to the Devonian Period, between 419 million and 358 million years ago, when life started its first big expansion onto land: by the end of the period, the first seed-bearing plants appeared and the earliest land animals, mostly arthropods, were well-established.
“The Devonian period fundamentally changed life on Earth,” said Professor Neil Davies from Cambridge’s Department of Earth Sciences, the study’s first author. “It also changed how water and land interacted with each other, since trees and other plants helped stabilise sediment through their root systems, but little is known about the very earliest forests.”
The fossil forest identified by the researchers was found in the Hangman Sandstone Formation, along the north Devon and west Somerset coasts. During the Devonian period, this region was not attached to the rest of England, but instead lay further south, connected to parts of Germany and Belgium, where similar Devonian fossils have been found.
“When I first saw pictures of the tree trunks I immediately knew what they were, based on 30 years of studying this type of tree worldwide” said co-author Dr Christopher Berry from Cardiff’s School of Earth and Environmental Sciences. “It was amazing to see them so near to home. But the most revealing insight comes from seeing, for the first time, these trees in the positions where they grew. It is our first opportunity to look directly at the ecology of this earliest type of forest, to interpret the environment in which Calamophyton trees were growing, and to evaluate their impact on the sedimentary system.”
The fieldwork was undertaken along the highest sea-cliffs in England, some of which are only accessible by boat, and revealed that this sandstone formation is in fact rich with plant fossil material from the Devonian period. The researchers identified fossilised plants and plant debris, fossilised tree logs, traces of roots and sedimentary structures, preserved within the sandstone. During the Devonian, the site was a semi-arid plain, criss-crossed by small river channels spilling out from mountains to the northwest.
“This was a pretty weird forest — not like any forest you would see today,” said Davies. “There wasn’t any undergrowth to speak of and grass hadn’t yet appeared, but there were lots of twigs dropped by these densely-packed trees, which had a big effect on the landscape.”
This period marked the first time that tightly-packed plants were able to grow on land, and the sheer abundance of debris shed by the Calamophyton trees built up within layers of sediment. The sediment affected the way that the rivers flowed across the landscape, the first time that the course of rivers could be affected in this way.
“The evidence contained in these fossils preserves a key stage in Earth’s development, when rivers started to operate in a fundamentally different way than they had before, becoming the great erosive force they are today,” said Davies. “People sometimes think that British rocks have been looked at enough, but this shows that revisiting them can yield important new discoveries.”
The research was supported in part by the Natural Environment Research Council (NERC), part of UK Research and Innovation (UKRI). Neil Davies is a Fellow of Churchill College, Cambridge.
Reference:
Neil S. Davies, William J. McMahon and Christopher M. Berry. Earth’s earliest forest: fossilized trees and vegetation-induced sedimentary structures from the Middle Devonian (Eifelian) Hangman Sandstone Formation, Somerset and Devon, SW England. Journal of the Geological Society, 2024 DOI: 10.1144/jgs2023-204
Note: The above post is reprinted from materials provided by University of Cambridge. Original written by Sarah Collins. The original text of this story is licensed under a Creative Commons License.
A detailed survey of the volcanic underwater deposits around the Kikai caldera in Japan clarified the deposition mechanisms as well as the event’s magnitude. As a result, the Kobe University research team found that the event 7,300 years ago was the largest volcanic eruption in the Holocene by far.
In addition to lava, volcanos eject large amounts of pumice, ashes and gases as a fast-moving flow, known as “pyroclastic flow,” and its sediments are a valuable data source on past eruptions. For volcanoes on land, geologists understand the sedimentation mechanism of pyroclastic flows well, but the sediments themselves get lost easily due to erosion. On the other hand, for volcanoes on oceanic islands or near the coast, the pyroclastic flow deposition process is largely unclear, both because the interaction with water is less well understood and because reliable data is difficult to obtain and therefore sparse. For these reasons, it is difficult to estimate the impact of many past eruptions on the climate and on history.
A Kobe University research team around SEAMA Nobukazu and SHIMIZU Satoshi took to the seas on the Kobe University-owned training vessel Fukae Maru (since replaced by the newly built Kaijin Maru) and conducted seismic imaging as well as sediment sampling around the Kikai caldera, off the south coast of Japan’s Ky?sh? island. The outstanding detail of the seismic reflection data revealed the sedimentary structure with a vertical resolution of 3 meters and down to a depth of several hundred meters below the seafloor. Shimizu explains: “Due to the fact that volcanic ejecta deposited in the sea preserve well, they record a lot of information at the time of eruption. By using seismic reflection surveys optimized for this target and by identifying the collected sediments, we were able to obtain important information on the distribution, volume, and transport mechanisms of the ejecta.”
In their article published in the Journal of Volcanology and Geothermal Research, the geoscientists report that an eruption that happened 7,300 years ago ejected a large amount of volcanic products (ash, pumice, etc.) that settled in an area measuring more than 4,500 square kilometers around the eruption site. With a dense-rock equivalent volume of between 133 and 183 cubic kilometers, the event was the largest volcanic eruption to have taken place within the Holocene (the most recent 11,700 years of Earth’s history following the end of the last ice age) known to science.
In the process of their analysis, the research team confirmed that the sedimentations on the ocean floor and those deposited on nearby islands have the same origin and from their distribution around the eruption site they could clarify the interaction between the pyroclastic flow and water. They noticed that the underwater portion of the flow could travel vast distances even uphill.
Their findings yield new insights into the elusive dynamics of volcanic mega events that may prove useful in identifying the remains of other events as well as in estimating their size. Seama explains, “Large volcanic eruptions such as those yet to be experienced by modern civilization rely on sedimentary records, but it has been difficult to estimate eruptive volumes with high precision because many of the volcanic ejecta deposited on land have been lost due to erosion. But giant caldera eruptions are an important phenomenon in geoscience, and because we also know that they influenced the global climate and thus human history in the past, understanding this phenomenon has also social significance.” In this light, it is fascinating to think that the event that created a caldera about the size of a modern capital city was in fact the largest volcanic event since humans have spread all over the globe.
This research was funded by the Ministry of Education, Culture, Sports, Science and Technology Japan under The Second Earthquake and Volcano Hazards Observation and Research Program (Earthquake and Volcano Hazard Reduction Research) and the Japan Society for the Promotion of Science (grant 20H00199).
Reference:
Satoshi Shimizu, Reina Nakaoka, Nobukazu Seama, Keiko Suzuki-Kamata, Katsuya Kaneko, Koji Kiyosugi, Hikaru Iwamaru, Mamoru Sano, Tetsuo Matsuno, Hiroko Sugioka, Yoshiyuki Tatsumi. Submarine pyroclastic deposits from 7.3 ka caldera-forming Kikai-Akahoya eruption. Journal of Volcanology and Geothermal Research, 2024; 108017 DOI: 10.1016/j.jvolgeores.2024.108017
Photo caption: Waves received in the wind tunnel of Ben Gurion University of the Negev with glass balls with a diameter of 90 microns. Two scales of waves can be seen in the image.
Sand ripples are fascinating. They are symmetrical, yet wind — which causes them — is very much not. Furthermore, they can be found on Mars and on Earth. They would be even more fascinating if the same effect found on Mars could be found here on Earth as well. What if one unified theory could explain their formation on two different planets of our solar system?
That is what Ben-Gurion University of the Negev physicist Prof.
Hezi Yizhaq and Prof. Itzhak Katra and their colleagues from Denmark, Germany, Italy, China, and the US contend in a cover article published in Nature Geoscience.
Sand ripples photographed on Mars by NASA’s Curiosity rover in 2015 showed two distinct patterns — large ripples (meter scale) and a shorter “impact” ripples pattern (decimeter scale). The prevailing theory proposed since then argues that the smaller scale ripples are produced by the impact mechanism of the particles transported by the wind like normal ripples on Earth and the larger ripples form due to hydrodynamic instability like subaqueous ripples.
Furthermore, it was believed that the physical conditions that produced them on Mars could not produce them on Earth.
However, Prof. Yizhaq and Prof. Katra have proven experimentally using Ben-Gurion University’s wind tunnel and Aarhus University’s Mars tunnel that such a phenomenon could exist on Earth — we just haven’t noticed it yet because we didn’t know we should be looking for it.
Imitating Martian sand was not easy because it’s finer than sand here on Earth, explains Prof.
Yizhaq, but the breakthrough occurred when they decided to try tiny glass balls to represent fine grains of sand.
Furthermore, the international research team has proposed a unified theoretical framework that would explain sand ripples on Mars and on Earth.
At its most basic level, sand ripples on Mars caused by wind look like sand ripples on Earth caused by water.
“There is much more research, both fieldwork and experimentally, needed to prove our theory, but it is amazing to propose something so radically new in a field I have been studying for over 20 years. It is exciting to go out and try to find on Earth what can clearly be seen on Mars,” says Prof. Yizhaq.
Prof. Yizhaq is a member of the Department of Solar Energy and Environmental Physics.
Prof. Itzhak Katra is a member of the Department of Environmental, Geoinformatics and Urban Planning Sciences.
The research was supported by the Israel Science Foundation (Grant no. 1270/20), the German-Israel Foundation for Scientific Research and Development (GIF) (Grant no. 155-301.10/2018), the National Natural Science Foundation of China, Texas A&M Engineering Experiment Station, Europlanet grant no. 871149, and the Horizon 2020 Research and Innovation Program.
Reference:
Hezi Yizhaq, Katharina Tholen, Lior Saban, Nitzan Swet, Conner Lester, Simone Silvestro, Keld R. Rasmussen, Jonathan P. Merrison, Jens J. Iversen, Gabriele Franzese, Klaus Kroy, Thomas Pähtz, Orencio Durán, Itzhak Katra. Coevolving aerodynamic and impact ripples on Earth. Nature Geoscience, 2024; 17 (1): 66 DOI: 10.1038/s41561-023-01348-3
For many hundreds of millions of years, the average temperature at the surface of the Earth has varied by not much more than 20° Celsius, facilitating life on our planet. To maintain such stable temperatures, Earth appears to have a ‘thermostat’ that regulates the concentration of atmospheric carbon dioxide over geological timescales, influencing global temperatures. The erosion and weathering of rocks are important parts of this ‘thermostat.’ A team led by LMU geologist Aaron Bufe and Niels Hovius from the German Research Centre for Geosciences has now modeled the influence of these processes on carbon in the atmosphere. Their surprising result: CO2 capture through weathering reactions is highest in low-relief mountain ranges with moderate erosion rates and not where erosion rates are fastest.
Weathering occurs where rock is exposed to water and wind. “When silicates weather, carbon is removed from the atmosphere and later precipitated as calcium carbonate. By contrast, weathering of other phases — such as carbonates and sulfides or organic carbon contained in rocks — releases CO2. These reactions are typically much faster than silicate weathering,” says Hovius.
“As a consequence, the impact of mountain building on the carbon cycle is complex.”
Weathering model shows common mechanisms
To address this complexity, the researchers used a weathering model to analyze fluxes of sulfide, carbonate, and silicate weathering in a number of targeted study regions — such as Taiwan and New Zealand — with large ranges in erosion rates.
“We discovered similar behaviors in all locations, pointing to common mechanisms,” says Bufe.
Further modelling showed that the relationship between erosion and CO2-fluxes is not linear, but that CO2 capture from weathering peaks at an erosion rate of approximately 0.1 millimeters per year.
When rates are lower or higher, less CO2 is sequestered and CO2 may even be released into the atmosphere.
“High erosion rates like in Taiwan or the Himalayas push weathering into being a CO2 source, because silicate weathering stops increasing with erosion rates at some point, whereas the weathering of carbonates and sulfides increases further,” explains Bufe.
In landscapes with moderate erosion rates of around 0.1 millimeters per year, the rapidly weathering carbonates and sulfides are largely depleted, whereas silicate minerals are abundant and weather efficiently. Where erosion is even slower than 0.1 millimeters per year, only few minerals are left to weather. The biggest CO2 sinks are therefore low-relief mountain ranges such as the Black Forest or the Oregon Coast Range, where erosion rates approach the optimum. “Over geological timescales, the temperature to which Earth’s ‘thermostat’ is set therefore depends strongly on the global distribution of erosion rates,” says Bufe. To understand the effects of erosion on Earth’s climate system in greater detail, Bufe thinks that future studies should additionally consider organic carbon sinks and weathering in floodplains.
Reference:
Aaron Bufe, Jeremy K. C. Rugenstein, Niels Hovius. CO 2 drawdown from weathering is maximized at moderate erosion rates. Science, 2024; 383 (6687): 1075 DOI: 10.1126/science.adk0957
Satellite image of gully landscapes on Mars, taken by HiRISE (High Resolution Imaging Experiment), a camera on board the Mars Reconnaissance Orbiter (photo no.: ESP_039114_1115). The white CO2 ice is visible on the sides of the gullies.
The period that liquid water was present on the surface of Mars may have been shorter than previously thought. Channel landforms called gullies, previously thought to be formed exclusively by liquid water, can also be formed by the action of evaporating CO2 ice. That is the conclusion of a new study by Lonneke Roelofs, a planetary researcher at Utrecht University. “This influences our ideas about water on Mars in general, and therefore our search for life on the planet.” The results of the study are published this week in the journal Communications Earth and Environment.
“The Martian atmosphere is 95% CO2,” Lonneke Roelofs explains.
“In winter, air temperatures drop below -120 degrees Celsius, which is cold enough for CO2 in the atmosphere to freeze.” In the process of freezing, CO2 gas can change directly to CO2 ice, skipping the liquid phase.
The process is similar to frost on Earth, where water vapour forms ice crystals and blankets the landscape in a white film.
Warmer spring temperatures, combined with the thin Martian atmosphere, causes CO2 ice to evaporate directly back to gas, again skipping the liquid phase.
“We call that ‘sublimation’. The process is extremely explosive due to Mars’ low air pressure. The created gas pressure pushes sediment grains apart causing the material to flow, similar to debris flows in mountainous areas on Earth. These flows can reshape the Martian landscape — even in the absence of water.”
Scientists have long hypothesised that CO2 ice could be a driving force behind these Martian landscape structures.
“But those hypotheses were mainly based on models or satellite studies,” Roelofs explains.
“With our experiments in a so-called ‘Mars chamber’, we were able to simulate this process under Martian conditions. Using this specialised lab equipment we could directly study this process with our own eyes. We even observed that debris flows driven by CO2 ice under Martian conditions flow just as efficiently as the debris flows driven by water on Earth.”
“We know for sure that there was once water on the surface of Mars. This study does not prove the contrary,” Roelofs says.
“But the emergence of life likely needs a long period where liquid water was present. Previously, we thought that these landscape structures were formed by debris flows driven by water, because of their similarity to debris flow systems on Earth. My research now shows that, in addition to debris flows powered by water, the sublimation of frozen CO2 can also serve as a driving force behind the formation of these Martian gully landscapes. That pushes the presence of water on Mars further into the past, making the chance of life on Mars smaller.” And that makes us even more unique than we thought.
Why Mars?
But what makes someone interested in landscapes 330 million km away? “Mars is our closest neighbour. It’s the only other rocky planet close to our solar system’s ‘green zone’. The zone is precisely far enough from the sun to allow for liquid water to exist, a prerequisite for life. So Mars is a place where we possibly can find answers to questions about how life developed, including potential extraterrestrial life,” answers Roelofs. “Plus, studying the formation of landscape structures on other planets is a way for us to step outside our Earthly context. You ask different questions, which leads to new insights on processes here on Earth. For example, we can also observe the process of gas-driven debris flows in pyroclastic flows around volcanoes, here on Earth. So this research could contribute to a better understanding of terrestrial volcanic hazards.”
Reference:
Lonneke Roelofs, Susan J. Conway, Tjalling de Haas, Colin Dundas, Stephen R. Lewis, Jim McElwaine, Kelly Pasquon, Jan Raack, Matthew Sylvest, Manish R. Patel. How, when and where current mass flows in Martian gullies are driven by CO2 sublimation. Communications Earth & Environment, 2024; 5 (1) DOI: 10.1038/s43247-024-01298-7
Grand Prismatic Spring in Yellowstone National Park, seen here from an aerial photo, provides a modern-day glimpse into the types of environments where sulfites may have accumulated and possibly played a role in kick-starting the earliest life on Earth.
Many artists have tried to depict what Earth might have looked like billions of years ago, before life made its appearance. Many scenes trade snow-covered mountains for lava-gushing volcanoes and blue skies for lightning bolts pummeling what’s below from a hazy sky.
But what did early Earth actually look like? This question has been the subject of intense scientific research for decades.
A publication led by Sukrit Ranjan, an assistant professor in the University of Arizona’s Lunar and Planetary Laboratory, shines a spotlight on sulfur, a chemical element that, while all familiar, has proved surprisingly resistant to scientific efforts in probing its role in the origin of life.
“Our picture of early Earth is pretty fuzzy,” said Ranjan, who explores sulfur concentrations in early Earth’s waters and atmosphere. The same processes that make our planet habitable — liquid water and plate tectonics — constantly destroy the rocks that hold Earth’s geologic record, he argues. “It’s great for us because it recycles nutrients that would otherwise be locked up in Earth’s crust, but it’s terrible for geologists in the sense that it removes the messengers.”
Published in the journal AGU Advances in December, Ranjan’s paper was selected as an editor’s highlight, in recognition of “experiments that were extremely difficult to perform but provide constraints for ongoing laboratory prebiotic chemistry experiments.”
At the core of efforts to pull back the curtain on the emergence of life on Earth has been a concept known as the “RNA world,” Ranjan said, referring to ribonucleic acid, a class of molecules that are present in every living cell and crucial to life as we know it.
The RNA world hypothesis is based on an interesting feature of modern biology, which is that of the four major categories of biomolecules — amino acids, carbohydrates, lipids and nucleic acids — RNA is the only one that can perform the role of an enzyme and the storage and replication of genetic information, by making copies of itself, all by itself. There’s just one problem: It’s really hard to make.
“For about 50 years, people have tried to figure out how to make RNA without enzymes, which is how biology does it,” Ranjan said, explaining that it wasn’t until the last five years that researchers figured out non-enzymatic pathways to make RNA.
“If we can get RNA, then on the far horizon we see a pathway to get everything else going,” he said. “And this begs the question: Was this molecule actually available earlier in any quantities whatsoever? And this is actually a major open question.”
Recently, scientists have completed a half-century quest to make RNA molecules without biological enzymes, a huge step forward to demonstrating the RNA world. However, these chemical pathways all rely on a critical sulfur molecule, called sulfite. By studying rock samples from some of Earth’s oldest rocks, scientists know there was plenty of sulfur to go around on the early, prebiotic Earth. But how much of it was in the atmosphere? How much of it ended up in water? And how much of it ended up as RNA-producing sulfite? Those are the questions Ranjan and his team set out to answer.
“Once it’s in the water, what happens to it? Does it stick around for a long time, or does it go away quickly?” he said. “For modern Earth we know the answer — sulfite loves to oxidize, or react with oxygen, so it’ll go away super-fast.”
By contrast, as geological evidence indicates, there was very little oxygen in early Earth’s atmosphere, which could have allowed sulfite to accumulate and last much longer. However, even in the absence of oxygen, sulfite is very reactive, and many reactions could have scrubbed it from the early Earth environment.
One such reaction is known as disproportionation, a process by which several sulfites react with each other, turning them into sulfate, and elemental sulfur, which are not useful for origin-of-life chemistry. But how fast is this process? Would it have allowed for sufficient quantities of sulfites to build up to kickstart life?
“No one has actually looked into this in depth outside of other contexts, mainly wastewater management,” Ranjan said.
His team then set out to investigate this problem under various conditions, an effort that took five years from designing the experiments to publishing the results.
“Of all the atoms that stock the prebiotic shipyard, including carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur, sulfur is perhaps the thorniest,” wrote Sonny Harman of NASA’s Ames Research Center, in a viewpoint article accompanying the publication. Because of its eagerness to enter into chemical reactions, “sulfur compounds tend to be more unstable, posing hazards to lab personnel and equipment, clogging up instrumentation and gumming up experiments.”
A lab tech’s nightmare
In their setup, Ranjan and his co-authors dissolved sulfite in water at various levels of acidity or alkalinity, locked it into a container under an oxygen-free atmosphere and let it “age,” as Ranjan put it. Every week, the team measured the concentrations of various sulfites with ultraviolet light. At the end of the experiment, they subjected them to a suite of analyses, all geared toward answering a relatively simple question, he said: “Just how much of this original molecule is left, and what did it turn into?”
Sulfites, it turned out, disproportionate much slower than what conventional wisdom held. Earlier studies, for example, had floated the idea of a sulfur haze engulfing the early Earth, but Ranjan’s team found that sulfites break down under ultraviolet light more quickly than expected. In the absence of an ozone layer during Earth’s early days, this process, known as photolysis, would have quickly purged sulfur compounds from the atmosphere and the water, albeit not quite as efficiently as the abundant oxygen in today’s world.
While it’s plausible that slow disproportionation could have allowed sulfites to accumulate, photolysis would have made that very unlikely except in certain environments such as shallow water pools, shaded from UV radiation, particularly if fed by surface runoff to provide mineral shields. Examples include underground pools or closed basin carbonate lakes, drainage-less depressions where sediments accumulate but water can only leave by evaporation.
“Think bodies of water like the Great Salt Lake in Utah or Mono Lake in California,” Ranjan said, adding that hydrothermal environments are emerging as hot candidates for life’s first appearance. Here, groundwater carrying dissolved minerals comes into contact with heat from volcanic activity, creating unique micro-environments that offer “safe spaces” for chemical process that could not occur elsewhere.
Such places can be found at mid-ocean ridges in the deep sea, but also on land, Ranjan said.
“A modern-day example of this is Yellowstone National Park, where we find pools that accumulate lots of sulfite, despite the oxygen,” he said, “and that can happen just because the sulfite is continually being replenished by volcanic outgassing.”
The study provides opportunities to test the hypothesis of sulfite availability in the evolution of the first molecules of life experimentally, the authors point out. Ranjan said one field of research in particular has him excited — phylogenetic microbiology, which uses genome analysis to reconstruct the blueprints of sulfur-using microorganisms believed to represent the oldest phyla on Earth.
There is evidence that these bacteria gain energy by reducing highly oxidized forms of sulfur to less oxidized ones. Intriguingly, Ranjan pointed out, they depend on a fairly complex enzyme machinery for the first step, reducing sulfate, sulfur’s abundant “modern” form, to sulfite, suggesting these enzymes are the product of a long evolutionary process. In contrast, only one enzyme is involved in the conversion from sulfite — the proposed key ingredient in “prebiotic puddle environments” — to sulfide.
“If true, this implies that sulfite was present in the natural environment in at least some water bodies, similar to what we argue here,” he said. “Geologists are just now turning to this. Can we use ancient rocks to test if they’re rich in sulfite? We don’t know the answer yet. This is still cutting-edge science.”
References:
Sukrit Ranjan, Khaled Abdelazim, Gabriella G. Lozano, Sangita Mandal, Cindy Y. Zhou, Corinna L. Kufner, Zoe R. Todd, Nita Sahai, Dimitar D. Sasselov. Geochemical and Photochemical Constraints on S[IV] Concentrations in Natural Waters on Prebiotic Earth. AGU Advances, 2023; 4 (6) DOI: 10.1029/2023AV000926
Scientists analyzed mercury levels from core samples from the Mochras Farm (Llanbedr) borehole in Wales to estimate how much and how rapidly carbon was released during ancient volcano events in Earth’s history Credit: Stephen Hesselbo. All Rights Reserved.
Massive volcanic events in Earth’s history that released large amounts of carbon into the atmosphere frequently correlate with periods of severe environmental change and mass extinctions. A new method to estimate how much and how rapidly carbon was released by the volcanoes could improve our understanding of the climate response, according to an international team led by researchers from Penn State and the University of Oxford.
The scientists reported this week (Feb. 26) in the journal Nature Geosciences that they have developed a new technique to estimate excess mercury left behind in the rock record due to ancient volcanic activity. The technique can estimate carbon emissions from large igneous provinces (LIPs), volcanic events that can last millions of years and produce magma that reaches Earth’s surface and forms lava flows hundreds of miles long.
“Large igneous provinces are often used as an analog for human-caused climate change because they occur relatively rapidly geologically and release a lot of carbon dioxide,” said Isabel Fendley, assistant research professor of geosciences at Penn State and lead author of the study. “But one big challenge we address with this study is that to date, it has been really difficult to figure out exactly how much carbon was released by these volcanoes.”
The researchers analyzed core samples that capture a 20-million-year record of the early Jurassic period and found mercury levels increased during the peak activity of the Karoo-Ferrar large igneous province and the associated Toarcian Oceanic Anoxic Event, a period of extensive environmental and climate change some 185 million years ago.
However, the total estimated carbon emissions using the mercury records were significantly lower than what carbon-cycle models had predicted would be necessary to cause the observed environmental changes.
The findings suggest the volcanism triggered positive Earth system feedbacks — climate and environmental responses to the initial warming that in turn produced more warming. These positive feedbacks may be as important as the primary emissions in these large carbon emission scenarios, and current carbon cycle models may be underestimating the effects of a given amount of emissions, the scientists said.
‘What this shows us is that there are Earth system responses that exacerbate the effects of the carbon the volcanoes emitted,” Fendley said. “And based on our results, these feedback processes are actually quite important but not well understood.”
Accurate estimates of LIP carbon emissions are important for understanding the impacts of positive and negative carbon-cycle feedback processes on future climate projections, the scientists said.
“In addition to historical climate change and understanding the history of life, it’s also relevant for how we understand Earth’s climate and how we investigate what happens to the environment after you release large amounts of carbon dioxide into the atmosphere,” Fendley said.
Estimating the quantity of carbon emissions associated with LIPs has been a challenge in part because scientists have an incomplete record of how much lava erupted. The Karoo-Ferrar LIP, for example, occurred on the former supercontinent Gondwana, and that material is now spread out across the southern hemisphere, spanning modern-day Southern Africa, Antarctica and Tasmania, the scientists said.
The researchers instead turned to mercury, which is released as a gas during volcanic eruptions but was otherwise rarely found in high concentrations in the environment prior to human activity. Looking at the chemistry of rocks in the core samples, the scientists were able to determine how much mercury would be expected based on environmental conditions and how much extra was present caused by the volcanoes.
They developed a method to convert the measured changes in mercury concentrations to the volume of mercury gas emissions. Using the ratio of mercury gas emissions to carbon emissions in modern volcanoes, they estimated how much carbon the ancient volcanoes released.
The researchers said the core samples, from the Mochras borehole in Wales, U.K., provided a unique opportunity to conduct this research. The long record showed the first clear evidence that there were significantly larger volcanic eruptions during this time period compared to the preceding 15 million years, the scientists said.
“The large amount of existing geochemical data from the Mochras Farm (Llanbedr) borehole in Wales, drilled by the British Geological Survey, plus the very well-constrained chronology, provided a unique opportunity that enabled this analysis,” Fendley said. “The decades-worth of previous work on the Mochras core enabled us to reconstruct original gas fluxes over millions of years, for periods that are traditional targets for paleo-environmental studies as well as the background state.”
Other researchers on this project were Joost Frieling, postdoctoral research assistant, and Tamsin Mather and Hugh Jenkyns, professors, at the University of Oxford; Michael Ruhl, assistant professor at Trinity College Dublin; and Stephen Hesselbo, professor at the University of Exeter.
European Research Council and the Natural Environment Research Council provided funding for this work.
Reference:
Isabel M. Fendley, Joost Frieling, Tamsin A. Mather, Micha Ruhl, Stephen P. Hesselbo, Hugh C. Jenkyns. Early Jurassic large igneous province carbon emissions constrained by sedimentary mercury. Nature Geoscience, 2024; DOI: 10.1038/s41561-024-01378-5
Note: The above post is reprinted from materials provided by Penn State. Original written by Matthew Carroll.
