Newly-described fossils reveal an ancient origin for New Zealand penguins

September 18, 2020

The dawn crested penguin Eudyptes atatu in New Zealand, three million years ago. Image by Simone Giovanardi. Permission for use of the image for a press release is granted by the artist. Credit: Massey University

New Zealand is surrounded by highly productive oceans that attract seabirds from around the world, forming a global hotspot for seabird diversity. Establishing how and when this hotspot formed has been challenged by a lack of fossil discoveries connecting New Zealand’s living seabirds to their ancient relatives.

Researchers from Massey University, Bruce Museum (CT, U.S.), Canterbury Museum, Museum of New Zealand Te Papa Tongarewa, and Iowa State University (IA, U.S.) have analyzed fossil bones from an ancient penguin discovered in coastal Taranaki in the North Island of New Zealand. Museum curators Alan Tennyson and Paul Scofield recognized the importance of fossil bones being found by local collectors and assembled collections to begin the investigation.

The newly described three-million-year old dawn crested penguin Eudyptes atatu from Taranaki now provides a crucial connection to the past, confirming crested penguins, and perhaps other types of seabird, have been living in Zealandia, or the New Zealand continent Te Riu-a-Māui, for millions of years.

“This has been an exciting research collaboration to be part of,” Daniel Thomas from the School of Natural and Computational Sciences at Massey University says.

“It’s given us an important into the evolution of crown penguins and re-enforces the importance of the New Zealand continent for seabird evolution. Our growing fossil record suggests that Zealandia was an incubator of penguin diversity in which the first penguins likely evolved and later dispersed throughout the Southern Hemisphere. The name of the newly described penguin species Eudyptes atatu comes from a contraction of ata tū, which is ‘dawn’ in Te Reo Maori. Dawn references the fact that this species is the beginning of our knowledge for crested penguins in New Zealand.”

The research is detailed further in a paper titled “Ancient crested penguin constrains timing of recruitment into seabird hotspot” published in the Proceedings of the Royal Society B. The study concludes that the ancestor of all penguins lived in Zealandia over 60 million years ago, and that the ancestor of crested penguins may have originated in Zealandia before its descendants dispersed throughout the Southern Hemisphere.

Reference:
Daniel B. Thomas et al. Ancient crested penguin constrains timing of recruitment into seabird hotspot, Proceedings of the Royal Society B: Biological Sciences (2020). DOI: 10.1098/rspb.2020.1497

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

Uncovering new understanding of Earth’s carbon cycle

September 12, 2020

A rough diamond from Kankan, Guinea, that was analyzed in a new study led by a PhD student at the U of A. The imperfections inside the diamond are small inclusions of a mineral called ferropericlase, which is from the lower mantle. Credit: Anetta Banas

In a new study led by a University of Alberta Ph.D. student, researchers used diamonds as breadcrumbs to provide insight into some of Earth’s deepest geologic mechanisms.

“Geologists have recently come to the realization that some of the largest, most valuable diamonds are from the deepest portions of our planet,” said Margo Regier, a Ph.D. student in the Faculty of Science under the supervision of Graham Pearson and Thomas Stachel. “While we are not yet certain why diamonds can grow to larger sizes at these depths, we propose a model where these ‘superdeep’ diamonds crystallize from carbon-rich magmas, which may be critical for them to grow to their large sizes.”

Beyond their beauty and industrial applications, diamonds provide unique windows into the deep Earth, allowing scientists to examine the transport of carbon through the mantle.

“The vast majority of Earth’s carbon is actually stored in its silicate mantle, not in the atmosphere,” Regier explained. “If we are to fully understand Earth’s whole carbon cycle, we need to understand this vast reservoir of carbon deep underground.”

The study revealed that the carbon-rich oceanic crust that sinks into the deep mantle releases most of its carbon before it gets to the deepest portion of the mantle. That means most carbon is recycled back to the surface, and only small amounts are stored in the deep mantle—which has significant implications for how scientists understand the Earth’s carbon cycle.

The mechanism is important to understand for a number of reasons, Regier noted.

“The movement of carbon between the surface and mantle affects Earth’s climate, the composition of its atmosphere and the production of magma from volcanoes,” said Regier.

“We do not yet understand if this carbon cycle has changed over time, nor do we know how much carbon is stored in the deepest parts of our planet. If we want to understand why our planet has evolved into its habitable state today and how the surfaces and atmospheres of other planets may be shaped by their interior processes, we need to better understand these variables.”

The study was made possible through a collaboration between researchers at the U of A and the University of Glasgow, including Jeff Harris, who collected the diamond samples. Support through federal funding from the Natural Sciences and Engineering Research Council of Canada, through the Diamond Exploration Research Training School at the U of A, was also integral in enabling the research.

The study, “The Lithospheric to Lower Mantle Carbon Cycle Recorded in Superdeep Diamonds,” was published in Nature.

Reference:
The lithospheric-to-lower-mantle carbon cycle recorded in superdeep diamonds. Nature (2020). doi.org/10.1038/s41586-020-2676-z

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

Understanding Earth’s ‘deep-carbon cycle’

September 12, 2020

New geologic findings about the makeup of the Earth’s mantle are helping scientists better understand long-term climate stability and even how seismic waves move through the planet’s layers.

The research by a team including Case Western Reserve University scientists focused on the “deep carbon cycle,” part of the overall cycle by which carbon moves through the Earth’s various systems.

In simplest terms, the deep carbon cycle involves two steps:

Surface carbon, mostly in the form of carbonates, is brought into the deep mantle by subducting oceanic plates at ocean trenches.
That carbon is then returned to the atmosphere as carbon dioxide (CO2) through mantle melting and magma degassing processes at volcanoes

Scientists have long suspected that partially melted chunks of this carbon are broadly distributed throughout the Earth’s solid mantle.

What they haven’t fully understood is how far down into the mantle they might be found, or how the geologically slow movement of the material contributes to the carbon cycle at the surface, which is necessary for life itself.

Deep carbon and climate change connection

“Cycling of carbon between the surface and deep interior is critical to maintaining Earth’s climate in the habitable zone over the long term — meaning hundreds of millions of years,” said James Van Orman, a professor of geochemistry and mineral physics in the College of Arts and Sciences at Case Western Reserve and an author on the study, recently published in the Proceedings of the National Academy of Sciences.

“Right now, we have a good understanding of the surface reservoirs of carbon, but know much less about carbon storage in the deep interior, which is also critical to its cycling.”

Van Orman said this new research showed — based on experimental measurements of the acoustic properties of carbonate melts, and comparison of these results to seismological data — that a small fraction (less than one-tenth of 1%) of carbonate melt is likely to be present throughout the mantle at depths of about 180-330 km.

“Based on this inference, we can now estimate the carbon concentration in the deep upper mantle and infer that this reservoir holds a large mass of carbon, more than 10,000 times the mass of carbon in Earth’s atmosphere,” Van Orman said.

That’s important, Van Orman said, because gradual changes in the amount of carbon stored in this large reservoir, due to exchange with the atmosphere, could have a corresponding effect on CO2 in the atmosphere — and therefore, on long-term climate change.

The first author of the article is Man Xu, who did much of the work as a PhD student at Case Western Reserve and is now a postdoctoral scholar at the University of Chicago.

Others on the project were from Florida State University, the University of Chicago and Southern University of Science and Technology (SUSTech) in Shenzhen, China.

Explaining seismic wave speed differences

The research also sheds light on seismology, especially deep earth research.

One way geologists better understand the deep interior is by measuring how seismic waves generated by earthquakes — fast-moving compressional waves and slower shear waves — move through the Earth’s layers.

Scientists have long wondered why the speed difference between the two types of seismic waves — P-waves and S-waves — peaked at depths of around 180 to 330 kilometers into the Earth.

Carbon-rich melts seem to answer that question: small quantities of these melts could be dispersed throughout the deep upper mantle and would explain the speed change, as the waves move differently through the melts.

Reference:
Man Xu, Zhicheng Jing, Suraj K. Bajgain, Mainak Mookherjee, James A. Van Orman, Tony Yu, Yanbin Wang. High-pressure elastic properties of dolomite melt supporting carbonate-induced melting in deep upper mantle. Proceedings of the National Academy of Sciences, 2020; 117 (31): 18285 DOI: 10.1073/pnas.2004347117

Note: The above post is reprinted from materials provided by Case Western Reserve University.

Coming up for air: Extinct sea scorpions could breathe out of water, fossil detective unveils

September 12, 2020

Eurypterid specimen image: Images of the eurypterid specimen fossil that led to Lamsdell’s discovery. Credit: Melanie Hopkins Photo

Scientists have long debated the respiratory workings of sea scorpions, but a new discovery by a West Virginia University geologist concludes that these largely aquatic extinct arthropods breathed air on land.

James Lamsdell dug into the curious case of a 340 million-year-old sea scorpion, or eurypterid, originally from France that had been preserved at a Glasgow, Scotland museum for the last 30 years.

An assistant professor of geology in the Eberly College of Arts and Sciences, Lamsdell had read about the “strange specimen” 25 years ago while conducting his doctoral studies. Existing research suggested it would occasionally go on land.

Yet nothing was known on whether it could breathe air. The closest living relative to the eurypterid is the horseshoe crab, which lays eggs on land but is unable to breathe above water.

These details puzzled Lamsdell through the years until he reached out to a colleague, Victoria McCoy at the University of Wisconsin-Milwaukee, and asked, “Do you have access to a CT scanner?”

“We wondered if we could apply new technology to look further into what was preserved of this specimen,” said Lamsdell, who heads a paleobiology lab at WVU. “I like the science and detective work that goes into research. And this was a cold case where we knew there was potential evidence.”

Through computed tomography (CT) imaging, Lamsdell and his team found that evidence, which is published in Current Biology.

Researchers managed to study the respiratory organs of the three-dimensional eurypterid, leading to two findings that stood out to Lamsdell. First, he noticed that each gill on the sea scorpion was composed of a series of plates. But the back contained fewer plates than the front, prompting researchers to question how it could even breathe.

Then they zeroed in on pillars connecting the different plates of the gill, which are seen in modern scorpions and spiders, Lamsdell said. These pillars, or small beams of tissue, are called trabeculae.

“That props the gills apart so they don’t collapse when out of water,” Lamsdell explained. “It’s something that modern arachnids still have. Finding that was the final indication.

“The reason we think they were coming onto land was to move between pools of water. They could also lay eggs in more sheltered, safer environments and migrate back into the open water.”

The discovery of air-breathing structures in the eurypterids indicate that terrestrial characteristics occurred in the arachnid stem lineage, the researchers wrote, suggesting that the ancestor of arachnids were semi-terrestrial.

In addition to Lamsdell and McCoy, co-authors include Opal Perron-Feller of Oberlin College and Melanie Hopkins of the American Museum of Natural History.

Now that Lamsdell has cracked the case living in the back of his head for 20-plus years, he believes there’s more to unearth from the fossil. He noted that the sea scorpion’s back legs expand into a paddle shape, which he suspects would have been used to swim. The bases of their legs also had spikes that ground up food for them that they maneuvered into their mouths, Lamsdell added.

“One of the things that would be really cool to do is to flesh out this model and try to reconstruct exactly how the legs could move and how they were positioned,” Lamsdell said, “like reconstructing the fossil as a living animal.”

Reference:
James C. Lamsdell, Victoria E. McCoy, Opal A. Perron-Feller, Melanie J. Hopkins. Air Breathing in an Exceptionally Preserved 340-Million-Year-Old Sea Scorpion. Current Biology, 2020; DOI: 10.1016/j.cub.2020.08.034

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

Thousands of species recorded in a speck of soil

September 12, 2020

Researchers collected and analyzed permafrost from four sites in the Yukon to develop a new technique to tease ancient DNA from soil, pulling the genomes of hundreds of extinct animals and thousands of plants from less than a gram of sediment. Credit: Tyler Murchie/ McMaster University

Researchers at McMaster University have developed a new technique to tease ancient DNA from soil, pulling the genomes of hundreds of animals and thousands of plants — many of them long extinct — from less than a gram of sediment.

The DNA extraction method, outlined in the journal Quarternary Research, allows scientists to reconstruct the most advanced picture ever of environments that existed thousands of years ago.

The researchers analyzed permafrost samples from four sites in the Yukon, each representing different points in the Pleistocene–Holocene transition, which occurred approximately 11,000 years ago.

This transition featured the extinction of a large number of animal species such as mammoths, mastodons and ground sloths, and the new process has yielded some surprising new information about the way events unfolded, say the researchers. They suggest, for example, that the woolly mammoth survived far longer than originally believed.

In the Yukon samples, they found the genetic remnants of a vast array of animals, including mammoths, horses, bison, reindeer and thousands of varieties of plants, all from as little as 0.2 grams of sediment.

The scientists determined that woolly mammoths and horses were likely still present in the Yukon’s Klondike region as recently as 9,700 years ago, thousands of years later than previous research using fossilized remains had suggested.

“That a few grams of soil contains the DNA of giant extinct animals and plants from another time and place, enables a new kind of detective work to uncover our frozen past,” says evolutionary geneticist Hendrik Poinar, a lead author on the paper and director of the McMaster Ancient DNA Centre. “This research allows us to maximize DNA retention and fine-tune our understanding of change through time, which includes climate events and human migration patterns, without preserved remains.”

The technique resolves a longstanding problem for scientists, who must separate DNA from other substances mixed in with sediment. The process has typically required harsh treatments that actually destroyed much of the usable DNA they were looking for. But by using the new combination of extraction strategies, the McMaster researchers have demonstrated it is possible to preserve much more DNA than ever.

“All of the DNA from those animals and plants is bound up in a tiny speck of dirt,” explains Tyler Murchie, a PhD candidate in the Department of Anthropology and a lead author of the study.

“Organisms are constantly shedding cells throughout their lives. Humans, for example, shed some half a billion skin cells every day. Much of this genetic material is quickly degraded, but some small fraction is safeguarded for millenia through sedimentary mineral-binding and is out there waiting for us to recover and study it. Now, we can conduct some remarkable research by recovering an immense diversity of environmental DNA from very small amounts of sediment, and in the total absence of any surviving biological tissues.”

Reference:
Tyler J. Murchie, Melanie Kuch, Ana T. Duggan, Marissa L. Ledger, Kévin Roche, Jennifer Klunk, Emil Karpinski, Dirk Hackenberger, Tara Sadoway, Ross MacPhee, Duane Froese, Hendrik Poinar. Optimizing extraction and targeted capture of ancient environmental DNA for reconstructing past environments using the PalaeoChip Arctic-1.0 bait-set. Quaternary Research, 2020; 1 DOI: 10.1017/qua.2020.59

Note: The above post is reprinted from materials provided by McMaster University. Original written by Michelle Donovan.

Volcanic ash may have a bigger impact on the climate than we thought

September 12, 2020

A plume of ash and dust rises from Pavlof Volcano on the Alaskan Peninsula in 2013. Credit: NASA

When volcanoes erupt, these geologic monsters produce tremendous clouds of ash and dust — plumes that can blacken the sky, shut down air traffic and reach heights of roughly 25 miles above Earth’s surface.

A new study led by the University of Colorado Boulder suggests that such volcanic ash may also have a larger influence on the planet’s climate than scientists previously suspected.

The new research, published in the journal Nature Communications, examines the eruption of Mount Kelut (or Kelud) on the Indonesian island of Java in 2014. Drawing on real-world observations of this event and advanced computer simulations, the team discovered that volcanic ash seems to be prone to loitering — remaining in the air for months or even longer after a major eruption.

“What we found for this eruption is that the volcanic ash can persist for a long time,” said Yunqian Zhu, lead author of the new study and a research scientist at the Laboratory for Atmospheric and Space Physics (LASP) at CU Boulder.

Lingering ash

The discovery began with a chance observation: Members of the research team had been flying an unmanned aircraft near the site of the Mount Kelut eruption — an event that covered large portions of Java in ash and drove people from their homes. In the process, the aircraft spotted something that shouldn’t have been there.

“They saw some large particles floating around in the atmosphere a month after the eruption,” Zhu said. “It looked like ash.”

She explained that scientists have long known that volcanic eruptions can take a toll on the planet’s climate. These events blast huge amounts of sulfur-rich particles high into Earth’s atmosphere where they can block sunlight from reaching the ground.

Researchers haven’t thought, however, that ash could play much of a role in that cooling effect. These chunks of rocky debris, scientists reasoned, are so heavy that most of them likely fall out of volcanic clouds not long after an eruption.

Zhu’s team wanted to find out why that wasn’t the case with Kelut. Drawing on aircraft and satellite observations of the unfolding disaster, the group discovered that the volcano’s plume seemed to be rife with small and lightweight particles of ash — tiny particles that were likely capable of floating in the air for long periods of time, much like dandelion fluff.

“Researchers have assumed that ash is similar to volcanic glass,” Zhu said. “But what we’ve found is that these floating ones have a density that’s more like pumice.”

Disappearing molecules

Study coauthor Brian Toon added that these pumice-like particles also seem to shift the chemistry of the entire volcanic plume.

Toon, a professor in LASP and the Department of Atmospheric and Oceanic Sciences at CU Boulder, explained that erupting volcanoes spew out a large amount of sulfur dioxide. Many researchers previously assumed that those molecules interact with others in the air and convert into sulfuric acid — a series of chemical reactions that, theoretically, could take weeks to complete. Observations of real-life eruptions, however, suggest that it happens a lot faster than that.

“There has been a puzzle of why these reactions occur so fast,” Toon said.

He and his colleagues think they’ve discovered the answer: Those molecules of sulfur dioxide seem to stick to the particles of ash floating in the air. In the process, they may undergo chemical reactions on the surface of the ash itself — potentially pulling around 43% more sulfur dioxide out of the air.

Ash, in other words, may hasten the transformation of volcanic gases in the atmosphere.

Just what the impact of those clouds of ash are on the climate isn’t clear. Long-lasting particles in the atmosphere could, potentially, darken and even help to cool the planet after an eruption. Floating ash might also blow all the way from sites like Kelut to the planet’s poles. There, it could kickstart chemical reactions that would damage Earth’s all-important ozone layer.

But the researchers say that one thing is clear: When a volcano blows, it may be time to pay a lot more attention to all that ash and its true impact on Earth’s climate.

“I think we’ve discovered something important here,” Toon said. “It’s subtle, but it could make a big difference.”

Reference:
Yunqian Zhu, Owen B. Toon, Eric J. Jensen, Charles G. Bardeen, Michael J. Mills, Margaret A. Tolbert, Pengfei Yu, Sarah Woods. Persisting volcanic ash particles impact stratospheric SO2 lifetime and aerosol optical properties. Nature Communications, 2020; 11 (1) DOI: 10.1038/s41467-020-18352-5

Note: The above post is reprinted from materials provided by University of Colorado at Boulder. Original written by Daniel Strain.

Has Earth’s oxygen rusted the Moon for billions of years?

September 12, 2020

Enhanced map of hematite (red) on Moon using a spheric projection (nearside only). Credit: Shuai Li

To the surprise of many planetary scientists, the oxidized iron mineral hematite has been discovered at high latitudes on the Moon, according to a study published today in Science Advances led by Shuai Li, assistant researcher at the Hawai’i Institute of Geophysics and Planetology (HIGP) in the UH Mānoa School of Ocean and Earth Science and Technology (SOEST).

Iron is highly reactive with oxygen — forming reddish rust commonly seen on Earth. The lunar surface and interior, however, are virtually devoid of oxygen, so pristine metallic iron is prevalent on the Moon and highly oxidized iron has not been confirmed in samples returned from the Apollo missions. In addition, hydrogen in solar wind blasts the lunar surface, which acts in opposition to oxidation. So, the presence of highly oxidized iron-bearing minerals, such as hematite, on the Moon is an unexpected discovery.

“Our hypothesis is that lunar hematite is formed through oxidation of lunar surface iron by the oxygen from the Earth’s upper atmosphere that has been continuously blown to the lunar surface by solar wind when the Moon is in Earth’s magnetotail during the past several billion years,” said Li.

To make this discovery, Li, HIGP professor Paul Lucey and co-authors from NASA’s Jet Propulsion Laboratory (JPL) and elsewhere analyzed the hyperspectral reflectance data acquired by the Moon Mineralogy Mapper (M3) designed by NASA JPL onboard India’s Chandrayaan-1 mission.

This new research was inspired by Li’s previous discovery of water ice in the Moon’s polar regions in 2018.

“When I examined the M3 data at the polar regions, I found some spectral features and patterns are different from those we see at the lower latitudes or the Apollo samples,” said Li. “I was curious whether it is possible that there are water-rock reactions on the Moon. After months investigation, I figured out I was seeing the signature of hematite.”

The team found the locations where hematite is present are strongly correlated with water content at high latitude Li and others found previously and are more concentrated on the nearside, which always faces the Earth.

“More hematite on the lunar nearside suggested that it may be related to Earth,” said Li. “This reminded me a discovery by the Japanese Kaguya mission that oxygen from the Earth’s upper atmosphere can be blown to the lunar surface by solar wind when the Moon is in the Earth’s magnetotail. So, Earth’s atmospheric oxygen could be the major oxidant to produce hematite. Water and interplanetary dust impact may also have played critical roles”

“Interestingly, hematite is not absolutely absent from the far-side of the Moon where Earth’s oxygen may have never reached, although much fewer exposures were seen,” said Li. “The tiny amount of water (< ~0.1 wt.%) observed at lunar high latitudes may have been substantially involved in the hematite formation process on the lunar far-side, which has important implications for interpreting the observed hematite on some water poor S-type asteroids.”

“This discovery will reshape our knowledge about the Moon’s polar regions,” said Li. “Earth may have played an important role on the evolution of the Moon’s surface.”

The research team hopes the NASA’s ARTEMIS missions can return hematite samples from the polar regions. The chemical signatures of those samples can confirm their hypothesis whether the lunar hematite is oxidized by Earth’s oxygen and may help reveal the evolution of the Earth’s atmosphere in the past billions of years.

Reference:
Shuai Li, Paul G. Lucey, Abigail A. Fraeman, Andrew R. Poppe, Vivian Z. Sun, Dana M. Hurley and Peter H. Schultz. Widespread hematite at high latitudes of the Moon. Science Advances, 2020 DOI: 10.1126/sciadv.aba1940

Note: The above post is reprinted from materials provided by University of Hawaii at Manoa. Original written by Marcie Grabowski.

Superheated rocks deep underground help explain earthquake patterns

September 12, 2020

Rock-melting forces occurring much deeper in the Earth than previously understood appear to drive tremors along a notorious segment of California’s San Andreas Fault, according to new USC research that helps explain how quakes happen.

The study from the emergent field of earthquake physics looks at temblor mechanics from the bottom up, rather than from the top down, with a focus on underground rocks, friction and fluids. On the segment of the San Andreas Fault near Parkfield, Calif., underground excitations — beyond the depths where quakes are typically monitored — lead to instability that ruptures in a quake.

“Most of California seismicity originates from the first 10 miles of the crust, but some tremors on the San Andreas Fault take place much deeper,” said Sylvain Barbot, assistant professor of Earth sciences at the USC Dornsife College of Letters, Arts and Sciences. “Why and how this happens is largely unknown. We show that a deep section of the San Andreas Fault breaks frequently and melts the host rocks, generating these anomalous seismic waves.” The newly published study appears in Science Advances. Barbot, the corresponding author, collaborated with Lifeng Wang of the China Earthquake Administration in China.

The findings are significant because they help advance the long-term goal of understanding how and where earthquakes are likely to occur, along with the forces that trigger temblors. Better scientific understanding helps inform building codes, public policy and emergency preparedness in quake-ridden areas like California. The findings may also be important in engineering applications where the temperature of rocks is changed rapidly, such as by hydraulic fracturing.

Parkfield was chosen because it is one of the most intensively monitored epicenters in the world. The San Andreas Fault slices past the town, and it’s regularly ruptured with significant quakes. Quakes of magnitude 6 have shaken the Parkfield section of the fault at fairly regular intervals in 1857, 1881, 1901, 1922, 1934, 1966 and 2004, according to the U.S. Geological Survey. At greater depths, smaller temblors occur every few months. So what’s happening deep in the Earth to explain the rapid quake recurrence?

Using mathematical models and laboratory experiments with rocks, the scientists conducted simulations based on evidence gathered from the section of the San Andreas Fault extending up to 36 miles north of — and 16 miles beneath — Parkfield. They simulated the dynamics of fault activity in the deep Earth spanning 300 years to study a wide range of rupture sizes and behaviors.

The researchers observed that, after a big quake ends, the tectonic plates that meet at the fault boundary settle into a go-along, get-along phase. For a spell, they glide past each other, a slow slip that causes little disturbance to the surface.

But this harmony belies trouble brewing. Gradually, motion across chunks of granite and quartz, the Earth’s bedrock, generates heat due to friction. As the heat intensifies, the blocks of rock begin to change. When friction pushes temperatures above 650 degrees Fahrenheit, the rock blocks grow less solid and more fluid-like. They start to slide more, generating more friction, more heat and more fluids until they slip past each other rapidly — triggering an earthquake.

“Just like rubbing our hands together in cold weather to heat them up, faults heat up when they slide. The fault movements can be caused by large changes in temperature,” Barbot said. “This can create a positive feedback that makes them slide even faster, eventually generating an earthquake.”

It’s a different way of looking at the San Andreas Fault. Scientists typically focus on movement in the top of Earth’s crust, anticipating that its motion in turn rejiggers the rocks deep below. For this study, the scientists looked at the problem from the bottom up.

“It’s difficult to make predictions,” Barbot added, “so instead of predicting just earthquakes, we’re trying to explain all of the different types of motion seen in the ground.”

The study was supported by grants from the National Natural Science Foundation of China (NSFC-41674067 and NSFC-U1839211) and the U.S. National Science Foundation (EAR-1848192).

Reference:
Lifeng Wang, Sylvain Barbot. Excitation of San Andreas tremors by thermal instabilities below the seismogenic zone. Science Advances, 2020; 6 (36): eabb2057 DOI: 10.1126/sciadv.abb2057

Note: The above post is reprinted from materials provided by University of Southern California. Original written by Gary Polakovic.

Rebirth of a volcano : Evolution of Bezymianny volcano, Kamchatka after the 1956 sector collapse

September 12, 2020

Bezymianny is an active stratovolcano on the Kamchatka peninsula in eastern Russia. Credit: GFZ

Volcanoes are born and die — and then grow again on their own remains. The decay of a volcano in particular is often accompanied by catastrophic consequences, as was the most recent case for Anak Krakatau in 2018. The flank of the volcano had collapsed sliding into the sea. The resulting tsunami killed several hundred people on Indonesia’s coast.

Continued volcanic activity after a collapse has not been documented in detail so far. Now and for the first time, researchers from the German Research Center for Geosciences GFZ and Russian volcanologists are presenting the results of a photogrammetric data series spanning seven decades for the Bezymianny volcano, Kamchatka, in the journal Nature Communications Earth and Environment. First author Alina Shevchenko from GFZ says, “thanks to the German-Russian cooperation we were able to analyze and reinterpret a unique data set.”

Bezymianny had a collapse of its eastern sector in 1956. Photographs of helicopter overflights from Soviet times in combination with more recent satellite drone data have now been analyzed at GFZ Potsdam using state-of-the-art methods. The images show the rebirth of the volcano after its collapse. The initial re-growth began at different vents about 400 meters apart. After about two decades, the activity increased and the vents slowly moved together. After about fifty years, the activity concentrated on a single vent, which allowed the growth of a new and steep cone.

The authors of the study determined an average growth rate of 26,400 cubic meters per day — equivalent to about a thousand large dump trucks. The results make it possible to predict when the volcanic building may once again reach a critical height, so that it may collapse again under its own weight. The numerical modeling also explains the changes in stress within the volcanic rock and thus the migration of the eruption vents. Thomas Walter, volcanologist at the GFZ and co-author of the study, summarizes: “Our results show that the decay and re-growth of a volcano has a major impact on the pathways of the magma in the depth. Thus, disintegrated and newly grown volcanoes show a kind of memory of their altered field of stress.” For future prognosis, this means that the history of birth and collapse must be included to be able to give estimates about possible eruptions or imminent collapses.

Reference:
Alina V. Shevchenko, Viktor N. Dvigalo, Thomas R. Walter, Rene Mania, Francesco Maccaferri, Ilya Yu. Svirid, Alexander B. Belousov, Marina G. Belousova. The rebirth and evolution of Bezymianny volcano, Kamchatka after the 1956 sector collapse. Communications Earth & Environment, 2020; 1 (1) DOI: 10.1038/s43247-020-00014-5

Note: The above post is reprinted from materials provided by GFZ GeoForschungsZentrum Potsdam, Helmholtz Centre.

Japan’s geologic history in question after discovery of metamorphic rock microdiamonds

September 12, 2020

Location and geological map of Yukinoura district, Saikai City, Nagasaki Prefecture, Japan. Credit: Professor Tadao Nishiyama

A collaboration of researchers based in Kumamoto University, Japan have discovered microdiamonds in the Nishisonogi metamorphic rock formation in Nagasaki Prefecture, Japan. Microdiamonds in metamorphic rocks are important minerals because they form in continental collision zones and show that the crust has penetrated deeper than 120 km below the surface. This is the second area in the world, after the Italian Alps, that shows microdiamonds can form in metamorphic rock through subduction of oceanic plates.

In recent years, microdiamonds have received a great deal of attention because they have been discovered in metamorphic rocks around the world and it has become clear that they are formed in collisions between continents. It was thought that Japan would not produce such microdiamonds because it is not a continental collision zone, but an oceanic plate subduction zone. However, the first microdiamonds from metamorphic rocks in Japan were found in the Nishisonogi metamorphic rock formation in the west coast of Nagasaki Prefecture.

The area where the microdiamonds were discovered is an approximately 100-million-year-old Cretaceous metamorphic rock formation. On the west coast of Saikai City in Nagasaki Prefecture, blocks of pelitic and basic schist are scattered amongst serpentinite that was created from mantle material. Such rocks are called a serpentinite mélange and indicate that they have risen from deep in the subduction zone. Researchers found microdiamonds here, in the serpentinite mélange. Their formation conditions have been estimated to be a temperature of about 450 °C and a pressure of about 2.8 GPa, which makes them the coldest diamonds ever formed. It has been thought that the Nishisonogi metamorphic rock was formed under a pressure of about 1 GPa, but it is now clear that they were ultrahigh-pressure metamorphic rocks that rose after subducting to 120 km — a very unexpected discovery.

“The discovery of microdiamonds from Japan’s first metamorphic rocks will rewrite Japan’s geological history,” said Professor Tadao Nishiyama, the leader of this study. “Until now, the Nagasaki metamorphic rocks were said to belong to a low-temperature, high-pressure-type metamorphic rock belt, the “Sanbagawa Belt,” which crosses the Japanese mainland. It has become clear, however, that they are independently-formed ultrahigh-pressure metamorphic rocks. I expect that there will be many discussions about what kind of plate movement created this formation.”

Reference:
Tadao Nishiyama, Hiroaki Ohfuji, Kousuke Fukuba, Masami Terauchi, Ukyo Nishi, Kazuki Harada, Kouhei Unoki, Yousuke Moribe, Akira Yoshiasa, Satoko Ishimaru, Yasushi Mori, Miki Shigeno, Shoji Arai. Microdiamond in a low-grade metapelite from a Cretaceous subduction complex, western Kyushu, Japan. Scientific Reports, 2020; 10 (1) DOI: 10.1038/s41598-020-68599-7

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

Mammoth graveyard unearthed at Mexico’s new airport

September 9, 2020

A huge mammoth graveyard has been uncovered at the site of Mexico City's new airport — A huge mammoth graveyard has been uncovered at the site of Mexico City’s new airport

Archaeologists in hard hats and face masks carefully remove earth from around enormous bones at the site of Mexico City’s new airport, where construction work has uncovered a huge trove of mammoth skeletons.

The remains of dozens of the extinct giants and other prehistoric creatures have been found in Zumpango on the northern edge of the capital, which sits on an ancient lake bed.

“More than 100 individual mammoths, individual camels, horses, bison, fish, birds, antelopes and rodents have already been recovered,” said army captain Jesus Cantoral, who heads the excavation team.

In total remains have been found at 194 spots across the site since the first discoveries were made in October last year during work on a fuel terminal, he told AFP.

Most of the animals are believed to have roamed the Earth between 10,000 and 25,000 years ago.

Experts worked painstakingly to extract the bones of a one of the mammoth skeletons, taking care not to disturb a mound of earth supporting another specimen.

At the same time thousands of construction workers continued to labor away across the site as dozens of excavators and trucks shifted earth and transported building materials.

The authorities say they have kept a careful watch to ensure the precious remains are preserved during work on the airport, which President Andres Manuel Lopez Obrador has promised will be inaugurated in March 2022.

Stuck in mud

Experts believe the mammoths were drawn to the area by food and water provided by a lake that existed in prehistoric times.

“The place had a lot of natural resources, enough for these individuals to survive for a long time and for many generations,” said archaeologist Araceli Yanez.

In winter the lake area became muddy, trapping the giant mammals who starved, she said.

“It attracted a large number of mammoths, and they got stuck, as is the case with this individual, and died here,” Yanez added.

The lake was also very good for preserving the remains.

Mexico has been the scene of surprising mammoth discoveries before.

In the 1970s, workers building the Mexico City subway found a mammoth skeleton while digging on the capital’s north side.

In 2012, workers digging to build a wastewater treatment plant outside the capital discovered hundreds of bones belonging to mammoths and other Ice Age animals.

And last year archaeologists found the skeletons of 14 mammoths in Tultepec, near the site of the new airport.

Some bore signs that the animals had been hunted, leading experts to conclude at the time that they had found “the world’s first mammoth trap.”

The government began construction of the new aviation hub in 2019 at the Santa Lucia military airbase, months after canceling work on another partially completed airport.

Lopez Obrador, who ran on a pro-austerity, anti-graft platform, had criticized that project championed by his predecessor Enrique Pena Nieto as an unnecessary mega-project marred by corruption.

His administration has tasked the military with overseeing construction of the new airport, which will house a museum showcasing the mammoth skeletons and other ancient remains.

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

New fossil ape discovered in India

September 9, 2020

Map illustrating the location of Kapi (black star) relative to modern (dark green) and historical (light green) populations of lesser apes and the approximate distribution of early fossil apes in East Africa (blue triangles). Green triangles mark the location of previously discovered fossil gibbons. The new fossil is millions of years older than any previously known fossil gibbon and highlights their migration from Africa to Asia. Credit: Luci Betti-Nash.

A 13-million-year-old fossil unearthed in northern India comes from a newly discovered ape, the earliest known ancestor of the modern-day gibbon. The discovery by Christopher C. Gilbert, Hunter College, fills a major void in the ape fossil record and provides important new evidence about when the ancestors of today’s gibbon migrated to Asia from Africa.

The findings have been published in the article “New Middle Miocene ape (primates: Hylobatidae) from Ramnagar, India fills major gaps in the hominoid fossil record” in the Proceedings of the Royal Society B.

The fossil, a complete lower molar, belongs to a previously unknown genus and species (Kapi ramnagarensis) and represents the first new fossil ape species discovered at the famous fossil site of Ramnagar, India, in nearly a century.

Gilbert’s find was serendipitous. Gilbert and team members Chris Campisano, Biren Patel, Rajeev Patnaik, and Premjit Singh were climbing a small hill in an area where a fossil primate jaw had been found the year before. While pausing for a short rest, Gilbert spotted something shiny in a small pile of dirt on the ground, so he dug it out and quickly realized he’d found something special.

“We knew immediately it was a primate tooth, but it did not look like the tooth of any of the primates previously found in the area,” he said. “From the shape and size of the molar, our initial guess was that it might be from a gibbon ancestor, but that seemed too good to be true, given that the fossil record of lesser apes is virtually nonexistent. There are other primate species known during that time, and no gibbon fossils have previously been found anywhere near Ramnagar. So we knew we would have to do our homework to figure out exactly what this little fossil was.”

Since the fossil’s discovery in 2015, years of study, analysis, and comparison were conducted to verify that the tooth belongs to a new species, as well as to accurately determine its place in the ape family tree. The molar was photographed and CT-scanned, and comparative samples of living and extinct ape teeth were examined to highlight important similarities and differences in dental anatomy.

“What we found was quite compelling and undeniably pointed to the close affinities of the 13-million-year-old tooth with gibbons,” said Alejandra Ortiz, who is part of the research team. “Even if, for now, we only have one tooth, and thus, we need to be cautious, this is a unique discovery. It pushes back the oldest known fossil record of gibbons by at least five million years, providing a much-needed glimpse into the early stages of their evolutionary history.”

In addition to determining that the new ape represents the earliest known fossil gibbon, the age of the fossil, around 13 million years old, is contemporaneous with well-known great ape fossils, providing evidence that the migration of great apes, including orangutan ancestors, and lesser apes from Africa to Asia happened around the same time and through the same places.

“I found the biogeographic component to be really interesting,” said Chris Campisano. “Today, gibbons and orangutans can both be found in Sumatra and Borneo in Southeast Asia, and the oldest fossil apes are from Africa. Knowing that gibbon and orangutan ancestors existed in the same spot together in northern India 13 million years ago, and may have a similar migration history across Asia, is pretty cool.”

Reference:
New Middle Miocene Ape (Primates: Hylobatidae) from Ramnagar, India Fills Major Gaps in the Hominoid Fossil Record, Proceedings of the Royal Society B (2020). rspb.royalsocietypublishing.or … .1098/rspb.2020.1655

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

True size of prehistoric mega-shark finally revealed

September 9, 2020

Palaeoartist reconstruction of a 16 m adult Megalodon. Credit: Reconstruction by Oliver E. Demuth

To date only the length of the legendary giant shark Megalodon had been estimated. But now, a new study led by the University of Bristol and Swansea University has revealed the size of the rest of its body, including fins that are as large as an adult human.

There is a grim fascination in determining the size of the largest sharks, but this can be difficult for fossil forms where teeth are often all that remain.

Today, the most fearsome living shark is the Great White, at over six metres (20 feet) long, which bites with a force of two tonnes.

Its fossil relative, the big tooth shark Megalodon, star of Hollywood movies, lived from 23 to around three million years ago, was over twice the length of a Great White and had a bite force of more than ten tonnes.

The fossils of the Megalodon are mostly huge triangular cutting teeth bigger than a human hand.

Jack Cooper, who has just completed the MSc in Palaeobiology at the University of Bristol’s School of Earth Sciences, and colleagues from Bristol and Swansea used a number of mathematical methods to pin down the size and proportions of this monster, by making close comparisons to a diversity of living relatives with ecological and physiological similarities to Megalodon.

The project was supervised by shark expert Dr Catalina Pimiento from Swansea University and Professor Mike Benton, a palaeontologist at Bristol. Dr Humberto Ferrón of Bristol also collaborated.

Their findings are published today in the journal Scientific Reports.

Jack Cooper said: “I have always been mad about sharks. As an undergraduate, I have worked and dived with Great whites in South Africa — protected by a steel cage of course. It’s that sense of danger, but also that sharks are such beautiful and well-adapted animals, that makes them so attractive to study.

“Megalodon was actually the very animal that inspired me to pursue palaeontology in the first place at just six years old, so I was over the moon to get a chance to study it.

“This was my dream project. But to study the whole animal is difficult considering that all we really have are lots of isolated teeth.”

Previously the fossil shark, known formally as Otodus megalodon, was only compared with the Great White. Jack and his colleagues, for the first time, expanded this analysis to include five modern sharks.

Dr Pimiento said: “Megalodon is not a direct ancestor of the Great White but is equally related to other macropredatory sharks such as the Makos, Salmon shark and Porbeagle shark, as well as the Great white. We pooled detailed measurements of all five to make predictions about Megalodon.”

Professor Benton added: “Before we could do anything, we had to test whether these five modern sharks changed proportions as they grew up. If, for example, they had been like humans, where babies have big heads and short legs, we would have had some difficulties in projecting the adult proportions for such a huge extinct shark.

“But we were surprised, and relieved, to discover that in fact that the babies of all these modern predatory sharks start out as little adults, and they don’t change in proportion as they get larger.”

Jack Cooper said: “This means we could simply take the growth curves of the five modern forms and project the overall shape as they get larger and larger — right up to a body length of 16 metres.”

The results suggest that a 16-metre-long Otodus megalodon likely had a head round 4.65 metres long, a dorsal fin approximately 1.62 metres tall and a tail around 3.85 metres high.

This means an adult human could stand on the back of this shark and would be about the same height as the dorsal fin.

The reconstruction of the size of Megalodon body parts represents a fundamental step towards a better understanding of the physiology of this giant, and the intrinsic factors that may have made it prone to extinction.

Reference:
Jack A. Cooper, Catalina Pimiento, Humberto G. Ferrón, Michael J. Benton. Body dimensions of the extinct giant shark Otodus megalodon: a 2D reconstruction. Scientific Reports, 2020; 10 (1) DOI: 10.1038/s41598-020-71387-y

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

Deep underground forces explain quakes on San Andreas Fault

September 9, 2020

The study from the emergent field of earthquake physics looks at temblor mechanics from the bottom up, rather than from the top down, with a focus on underground rocks, friction and fluids. On the segment of the San Andreas Fault near Parkfield, Calif., underground excitations—beyond the depths where quakes are typically monitored—lead to instability that ruptures in a quake.

“Most of California seismicity originates from the first 10 miles of the crust, but some tremors on the San Andreas Fault take place much deeper,” said Sylvain Barbot, assistant professor of Earth sciences at the USC Dornsife College of Letters, Arts and Sciences. “Why and how this happens is largely unknown. We show that a deep section of the San Andreas Fault breaks frequently and melts the host rocks, generating these anomalous seismic waves.”The newly published study appears in Science Advances. Barbot, the corresponding author, collaborated with Lifeng Wang of the China Earthquake Administration in China.

Parkfield was chosen because it is one of the most intensively monitored epicenters in the world. The San Andreas Fault slices past the town, and it’s regularly ruptured with significant quakes. Quakes of magnitude 6 have shaken the Parkfield section of the fault at fairly regular intervals in 1857, 1881, 1901, 1922, 1934, 1966 and 2004, according to the U.S. Geological Survey. At greater depths, smaller temblors occur every few months.So what’s happening deep in the Earth to explain the rapid quake recurrence?

USC researchers seek to understand rocks beneath the San Andreas Fault

So what’s happening deep in the Earth to explain the rapid quake recurrence?

Using mathematical models and laboratory experiments with rocks, the scientists conducted simulations based on evidence gathered from the section of the San Andreas Fault extending up to 36 miles north of—and 16 miles beneath—Parkfield. They simulated the dynamics of fault activity in the deep Earth spanning 300 years to study a wide range of rupture sizes and behaviors.

“It’s difficult to make predictions,” Barbot added, “so instead of predicting just earthquakes, we’re trying to explain all of the different types of motion seen in the ground.”

Reference:
“Excitation of San Andreas tremors by thermal instabilities below the seismogenic zone” Science Advances (2020). advances.sciencemag.org/lookup … .1126/sciadv.abb2057

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

Meteorite strikes may create unexpected form of silica

September 1, 2020

Quartz is one of the most common crystals on Earth (Credit: Sinclair Stammers/SPL)

When a meteorite hurtles through the atmosphere and crashes to Earth, how does its violent impact alter the minerals found at the landing site? What can the short-lived chemical phases created by these extreme impacts teach scientists about the minerals existing at the high-temperature and pressure conditions found deep inside the planet?

New work led by Carnegie’s Sally June Tracy examined the crystal structure of the silica mineral quartz under shock compression and is challenging longstanding assumptions about how this ubiquitous material behaves under such intense conditions. The results are published in Science Advances.

“Quartz is one of the most abundant minerals in Earth’s crust, found in a multitude of different rock types,” Tracy explained. “In the lab, we can mimic a meteorite impact and see what happens.”

Tracy and her colleagues — Washington State University’s (WSU) Stefan Turneaure and Princeton University’s Thomas Duffy, a former Carnegie Fellow — used a specialized cannon-like gas gun to accelerate projectiles into quartz samples at extremely high speeds — several times faster than a bullet fired from a rifle. Special x-ray instruments were used to discern the crystal structure of the material that forms less than one-millionth of a second after impact. Experiments were carried out at the Dynamic Compression Sector (DCS), which is operated by WSU and located at the Advanced Photon Source, Argonne National Laboratory.

Quartz is made up of one silicon atom and two oxygen atoms arranged in a tetrahedral lattice structure. Because these elements are also common in the silicate-rich mantle of the Earth, discovering the changes quartz undergoes at high-pressure and -temperature conditions, like those found in the Earth’s interior, could also reveal details about the planet’s geologic history.

When a material is subjected to extreme pressures and temperatures, its internal atomic structure can be re-shaped, causing its properties to shift. For example, both graphite and diamond are made from carbon. But graphite, which forms at low pressure, is soft and opaque, and diamond, which forms at high pressure, is super-hard and transparent. The different arrangements of carbon atoms determine their structures and their properties, and that in turn affects how we engage with and use them.

Despite decades of research, there has been a long-standing debate in the scientific community about what form silica would take during an impact event, or under dynamic compression conditions such as those deployed by Tracy and her collaborators. Under shock loading, silica is often assumed to transform to a dense crystalline form known as stishovite — a structure believed to exist in the deep Earth. Others have argued that because of the fast timescale of the shock the material will instead adopt a dense, glassy structure.

Tracy and her team were able to demonstrate that counter to expectations, when subjected to a dynamic shock of greater than 300,000 times normal atmospheric pressure, quartz undergoes a transition to a novel disordered crystalline phase, whose structure is intermediate between fully crystalline stishovite and a fully disordered glass. However, the new structure cannot last once the burst of intense pressure has subsided.

“Dynamic compression experiments allowed us to put this longstanding debate to bed,” Tracy concluded. “What’s more, impact events are an important part of understanding planetary formation and evolution and continued investigations can reveal new information about these processes.”

This research was supported by the Defense Threat Reduction Agency and the NSF. Washington State University (WSU) provided experimental support through awards from the U.S. Department of Energy (DOE)/National Nuclear Security Agency (NNSA).

This work is based on experiments performed at the Dynamic Compression Sector, operated by WSU under a DOE/ NNSA award. This research used the resources of the Advanced Photon Source, a Department of Energy Office of Science User Facility operated for the DOE Office of Science by the Argonne National .

Reference:
Sally June Tracy, Stefan J. Turneaure, Thomas S. Duffy. Structural response of α-quartz under plate-impact shock compression. Science Advances, 2020; 6 (35): eabb3913 DOI: 10.1126/sciadv.abb3913

Note: The above post is reprinted from materials provided by Carnegie Institution for Science.

Newly discovered rare dinosaur embryos show sauropods had rhino-like horns

September 1, 2020

Sauropod Embryo. Credit: University of Manchester

An incredibly rare dinosaur embryo discovered perfectly preserved inside its egg has shown scientists new details of the development and appearance of sauropods which lived 80 million years ago.

Sauropods were the giant herbivores made famous as being ‘veggie-saurs’ in the 1993 film Jurassic Park. The incredible new find of an intact embryo has shown for the first time that these dinosaurs had stereoscopic vision and a horn on the front of the face which was then lost in adulthood.

The international research team say that this is the most complete and articulate skull known from any titanosaur, the last surviving group of long-necked sauropods and largest land animals known to have ever existed.

The sauropod egg was discovered in Patagonia, Argentina, in an area not previously known to provide evidence of dinosaur fossils. It was imperative the egg was repatriated to Argentina however as it is illegal to permanently remove fossils from the country.

Dr John Nudds from The University of Manchester said: “The preservation of embryonic dinosaurs preserved inside their eggs is extremely rare. Imagine the huge sauropods from Jurassic Park and consider that the tiny skulls of their babies, still inside their eggs, are just a couple of centimetres long.

“We were able to reconstruct the embryonic skull prior to hatching. The embryos possessed a specialised craniofacial anatomy that precedes the post-natal transformation of the skull in adult sauropods. Part of the skull of these embryonic sauropods was extended into an elongated snout or horn, so that they possessed a peculiarly shaped face.”

The examination of the amazing specimen enabled the team to revise opinions of how babies of these giant dinosaurs may be hatched and to test previously held ideas about sauropodomorph reproduction. The elongated horn is now thought to have been used as an ‘egg tooth’ on hatching to allow babies to break through their shell.

The findings, published today in Current Biology, were the result of a novel technique to reveal embryonic dinosaurs in their shells. The embryo within the egg was revealed by carefully dissolving the egg around it using an acid preparation. The team were then able to perform a virtual dissection of the specimen at the European Synchrotron Radiation Facility (ESRF) in Grenoble.

Sauropod embryology remains one of the least explored areas of the life history of dinosaurs. The first definitive discovery of sauropod embryos came with the finding of an enormous nesting ground of titanosaurian dinosaurs discovered in Upper Cretaceous deposits of northern Patagonia, Argentina, 25 years ago. This new discovery however, is the first time a fully intact embryo has been able to be studied.

Other eggs were also found at the Argentinian site which the scientists now aim to examine in a similar fashion. It is thought that some of the eggs could contain well-preserved dinosaur skin which could help further piece together the mysteries of some of the most fascinating animals to ever walk the Earth.

Reference:
Martin Kundrát, Rodolfo A. Coria, Terry W. Manning, Daniel Snitting, Luis M. Chiappe, John Nudds, Per E. Ahlberg. Specialized Craniofacial Anatomy of a Titanosaurian Embryo from Argentina. Current Biology, 2020; DOI: 10.1016/j.cub.2020.07.091

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

Meteorite study suggests Earth may have been wet since it formed

September 1, 2020

Piece of the meteorite Sahara 97096 (about 10 cm long), an enstatite chondrite that contains about 0.5 weight % of water. If Earth formed entirely of this material, it would have received 23 times the total mass of water present in the Earth's oceans. Credit: L. Piani, Museum of Natural History in Paris — Piece of the meteorite Sahara 97096 (about 10 cm long), an enstatite chondrite that contains about 0.5 weight % of water. If Earth formed entirely of this material, it would have received 23 times the total mass of water present in the Earth’s oceans. Credit: L. Piani, Museum of Natural History in Paris

A new study finds that Earth’s water may have come from materials that were present in the inner solar system at the time the planet formed — instead of far-reaching comets or asteroids delivering such water. The findings published Aug. 28 in Science suggest that Earth may have always been wet.

Researchers from the Centre de Recherches Petrographiques et Geochimiques (CRPG, CNRS/Universite de Lorraine) in Nancy, France, including one who is now a postdoctoral fellow at Washington University in St. Louis, determined that a type of meteorite called an enstatite chondrite contains sufficient hydrogen to deliver at least three times the amount of water contained in the Earth’s oceans, and probably much more.

Enstatite chondrites are entirely composed of material from the inner solar system — essentially the same stuff that made up the Earth originally.

“Our discovery shows that the Earth’s building blocks might have significantly contributed to the Earth’s water,” said lead author Laurette Piani, a researcher at CPRG. “Hydrogen-bearing material was present in the inner solar system at the time of the rocky planet formation, even though the temperatures were too high for water to condense.”

The findings from this study are surprising because the Earth’s building blocks are often presumed to be dry. They come from inner zones of the solar system where temperatures would have been too high for water to condense and come together with other solids during planet formation.

The meteorites provide a clue that water didn’t have to come from far away.

“The most interesting part of the discovery for me is that enstatite chondrites, which were believed to be almost ‘dry,’ contain an unexpectedly high abundance of water,” said Lionel Vacher, a postdoctoral researcher in physics in Arts & Sciences at Washington University in St. Louis.

Vacher prepared some of the enstatite chondrites in this study for water analysis while he was completing his PhD at Universite de Lorraine. At Washington University, Vacher is working on understanding the composition of water in other types of meteorites.

Enstatite chondrites are rare, making up only about 2 percent of known meteorites in collections.

But their isotopic similarity to Earth make them particularly compelling. Enstatite chondrites have similar oxygen, titanium and calcium isotopes as Earth, and this study showed that their hydrogen and nitrogen isotopes are similar to Earth’s, too. In the study of extraterrestrial materials, the abundances of an element’s isotopes are used as a distinctive signature to identify where that element originated.

“If enstatite chondrites were effectively the building blocks of our planet — as strongly suggested by their similar isotopic compositions — this result implies that these types of chondrites supplied enough water to Earth to explain the origin of Earth’s water, which is amazing!” Vacher said.

The paper also proposes that a large amount of the atmospheric nitrogen — the most abundant component of the Earth’s atmosphere — could have come from the enstatite chondrites.

“Only a few pristine enstatite chondrites exist: ones that were not altered on their asteroid nor on Earth,” Piani said. “In our study we have carefully selected the enstatite chondrite meteorites and applied a special analytical procedure to avoid being biased by the input of terrestrial water.”

Coupling two analytical techniques — conventional mass spectrometry and secondary ion mass spectrometry (SIMS) — allowed researchers to precisely measure the content and composition of the small amounts of water in the meteorites.

Prior to this study, “it was commonly assumed that these chondrites formed close to the sun,” Piani said. “Enstatite chondrites were thus commonly considered ‘dry,’ and this frequently reasserted assumption has probably prevented any exhaustive analyses to be done for hydrogen.”

Reference:
Laurette Piani, Yves Marrocchi, Thomas Rigaudier, Lionel G. Vacher, Dorian Thomassin, Bernard Marty. Earth’s water may have been inherited from material similar to enstatite chondrite meteorites. Science, 2020 DOI: 10.1126/science.aba1948

Note: The above post is reprinted from materials provided by Washington University in St. Louis. Original written by Talia Ogliore.

Probing the origin of the mantle’s chemically distinct ‘scars’

September 1, 2020

Basalt, the most-common rock on Earth’s surface, encases green crystals--a geologic "nesting doll" phenomenon called a xenolith. Basalts such as this one derive from a section of the mantle that has been depleted in incompatible trace elements, which is usually attributed to continental crust formation. In their work, Tucker and his collaborators propose another mechanism that would impart this signature. Credit: Carnegie Institution for Science — Basalt, the most-common rock on Earth’s surface, encases green crystals–a geologic “nesting doll” phenomenon called a xenolith. Basalts such as this one derive from a section of the mantle that has been depleted in incompatible trace elements, which is usually attributed to continental crust formation. In their work, Tucker and his collaborators propose another mechanism that would impart this signature. Credit: Carnegie Institution for Science

The composition of Earth’s mantle was more shaped by interactions with the oceanic crust than previously thought, according to work from Carnegie’s Jonathan Tucker and Peter van Keken along with colleagues from Oxford that was recently published in Geochemistry, Geophysics, Geosystems.

During its evolution, our planet separated into distinct layers—core, mantle, and crust. Each has its own composition and the dynamic processes through which these layers interact with their neighbors can teach us about Earth’s geologic history.

Plate tectonic processes allow for continuous evolution of the crust and play a key role in our planet’s habitability. Earth has two kinds of tectonic plates: those that host continents, which have survived for billions of years, and those that are mostly covered by oceans. Oceanic plates are created by the upward motion of mantle material that occurs when plates spread apart. They are destroyed by sliding under continental plates and back into the mantle, a process that also forms new continental crust.

“The chemical composition of the mantle is influenced by continent formation and geoscientists can read chemical markers left behind by this process,” Tucker explained.

For example, some of the elements found in crustal rocks don’t play nicely with the mantle’s minerals. When continental crust formation draws these elements out of the mantle, they leave behind a depleted residue, like sucking the juice out of a Sno-Cone and leaving just ice. This is referred to as crust extraction and is usually thought to create “scars” that are easy to spot and identify in rocks. It also leaves behind distinct zones in the mantle that are depleted of these particular elements.

“It’s long been thought that these chemical scars are the product of crust formation,” Tucker explained. “But mantle’s inaccessibility means that it’s difficult to know for sure using rock and mineral samples alone.”

To probe the question of the origin of these depleted reservoirs in the mantle, Tucker, van Keken, and their Oxford colleagues Rosemary Jones and Chris Ballentine developed a new model, which showed that the “scar-forming” process of sequestering of incompatible elements from the rest of the mantle is occurring not just in the crust but independently in the deep mantle thanks to old oceanic plates that were drawn all the way down.

“Our work demonstrates that the processes determining the mantle’s composition are more complicated than we previously thought,” Tucker concluded.

Reference:
Jonathan M. Tucker et al. A Role for Subducted Oceanic Crust in Generating the Depleted Mid‐Ocean Ridge Basalt Mantle, Geochemistry, Geophysics, Geosystems (2020). DOI: 10.1029/2020GC009148

Note: The above post is reprinted from materials provided by Carnegie Institution for Science.

How to weigh a dinosaur

September 1, 2020

The largest and the smallest: dinosaurs reached an amazing range in size through the Mesozoic Era. Credit: Vitor Silva

How do you weigh a long-extinct dinosaur? A couple of ways, as it turns out, neither of which involve actual weighing — but according to a new study, different approaches still yield strikingly similar results.

New research published September 1 in the journal Biological Reviews involved a review of dinosaur body mass estimation techniques carried out over more than a century.

The findings should give us some confidence that we are building an accurate picture of these prehistoric animals, says study leader Dr. Nicolás Campione — particularly our knowledge of the more massive dinosaurs that have no correlates in the modern world.

“Body size, in particular body mass, determines almost at all aspects of an animal’s life, including their diet, reproduction, and locomotion,” said Dr. Campione, a member of the University of New England’s Palaeoscience Research Centre.

“If we know that we have a good estimate of a dinosaur’s body mass, then we have a firm foundation from which to study and understand their life retrospectively.”

Estimating the mass of a dinosaur like the emblematic Tyrannosaurus rex is no small feat — it is a creature that took its last breath some 66 million years ago and, for the most part, only its bones remain today. It is a challenge that has taxed the ingenuity of palaeobiologists for more than a century. Scientific estimates of the mass of the biggest land predator of all time have differed substantially, ranging from about three tonnes to over 18 tonnes.

The research team led by Dr. Campione compiled and reviewed an extensive database of dinosaur body mass estimates reaching back to 1905, to assess whether different approaches for calculating dinosaur mass were clarifying or complicating the science.

Although a range of different methods to estimating body mass have been tried over the years, they all come down to two fundamental approaches. Scientists have either measured and scaled bones in living animals, such as the circumference of the arm (humerus) and leg (femur) bones, and compared them to dinosaurs; or they have calculated the volume of three-dimensional reconstructions that approximate what the animal may have looked like in real life. Debate over which method is ‘better’ has raged in the literature.

The researchers found that once scaling and reconstruction methods are compared en masse, most estimates agree. Apparent differences are the exception, not the rule.

“In fact, the two approaches are more complementary than antagonistic,” Dr. Campione said.

The bone scaling method, which relies on relationships obtained directly from living animals of known body mass, provides a measure of accuracy, but often of low precision; whereas reconstructions that consider the whole skeleton provide precision, but of unknown accuracy. This is because reconstructions depend on our own subjective ideas about what extinct animals looked like, which have changed appreciably over time.

“There will always be uncertainty around our understanding of long-extinct animals, and their weight is always going to be a source of it,” said Dr. David Evans, Temerty Chair of Vertebrate Palaeontology at the Royal Ontario Museum in Toronto, senior author on the new paper. “Our new study suggests we are getting better at weighing dinosaurs, and it paves the way for more realistic dinosaur body mass estimation in the future.”

The researchers recommend that future work seeking to estimate the sizes of Mesozoic dinosaurs, and other extinct animals, need to better-integrate the scaling and reconstruction approaches to reap their benefits.

Drs. Campione and Evans suggest that an adult T. rex would have weighed approximately seven tonnes — an estimate that is consistent across reconstruction and limb bone scaling approaches alike. But the research emphasizes the inaccuracy of such single values and the importance of incorporating uncertainty in mass estimates, not least because dinosaurs, like humans, did not come in one neat package. Such uncertainties suggest an average minimum weight of five tonnes and a maximum average weight of 10 tonnes for the ‘king’ of dinosaurs.

“It is only through the combined use of these methods and through understanding their limits and uncertainties that we can begin to reveal the lives of these, and other, long-extinct animals,” Dr Campione said.

Reference:
Nicolás E. Campione, David C. Evans. The accuracy and precision of body mass estimation in non‐avian dinosaurs. Biological Reviews, 2020; DOI: 10.1111/brv.12638

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

Using math to examine the sex differences in dinosaurs

September 1, 2020

Male lions typically have manes. Male peacocks have six-foot-long tail feathers. Female eagles and hawks can be about 30% bigger than males. But if you only had these animals’ fossils to go off of, it would be hard to confidently say that those differences were because of the animals’ sex. That’s the problem that paleontologists face: it’s hard to tell if dinosaurs with different features were separate species, different ages, males and females of the same species, or just varied in a way that had nothing to do with sex. A lot of the work trying to show differences between male and female dinosaurs has come back inconclusive. But in a new paper, scientists show how using a different kind of statistical analysis can often estimate the degree of sexual variation in a dataset of fossils.

“It’s a whole new way of looking at fossils and judging the likelihood that the traits we see correlate with sex,” says Evan Saitta, a research associate at Chicago’s Field Museum and the lead author of the new paper in the Biological Journal of the Linnean Society. “This paper is part of a larger revolution of sorts about how to use statistics in science, but applied in the context of paleontology.”

Unless you find a dinosaur skeleton that contains the fossilized eggs that it was about to lay, or a similar dead giveaway, it’s hard to be sure about an individual dinosaur’s sex. But many birds, the only living dinosaurs, vary a lot between males and females on average, a phenomenon called sexual dimorphism. Dinosaurs’ cousins, the crocodilians, show sexual dimorphism too. So it stands to reason that in many species of dinosaurs, males and females would differ from each other in a variety of traits.

But not all differences in animals of the same species are linked to their sex. For example, in humans, average height is related to sex, but other traits like eye color and hair color don’t neatly map onto men versus women. We often don’t know precisely how the traits we see in dinosaurs relate to their sex, either. Since we don’t know if, say, larger dinosaurs were female, or dinosaurs with bigger crests on their heads were male, Saitta and his colleagues looked for patterns in the differences between individuals of the same species. To do that, they examined measurements from a bunch of fossils and modern species and did a lot of math.

Other paleontologists have tried to look for sexual dimorphism in dinosaurs using a form of statistics (called significance testing, for all you stats nerds) where you collect all your data points and then calculate the probability that those results could have happened by pure chance rather than an actual cause (like how doctors determine whether a new medicine is more helpful than a placebo). This kind of analysis sometimes works for big, clean datasets. But, says Saitta, “with a lot of these dinosaur tests, our data is pretty bad” — there aren’t that many fossil specimens, or they’re incomplete or poorly preserved. Using significance testing in these cases, Saitta argues, results in a lot of false negatives: since the samples are small, it takes an extreme amount of variation between the sexes to trigger a positive test result. (Significance testing isn’t just a consideration for paleontologists — concerns over a “replication crisis” have plagued researchers in psychology and medicine, where certain studies are difficult to reproduce.)

Instead, Saitta and his colleagues experimented with another form of stats, called effect size statistics. Effect size statistics is better for smaller datasets because it attempts to estimate the degree of sex differences and calculate the uncertainty in that estimate. This alternative statistical method takes natural variations into account without viewing dimorphism as black-or-white-many sexual dimorphisms can be subtle. Co-author Max Stockdale of the University of Bristol wrote the code to run the statistical simulations. Saitta and his colleagues uploaded measurements of dinosaur fossils to the program, and it yielded estimates of body mass dimorphism and error bars in those estimates that would have simply been dismissed using significance testing.

“We showed that if you adopt this paradigm shift in statistics, where you attempt to estimate the magnitude of an effect and then put error bars around that, you can often produce a fairly accurate estimate of sexual variation even when the sexes of the individuals are unknown,” says Saitta.

For instance, Saitta and his colleagues found that in the dinosaur Maiasaura, adult specimens vary a lot in size, and the analyses show that these are likelier to correspond to sexual variation than differences seen in other dinosaur species. But while the current data suggest that one sex was about 45% bigger than the other, they can’t tell if the bigger ones are males or females.

While there’s a lot of work yet to be done, Saitta says he’s excited that the statistical simulations gave such consistent results despite the limits of the fossil data.

“Sexual selection is such an important driver of evolution, and to limit ourselves to ineffective statistical approaches hurts our ability to understand the paleobiology of these animals,” he says. “We need to account for sexual variation in the fossil record.”

“I’m happy to play a small part in this sort of statistical revolution,” he adds. “Effect size statistics has a major impact for psychological and medical research, so to apply it to dinosaurs and paleontology is really cool.”

Reference:
Evan T Saitta, Maximilian T Stockdale, Nicholas R Longrich, Vincent Bonhomme, Michael J Benton, Innes C Cuthill, Peter J Makovicky. An effect size statistical framework for investigating sexual dimorphism in non-avian dinosaurs and other extinct taxa. Biological Journal of the Linnean Society, 2020; DOI: 10.1093/biolinnean/blaa105

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

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