An artist’s impression of the pliosaur by Megan Jacobs, University of Portsmouth
Over 20 years ago, the BBC’s Walking with Dinosaurs TV documentary series showed a 25-metre long Liopleurodon. This sparked heated debates over the size of this pliosaur as it was thought to have been wildly overestimated and more likely to have only reached an adult size of just over six metres long.
The speculation was set to continue, but now a chance discovery in an Oxfordshire museum has led to University of Portsmouth palaeontologists publishing a paper on a similar species potentially reaching a whopping 14.4 metres — twice the size of a killer whale.
Professor David Martill from the University of Portsmouth’s School of the Environment, Geography and Geosciences, said: “I was a consultant for the BBC’s pilot programme ‘Cruel Sea’ and I hold my hands up — I got the size of Liopleurodon horrendously wrong. I based my calculations on some fragmentary material which suggested a Liopleurodon could grow to a length of 25 metres, but the evidence was scant and it caused a lot of controversy at the time.
“The size estimate on the BBC back in 1999 was overdone, but now we have some evidence that is much more reliable after a serendipitous discovery of four enormous vertebrate.”
Professor Martill’s co-author, Megan Jacobs, was photographing an ichthyosaur skeleton at Abingdon County Hall Museum, while Dave looked through drawers of fossils. He found a large vertebra and was thrilled to discover the curator had three more of them in storage.
The vertebrae are clearly identifiable as being closely related to a Pliosaurus species or similar animal. Pliosaurs were like plesiosaurs, but with a bigger elongated head, similar to a crocodile, and a shorter neck. They had four flippers, which acted as powerful paddles to propel them through water and a relatively short tail.
After conducting topographic scans, Professor Martill and colleagues calculated this Late Jurassic marine reptile could have grown to between 9.8 and 14.4 metres long.
He said: “We know these pliosaurs were very fearsome animals swimming in the seas that covered Oxfordshire 145-152 million years ago. They had a massive skull with huge protruding teeth like daggers — as big, if not bigger than a T. rex, and certainly more powerful.
“They were at the top of the marine food chain and probably preyed on ichthyosaurs, long-necked plesiosaurs and maybe even smaller marine crocodiles, simply by biting them in half and taking chunks off them. We know they were massacring smaller marine reptiles because you can see bite marks in ichthyosaur bones in examples on display in The Etches Collection in Dorset.”
The vertebrae were originally discovered during temporary excavations at Warren Farm in the River Thames Valley in Oxfordshire and come from the Kimmeridge Clay Formation. This deposit is Late Jurassic in age, around 152 million years old.
Professor Martill added: “It’s wonderful to prove there was indeed a truly gigantic pliosaur species in the Late Jurassic seas. Although not yet on a par with the claims made for Liopleurodon in the iconic BBC TV series Walking With Dinosaurs, it wouldn’t surprise me if one day we find some clear evidence that this monstrous species was even bigger.”
Reference:
David M. Martill, Megan L. Jacobs, Roy E. Smith. A truly gigantic pliosaur (Reptilia, Sauropterygia) from the Kimmeridge Clay Formation (Upper Jurassic, Kimmeridgian) of England. Proceedings of the Geologists’ Association, 2023; DOI: 10.1016/j.pgeola.2023.04.005
The strange ridges on the teeth indicate a specialised feeding strategy, however its diet remains a mystery. (Photo by Dr Nick Longrich)
Scientists have discovered a new species of mosasaur, a sea-dwelling lizard from the age of the dinosaurs, with strange, ridged teeth unlike those of any known reptile. Along with other recent finds from Africa, it suggests that mosasaurs and other marine reptiles were evolving rapidly up until 66 million years ago, when they were wiped out by an asteroid along with the dinosaurs and around 90% of all species on Earth.
The new species, Stelladens mysteriosus, comes from the Late Cretaceous of Morocco and was around twice the size of a dolphin.
It had a unique tooth arrangement with blade-like ridges running down the teeth, arranged in a star-shaped pattern, reminiscent of a cross-head screwdriver.
Most mosasaurs had two bladelike, serrated ridges on the front and back of the tooth to help cut prey, however Stelladens had anywhere from four to six of these blades running down the tooth.
“It’s a surprise,” said Dr Nick Longrich from the Milner Centre for Evolution at the University of Bath, who led the study. “It’s not like any mosasaur, or any reptile, even any vertebrate we’ve seen before.”
Dr Nathalie Bardet, a marine reptile specialist from the Museum of Natural History in Paris, said: “I’ve worked on the mosasaurs of Morocco for more than 20 years, and I’d never seen anything like this before — I was both perplexed and amazed!”
That several teeth were found with the same shape suggests their strange shape was not the result of a pathology or a mutation.
The unique teeth suggest a specialised feeding strategy, or a specialised diet, but it remains unclear just what Stelladens ate.
Dr Longrich said: “We have no idea what this animal was eating, because we don’t know of anything similar either alive today, or from the fossil record.
“It’s possible it found a unique way to feed, or maybe it was filling an ecological niche that simply doesn’t exist today. The teeth look like the tip of a Phillips-head screwdriver, or maybe a hex wrench.
“So what’s it eating? Phillips head screws? IKEA furniture? Who knows.”
The teeth were small, but stout and with wear on the tips, which seemed to rule out soft-bodied prey. The teeth weren’t strong enough to crush heavily armoured animals like clams or sea urchins, however.
“That might seem to suggest it’s eating something small, and lightly armoured — thin-shelled ammonites, crustaceans, or bony fish — but it’s hard to know,” said Longrich. “There were weird animals living in the Cretaceous- ammonites, belemnites, baculites — that no longer exist. It’s possible this mosasaur ate something, and occupied a niche, that simply doesn’t exist anymore, and that might explain why nothing like this is ever seen again.
“Evolution isn’t always predictable. Sometimes it goes off in a unique direction, and something evolves that’s never been seen before, and then it never evolves again.”
The mosasaurs lived alongside dinosaurs but weren’t dinosaurs. Instead, they were giant lizards, relatives of Komodo dragons, snakes, and iguanas, adapted for a life at sea.
Mosasaurs evolved around 100 million years ago, and diversified up to 66 million years ago, when a giant asteroid hit the Yucatan Peninsula in Mexico, plunging the world into darkness.
Although scientists have debated the role of environmental changes towards the end of the Cretaceous in the extinction, Stelladens, along with recent discoveries from of Morocco, suggests that mosasaurs were evolving rapidly up to the very end — they went out at their peak, rather than fading away.
The new study shows that even after years of work in the Cretaceous of Morocco, new species are continuing to be discovered. The reason may be that most species are rare.
The authors of the study predict that in a very diverse ecosystem, it may take decades to find all of the rare species.
“We’re not even close to finding everything in these beds,” said Longrich, “This is the third new species to appear, just this year. The amount of diversity at the end of the Cretaceous is just staggering.”
Nour-Eddine Jalil, a professor at the Natural History Museum and a researcher at Univers Cadi Ayyad in Morocco, said: “The fauna has produced an incredible number of surprises — mosasaurs with teeth arranged like a saw, a turtle with a snout in the form of snorkel, a multitude of vertebrates of various shapes and sizes, and now a mosasaur with star-shaped teeth.
“We would say the works of an artist with an overflowing imagination.
“Morocco’s sites offer an unparalleled picture of the amazing biodiversity just before the great crisis of the end of the Cretaceous.”
Reference:
Nicholas R. Longrich, Nour-Eddine Jalil, Xabier Pereda-Suberbiola, Nathalie Bardet. Stelladens mysteriosus: A Strange New Mosasaurid (Squamata) from the Maastrichtian (Late Cretaceous) of Morocco. Fossils, 2023; 1 (1): 2 DOI: 10.3390/fossils1010002
An MIT study of the freshwater greenfin darter fish suggests river erosion can be a driver of biodiversity in tectonically inactive regions. Credits: Image: Jose-Luis Olivares/MIT with fish photo by Isaac Szabo
New findings could explain biodiversity hotspots in tectonically quiet regions.
If we could rewind the tape of species evolution around the world and play it forward over hundreds of millions of years to the present day, we would see biodiversity clustering around regions of tectonic turmoil. Tectonically active regions such as the Himalayan and Andean mountains are especially rich in flora and fauna due to their shifting landscapes, which act to divide and diversify species over time.
But biodiversity can also flourish in some geologically quieter regions, where tectonics hasn’t shaken up the land for millennia. The Appalachian Mountains are a prime example: The range has not seen much tectonic activity in hundreds of millions of years, and yet the region is a notable hotspot of freshwater biodiversity.
Now, an MIT study identifies a geological process that may shape the diversity of species in tectonically inactive regions. In a paper appearing in Science, the researchers report that river erosion can be a driver of biodiversity in these older, quieter environments.
They make their case in the southern Appalachians, and specifically the Tennessee River Basin, a region known for its huge diversity of freshwater fishes. The team found that as rivers eroded through different rock types in the region, the changing landscape pushed a species of fish known as the greenfin darter into different tributaries of the river network. Over time, these separated populations developed into their own distinct lineages.
The team speculates that erosion likely drove the greenfin darter to diversify. Although the separated populations appear outwardly similar, with the greenfin darter’s characteristic green-tinged fins, they differ substantially in their genetic makeup. For now, the separated populations are classified as one single species.
“Give this process of erosion more time, and I think these separate lineages will become different species,” says Maya Stokes PhD ’21, who carried out part of the work as a graduate student in MIT’s Department of Earth, Atmospheric and Planetary Sciences (EAPS).
The greenfin darter may not be the only species to diversify as a consequence of river erosion. The researchers suspect that erosion may have driven many other species to diversify throughout the basin, and possibly other tectonically inactive regions around the world.
“If we can understand the geologic factors that contribute to biodiversity, we can do a better job of conserving it,” says Taylor Perron, the Cecil and Ida Green Professor of Earth, Atmospheric, and Planetary Sciences at MIT.
The study’s co-authors include collaborators at Yale University, Colorado State University, the University of Tennessee, the University of Massachusetts at Amherst, and the Tennessee Valley Authority (TVA). Stokes is currently an assistant professor at Florida State University.
Fish in trees
The new study grew out of Stokes’ PhD work at MIT, where she and Perron were exploring connections between geomorphology (the study of how landscapes evolve) and biology. They came across work at Yale by Thomas Near, who studies lineages of North American freshwater fishes. Near uses DNA sequence data collected from freshwater fishes across various regions of North America to show how and when certain species evolved and diverged in relation to each other.
Near brought a curious observation to the team: a habitat distribution map of the greenfin darter showing that the fish was found in the Tennessee River Basin — but only in the southern half. What’s more, Near had mitochondrial DNA sequence data showing that the fish’s populations appeared to be different in their genetic makeup depending on the tributary in which they were found.
To investigate the reasons for this pattern, Stokes gathered greenfin darter tissue samples from Near’s extensive collection at Yale, as well as from the field with help from TVA colleagues. She then analyzed DNA sequences from across the entire genome, and compared the genes of each individual fish to every other fish in the dataset. The team then created a phylogenetic tree of the greenfin darter, based on the genetic similarity between fish.
From this tree, they observed that fish within a tributary were more related to each other than to fish in other tributaries. What’s more, fish within neighboring tributaries were more similar to each other than fish from more distant tributaries.
“Our question was, could there have been a geological mechanism that, over time, took this single species, and splintered it into different, genetically distinct groups?” Perron says.
A changing landscape
Stokes and Perron started to observe a “tight correlation” between greenfin darter habitats and the type of rock where they are found. In particular, much of the southern half of the Tennessee River Basin, where the species abounds, is made of metamorphic rock, whereas the northern half consists of sedimentary rock, where the fish are not found.
They also observed that the rivers running through metamorphic rock are steeper and more narrow, which generally creates more turbulence, a characteristic greenfin darters seem to prefer. The team wondered: Could the distribution of greenfin darter habitat have been shaped by a changing landscape of rock type, as rivers eroded into the land over time?
To check this idea, the researchers developed a model to simulate how a landscape evolves as rivers erode through various rock types. They fed the model information about the rock types in the Tennessee River Basin today, then ran the simulation back to see how the same region may have looked millions of years ago, when more metamorphic rock was exposed.
They then ran the model forward and observed how the exposure of metamorphic rock shrank over time. They took special note of where and when connections between tributaries crossed into non-metamorphic rock, blocking fish from passing between those tributaries. They drew up a simple timeline of these blocking events and compared this to the phylogenetic tree of diverging greenfin darters. The two were remarkably similar: The fish seemed to form separate lineages in the same order as when their respective tributaries became separated from the others.
“It means it’s plausible that erosion through different rock layers caused isolation between different populations of the greenfin darter and caused lineages to diversify,” Stokes says.
This research was supported, in part, by the Terra Catalyst Fund and the U.S. National Science Foundation through the AGeS Geochronology Program and the Graduate Research Fellowship Program. While at MIT, Stokes received support through the Martin Fellowship for Sustainability and the Hugh Hampton Young Fellowship.
Reference:
Maya F. Stokes, Daemin Kim, Sean F. Gallen, Edgar Benavides, Benjamin P. Keck, Julia Wood, Samuel L. Goldberg, Isaac J. Larsen, Jon Michael Mollish, Jeffrey W. Simmons, Thomas J. Near, J. Taylor Perron. Erosion of heterogeneous rock drives diversification of Appalachian fishes. Science, 2023; 380 (6647): 855 DOI: 10.1126/science.add9791
Eruption of Tonga underwater volcano found to disrupt satellite signals halfway around the world. Credit: ERG science center
An international team has used satellite- and ground-based ionospheric observations to demonstrate that an air pressure wave triggered by volcanic eruptions could produce an equatorial plasma bubble (EPB) in the ionosphere, severely disrupting satellite-based communications. Their findings were published in the journal Scientific Reports.
The ionosphere is the region of the Earth’s upper atmosphere where molecules and atoms are ionized by solar radiation, creating positively charged ions. The area with the highest concentration of ionized particles is called the F-region, an area 150 to 800 km above the Earth’s surface. The F-region plays a crucial role in long-distance radio communication, reflecting and refracting radio waves used by satellite and GPS tracking systems back to the Earth’s surface.
These important transmissions can be disrupted by irregularities in the F-region. During the day, the ionosphere is ionized by the Sun’s ultraviolet radiation, creating a density gradient of electrons with the highest density near the equator. However, disruptions to this, such as the movement of plasma, electric fields, and neutral winds, can cause the formation of a localized irregularity of enhanced plasma density. This region can grow and evolve, creating a bubble-like structure called an EPB. EPB can delay radio waves and degrade the performance of GPS.
Since these density gradients can be affected by atmospheric waves, it has long been hypothesized that they are formed by terrestrial events such as volcanic activity. For an international team led by Designated Assistant Professor Atsuki Shinbori (he, him) and Professor Yoshizumi Miyoshi (he, him) of the Institute for Space-Earth Environmental Research (ISEE), Nagoya University, in collaboration with NICT, The University of Electro-Communications, Tohoku University, Kanazawa University, Kyoto University and ISAS, the Tonga volcano eruption offered them a perfect opportunity to test this theory.
The Tonga volcano eruption was the biggest submarine eruption in history. This allowed the team to test their theory using the Arase satellite to detect EPB occurrences, the Himawari-8 satellite to check the initial arrival of air pressure waves and ground-based ionospheric observations to track the motion of the ionosphere. They observed an irregular structure of the electron density across the equator that occurred after the arrival of pressure waves generated by the volcanic eruption.
“The results of this study showed EPBs generated in the equatorial to low-latitude ionosphere in Asia in response to the arrival of pressure waves caused by undersea volcanic eruptions off Tonga,” Shinbori said.
The group also made a surprising discovery. For the first time, they showed that ionospheric fluctuations start a few minutes to a few hours earlier than the atmospheric pressure waves involved in the generation of plasma bubbles. This could have important implications because it suggests that the long-held model of geosphere-atmosphere-cosmosphere coupling, which states that ionospheric disturbances only happen after the eruption, needs revision.
“Our new finding is that the ionospheric disturbances are observed several minutes to hours before the initial arrival of the shock waves triggered by the Tonga volcanic eruption,” Shinbori said. “This suggests that the propagation of the fast atmospheric waves in the ionosphere triggered the ionospheric disturbances before the initial arrival of the shock waves. Therefore, the model needs to be revised to account for these fast atmospheric waves in the ionosphere.”
They also found that the EPB extended much further than predicted by the standard models. “Previous studies have shown that the formation of plasma bubbles at such high altitudes is a rare occurrence, making this a very unusual phenomenon,” Shinbori said. “We found that the EPB formed by this eruption reached space even beyond the ionosphere, suggesting that we should pay attention to the connection between the ionosphere and the cosmosphere when extreme natural phenomenon, such as the Tonga event, occur.”
“The results of this research are significant not only from a scientific point of view but also from the point of view of space weather and disaster prevention,” he said. “In the case of a large-scale event, such as the Tonga volcano eruption, observations have shown that a hole in the ionosphere can form even under conditions that are considered unlikely to occur under normal circumstances. Such cases have not been incorporated into space weather forecast models. This study will contribute to the prevention of satellite broadcasting and communication failures associated with ionospheric disturbances caused by earthquakes, volcanic eruptions, and other events.”
Annotated seismic cross-section of the Fontanelas volcano. Source: Pereira and Gamboa, 2023
A new study published in Geology concludes that an extinct volcano off the shore of Portugal could store as much as 1.2-8.6 gigatons of carbon dioxide, the equivalent of ~24-125 years of the country’s industrial emissions. For context, in 2022 a total of 42.6 megatons (0.0426 gigatons) of carbon dioxide was removed from the atmosphere by international carbon capture and storage efforts, according to the Global CCS Institute. The new study suggests that carbon capture and storage in offshore underwater volcanoes could be a promising new direction for removal and storage of much larger volumes of the greenhouse gas from the atmosphere.
“We know that most countries, including Portugal, are making efforts to decarbonize the economy and our human activities, this is a message that this may be one of the instruments to solve the problem” says Ricardo Pereira, a geologist at the NOVA School of Science and Technology, and co-author of the study.
Storing carbon dioxide in an extinct volcano would rely on a process known as ‘in situ mineral carbonation.’ In this process, carbon dioxide reacts with elements in certain types of rocks to produce new minerals that safely and permanently store the carbon dioxide. Elements like calcium, magnesium, and iron combine with carbon dioxide to form the minerals calcite, dolomite, and magnesite, respectively. Rocks that contain large amounts of calcium, iron, and magnesium are ideal candidates for this process — such as the volcanic basalts that make up most of the sea floor. Knowing this, the researchers targeted an offshore volcano for a few reasons — the structure of the volcano could provide an ideal architecture for carbon injection and storage, the rocks are the right type for the reactions involved, and the location Is not too close to large populations, but also not too far.
Most carbon capture projects have relied on injection of carbon dioxide into porous sedimentary basins that are sealed to prevent migration of the gas out of reservoirs. In these cases, the carbon will eventually start to form minerals, but only over longer periods of time — decades to centuries. In 2016, researchers published findings that 95% of carbon dioxide injected into underground basalts in Iceland had mineralized within just two years. The much shorter mineralization time makes the process safer and more effective — once carbon is stored in minerals, issues like potential leaks are no longer a concern.
Davide Gamboa, a geologist at the University of Aveiro and co-author of the study, explains, “What makes mineral carbonation really interesting is the time. The faster it gets into a mineral, the safer it becomes, and once it’s a mineral, it is permanent.”
The researchers studied the storage potential at the ancient Fontanelas volcano, which is partially buried ~100 kilometers offshore from Lisbon, with a peak ~1500 meters below sea-level.
To estimate the potential volume of carbon dioxide that could be stored at this site, the authors used 2D and 3D seismic studies of the undersea volcano that had been produced during offshore oil exploration, as well as data from samples that had been dredged from the area in 2008. The dredged samples contained naturally formed carbonate minerals, indicating that the chemical reactions required to store carbon were already happening, and that intentional efforts to mineralize carbon in these rocks should be successful. The samples also had up to 40% pore space — meaning there are spaces within the rocks where carbon dioxide could be injected and mineralized. The researchers also indicate that low-permeability layers imaged around the flanks of the volcano could help with containing the carbon dioxide before it is mineralized.
While this study demonstrated a large potential carbon storage capacity at the Fontanelas volcano, the authors highlight that many other places around the world may have similar offshore volcanoes that could be candidates for carbon capture and storage.
Reference:
Ricardo Pereira, Davide Gamboa. In situ carbon storage potential in a buried volcano. Geology, 2023; DOI: 10.1130/G50965.1
Metamorphosed banded iron formation from southern Wyoming showing deformation and folding. The rock is approximately 2.7 billion years old. Dark bands are iron oxides (magnetite, hematite) and yellow-orange bands are chert with iron oxide inclusions (jasper). (Photo by Linda Welzenbach-Fries/Rice University)
Visually striking layers of burnt orange, yellow, silver, brown and blue-tinged black are characteristic of banded iron formations, sedimentary rocks that may have prompted some of the largest volcanic eruptions in Earth’s history, according to new research from Rice University.
The rocks contain iron oxides that sank to the bottom of oceans long ago, forming dense layers that eventually turned to stone. The study published this week in Nature Geoscience suggests the iron-rich layers could connect ancient changes at Earth’s surface — like the emergence of photosynthetic life — to planetary processes like volcanism and plate tectonics.
In addition to linking planetary processes that were generally thought to be unconnected, the study could reframe scientists’ understanding of Earth’s early history and provide insight into processes that could produce habitable exoplanets far from our solar system.
“These rocks tell — quite literally — the story of a changing planetary environment,” said Duncan Keller, the study’s lead author and a postdoctoral researcher in Rice’s Department of Earth, Environmental and Planetary Sciences. “They embody a change in the atmospheric and ocean chemistry.”
Banded iron formations are chemical sediments precipitated directly from ancient seawater rich in dissolved iron. Metabolic actions of microorganisms, including photosynthesis, are thought to have facilitated the precipitation of the minerals, which formed layer upon layer over time along with chert (microcrystalline silicon dioxide). The largest deposits formed as oxygen accumulated in Earth’s atmosphere about 2.5 billion years ago.
“These rocks formed in the ancient oceans, and we know that those oceans were later closed up laterally by plate tectonic processes,” Keller explained.
The mantle, though solid, flows like a fluid at about the rate that fingernails grow. Tectonic plates — continent-sized sections of the crust and uppermost mantle — are constantly on the move, largely as a result of thermal convection currents in the mantle. Earth’s tectonic processes control the life cycles of oceans.
“Just like the Pacific Ocean is being closed today — it’s subducting under Japan and under South America — ancient ocean basins were destroyed tectonically,” he said. “These rocks either had to get pushed up onto continents and be preserved — and we do see some preserved, that’s where the ones we’re looking at today come from — or subducted into the mantle.”
Because of their high iron content, banded iron formations are denser than the mantle, which made Keller wonder whether subducted chunks of the formations sank all the way down and settled in the lowest region of the mantle near the top of Earth’s core. There, under immense temperature and pressure, they would have undergone profound changes as their minerals took on different structures.
“There’s some very interesting work on the properties of iron oxides at those conditions,” Keller said. “They can become highly thermally and electrically conductive. Some of them transfer heat as easily as metals do. So it’s possible that, once in the lower mantle, these rocks would turn into extremely conductive lumps like hot plates.”
Keller and his co-workers posit that regions enriched in subducted iron formations might aid the formation of mantle plumes, rising conduits of hot rock above thermal anomalies in the lower mantle that can produce enormous volcanoes like the ones that formed the Hawaiian Islands. “Underneath Hawaii, seismological data show us a hot conduit of upwelling mantle,” Keller said. “Imagine a hot spot on your stove burner. As the water in your pot is boiling, you’ll see more bubbles over a column of rising water in that area. Mantle plumes are sort of a giant version of that.”
“We looked at the depositional ages of banded iron formations and the ages of large basaltic eruption events called large igneous provinces, and we found that there’s a correlation,” Keller said. “Many of the igneous events — which were so massive that the 10 or 15 largest may have been enough to resurface the entire planet — were preceded by banded iron formation deposition at intervals of roughly 241 million years, give or take 15 million. It’s a strong correlation with a mechanism that makes sense.”
The study showed that there was a plausible length of time for banded iron formations to first be drawn deep into the lower mantle and to then influence heat flow to drive a plume toward Earth’s surface thousands of kilometers above.
In his effort to trace the journey of banded iron formations, Keller crossed disciplinary boundaries and ran into unexpected insights.
“If what’s happening in the early oceans, after microorganisms chemically change surface environments, ultimately creates an enormous outpouring of lava somewhere else on Earth 250 million years later, that means these processes are related and ‘talking’ to each other,” Keller said. “It also means it’s possible for related processes to have length scales that are far greater than people expected. To be able to infer this, we’ve had to draw on data from many different fields across mineralogy, geochemistry, geophysics and sedimentology.”
Keller hopes the study will spur further research. “I hope this motivates people in the different fields that it touches,” he said. “I think it would be really cool if this got people talking to each other in renewed ways about how different parts of the Earth system are connected.”
Keller is part of the CLEVER Planets: Cycles of Life-Essential Volatile Elements in Rocky Planets program, an interdisciplinary, multi-institutional group of scientists led by Rajdeep Dasgupta, Rice’s W. Maurice Ewing Professor of Earth Systems Science in the Department of Earth, Environmental and Planetary Sciences.
“This is an extremely interdisciplinary collaboration that’s looking at how volatile elements that are important for biology — carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur — behave in planets, at how planets acquire these elements and the role they play in potentially making planets habitable,” Keller said.
“We’re using Earth as the best example that we have, but we’re trying to figure out what the presence or absence of one or some of these elements might mean for planets more generally,” he added.
Cin-Ty Lee, Rice’s Harry Carothers Wiess Professor of Geology, Earth, Environmental and Planetary Sciences, and Dasgupta are co-authors on the study. Other co-authors are Santiago Tassara, an assistant professor at Bernardo O’Higgins University in Chile, and Leslie Robbins, an assistant professor at the University of Regina in Canada, who both did postdoctoral work at Yale University, and Yale Professor of Earth and Planetary Sciences Jay Ague, Keller’s doctoral adviser.
NASA (80NSSC18K0828) and the Natural Sciences and Engineering Research Council of Canada (RGPIN-2021-02523) supported the research.
Reference:
Duncan S. Keller, Santiago Tassara, Leslie J. Robbins, Cin-Ty A. Lee, Jay J. Ague, Rajdeep Dasgupta. Links between large igneous province volcanism and subducted iron formations. Nature Geoscience, 2023; DOI: 10.1038/s41561-023-01188-1
Note: The above post is reprinted from materials provided by Rice University. Original written by Silvia Cernea Clark.
A microscope image from an experiment conducted for this study. The image contains glass (brown), large garnets (pink) and other small mineral crystals. The field of view is 410 microns wide, about size of a sugar crystal. Credit: Science (2023). DOI: 10.1126/science.ade3418
Continents are part of what makes Earth uniquely habitable for life among the planets of the solar system, yet surprisingly little is understood about what gave rise to these huge pieces of the planet’s crust and their special properties. New research from Elizabeth Cottrell, research geologist and curator of rocks at the Smithsonian’s National Museum of Natural History, and lead study author Megan Holycross, formerly a Peter Buck Fellow and National Science Foundation Fellow at the museum and now an assistant professor at Cornell University, deepens the understanding of Earth’s crust by testing and ultimately eliminating one popular hypothesis about why continental crust is lower in iron and more oxidized compared to oceanic crust. The iron-poor composition of continental crust is a major reason why vast portions of the Earth’s surface stand above sea level as dry land, making terrestrial life possible today.
The study, published today in Science, uses laboratory experiments to show that the iron-depleted, oxidized chemistry typical of Earth’s continental crust likely did not come from crystallization of the mineral garnet, as a popular explanation proposed in 2018.
The building blocks of new continental crust issue forth from the depths of the Earth at what are known as continental arc volcanoes, which are found at subduction zones where an oceanic plate dives beneath a continental plate. In the garnet explanation for continental crust’s iron-depleted and oxidized state, the crystallization of garnet in the magmas beneath these continental arc volcanoes removes non-oxidized (reduced or ferrous, as it is known among scientists) iron from the terrestrial plates, simultaneously depleting the molten magma of iron and leaving it more oxidized.
One of the key consequences of Earth’s continental crust’s low iron content relative to oceanic crust is that it makes the continents less dense and more buoyant, causing the continental plates to sit higher atop the planet’s mantle than oceanic plates. This discrepancy in density and buoyancy is a major reason that the continents feature dry land while oceanic crusts are underwater, as well as why continental plates always come out on top when they meet oceanic plates at subduction zones.
The garnet explanation for the iron depletion and oxidation in continental arc magmas was compelling, but Cottrell said one aspect of it did not sit right with her.
“You need high pressures to make garnet stable, and you find this low-iron magma at places where crust isn’t that thick and so the pressure isn’t super high,” she said.
In 2018, Cottrell and her colleagues set about finding a way to test whether the crystallization of garnet deep beneath these arc volcanoes is indeed essential to the process of creating continental crust as is understood. To accomplish this, Cottrell and Holycross had to find ways to replicate the intense heat and pressure of the Earth’s crust in the lab, and then develop techniques sensitive enough to measure not just how much iron was present, but to differentiate whether that iron was oxidized.
To recreate the massive pressure and heat found beneath continental arc volcanoes, the team used what are called piston-cylinder presses in the museum’s High-Pressure Laboratory and at Cornell. A hydraulic piston-cylinder press is about the size of a mini fridge and is mostly made of incredibly thick and strong steel and tungsten carbide. Force applied by a large hydraulic ram results in very high pressures on tiny rock samples, about a cubic millimeter in size. The assembly consists of electrical and thermal insulators surrounding the rock sample, as well as a cylindrical furnace. The combination of the piston-cylinder press and heating assembly allows for experiments that can attain the very high pressures and temperatures found under volcanoes.
In 13 different experiments, Cottrell and Holycross grew samples of garnet from molten rock inside the piston-cylinder press under pressures and temperatures designed to simulate conditions inside magma chambers deep in Earth’s crust. The pressures used in the experiments ranged from 1.5 to 3 gigapascals — that is roughly 15,000 to 30,000 Earth atmospheres of pressure or 8,000 times more pressure than inside a can of soda. Temperatures ranged from 950 to 1,230 degrees Celsius, which is hot enough to melt rock.
Next, the team collected garnets from Smithsonian’s National Rock Collection and from other researchers around the world. Crucially, this group of garnets had already been analyzed so their concentrations of oxidized and unoxidized iron were known.
Finally, the study authors took the materials from their experiments and those gathered from collections to the Advanced Photon Source at the U.S. Department of Energy’s Argonne National Laboratory in Illinois. There the team used high-energy X-ray beams to conduct X-ray absorption spectroscopy, a technique that can tell scientists about the structure and composition of materials based on how they absorb X-rays. In this case, the researchers were looking into the concentrations of oxidized and unoxidized iron.
The samples with known ratios of oxidized and unoxidized iron provided a way to check and calibrate the team’s X-ray absorption spectroscopy measurements and facilitated a comparison with the materials from their experiments.
The results of these tests revealed that the garnets had not incorporated enough unoxidized iron from the rock samples to account for the levels of iron-depletion and oxidation present in the magmas that are the building blocks of Earth’s continental crust.
“These results make the garnet crystallization model an extremely unlikely explanation for why magmas from continental arc volcanoes are oxidized and iron depleted,” Cottrell said. “It’s more likely that conditions in Earth’s mantle below continental crust are setting these oxidized conditions.”
Like so many results in science, the findings lead to more questions: “What is doing the oxidizing or iron depleting?” Cottrell asked. “If it’s not garnet crystallization in the crust and it’s something about how the magmas arrive from the mantle, then what is happening in the mantle? How did their compositions get modified?”
Cottrell said that these questions are hard to answer but that now the leading theory is that oxidized sulfur could be oxidizing the iron, something a current Peter Buck Fellow is investigating under her mentorship at the museum.
This study is an example of the kind of research that museum scientists will tackle under the museum’s new Our Unique Planet initiative, a public-private partnership, which supports research into some of the most enduring and significant questions about what makes Earth special. Other research will investigate the source of Earth’s liquid oceans and how minerals may have served as templates for life.
This research was supported by funding from the Smithsonian, the National Science Foundation, the Department of Energy and the Lyda Hill Foundation.
Reference:
Megan Holycross, Elizabeth Cottrell. Garnet crystallization does not drive oxidation at arcs. Science, 2023; 380 (6644): 506 DOI: 10.1126/science.ade3418
Ammonite fossil From the Ohmden quarry, Posidonia shale lagerstatte. Credit: Sinjini Sinha
All that glitters is not gold, or even fool’s gold in the case of fossils.
A recent study by scientists at The University of Texas at Austin and collaborators found that many of the fossils from Germany’s Posidonia shale do not get their gleam from pyrite, commonly known as fool’s gold, which was long thought to be the source of the shine. Instead, the golden hue is from a mix of minerals that hints at the conditions in which the fossils formed.
The discovery is important for understanding how the fossils — which are among the world’s best-preserved specimens of sea life from the Early Jurassic — came to form in the first place, and the role that oxygen in the environment had in their formation.
“When you go to the quarries, golden ammonites peek out from black shale slabs,” said study co-author Rowan Martindale, an associate professor at the UT Jackson School of Geosciences. “But surprisingly, we struggled to find pyrite in the fossils. Even the fossils that looked golden, are preserved as phosphate minerals with yellow calcite. This dramatically changes our view of this famous fossil deposit.”
The research was published in Earth Science Reviews. Drew Muscente, a former assistant professor at Cornell College and former Jackson School postdoctoral researcher, led the study.
The fossils of the Posidonia Shale date back to 183 million years ago, and include rare soft-bodied specimens such as ichthyosaur embryos, squids with ink-sacs, and lobsters. To learn more about the fossilization conditions that led to such exquisite preservation, the researchers put dozens of samples under scanning electron microscopes to study their chemical composition.
“I couldn’t wait to get them in my microscope and help tell their preservational story,” said co-author Jim Schiffbauer, an associate professor at the University of Missouri Department of Geological Sciences, who handled some of the larger samples.
The researchers found that in every instance, the fossils were primarily made up of phosphate minerals even though the surrounding black shale rock was dotted with microscopic clusters of pyrite crystals, called framboids.
“I spent days looking for the framboids on the fossil,” said co-author Sinjini Sinha, a doctoral student at the Jackson School. “For some of the specimens, I counted 800 framboids on the matrix while there was maybe three or four on the fossils.”
The fact that pyrite and phosphate are found in different places on the specimens is important because it reveals key details about the fossilization environment. Pyrite forms in anoxic (without oxygen) environments, but phosphate minerals need oxygen. The research suggests that although an anoxic seafloor sets the stage for fossilization — keeping decay and predators at bay — it took a pulse of oxygen to drive the chemical reactions needed for fossilization.
These findings complement earlier research carried out by the team on the geochemical conditions of sites known for their caches of exceptionally preserved fossils, called konservat-lagerstätten. However, the results of these studies contradict long-standing theories about the conditions needed for exceptional fossil preservation in the Posidonia.
“It’s been thought for a long time that the anoxia causes the exceptional preservation, but it doesn’t directly help,” said Sinha. “It helps with making the environment conducive to faster fossilization, which leads to the preservation, but it’s oxygenation that’s enhancing preservation.”
It turns out, the oxygenation — and the phosphate and accompanying minerals — also enhanced the fossil’s shine.
The research was funded by Cornell College and the National Science Foundation. The Posidonia fossil specimens used in this study are now part of the collections at the Jackson School’s Non-Vertebrate Paleontology Laboratory.
Reference:
A.D. Muscente, Olivia Vinnes, Sinjini Sinha, James D. Schiffbauer, Erin E. Maxwell, Günter Schweigert, Rowan C. Martindale. What role does anoxia play in exceptional fossil preservation? Lessons from the taphonomy of the Posidonia Shale (Germany). Earth-Science Reviews, 2023; 238: 104323 DOI: 10.1016/j.earscirev.2023.104323
The discovery of the driving force behind the world’s deadliest volcanic events could help improve forecasting of their devastating effects, new research suggests.
The findings reveal the mechanism that enables dense, scorching avalanches of a mixture of rock, ash and gases ejected during volcanic eruptions—called pyroclastic flows—to travel at up to 100 miles per hour.
Better predicting the path of pyroclastic flows—which can reach temperatures of 600°C—could help prevent injuries and deaths following volcanic eruptions, researchers say.
More than 600 million people around the world live in regions that could be hit by pyroclastic flows.
The pyroclastic flow triggered by the eruption of Mount Vesuvius in 79 AD is one of the most famous examples of these lethal events.
While scientists have long been aware of the immense dangers they pose, the underlying mechanism that enables them to travel at such high speed and long distances—up to 12 miles—had remained unknown.
Fluid-like behavior
Now, a team led by an Edinburgh researcher has revealed the science behind so-called block-and-ash flows, the most common and destructive type of pyroclastic flow. Their work is published in the journal Nature Communications.
They identified a mechanism that greatly reduces the friction of the dense volcanic mixtures, enabling them to travel at high speed.
The process—called fragmentation-induced fluidization—causes the base layer of pyroclastic flows to exhibit fluid-like behavior.
This effect is triggered by rapidly compacting the mixture, and raising the pressure between fine particles after large blocks have disintegrated into powder.
This enhanced fluidity, coupled with the large amounts—often millions of tons—of volcanic material, is the reason pyroclastic flows can travel far at high speeds as dense avalanches, destroying everything in their path, the team says.
Density changes
The researchers conducted a comprehensive analysis by examining pyroclastic flow deposits from previous eruptions at Mount Merapi in Java, Indonesia, in 2006 and 2010.
They also carried out laboratory experiments and ran computer simulations to investigate the impact of density changes within pyroclastic flows and the ability of their granular mixtures to become fluid-like.
“The discovery of the fragmentation-induced fluidization process is hugely significant, as it enables us to develop more reliable numerical models that can accurately evaluate pyroclastic flow hazards around both current and potentially future active volcanoes. Our findings not only reveal a fundamental geoscience principle but also urges us to reconsider the focus of our field-based studies. This work lays the foundation for a multitude of investigations that my research group at University of Edinburgh will undertake, ultimately refining and reshaping our understanding of volcanic hazards,” says Dr. Eric Breard, School of GeoSciences.
Reference:
Eric C. P. Breard et al, The fragmentation-induced fluidisation of pyroclastic density currents, Nature Communications (2023). DOI: 10.1038/s41467-023-37867-1
New lab work suggests that rock roughness affects earthquake aftershock dynamics along faults. Credit: Dextersinister/Wikimedia Commons, CC BY-SA 4.0
When an earthquake hits, it is rarely an isolated event. Foreshocks precede quakes, and aftershocks follow them. To quantify seismic hazards, scientists must disentangle the factors that contribute to these shaking sequences.
In recent years, advancements in laboratory methods have enabled deeper exploration of earthquake dynamics. Now, Goebel and colleagues present new lab findings highlighting how the roughness of the rocks sliding past each other in a fault zone may influence aftershocks.
The researchers created fractures of varying roughness in several granite cylinders ranging from 40 to 50 millimeters in diameter. Then they applied pressure to the fractured granite to simulate sliding motions along a fault. They measured the resulting seismic disturbances in high resolution in the form of acoustic emission wave measurements.
The result was a realistic and manipulable simulation of actual earthquakes: Spacing and timing of the main slips, foreshocks, and aftershocks in the granite cylinders resembled those of real-world Southern California earthquakes.
The researchers found that after a major slip along a fracture—analogous to a main earthquake along a fault—the granite cylinders underwent periods of relaxation of built-up stress as well as aftershocks. Fractures with greater roughness moved less along the fracture during the main slip event but had more aftershocks; smoother fractures had more slip but fewer aftershocks.
These findings suggest that in nature, fault surface roughness may play a key role in the production of aftershocks following a main earthquake event.
The research is published in the journal Geophysical Research Letters.
Reference:
Thomas H. W. Goebel et al, Fault Roughness Promotes Earthquake‐Like Aftershock Clustering in the Lab, Geophysical Research Letters (2023). DOI: 10.1029/2022GL101241
Crinoids, also known as sea lilies or feather stars, are a group of marine animals that belong to the phylum Echinodermata. These creatures have been around for more than 500 million years, and they play an important role in the marine ecosystem. They are filter feeders, using their feather-like arms to capture plankton and other small organisms.
One of the interesting things about crinoids is that they have a complex anatomy that can be preserved in fossil form. The stem of a crinoid is made up of many small plates called ossicles, which are connected by flexible ligaments. The crown of the crinoid, which contains the feeding apparatus, is made up of a series of arms that are covered in small pinnules. These pinnules are used to capture plankton and other small organisms and bring them to the mouth of the crinoid.
Fossil crinoids come in many different shapes and sizes. Some crinoids have long, slender stems, while others have short, squat stems. The crowns of crinoids can also vary in shape and size, with some crowns being very small and others being quite large.
Where are crinoids found?
Fossil crinoids are often found in sedimentary rocks, which form when layers of sediment are deposited and compressed over time. These rocks can be found all over the world, and they can provide valuable information about the history of life on Earth. Fossil crinoids have been found in rocks dating back to the Ordovician period, which began around 485 million years ago.
In this article, we will explore some of the largest fossil crinoids ever discovered, including their size, location, and significance.
Taxocrinus saratogensis
One of the largest fossil crinoids ever discovered was found in the state of Indiana in the United States. The crinoid, which belongs to the species Taxocrinus saratogensis, was discovered in 1906 by a team of geologists led by John M. Clarke. The specimen is estimated to be around 350 million years old and is believed to have lived during the Devonian period.
The crinoid is incredibly large, with a stem measuring more than 40 feet in length and a crown that measures more than 10 feet in diameter. The entire specimen is estimated to have weighed more than 10 tons when it was alive. This makes it one of the largest fossil crinoids ever discovered.
The discovery of Taxocrinus saratogensis was an important event in the history of paleontology. At the time, it was the largest fossil crinoid ever discovered, and it provided valuable information about the morphology and biology of these ancient creatures. Today, the specimen is housed at the American Museum of Natural History in New York City.
Uintacrinus socialis
Another large fossil crinoid was discovered in the state of Missouri in the United States. The crinoid, which belongs to the species Uintacrinus socialis, was discovered in the early 20th century. The specimen is estimated to be around 300 million years old and is believed to have lived during the Carboniferous period.
The crinoid is also quite large, with a stem measuring more than 30 feet in length and a crown that measures around 6 feet in diameter. The entire specimen is estimated to have weighed more than 5 tons when it was alive.
The discovery of Uintacrinus socialis was significant because it provided valuable information about the evolution of crinoids. This species had a unique morphology that differed from other crinoids, and its discovery helped scientists to better understand the diversity of these ancient creatures.
Marsupitsa fragilis
In addition to the two specimens mentioned above, there have been many other impressive fossil crinoids discovered around the world. One of these is Marsupitsa fragilis, which was discovered in the United Kingdom in the 19th century.
The crinoid, which is estimated to be around 350 million years old, has a stem measuring around 20 feet in length and a crown measuring around 3 feet in diameter. The specimen is notable for its delicate and intricate morphology, which has been well-preserved in the fossil record.
The discovery of Marsupitsa fragilis was significant because it provided valuable information about the diversity and complexity of crinoids during the Devonian period. This species had a unique morphology that differed from other crinoids, and its discovery helped scientists to better understand the evolution of these ancient creatures.
Pachylocrinus nodosus
Another large fossil crinoid was discovered in the state of Texas in the United States. The crinoid, which belongs to the species Pachylocrinus nodosus, was discovered in the early 20th century. The specimen is estimated to be around 90 million years old and is believed to have lived during the Cretaceous period.
The crinoid is quite large, with a stem measuring around 20 feet in length and a crown measuring around 3 feet in diameter. The specimen is notable for its robust and heavily armored morphology, which has been well-preserved in the fossil record.
The discovery of Pachylocrinus nodosus was significant because it provided valuable information about the evolution of crinoids during the Cretaceous period. This species had a unique morphology that differed from other crinoids, and its discovery helped scientists to better understand the diversity of these ancient creatures.
Agaricocrinus americanus
Agaricocrinus americanus is another large fossil crinoid that was discovered in the state of Indiana in the United States. The crinoid is estimated to be around 350 million years old and has a stem measuring around 20 feet in length and a crown measuring around 3 feet in diameter.
The specimen is notable for its unusual morphology, which includes a crown that is shaped like a mushroom. This morphology is quite different from that of other crinoids, and its discovery has provided valuable information about the diversity of these ancient creatures during the Devonian period.
Encrinus liliiformis
Encrinus liliiformis is a large fossil crinoid that was discovered in Germany in the 19th century. The crinoid is estimated to be around 180 million years old and has a stem measuring around 10 feet in length and a crown measuring around 2 feet in diameter.
The specimen is notable for its delicate and intricate morphology, which has been well-preserved in the fossil record. The discovery of Encrinus liliiformis was significant because it provided valuable information about the diversity and complexity of crinoids during the Jurassic period.
Bathycrinus giganteus
Bathycrinus giganteus is a large fossil crinoid that was discovered in the Pacific Ocean in the 20th century. The crinoid is estimated to be around 35 million years old and has a stem measuring around 10 feet in length and a crown measuring around 1 foot in diameter.
The specimen is notable for its unusual morphology, which includes a crown that is shaped like a basket. This morphology is quite different from that of other crinoids, and its discovery has provided valuable information about the diversity of these ancient creatures during the Paleogene period.
Isocrinus nicoletti
Finally, we come to Isocrinus nicoletti, another large fossil crinoid that was discovered in the state of Indiana in the United States. The crinoid, which is estimated to be around 350 million years old, has a stem measuring around 20 feet in length and a crown measuring around 3 feet in diameter.
The specimen is notable for its unusual morphology, which includes a long, slender stem and a crown that is divided into numerous branches. This morphology is quite different from that of other crinoids, and its discovery has provided valuable information about the diversity of these ancient creatures during the Devonian period.
Conclusion
In conclusion, the discovery of large fossil crinoids is a testament to the incredible diversity of life that has existed on Earth throughout its history. These ancient creatures provide a glimpse into the past and help us to better understand the evolution of life on our planet. As scientists continue to study these fascinating fossils, we can expect to learn even more about the history of life on Earth.
Argentinosaurus is still widely considered the heaviest dinosaur. Based on its mid-range estimate, it weighed the same as about nine T. rexes or 13 African elephants!
Dinosaurs were some of the largest creatures to ever roam the earth. These prehistoric giants come in a variety of shapes and sizes, from the small and agile to the massive and lumbering. Among the most awe-inspiring of these creatures were the largest dinosaurs, massive beasts that could weigh up to 100 tons and stretch dozens of meters in length. In this article, we’ll take a closer look at some of the biggest and most impressive dinosaurs ever to have lived.
Patagotitan mayorum
The largest dinosaur discovered to date is the Patagotitan mayorum, a species of titanosaur that lived in what is now Argentina during the Late Cretaceous period (about 100 million years ago). This massive creature weighed an estimated 69 tons and measured around 122 feet (37 meters) in length. That’s longer than a basketball court! Its leg bones alone measured over 7 feet long.
Titanosaurs
Titanosaurs were a group of long-necked herbivores that lived during the Late Cretaceous period. They were among the last surviving dinosaurs before the mass extinction event that wiped out all non-avian dinosaurs about 66 million years ago. Titanosaurs were also some of the largest animals to ever walk the earth, with some species weighing up to 100 tons.
Argentinosaurus huinculensis
Another contender for the title of largest dinosaur is Argentinosaurus huinculensis, also a titanosaur that lived in what is now Argentina around 90 million years ago. This dinosaur is estimated to have weighed between 60 and 100 tons and measured up to 115 feet (35 meters) in length. However, the fossils of this dinosaur are fragmentary, so its exact size is difficult to determine.
Sauroposeidon proteles
Sauroposeidon proteles is another contender for the title of largest dinosaur. This dinosaur lived about 110 million years ago in what is now North America. Sauroposeidon was also a titanosaur, and it is estimated to have measured up to 56 feet (17 meters) tall, making it the tallest dinosaur ever discovered. However, its weight is estimated to have been around 55 tons, which is smaller than both Patagotitan and Argentinosaurus.
Dreadnoughtus schrani
Dreadnoughtus schrani is another giant titanosaur that lived in what is now Argentina about 77 million years ago. This dinosaur is estimated to have weighed around 65 tons and measured up to 85 feet (26 meters) in length. Like the other titanosaurs, Dreadnoughtus was a herbivore with a long neck and tail.
Spinosaurus aegypticus
Aside from the titanosaurs, there were other dinosaurs that were among the largest ever to have lived. For example, the Spinosaurus aegypticus was a massive theropod dinosaur that lived during the Late Cretaceous period in what is now North Africa. This dinosaur is estimated to have measured up to 59 feet (18 meters) in length and weighed around 12 tons. What made Spinosaurus unique among theropods was its elongated snout, which likely helped it catch fish in the rivers and lakes that it inhabited.
Giganotosaurus carolinii
Another massive theropod dinosaur was the Giganotosaurus carolinii, which lived in what is now Argentina during the Late Cretaceous period. This dinosaur is estimated to have measured up to 46 feet (14 meters) in length and weighed around 8 tons. Giganotosaurus was a relative of the more famous Tyrannosaurus rex, and it likely filled a similar ecological niche as a top predator.
Brachiosaurus altithorax
Finally, we have the long-necked sauropod dinosaur called the Brachiosaurus altithorax. This dinosaur lived during the Late Jurassic period in what is now North America, and it is estimated to have weighed around 88 tons and measured up to 85 feet (26 meters) in length. Brachiosaurus is famous for its long neck, which it used to reach high branches and leaves in trees.
So, which dinosaur was the largest? It’s difficult to say for sure, as different species have been estimated to be the largest based on different criteria. However, the Patagotitan mayorum is currently considered the largest dinosaur ever discovered based on its estimated weight and length. Of course, there may be even larger dinosaurs out there waiting to be discovered, so the title of “largest dinosaur” could change in the future.
Conclusion
In conclusion, the largest dinosaurs were among the most impressive creatures to ever walk the earth. These massive beasts included long-necked titanosaurs, powerful theropods, and towering sauropods. While we may never see these creatures in person, their fossils and remains continue to inspire awe and wonder among scientists and dinosaur enthusiasts alike.
Gemstones have captivated humans for millennia with their beauty, rarity, and unique qualities. While there are countless gemstones known to us today, one gemstone stands out as the most unique and intriguing: Painite. Discovered in 1951, Painite is an incredibly rare and enigmatic gemstone whose formation is still not fully understood. In this article, we will explore the fascinating geological story of Painite, examining its formation process and the characteristics that make it the most unique gemstone in the world.
Discovery and Rarity
Painite was first discovered in Myanmar (formerly Burma) by British gemologist Arthur C.D. Pain, after whom the gemstone was named. For decades, only a few specimens were known to exist, making it one of the rarest gemstones on Earth. In fact, the Guinness World Records once listed Painite as the world’s rarest mineral. However, in recent years, more Painite deposits have been discovered, though the gemstone remains exceedingly rare and highly valuable.
Formation and Geological Context
Painite is a borate mineral with the chemical formula CaZrB(Al9O18). Its formation is thought to occur in metamorphic rocks, particularly in the contact zones between marbles and boron-rich granitic pegmatites. These pegmatites are formed when molten rock cools and crystallizes slowly, allowing the formation of large crystal structures. The presence of boron, an essential element in Painite’s composition, is a key factor in its formation.
Painite’s unique crystal structure is characterized by a hexagonal system, making it visually distinct from other gemstones. Its color varies from reddish-brown to dark brown and sometimes exhibits a slight orange hue. This unique gemstone also exhibits pleochroism, a phenomenon where the gemstone displays different colors when viewed from different angles.
The formation of Painite is a complex process that is not yet fully understood. Several factors are believed to contribute to its rarity, including the specific geological conditions required for its formation, the scarcity of its constituent elements, and the unique combination of pressure and temperature needed for the crystal to grow. Furthermore, Painite’s formation is thought to be associated with the presence of other rare minerals such as ruby, sapphire, and spinel, which are also found in the Mogok region of Myanmar where Painite was first discovered.
Significance and Value
The rarity and uniqueness of Painite make it a highly sought-after gemstone among collectors and connoisseurs. While its hardness, measured at 8 on the Mohs scale, makes it suitable for use in jewelry, its extreme scarcity means that most Painite specimens are preserved as mineral specimens in private collections or museums.
In recent years, Painite’s value has increased exponentially as its rarity has become more widely recognized. As more deposits are discovered, and our understanding of its formation process deepens, the fascination with this enigmatic gemstone is likely to continue. Painite serves as a testament to the wonders of Earth’s geological processes, providing a tangible reminder of the incredible diversity and beauty of the natural world.
Conclusion
Painite’s unique characteristics, geological context, and rarity make it the most unique gemstone in the world. Its formation process, while still not fully understood, is a fascinating story that highlights the complexity and wonder of Earth’s geological processes. As we continue to explore and uncover the mysteries of this exceptional gemstone, Painite will undoubtedly continue to captivate and inspire both scientists and gem enthusiasts alike.
Artist’s impression of two Troodons with a common nest. Illustration: Alex Boersma/PNAS
In millions of years and with a long sequence of small changes, evolution has shaped a particular group of dinosaurs, the theropods, into the birds we watch fly around the planet today. In fact, birds are the only descendants of dinosaurs which survived the catastrophic extinction 66 million years ago that ended the Cretaceous period.
Troodon was such a theropod. The carnivorous dinosaur was about two meters long and populated the vast semi-arid landscapes of North America about 75 million years ago. Like some of its dinosaur relatives, Troodon presented some bird-like features like hollow and light bones. Troodon walked on two legs and had fully developed feathery wings, but its relatively large size precluded it from flying. Instead, it probably ran quite fast and caught its prey using its strong claws. Troodon females laid eggs more similar to the asymmetric eggs of modern birds than to round ones of reptiles, the oldest relatives of all dinosaurs. These eggs were coloured and have been found half buried into the ground, probably allowing Troodon to sit and brood them.
An international team of scientists led by Mattia Tagliavento and Jens Fiebig from Goethe University Frankfurt, Germany, has now examined the calcium carbonate of some well-preserved Troodon eggshells. The researchers used a method developed by Fiebig’s group in 2019 called “dual clumped isotope thermometry.” By using this method, they could measure the extent to which heavier varieties (isotopes) of oxygen and carbon clump together in carbonate minerals. The prevalence of isotopic clumping, which is temperature-dependent, made it possible for scientists to determine the temperature at which the carbonates crystallized.
When analyzing Troodon eggshells, the research team was able to determine that the eggshells were produced at temperatures of 42 and 30 degrees Celsius. Mattia Tagliavento, leading author of the study, explains: “The isotopic composition of Troodon eggshells provides evidence that these extinct animals had a body temperature of 42°C, and that they were able to reduce it to about 30°C, like modern birds.”
The scientists then compared isotopic compositions of eggshells of reptiles (crocodile, alligator, and various species of turtle) and modern birds (chicken, sparrow, wren, emu, kiwi, cassowary and ostrich) to understand if Troodon was closer to either birds or reptiles. They revealed two different isotopic patterns: reptile eggshells have isotopic compositions matching the temperature of the surrounding environment. This is in line with these animals being cold-blooded and forming their eggs slowly. Birds, however, leave a recognizable so-called non-thermal signature in the isotopic composition, which indicates that eggshell formation happens very fast. Tagliavento: “We think this very high production rate is connected to the fact that birds, unlike reptiles, have a single ovary. Since they can produce just one egg at the time, birds have to do it more rapidly.”
When comparing these results to Troodon eggshells, the researchers did not detect the isotopic composition which is typical for birds. Tagliavento is convinced: “This demonstrates that Troodon formed its eggs in a way more comparable to modern reptiles, and it implies that its reproductive system was still constituted of two ovaries.”
The researchers finally combined their results with existing information concerning body and eggshell weight, deducing that Troodon produced only 4 to 6 eggs per reproductive phase. “This observation is particularly interesting because Troodon nests are usually large, containing up to 24 eggs,” Tagliavento explains. “We think this is a strong suggestion that Troodon females laid their eggs in communal nests, a behaviour that we observe today among modern ostriches.”
These are extremely exciting findings, Jens Fiebig comments: “Originally, we developed the dual clumped isotope method to accurately reconstruct Earth’s surface temperatures of past geological eras. This study demonstrates that our method is not limited to temperature reconstruction, it also presents the opportunity to study how carbonate biomineralization evolved throughout Earth’s history.”
Reference:
Mattia Tagliavento, Amelia J. Davies, Miguel Bernecker, Philip T. Staudigel, Robin R. Dawson, Martin Dietzel, Katja Götschl, Weifu Guo, Anne S. Schulp, François Therrien, Darla K. Zelenitsky, Axel Gerdes, Wolfgang Müller, Jens Fiebig. Evidence for heterothermic endothermy and reptile-like eggshell mineralization in Troodon , a non-avian maniraptoran theropod. Proceedings of the National Academy of Sciences, 2023; 120 (15) DOI: 10.1073/pnas.2213987120
An illustration showing how some Earth’s signature features, such as its abundance of water and its overall oxidized state could potentially be attributable to interactions between the molecular hydrogen atmospheres and magma oceans on the planetary embryos that comprised Earth’s formative years. Illustration by Edward Young/UCLA and Katherine Cain/Carnegie Institution for Science.
Our planet’s water could have originated from interactions between the hydrogen-rich atmospheres and magma oceans of the planetary embryos that comprised Earth’s formative years, according to new work from Carnegie Science’s Anat Shahar and UCLA’s Edward Young and Hilke Schlichting. Their findings, which could explain the origins of Earth’s signature features, are published in Nature.
For decades, what researchers knew about planet formation was based primarily on our own Solar System. Although there are some active debates about the formation of gas giants like Jupiter and Saturn, it is widely agreed upon that Earth and the other rocky planets accreted from the disk of dust and gas that surrounded our Sun in its youth.
As increasingly larger objects crashed into each other, the baby planetesimals that eventually formed Earth grew both larger and hotter, melting into a vast magma ocean due to the heat of collisions and radioactive elements. Over time, as the planet cooled, the densest material sank inward, separating Earth into three distinct layers — the metallic core, and the rocky, silicate mantle and crust.
However, the explosion of exoplanet research over the past decade informed a new approach to modeling the Earth’s embryonic state.
“Exoplanet discoveries have given us a much greater appreciation of how common it is for just-formed planets to be surrounded by atmospheres that are rich in molecular hydrogen, H2, during their first several million years of growth,” Shahar explained. “Eventually these hydrogen envelopes dissipate, but they leave their fingerprints on the young planet’s composition.”
Using this information, the researchers developed new models for Earth’s formation and evolution to see if our home planet’s distinct chemical traits could be replicated.
Using a newly developed model, the Carnegie and UCLA researchers were able to demonstrate that early in Earth’s existence, interactions between the magma ocean and a molecular hydrogen proto-atmosphere could have given rise to some of Earth’s signature features, such as its abundance of water and its overall oxidized state.
The researchers used mathematical modeling to explore the exchange of materials between molecular hydrogen atmospheres and magma oceans by looking at 25 different compounds and 18 different types of reactions — complex enough to yield valuable data about Earth’s possible formative history, but simple enough to interpret fully.
Interactions between the magma ocean and the atmosphere in their simulated baby Earth resulted in the movement of large masses of hydrogen into the metallic core, the oxidation of the mantle, and the production of large quantities of water.
Even if all of the rocky material that collided to form the growing planet was completely dry, these interactions between the molecular hydrogen atmosphere and the magma ocean would generate copious amounts of water, the researchers revealed. Other water sources are possible, they say, but not necessary to explain Earth’s current state.
“This is just one possible explanation for our planet’s evolution, but one that would establish an important link between Earth’s formation history and the most common exoplanets that have been discovered orbiting distant stars, which are called Super-Earths and sub-Neptunes,” Shahar concluded.
This project was part of the interdisciplinary, multi-institution AEThER project, initiated and led by Shahar, which seeks to reveal the chemical makeup of the Milky Way galaxy’s most common planets — Super-Earths and sub-Neptunes — and to develop a framework for detecting signatures of life on distant worlds. Funded by the Alfred P. Sloan Foundation, this effort was developed to understand how the formation and evolution of these planets shape their atmospheres. This could — in turn — enable scientists to differentiate true biosignatures, which could only be produced by the presence of life, from atmospheric molecules of non-biological origin.
“Increasingly powerful telescopes are enabling astronomers to understand the compositions of exoplanet atmospheres in never-before-seen detail,” Shahar said. “AEThER’s work will inform their observations with experimental and modeling data that, we hope, will lead to a foolproof method for detecting signs of life on other worlds.”
Reference:
Edward D. Young, Anat Shahar, Hilke E. Schlichting. Earth shaped by primordial H2 atmospheres. Nature, 2023; 616 (7956): 306 DOI: 10.1038/s41586-023-05823-0
How did the Andes — the world’s longest mountain range — reach its enormous size? This is just one of the geological questions that a new method developed by researchers at the University of Copenhagen may be able to answer. With unprecedented precision, the method allows researchers to estimate how Earth’s tectonic plates changed speed over the past millions of years.
The Andes is Earth’s longest above-water mountain range. It spans 8900 kilometres along South America’s western periphery, is up to 700 kilometres wide, and in some places, climb nearly seven kilometres into the sky. But exactly how this colossal mountain range emerged from Earth’s interior remains unclear among geologists.
University of Copenhagen researchers come with a new hypothesis. Using a novel method developed by one of the researchers, they closely studied the tectonic plate upon which the range is saddled. Their finding has shed new light on how the Andes came into being.
Tectonic plates cover Earth’s surface like massive puzzle pieces. They shift a few centimeters each year, at about the same pace as our nails grow. From time to time, these plates can suddenly speed up or slow down. However, we know little about the fierce forces behind these events. The UCPH researchers arrived at estimates that are more precise than ever, both with regards to how much and how often the plates changed velocity historically.
The researchers’ new calculations demonstrate that the South American plate suddenly and spectacularly shifted gears and slowed on two significant occasions over the past 15 million years. And this may have contributed to the widening of the enormous chain. The study’s results have been published in the journal Earth and Planetary Science Letters.
Remarkably, the two sudden slowdowns occurred between periods when the Andean range was under compression and growing rapidly taller:
“In the periods up until the two slowdowns, the plate immediately to the west, the Nazca Plate, plowed into the mountains and compressed them, causing them to grow taller. This result could indicate that part of the preexistent range acted as a brake on both the Nazca and the South-American plate. As the plates slowed down their speed, the mountains instead grew wider,” explains first author and PhD student Valentina Espinoza of the Department of Geosciences and Natural Resource Management.
Mountains made the plate heavier
According to the new study, the South American plate slowed down by 13% during a period that occurred 10-14 million years ago, and 20% during another period 5-9 million years ago. In geologic time, these are very rapid and abrupt changes. According to the researchers, there are mainly two possible reasons for South America’s sudden slowdowns.
One could, as mentioned, be related to the extension of the Andes, where the pressure relaxed and the mountains grew wider. The researchers’ hypothesis is that the interaction between the expansion of the mountains and the lower speed of the plate was due to a phenomenon called delamination. That is, a great deal of unstable material beneath the Andes tore free and sank into the mantle, causing major readjustments in the plate’s configuration.
This process caused the Andes to change shape and grow laterally. It was during these periods that the mountain chain expanded into Chile to the west and Argentina to the east. As the plate accumulated more mountain material and became heavier, the plate’s movement slowed.
“If this explanation is the right one, it tells us a lot about how this huge mountain range came to be. But there is still plenty that we don’t know. Why did it get so big? At what speed did it form? How does the mountain range sustain itself? And will it eventually collapse?” says Valentina Espinoza.
According to the researchers, another possible explanation for why the plate slowed is that there was a change in the pattern flow of heat from the Earth’s interior, known as convection, that moved up into the uppermost viscous layer of the mantle which tectonic plates float on top of. That change manifested itself as a change in the plate’s movement.
The researchers now have the information and tools to begin testing their hypotheses through modelling and experimentation.
May become a new standard model
The method to calculate the changes of tectonic plate motion builds upon the previous work of associate professor and study co-author Giampiero Iaffaldano and Charles DeMets in 2016. The special thing about the method is that it utilises high-resolution geological data, typically used only to calculate the motion of plates relative to each other. Here, the same data has been used to calculate changes in the motion of plates relative to the planet itself. It provides estimates with unprecedented accuracy.
After testing the method with a combination of six other tectonic plates, the researchers believe that it could become a new standard method:
“This method can be used for all plates, as long as high-resolution data are available. My hope is that such method will be used to refine historic models of tectonic plates and thereby improve the chance of reconstructing geological phenomena that remain unclear to us,” says Giampiero Iaffaldano, who concludes:
“If we can better understand the changes that have occurred in the motions of plates over time, we can have a chance at answering some of the greatest mysteries of our planet and its evolution. We still know so little about, for example: the temperature of Earth’s interior, or about when plates began moving. Our method can most likely be used to find pieces for this great big puzzle.”
FACT BOX: ABOUT THE METHOD
Tectonic plates change speed often, but high-resolution data is needed to identify their rapid changes over time spans of less than a couple million years.
One key aspect of the method developed by Giampiero Iaffaldano and Charles DeMets in 2016 differs from others. Typically, high-resolution data is only used to calculate the relative motion of plates, i.e. their motion relative to other plates. Their method uses this same kind of data to calculate the absolute motion of plates, i.e. the movement of plates relative to Earth itself. This results in far more accurate estimates than the ones currently obtained through hotspot volcanic chains.
FACT BOX: ABOUT PLATE TECTONICS
The theory of plate tectonics, first recognized in the 1960s, states that Earth is covered by an outer shell (the lithosphere), divided into a number of rigid plates that float on top the upper part of Earth’s mantle (the asthenosphere).
Observations show that plates come in all sorts of sizes, from the Pacific plate covering an area of 100 million square meters, to microplates with a hundredth times smaller. Tectonic plates may comprise a continental portion, that can reach up to 350 kilometers thick, and oceanic part, which rarely exceeds 100 kilometers thick.
Reference:
Valentina Espinoza, Giampiero Iaffaldano. Rapid absolute plate motion changes inferred from high-resolution relative spreading reconstructions: A case study focusing on the South America plate and its Atlantic/Pacific neighbors. Earth and Planetary Science Letters, 2023; 604: 118009 DOI: 10.1016/j.epsl.2023.118009
Earthquakes and volcanism occur as a result of plate tectonics. The movement of tectonic plates themselves is largely driven by the process known as subduction. The question of how new active subduction zones come into being, however, is still under debate. An example of this is the volcanic Lesser Antilles arc in the Caribbean. A research team including geophysicists Dr. Nicolas Riel and Professor Boris Kaus of Johannes Gutenberg University Mainz (JGU) as well as researchers from Universidade de Lisboa (ULisboa) recently developed models that simulated the occurrences in the Caribbean region during the Cretaceous, when a subduction event in the Eastern Pacific led to the formation of a new subduction zone in the Atlantic. The computer simulations show how the collision of the old Caribbean plateau with the Greater Antilles arc contributed to the creation of this new Atlantic subduction zone. Some 86 million years ago, the triggered processes subsequently resulted in a major mantle flow and thus to the development of the Caribbean large igneous province.
Subduction as a driving force of plate tectonics
Subduction is a geological process in which the cold oceanic lithosphere, which is part of the rocky and about 100 kilometer thick outermost layer of the planet, runs into the edge of a continental plate and slides beneath it to be recycled back into the Earth’s mantle. Together with the release of hot mantle material in the form of mantle plumes and new oceanic floor generation at mid-ocean ridges, subduction events form the backbone of plate tectonics. However, it is largely unknown how active subduction zones form mainly because there are very few examples of ongoing subduction initiation currently here on Earth. With this in view, Dr. Nicolas Riel and Professor Boris Kaus of the JGU Institute of Geosciences decided to investigate the geodynamic conditions that would have predominated in the Caribbean region in the late Cretaceous period. “In terms of its plate tectonics, the Caribbean is a particularly interesting location,” said Professor Boris Kaus, head of the Geodynamics & Geophysics group at Mainz University. The Caribbean region can be seen as a kind of natural laboratory in which, over millions of years, plate tectonics resulted in the transfer of a subduction zone from the Pacific to the Atlantic. This was associated with very extensive magmatic activity that accounted for the origin of the Caribbean large igneous province (or CLIP for short). This structure of magmatic rock is now the center of the Caribbean plate.
For their computer simulations, the researchers selected a point in time 140 million years ago when the so-called Farallon plate, an ancient major plate in the Eastern Pacific, began to move east and subduct beneath the South American margin, thus shifting the old Caribbean plateau in the direction of the Farallon trench. About 135 million years ago, the old Caribbean plateau came into collision with the proto-Caribbean plate. As the simulations showed, the subduction of the Farallon plate was then temporarily interrupted while the subduction of the proto-Caribbean plate was initiated. Several subsequent phases follow over a period of some 50 million years, including the renewed subduction of the Farallon plate at the western end of the old plateau, the formation of a mantle plume, and the transfer of the Greater Antilles arc onto the retreating proto-Caribbean plate.
Simultaneous subduction of two plates forced part of the mantle upwards
“With the help of our computer simulations, we can better understand the physical process,” added Dr. Nicolas Riel, the lead author of the corresponding article recently published in Nature Communications. “We were all surprised by the results showing that 90 to 86 million years ago the renewal of the Farallon plate subduction led to a major mantle flow, triggering the formation of a plume. This produced a huge amount of magma.” This molten rock material added to the thickness of the crust of the Caribbean plate, making it up to 22 kilometers in depth, thus 8 to 10 kilometers thicker than the standard for the oceanic crust. It was previously assumed that the mantle plume induced the renewal of the Farallon plate subduction.
“We are in the unique situation of being able to carry out very realistic simulations,” said Boris Kaus. His team is one of the few groups worldwide that can use supercomputer modeling to test to the plausibility of their physical assumptions and thus to analyze what plate tectonic events actually occurred in the Caribbean. For their complex calculations, the researchers had access to the MOGON II supercomputer operated by Johannes Gutenberg University Mainz and the Helmholtz Institute Mainz (HIM), one of the fastest high-performance computers in the world.
Research under the aegis of TeMaS
The geophysical research was undertaken under the aegis of the Terrestrial Magmatic Systems (TeMaS) research platform, a joint project of the universities of Mainz, Frankfurt, and Heidelberg. TeMaS coordinates interdisciplinary research on magmatic processes in the broadest sense, from the generation of magma in the Earth’s mantle through to its eruption in volcanoes and how this impacts the atmosphere and climate. TeMaS is a High-potential Research Area at JGU, funded by the Ministry of Science and Health of Rhineland-Palatinate.
Boris Kaus is Head of the Geodynamics & Geophysics group at the JGU Institute of Geosciences. In 2018, he was granted an ERC Consolidator Grant, one of the most richly endowed EU funding awards, to support his research into magmatic processes. As part of the ERC project MAGMA, short for “Melting And Geodynamic Models of Ascent,” Kaus and his team developed numerical models that enabled them to simulate magmatic events. The geophysicist is also a Fellow of the Gutenberg Research College (GRC) of JGU.
Reference:
Nicolas Riel, João C. Duarte, Jaime Almeida, Boris J. P. Kaus, Filipe Rosas, Yamirka Rojas-Agramonte, Anton Popov. Subduction initiation triggered the Caribbean large igneous province. Nature Communications, 2023; 14 (1) DOI: 10.1038/s41467-023-36419-x
The massive Feb. 6 quake in Eastern Turkey killed more than 50,000 people and toppled more than 100,000 buildings. (Photo/Ahmet Ertas via Pixabay)
Researchers know a lot about Turkey’s next major earthquake. They can pinpoint the probable epicenter, estimate its strength and see the spatial footprint of where damage is most likely to occur.
They just can’t say when it will happen.
That’s the main takeaway from a new USC-led study that appears today (April 20) in Seismica.
Using remote sensing, USC geophysicist Sylvain Barbot and his fellow researchers documented the massive Feb. 6 quake that killed more than 50,000 people in Eastern Turkey and toppled more than 100,000 buildings.
Alarmingly, researchers found that a section of the fault remains unbroken and locked — a sign that the plates there may, when friction intensifies, generate another magnitude 6.8 earthquake when it finally gives way.
“We know a little bit better what to prepare for. We don’t know the timing, but we know where it can happen,” Barbot said.
Major earthquakes are caused by the slipping of tectonic plates. The plates, slowly moving pieces of the earth’s crust, press against each other, gradually accumulating force over the course of decades, centuries and eons. When the plates finally slip, the energy explodes in traveling waves through the earth’s crust.
The Kahramanmaras, Turkey, magnitude 7.8 mainshock occurred Feb. 6, followed by a magnitude 7.6 aftershock on a separate fault further west. Another quake occurred two weeks later, a magnitude 6.4 on Feb. 20. A plotting of data (see above) shows seismic activity and the amount of slippage along the faults.
The area beneath Turkey’s Pütürge district shows a swarm of seismic activity along the fault — but no slippage. That means that part of the fault is locked, or stuck, but it is likely to slip sometime — anytime — in the future.
“What we’ve seen in photos of the buildings that collapsed is that some of them were pancakes but others were literally pulverized,” Barbot said. “So that means another degree of failure; even the concrete itself disintegrated. There is the possibility that this earthquake produced more shaking than was anticipated in the building codes. We won’t know without more research.
“So, we have this region where we can expect a 6.8 magnitude earthquake and two things can happen from here. The population needs to be prepared for that. But also the scientific community because that gives us an opportunity to prepare a monitoring experiment to see how an earthquake starts and ends.”
Reference:
Sylvain Barbot, Heng Luo, Teng Wang, Yariv Hamiel, Oksana Piatibratova, Muhammad Tahir Javed, Carla Braitenberg, Gokhan Gurbuz. Slip distribution of the February 6, 2023 Mw 7.8 and Mw 7.6, Kahramanmaraş, Turkey earthquake sequence in the East Anatolian Fault Zone. Seismica, 2023; 2 (3) DOI: 10.26443/seismica.v2i3.502
Ridgecrest seismic station deployed in 2019. | USGS
Faults in the Ridgecrest, California area were very sensitive to solid earth tidal stresses in the year and a half before the July 2019 Ridgecrest earthquake sequence, researchers reported at the Seismological Society of America (SSA)’s 2023 Annual Meeting.
“The signal of tidal modulation becomes extremely strong” after 2018, said Eric Beauce of Lamont-Doherty Earth Observatory, who noted that the signal was identified with seismicity that occurred around the faults that broke in the 2019 magnitude 7.1 earthquake.
The link does not mean that tidal stresses — which are very small compared to other tectonic stresses — triggered the earthquake, however.
“We don’t know if something started to happen in the fault zone, something that is an indicator of the upcoming earthquake,” Beauce said. “Maybe that process changed the properties of the crust in a way that made the crust be more sensitive to tidal stresses.”
Pulled by the same gravitational forces of sun and moon that create ocean tides, the solid earth also deforms in the same periodic way. People can’t feel the changes, but the ground deforms between 10 to 20 centimeters a day.
These solid tides “induce very, very small stress changes in the crust,” Beauce explains, “which can induce stress changes in all the faults within the crust.”
Although researchers have known about these tiny stress changes for more than a century, it has been difficult to extract their signal from the seismic record, and to determine whether they modulate seismicity.
In the past ten years, however, better earthquake detection and analysis techniques have made it possible to search through earthquake catalogs to find the signal of tidal stresses, Beauce said.
He and his colleagues built a rich, high-resolution earthquake catalog, using machine learning algorithms along with other techniques, for the past decade of microseismicity in the Ridgecrest area. (Microseismicity usually refers to earthquakes of magnitude 2.0 or smaller).
They found that “there is suggestive evidence that peak seismicity happens when tidal stresses are maximum,” Beauce said, “but this modulation is weak, and because it is weak, it is only suggested.”
Other researchers looking at the 2004 Indian Ocean and 2011 Tohoku megathrust earthquakes have detected an increase in modulation of seismicity connected to tidal stresses, decades before the earthquakes, said Beauce. And some scientists have been able to generate similar results in lab-created earthquake experiments.
The tidal findings do not have direct implications for earthquake forecasting, “as we do not know if we are looking at a general phenomenon or one specific to the Ridgecrest earthquake only, said Beauce, “but I see it as a way of getting new observational constraints on the physics of earthquakes, possibly the preparation and nucleation of earthquakes.”
A juvenile Edmontosaurus disappears into the enormous, lipped mouth of Tyrannosaurus. Credit Dr Mark Witton
A new study suggests that predatory dinosaurs, such as Tyrannosaurus rex, did not have permanently exposed teeth as depicted in films such as Jurassic Park, but instead had scaly, lizard-like lips covering and sealing their mouths.
Researchers and artists have debated whether theropod dinosaurs, the group of two-legged dinosaurs that includes carnivores and top predators like T. rex and Velociraptor, as well as birds, had lipless mouths where perpetually visible upper teeth hung over their lower jaws, similar to the mouth of a crocodile.
However, an international team of researchers challenge some of the best-known depictions, and say these dinosaurs had lips similar to those of lizards and their relative, the tuatara — a rare reptile found only in New Zealand, which are the last survivors of an order of reptiles that thrived in the age of the dinosaurs.
In the most detailed study of this issue yet, the researchers examined the tooth structure, wear patterns and jaw morphology of lipped and lipless reptile groups and found that theropod mouth anatomy and functionality resembles that of lizards more than crocodiles. This implies lizard-like oral tissues, including scaly lips covering their teeth.
These lips were probably not muscular, like they are in mammals. Most reptile lips cover their teeth but cannot be moved independently — they cannot be curled back into a snarl, or make other sorts of movements we associate with lips in humans or other mammals.
Study co-author Derek Larson, Collections Manager and Researcher in Palaeontology at the Royal BC Museum in Canada, said: “Palaeontologists often like to compare extinct animals to their closest living relatives, but in the case of dinosaurs, their closest relatives have been evolutionarily distinct for hundreds of millions of years and today are incredibly specialised.
“It’s quite remarkable how similar theropod teeth are to monitor lizards. From the smallest dwarf monitor to the Komodo dragon, the teeth function in much the same way. So, monitors can be compared quite favourably with extinct animals like theropod dinosaurs based on this similarity of function, even though they are not closely related.”
Co-author Dr Mark Witton from the University of Portsmouth said: “Dinosaur artists have gone back and forth on lips since we started restoring dinosaurs during the 19th century, but lipless dinosaurs became more prominent in the 1980s and 1990s. They were then deeply rooted in popular culture through films and documentaries — Jurassic Park and its sequels, Walking with Dinosaurs and so on.
“Curiously, there was never a dedicated study or discovery instigating this change and, to a large extent, it probably reflected preference for a new, ferocious-looking aesthetic rather than a shift in scientific thinking. We’re upending this popular depiction by covering their teeth with lizard-like lips. This means a lot of our favourite dinosaur depictions are incorrect, including the iconic Jurassic Park T. rex.”
The results, published in the journal Science, found that tooth wear in lipless animals was markedly different from that seen in carnivorous dinosaurs and that dinosaur teeth were no larger, relative to skull size, than those of modern lizards, implying they were not too big to cover with lips.
Also, the distribution of small holes around the jaws, which supply nerves and blood to the gums and tissues around the mouth, were more lizard-like in dinosaurs than crocodile-like. Furthermore, modelling mouth closure of lipless theropod jaws showed that the lower jaw either had to crush jaw-supporting bones or disarticulate the jaw joint to seal the mouth.
“As any dentist will tell you, saliva is important for maintaining the health of your teeth. Teeth that are not covered by lips risk drying out and can be subject to more damage during feeding or fighting, as we see in crocodiles, but not in dinosaurs,” said co-author Kirstin Brink, Assistant Professor of Palaeontology at the University of Manitoba.
She added: “Dinosaur teeth have very thin enamel and mammal teeth have thick enamel (with some exceptions). Crocodile enamel is a bit thicker than dinosaur enamel, but not as thick as mammalian enamel. There are some mammal groups that do have exposed enamel, but their enamel is modified to withstand exposure.”
Thomas Cullen, Assistant Professor of Paleobiology at Auburn University and study lead author, said: “Although it’s been argued in the past that the teeth of predatory dinosaurs might be too big to be covered by lips, our study shows that, in actuality, their teeth were not atypically large. Even the giant teeth of tyrannosaurs are proportionally similar in size to those of living predatory lizards when compared for skull size, rejecting the idea that their teeth were too big to cover with lips.”
The results provide new insights into how we reconstruct the soft-tissues and appearance of dinosaurs and other extinct species. This can give crucial information on how they fed, how they maintained their dental health, and the broader patterns of their evolution and ecology.
Dr Witton said: “Some take the view that we’re clueless about the appearance of dinosaurs beyond basic features like the number of fingers and toes. But our study, and others like it, show that we have an increasingly good handle on many aspects of dinosaur appearance. Far from being clueless, we’re now at a point where we can say ‘oh, that doesn’t have lips? Or a certain type of scale or feather?’ Then that’s as realistic a depiction of that species as a tiger without stripes.”
The researchers point out that their study doesn’t say that no extinct animals had exposed teeth — some, like sabre-toothed carnivorous mammals, or marine reptiles and flying reptiles with extremely long, interlocking teeth, almost certainly did.
Reference:
Thomas M. Cullen, Derek W. Larson, Mark P. Witton, Diane Scott, Tea Maho, Kirstin S. Brink, David C. Evans, Robert Reisz. Theropod dinosaur facial reconstruction and the importance of soft tissues in paleobiology. Science, 2023; 379 (6639): 1348 DOI: 10.1126/science.abo7877
