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Welcome Stranger Nugget : World’s Largest Gold Nugget found in Australia

Welcome Stranger Nugget
Welcome Stranger Nugget

Gold nuggets are pieces of native gold which occur naturally. Water and erosion concentrate the accumulation of nuggets which are collected by the methods of placer or lode mining. Nuggets are also frequently found in leftover layers where veins or lodes that contain gold have decayed. Nuggets can also be found today in the tailing piles of former mining operations, in particular the tailings of old dredging operations.

Nuggets of composition are never totally pure, or 24K. The bulk of nuggets are pure around 20-22 K or 83-92 per cent. The “fineness” of nuggets is noted for their pureness. As an example “865 perfect” means the nugget will be 865 gold parts per thousand. The common impurities present in gold nuggets include copper and silver.

Can you imagine a 2,332 ounce nugget of solid gold? Considered the largest gold nugget ever found, the Welcome Stranger Nugget was discovered buried just inches below the surface in Moliagul, Victoria, Australia on February 5th, 1869. Unbelievable!

The Holtermann Nugget found at Hill End, New South Wales, Australia in 1872, at 290 kg. was huge, and indeed remains the largest single mass of gold ever discovered, but it can’t really be called a “nugget” in my book. We could go into hard rock vs placer, but the essence is that a gold nugget has left the lode at some point and is no longer in the host rock. The Holtermann was what the Aussies call “reef gold” after the quartz reefs sought after by the hard rock miners.

Found near Wedderburn, Australia in October 1980, the magnificent Hand of Faith gold nugget was found using a metal detector. This incredible treasure was discovered in a vertical position, laying just six inches below the surface. The Hand of Faith nugget weighs a massive 875 troy ounces (61 pounds, 11 ounces). Kevin Hiller and his family were prospecting behind their modest trailer home when they made this incredible discovery. It is impossible to imagine their excitement and joy; what an amazing find! The Hand of Faith is presently on display at the Golden Nugget Hotel and Casino in Las Vegas, Nevada, USA.

Nuggets are generally considered parts that broke off from the original gold mine and were taken to a new location through water or erosion. The Holtermann Nugget, by applying this description, the greatest mass of gold ever discovered, is not really a nugget. The Holtermann Nugget, discovered in October 1872, is “reef gold,” rather than a diamond nugget. Nonetheless, an amazing find was the Holtermann Nugget, discovered at Hill End, New South Wales, Australia. Reef gold, usually quartz, occurs as a “vein” included in rock. This nugget was a quartz reef. The gold was retrieved by scraping the rock around the vein in one giant piece which weighed 286 kilograms (about 630 pounds). The true weight of this gold mass is unknown as several pieces are believed to have been broken away in the excavation and mining process.

Throughout history several magnificent nuggets have been discovered:

Three large nuggets were found in Montana near the famed Alder Gulch, the most substantial weighing in at 42 pounds. Discovered by Thomas Ramon and Joseph Lefebre in January 1902, the nugget was the size of a man’s fist and very small, with impurities of only 5 per cent.

Early prospectors didn’t find all the gold in Montana. A gold nugget weighing about 2 pounds (27.5 ounces) is the largest gold nugget found in Montana during the last 80 years. The Highland Centennial Gold Nugget was recovered in September 1989 by the Stratton family while working a placer claim in the Highland Mountains south of Butte. The nugget is currently on display at the Mineral Museum at the University of Montana in Butte, Montana.

Alaska is famous for the gold discovered there including the Centennial Nugget found near Ruby, Alaska, on Swift Creek. This treasure discovery is reportedly the largest nugget ever discovered in Alaska and weights 294.1 troy ounces. About the height of a softball, Barry Clay found this formidable nugget in 1998. It has been donated, and is now in a private collection.

Another Alaskan nugget of note was found on Anvil Creek near Nome, Alaska on September 29th, 1901, the Anvil Nugget weighed 108 troy ounces.

California and gold go hand-in-hand. The largest nugget ever discovered in California was located in 1854 at Carson Hill above the Stanislaus River. The nugget weighed 195 pounds.

Earth formed much faster than previously thought

They may not look like much, but CI chondrites – small fragile meteorites as shown here – are thought to be our best compositional equivalents of the bulk material of our solar system.
They may not look like much, but CI chondrites – small fragile meteorites as shown here – are thought to be our best compositional equivalents of the bulk material of our solar system.

The precursor of our planet, the proto-Earth, formed within a time span of approximately five million years, shows a new study from the Centre for Star and Planet Formation (StarPlan) at the Globe Institute at the University of Copenhagen.

On an astronomical scale, this is extremely fast, the researchers explain.

If you compare the solar system’s estimated 4.6 billion years of existence with a 24-hour period, the new results indicate that the proto-Earth formed in what corresponds to about a minute and a half.

Thus, the results from StarPlan break with the traditional theory that the proto-Earth formed by random collisions between larger and larger planetary bodies throughout several tens of millions of years — equivalent to about 5-15 minutes out of the above-mentioned fictional 24 hours of formation.

Instead, the new results support a more recent, alternative theory about the formation of planets through the accretion of cosmic dust. The study’s lead author, Associate Professor Martin Schiller, explains it as follows:

“The other idea is that we start from dust, essentially. Millimetre-sized objects, all coming together, raining down on the growing body and making the planet in one go,” he says, adding:

“Not only is this implication of the rapid formation of the Earth interesting for our solar system. It is also interesting to assess how likely it is for planets to form somewhere else in the galaxy.”

The bulk composition of the solar system

The key to the new finding came in the form of the most precise measurements of iron isotopes that have so far been published scientifically.

By studying the isotopic mixture of the metallic element in different meteorites, the researchers found only one type of meteoritic material with a composition similar to Earth: The so-called CI chondrites.

The researchers behind the study describe the dust in this fragile type of meteorite as our best equivalent to the bulk composition of the solar system itself. It was dust like this combined with gas that was funnelled via a circumstellar accretion disk onto the growing Sun.

This process lasted about five million years and our planets were made from material in this disk. Now, the researchers estimate that the proto-Earth’s ferrous core also formed already during this period, removing early accreted iron from the mantle.

Two different iron compositions

Other meteorites, for example from Mars, tell us that at the beginning the iron isotopic composition of material contributing to the growing Earth was different. Most likely due to thermal processing of dust close to the young sun, the researchers from StarPlan explain.

After our solar system’s first few hundred thousands of years it became cold enough for unprocessed CI dust from further out in the system to enter the accretion region of the proto-Earth.

“This added CI dust overprinted the iron composition in the Earth’s mantle, which is only possible if most of the previous iron was already removed into the core. That is why the core formation must have happened early,” Martin Schiller explains.

“If the Earth’s formation was a random process where you just smashed bodies together, you would never be able to compare the iron composition of the Earth to only one type of meteorite. You would get a mixture of everything,” he adds.

More planets, more water, perhaps more life

Based on the evidence for the theory that planets form through the accretion of cosmic dust, the researchers believe that the same process may occur elsewhere in the universe.

This means that also other planets may likely form much faster than if they grow solely from random collisions between objects in space.

This assumption is corroborated by the thousands of exoplanets — planets in other galaxies — that astronomers have discovered since the mid-nineties, explains Centre Leader and co-author of the study, Professor Martin Bizzarro:

“Now we know that planet formation happens everywhere. That we have generic mechanisms that work and make planetary systems. When we understand these mechanisms in our own solar system, we might make similar inferences about other planetary systems in the galaxy. Including at which point and how often water is accreted,” he says, adding:

“If the theory of early planetary accretion really is correct, water is likely just a by-product of the formation of a planet like the Earth — making the ingredients of life, as we know it, more likely to be found elsewhere in the universe.”

Reference:
Martin Schiller, Martin Bizzarro, Julien Siebert. Iron isotope evidence for very rapid accretion and differentiation of the proto-Earth. Science Advances, 2020; 6 (7): eaay7604 DOI: 10.1126/sciadv.aay7604

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

Asteroid impact enriches certain elements in seawater

Asteroid impact
Representative Image : Asteroid impact

Asteroid strikes upset the environment and provide clues via the elements they leave behind. Now, University of Tsukuba researchers have linked elements that are enriched in the Cretaceous–Paleogene (KPg) boundary clays from Stevns Klint, Denmark, to the impact of the asteroid that produced the Chicxulub crater at the Yucatán Peninsula, Mexico. This corresponds to one of the “Big Five” mass extinctions, which occurred at the KPg boundary at the end of the Cretaceous, 66 million years ago. The findings provide a better understanding of which processes lead to enrichment of these types of elements—an understanding that may be applied to other geological boundary events as well.

In a study published in the Geological Society of America Bulletin, the researchers analyzed the concentrations of certain elements within the KPg boundary clays—such as copper, silver, and lead—to determine which processes led to the element enrichment after the end-Cretaceous asteroid impact. Two enriched components were found in the boundary layer, each with distinctly different compositions of elements. One component was incorporated in pyrite (FeS2), whereas the other component was not related to pyrite.

“Since the enrichments of elements in these two components of the boundary clay were accompanied by enrichments of iridium,” says first author Professor Teruyuki Maruoka, “both two components might have been induced by processes related to the asteroid impact.”

Iron oxides/hydroxides acted as a carrier phase that supplied chalcophile elements (elements concentrated in sulfide minerals) to the KPg boundary clays on the sea floor. The vapor cloud of the asteroid impact produced iron oxides/hydroxides, which could have carried chalcophile elements in oceans and been the source of iron in the pyrite grains holding chalcophile elements.

“These could have been incorporated into the pyrite as impurities,” explains Professor Maruoka. “Furthermore, both iron oxides/hydroxides and chalcophile elements could have been released to the environment from the rocks that were struck by the asteroid impact.”

Additionally, organic matter in the oceans could have accumulated copper and silver. As such matter degraded on the sea floor, it could have released these elements, which then formed copper- or silver-enriched grains in the KPg boundary clays. This, in turn, may have led to the formation of discrete grains that differ from pyrite. Acid rain that occurred after the end-Cretaceous asteroid impact could have supplied elements such as copper, silver, and lead to the ocean, as these elements are typical constituents of acid-soluble sulfides and were enriched in the second chalcophile component not related to pyrite.

These findings will hopefully provide further avenues to increase our understanding of the events around the end-Cretaceous impact, and potentially other major boundary events.

Reference:
Teruyuki Maruoka et al. Enrichment of chalcophile elements in seawater accompanying the end-Cretaceous impact event, GSA Bulletin (2020). DOI: 10.1130/B35403.1

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

South American volcano showing early warning signs of ‘potential collapse’

volcanic eruption in australia
Representative Image : Volcanic eruption in australia. Image courtesy of Pete Johnson

South American volcano showing early warning signs of ‘potential collapse’, research shows

One of South America’s most prominent volcanoes is producing early warning signals of a potential collapse, new research has shown.

Tungurahua volcano in Ecuador — known locally as “The Black Giant” — is displaying the hallmarks of flank instability, which could result in a colossal landslide.

New research, led by Dr James Hickey from the Camborne School of Mines, has suggested that the volcano’s recent activity has led to significant rapid deformation on the western flank.

The researchers believe that the driving force causing this deformation could lead to an increased risk of the flank collapsing, causing widespread damage to the surrounding local area.

The research recommends the volcano should be closely monitored to watch for stronger early warning signs of potential collapse.

The study is published in the journal Earth & Planetary Science Letters.

Dr Hickey, who is based at the University of Exeter’s Penryn Campus, Cornwall, said: “Using satellite data we have observed very rapid deformation of Tungurahua’s west flank, which our research suggests is caused by imbalances between magma being supplied and magma being erupted.”

Tungurahua volcano has a long history of flank collapse, and has also been frequently active since 1999. The activity in 1999 led to the evacuation of 25,000 people from nearby communities.

A previous eruption of Tungurahua, around 3,000 years ago, caused a prior, partial collapse of the west flank of the volcanic cone.

This collapse led to a wide-spread debris avalanche of moving rock, soil, snow and water that covered 80 square kilometres — the equivalent of more than 11,000 football fields.

Since then, the volcano has steadily been rebuilt over time, peaking with a steep-sided cone more than 5000 m in height.

However, the new west flank, above the site of the 3000 year old collapse, has shown repeated signs of rapid deformation while the other flanks remain stable.

The new research has shown that this deformation can be explained by shallow, temporary magma storage beneath the west flank. If this magma supply is continued, the sheer volume can cause stress to accumulate within the volcanic cone — and so promote new instability of the west flank and its potential collapse.

Dr Hickey added: “Magma supply is one of a number of factors that can cause or contribute to volcanic flank instability, so while there is a risk of possible flank collapse, the uncertainty of these natural systems also means it could remain stable. However, it’s definitely one to keep an eye on in the future.”

Reference:
James Hickey, Ryan Lloyd, Juliet Biggs, David Arnold, Patricia Mothes, Cyril Muller. Rapid localized flank inflation and implications for potential slope instability at Tungurahua volcano, Ecuador. Earth and Planetary Science Letters, 2020; 534: 116104 DOI: 10.1016/j.epsl.2020.116104

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

Fossils help identify a lone ‘bright spot’ in a similar state to coral reefs before human impact

Fossil coral close-up Credit: Aaron O'Dea
Fossil coral close-up Credit: Aaron O’Dea

Researchers at the Smithsonian Tropical Research Institute (STRI) discovered a massive, 7,000-year-old fossilized coral reef near the institute’s Bocas del Toro Research Station in Panama. Spanning about 50 hectares, it rewards paleontologists with an unusual glimpse of a “pristine” reef that formed before humans arrived.

“All modern reefs in the Caribbean have been impacted in some way by humans,” said STRI staff scientist Aaron O’Dea. “We wanted to quantify that impact by comparing reefs that formed before and after human settlement.”

Using a large excavator, the team dug 4-meter-deep trenches into the fossil reef and bagged samples of rubble. They dated the reef with high resolution radiometric dating.

“The fossils are exquisitely preserved,” O’Dea said. “We found branching corals in life position with chemically pristine fossil preservation. Now we are classifying everything from snails and clams to sea urchins, sponge spicules and shark dermal denticles.”

Archaeological evidence from Bocas del Toro indicates that settlers did not make extensive use of marine resources until around 2,000 years ago. So, the fossilized reef predates human impact by a few thousand years. After comparing fossilized corals with corals from nearby reefs, the team was surprised to find a modern reef that closely resembled the pre-settlement reef. They dubbed this a “bright spot,” and asked why this reef is more similar to the prehistoric reef than the others.

“Most of the reefs in Bocas today look nothing like they did 7,000 years ago,” said Andrew Altieri, former STRI scientist and now assistant professor at the University of Florida, Gainesville. “That confirmed our expectations given what we know about recent deterioration caused by humans. So we were really surprised when we discovered one modern reef that is indistinguishable in its community composition to the ancient reefs.”

When the team cored this “bright spot” reef, they discovered that it had been in this state for centuries. “This suggests resilience,” said Mauro Lepore, former STRI post-doctoral fellow. “And that kind of information can be really powerful for conservation.”

“This finding begs the question of what’s so special about this reef,” O’Dea said. The team evaluated current environmental factors such as water quality, hypoxia, temperature, aspect and shape, but none of those explained why this reef is more like the pre-human impact reef. The only clues were that it was the furthest away from human activity and that the staghorn coral, which dominates the reef, had previously been shown to consist of clones resilient to white band disease.

More work is needed to understand why this bright spot persists in the face of human impacts. However, the team propose that these kinds of fossil records can help in conservation by establishing which ecosystems have been irrevocably altered and those which preserve elements of what was natural. Once identified, these “bright spots” could act as a guide to conserve other ecosystems.

Reference:
Aaron O’Dea et al, Defining variation in pre-human ecosystems can guide conservation: An example from a Caribbean coral reef, Scientific Reports (2020). DOI: 10.1038/s41598-020-59436-y

Note: The above post is reprinted from materials provided by Smithsonian Tropical Research Institute.

Vellbergia bartholomaei : Tiny prehistoric lizard sheds light on reptile evolution

lizard
Representative Image : Lizard

The discovery of a new species of prehistoric reptile from Germany is reported this week in Scientific Reports. The anatomical features of the species, named Vellbergia bartholomaei, add to our understanding of the early evolution of lepidosauromorphs.

Lepidosauromorphs are one of the largest and most diverse tetrapod lineages with over 10,500 species. Ancestors to modern-day lizards, snakes and reptiles known as tuataras, lepidosauromorph specimens have only been found across a few Triassic sites and their early evolution remains largely unknown.

Gabriela Sobral and colleagues discovered the small fossil within the Middle Triassic (247 to 237 million-year-old) deposits of Vellberg, Germany. Analyses suggest that the specimen is a previously unknown species of early lepidosauromorph. One of the smallest found at the site, it could represent the first juvenile fossil collected at Vellberg. V. bartholomaei differs from other lepidosauromorph species owing to its distinct characteristics, including narrow, slender and short teeth relative to the lower jaw, but shares a mosaic of features found in the predecessors of present-day lizards and tuataras. The findings, which suggest that Vellbergia may be a common ancestor of the two lineages, further our understanding of early reptile evolution.

The fossil adds to evidence implicating Vellberg as an important site for understanding early lepidosauromorph evolution. Owing to the poor fossil record for the Early Triassic period, specimens from the Middle Triassic are of fundamental importance to understanding how vertebrates recovered after the Permian–Triassic mass extinction (around 252 million years ago), the Earth’s most severe known extinction event, and how they diversified into modern species.

Reference:
A tiny new Middle Triassic stem-lepidosauromorph from Germany: implications for the early evolution of lepidosauromorphs and the Vellberg fauna, Scientific Reports (2020). DOI: 10.1038/s41598-020-58883-x

Note: The above post is reprinted from materials provided by Nature Publishing Group .

Egoria malashichevi : Palaeontologists identify new Jurassic amphibian

A group of Russian and German palaeontologists have described a previously unknown genus and species of prehistoric salamanders. The new amphibian is named Egoria malashichevi -- in honor of Yegor Malashichev a talented scientist and associate professor of the Department of Vertebrate Zoology at St Petersburg University, who passed away at the end of 2018. Credit: Pavel Skutschas
A group of Russian and German palaeontologists have described a previously unknown genus and species of prehistoric salamanders. The new amphibian is named Egoria malashichevi — in honor of Yegor Malashichev a talented scientist and associate professor of the Department of Vertebrate Zoology at St Petersburg University, who passed away at the end of 2018. Credit: Pavel Skutschas

A group of Russian and German palaeontologists have described a previously unknown genus and species of prehistoric salamanders. The new amphibian is named Egoria malashichevi—in honor of Yegor Malashichev a talented scientist and associate professor of the Department of Vertebrate Zoology at St Petersburg University, who passed away at the end of 2018.

The palaeontologists found the remains of the ancient amphibian at the Berezovsky quarry, a fossil locality in the Krasnoyarsk Krai near the town of Sharypovo. Fossils of ancient fish, various reptiles, mammals, herbivorous and predatory dinosaurs have been previously found there. The research materials were collected on field expeditions in the mid-2010s. In these expeditions the scientists from St Petersburg University worked alongside experts from the University of Bonn (Germany), the Tomsk State University, the Zoological Institute of the Russian Academy of Sciences, and the Sharypovo Museum of Local History and Nature.

Four vertebrate fossils enabled the scientists to declare the finding of a new genus and species. These were: three trunk vertebrae and the atlas—the first and, in the case of the salamander, the only cervical vertebra. Since the atlas is a highly specialised vertebra, providing for attachment and rotation movements of the skull, it has a rather complex structure, the scientists explain. It is therefore most suitable for describing a new species as it provides much information for analysis. The amphibian proved to have belonged to the geologically oldest stem salamanders.

It was not the first time that remains of ancient salamanders had been found at the Berezovsky quarry. One of them—a basal stem salamander Urupia monstrosa, named after the nearby Uryup River—was about 50-60 centimetres long. Another one—Kiyatriton krasnolutskii—was named after a local historian Sergei Krasnolutskii, the discoverer of the fossil locality Berezovsky quarry. By contrast, this one was quite small in size (about 10-15 centimetres) and looked more like modern Hynobiidae. The newly discovered salamander, judging by the size of the vertebrae, was of medium length (about 20 centimetres).

“Salamanders first appear in the fossil records in the Middle Jurassic, including representatives of both the present-day salamander families and the most primitive ones,” said Pavel Skutschas, associate professor of St Petersburg University, doctor of biology, expert in Mesozoic vertebrates. “When they had just appeared, salamanders made efforts to occupy different ecological niches. Thus, the stem salamanders filled the niche of large water bodies; while those close to the present-day salamanders found their niche in small water bodies. As for the newly discovered salamander, it occupied a middle position, although morphologically, it is closer to the primitive.”

The scientists not only described the external characteristics of the specimens, but were able to look inside the fossils. In this they were assisted by the experts from the “Centre of X-ray diffraction studies’ at the Research Park of St Petersburg University, where the specimens were scanned on up-to-date microtomography scanners. Based on the obtained data, the palaeontologists created 3-D reconstructions of the vertebrae and described their internal structure. As expected, it proved to be very similar to that of the large stem salamanders.

The ancient amphibian received the name Egoria malashichevi—in honour of Yegor Malashichev, associate professor of the Department of Vertebrate Zoology at St Petersburg University, who, among other things, studied the morphology of caudate amphibians. “Yegor Malashichev was a wonderful person and a very talented scientist. He supported aspiring palaeontologists and did everything to help them to stay in scientific research,” remarked Pavel Skutschas. Additionally, Malashichev studied the phenomenon of lateralisation (body asymmetries associated with the functioning of the nervous system), as well as other asymmetries in motor performance and visual perception. Yegor Malashichev’s professional career was almost exclusively connected with St Petersburg University. In 1996, he graduated from the Faculty of Biology and Soil Science. In 2000, he began to teach there, and in 2003, he defended his dissertation and was awarded a Ph.D. in biology. Sadly, in late 2018, he passed away unexpectedly.

The next step for the palaeontologists is to compare the bones of the ‘Berezovsky’ salamanders with the fossils from Great Britain: the ‘Kirtlington’ salamanders which were found at the Kirtlington quarry in Oxfordshire. The Siberian and British faunas of the mid-Jurassic time were very similar. Besides, the palaeontologists are aware of similar amphibians that lived in the territory of present-day England. “They may be representatives of the same genera. However, to ascertain this, a detailed comparison of the palaeontological collections is required. In the coming spring, our colleagues from England will come to St Petersburg to study our research materials. We may discover that Urupia and Egoria used to have a very wide habitat, extending across Europe and Asia,” said Pavel Skutschas.

Reference:
A new small-sized stem salamander from the Middle Jurassic of Western Siberia, Russia. DOI: 10.1371/journal.pone.0228610

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

Fish in the Sahara? Yes, in the early Holocene

View of Takarkori shelter from the west. Credit: Savino di Lernia, 2020
View of Takarkori shelter from the west. Credit: Savino di Lernia, 2020

Catfish and tilapia make up many of the animal remains uncovered in the Saharan environment of the Takarkori rock shelter in southwestern Libya, according to a study published February 19, 2020 in the open-access journal PLOS ONE by Wim Van Neer from the the Natural History Museum in Belgium, Belgium and Savino di Lernia, Sapienza University of Rome, Italy, and colleagues.

Today, the Saharan Tadrart Acacus mountains are windy, hot, and hyperarid; however, the fossil record shows that for much of the early and middle Holocene (10,200 to 4650 years BP), this region was humid and rich in water as well as life, with evidence of multiple human settlements and diverse fauna.

Rock shelters within the Tadrart Acacus preserve not only significant floral and faunal remains, but also significant cultural artifacts and rock art due to early Holocene occupation of these shelters. In this study, the authors worked with the Libyan Department of Antiquities in excavating parts of the Takarkori rock shelter to identify and date animal remains found at this site and investigate shifts in the abundance and type of these animal remains over time.

Fish remains made up almost 80 percent of the entire find overall, which numbered 17,551 faunal remains total (19 percent of these were mammal remains, with bird, reptile, mollusc, and amphibian remains the last 1.3 percent). All of the fish and most of the other remains were determined to be human food refuse, due to cut marks and traces of burning—the two fish genera at Takarkori were identified as catfish and tilapia.

Based on the relative dates for these remains, the amount of fish decreased over time (from 90 percent of all remains 10,200-8000 years BP versus only 40 percent of all remains 5900-4650 years BP) as the number of mammal remains increased, suggesting the inhabitants of Takarkori gradually focused more on hunting/livestock. The authors also found the proportion of tilapia specifically decreased more significantly over time, which may have been because catfish have accessory breathing organs allowing them to breathe air and survive in shallow, high-temperature waters—further evidence that this now-desert environment became less favorable to fish as the aridity increased.

The authors add: “This study reveals the ancient hydrographic network of the Sahara and its interconnection with the Nile, providing crucial information on the dramatic climate changes that led to the formation of the largest hot desert in the world. Takarkori rock shelter has once again proved to be a real treasure for African archaeology and beyond: a fundamental place to reconstruct the complex dynamics between ancient human groups and their environment in a changing climate.”

Reference:
Van Neer W, Alhaique F, Wouters W, Dierickx K, Gala M, Goffette Q, et al. (2020) Aquatic fauna from the Takarkori rock shelter reveals the Holocene central Saharan climate and palaeohydrography. PLoS ONE 15(2): e0228588. doi.org/10.1371/journal.pone.0228588

Note: The above post is reprinted from materials provided by Public Library of Science.

New pieces of evidence found in the Alborán Sea possibly related to the megaflood that refilled the Mediterranean 5.3 million years ago

Isobath map of the eastern Alborán basin with the volcanic edifice location. Orange lines show the main flood paths. (Image: García-Castellanos et al, 2020, Earth-Sciences Reviews)
Isobath map of the eastern Alborán basin with the volcanic edifice location. Orange lines show the main flood paths. (Image: García-Castellanos et al, 2020, Earth-Sciences Reviews)

Under the waters of the eastern Alborán Sea and buried at the shadow of an old volcanic edifice lies a body of sediments that may have been originated by a massive flood that refilled a partially desiccated Mediterranean 5.3 million years ago. This mass of sediments, seen in seismic reflection profiles, represents new possible megaflood deposit of the so-called Zanclean flood, according to a new article published in “Earth-Science Reviews” journal.

This review study summarises the latest stratigraphic pieces of evidence published suporting the Zanclean flood hypothesis. Zanclean flood is an event proposed for the termination of the Messinian Salinity Crisis, during which the Mediterranean Sea underwent a period of isolation from the Atlantic Ocean evolving into giant saline sea about 6 million years ago.

“The identified sediments are compatible with a megaflood event refilling the Mediterranean Sea through the Strait of Gibraltar. It’s an enlarged body deposited in the protected area at the lee side of a submarine volcano”, said Daniel García-Castellanos, researcher at Institute of Earth Sciences Jaume Almera of the Spanish Scientific Research Council (ICTJA-CISC) and leading author of the study.

According to the research, the newly identified deposits form an elongated body up to 163 m thick, 35 km long and 7 km wide. The identification of these deposits is based on seismic reflection profiles of the sea subsurface of the eastern Alborán basin. This deposit is parallel to the main flood erosive channel which was identified in 2009 in the Alborán basin.

This erosive channel extends along 390 km from the Gulf of Cadiz (Atlantic Ocean) until the Algerian Basin, through the Strait of Gibraltar and crossing the deepest parts of the Alboran Sea. An outburst flood erosion may have eroded the channel due to the breaching of the Strait of Gibraltar once the connection between the Atlantic Ocean and the Mediterranean Sea was restored about 5,3 million years ago.

Once the massive inflow of water entered in the Alboran basin, the channel split into two branches to overcome the topographic obstacles in its path. The volcanic edifice may have been one of these topographic obstacles during the flood leading to the deposition of the recently identified sediments along the seamount lee side.
Other pieces of evidence in the Eastern Mediterranean:

These sediments identified in the Alborán Sea can be added to the rest of evidence found and published in recent years that support the hypothesis of a massive flood and are summarised in the present article.

The Noto Canyon, in the northern Malta Escarpment, and a body of sediments of up to 860 m in thickness buried at the east of this canyon are two of the other pieces of evidence proposed in this article that may sustain the megaflood hypothesis. Both parts of evidence were analysed in a previous study published in Scientific Reports in 2018.

However, and despite all summarised pieces of evidence, Daniel García-Castellanos is cautious. “Ten years after publishing the first observations that were related with the Zanclean flood we are still finding new evidences to sustain it, but they are not conclusive. All of the evidences that have been summarised in this article may have other possible interpretations and, before convincing the scientific community it will be necessary to have other studies that consider the hypothesis from other angles”, said García-Castellanos.

Researchers from the University of Malta, the Helmholtz Centre for Ocean Research (GEOMAR), the Instituto de Ciencias del Mar (ICM-CSIC), IstitutoNazionale di oceanografia e di geofisicaSperimentale (OGS) and the University of Sevilla also participated in the study.

Reference:
Garcia-Castellanos, D., Micallef, A., Estrada, F., Camerlenghi, A., Ercilla, G., Periáñez, R., & Abril, J. M. (2020). The Zancleanmegaflood of the Mediterranean – Searching for independent evidence.Earth-Science Reviews, 201, 103061. https://doi.org/10.1016/j.earscirev.2019.103061

Note: The above post is reprinted from materials provided by Institue of Earth Sciences Jaume Almera(ICTJA-CSIC).

Oldest known record of amphibian tracks in the UK

NHMUK PV R 9372, Palaeosauropus sp., (a) colour photograph of the original sandstone slab and tracks, (b) 3D digital render of the plaster cast of the sandstone slab and tracks and (c) black and white photograph of the original sandstone slab and tracks. In (b), left manus and pes prints are denoted a and b respectively, the right pes prints c and e, with print d being the right manus. The indented area left of print e is identified as damage to the specimen rather than a footprint impression.
NHMUK PV R 9372, Palaeosauropus sp., (a) colour photograph of the original sandstone slab and tracks, (b) 3D digital render of the plaster cast of the sandstone slab and tracks and (c) black and white photograph of the original sandstone slab and tracks. In (b), left manus and pes prints are denoted a and b respectively, the right pes prints c and e, with print d being the right manus. The indented area left of print e is identified as damage to the specimen rather than a footprint impression.

A new paper has revealed an ancient trackway, found imprinted on a block of sandstone from the base of Hardraw Force Waterfall in Wensleydale, North Yorkshire, is the oldest record of amphibian tracks in the UK dating back 340 million years.

The trace fossil, currently on display at the Natural History Museum, was 3-D scanned in order to visualise it in further detail as part of a research project by a previous undergraduate student from the University of Birmingham, Hannah Bird. The tracks belong to the earliest relatives of modern amphibians called temnospondyls, specifically the edopoids, or “glutton-faced animals.”

Hannah Bird elaborated: “We used scanning and photography to make a 3-D digital model, allowing us to better visualise and identify the footprints and invertebrate traces. Determining whether individual prints were made by hands or feet, as well as the direction of movement, certainly proved troublesome at times but we were finally able to reconstruct how this amphibian might have moved in life.”

Edopoids were crocodile-like animals, at least two metres in length. It was revealed that the edopoid walked across the sandy bed of river delta along with contemporary invertebrate animals including arthropods, worms and molluscs.

The study has presented a rare insight into the early Carboniferous period and tetrapod diversification in the United Kingdom as well as how temnospondyls spread across Euramerica.

Scientific Associate of the Natural History Museum Angela Milner said: “Although this specimen has been in the Natural History Museum’s collection for a long time, modern 3-D scanning techniques have revealed a wealth of detail that was almost impossible to see on the original tracks.”

Abstract

The ichnological fossil record has previously provided key evidence for the diversification of land vertebrates (tetrapods) during the Carboniferous Period, following the invasion of the land. Within the UK, tetrapod ichnofossils from the late Carboniferous of the English Midlands are well documented, but few such fossils are known from earlier in the period. We present a rare ichnological insight into early Carboniferous tetrapod diversification in the United Kingdom based on a Visean-aged specimen collected from an interdistributary trough palaeoenvironment at Hardraw Scar, Wensleydale, North Yorkshire. This specimen represents the stratigraphically oldest known tetrapod trackway from the UK. We refer this specimen to Palaeosauropus sp., providing the earliest known occurrence of an edopoid temnospondyl. Supplementing the sparse record of contemporary body fossils from the early Carboniferous, this provides further insights into the diversification of temnospondyl amphibians across Euramerica.

Refrence:
Hannah C. Bird et al. A lower Carboniferous (Visean) tetrapod trackway represents the earliest record of an edopoid amphibian from the UK, Journal of the Geological Society (2019). DOI: 10.1144/jgs2019-149

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

Fossilized insect from 100 million years ago is oldest record of primitive bee with pollen

100-million-year-old Discoscapa apicula. The bee is carrying four beetle triungulins. Credit: George Poinar Jr., OSU College of Science.
100-million-year-old Discoscapa apicula. The bee is carrying four beetle triungulins. Credit: George Poinar Jr., OSU College of Science.

Beetle parasites clinging to a primitive bee 100 million years ago may have caused the flight error that, while deadly for the insect, is a boon for science today.

The female bee, which became stuck in tree resin and thus preserved in amber, has been identified by Oregon State University researcher George Poinar Jr. as a new family, genus and species.

The mid-Cretaceous fossil from Myanmar provides the first record of a primitive bee with pollen and also the first record of the beetle parasites, which continue to show up on modern bees today.

The findings, published in BioOne Complete, shed new light on the early days of bees, a key component in evolutionary history and the diversification of flowering plants.

Insect pollinators aid the reproduction of flowering plants around the globe and are also ecologically critical as promoters of biodiversity. Bees are the standard bearer because they’re usually present in the greatest numbers and because they’re the only pollinator group that feeds exclusively on nectar and pollen throughout their life cycle.

Bees evolved from apoid wasps, which are carnivores. Not much is known, however, about the changes wasps underwent as they made that dietary transition.

Poinar, professor emeritus in the OSU College of Science and an international expert in using plant and animal life forms preserved in amber to learn more about the biology and ecology of the distant past, classified the new find as Discoscapa apicula, in the family Discoscapidae.

The fossilized bee shares traits with modern bees — including plumose hairs, a rounded pronotal lobe, and a pair of spurs on the hind tibia — and also those of apoid wasps, such as very low-placed antennal sockets and certain wing-vein features.

“Something unique about the new family that’s not found on any extant or extinct lineage of apoid wasps or bees is a bifurcated scape,” Poinar said, referring to a two-segment antennae base. “The fossil record of bees is pretty vast, but most are from the last 65 million years and look a lot like modern bees. Fossils like the one in this study can tell us about the changes certain wasp lineages underwent as they became palynivores — pollen eaters.”

Numerous pollen grains on Discoscapa apicula show the bee had recently been to one or more flowers.

“Additional evidence that the fossil bee had visited flowers are the 21 beetle triungulins — larvae — in the same piece of amber that were hitching a ride back to the bee’s nest to dine on bee larvae and their provisions, food left by the female,” Poinar said. “It is certainly possible that the large number of triungulins caused the bee to accidently fly into the resin.”

Reference:
George Poinar. Discoscapidae fam. nov. (Hymenoptera: Apoidea), a new family of stem lineage bees with associated beetle triungulins in mid-Cretaceous Burmese amber. Palaeodiversity, 2020; 12 (1): 1 DOI: 10.18476/pale.v13.a1

Note: The above post is reprinted from materials provided by Oregon State University. Original written by Steve Lundeberg.

Argentine researchers find distant Tyrannosaurus relative

The new dinosaur is called Tralkasaurus, which means "thunder reptile" in the indigenous Mapuche language common in Patagonia. In this file photo, a boy in Melbourne, Australia inspects the teeth of a theropod dinosaur
The new dinosaur is called Tralkasaurus, which means “thunder reptile” in the indigenous Mapuche language common in Patagonia. In this file photo, a boy in Melbourne, Australia inspects the teeth of a theropod dinosaur

The remains of a 90-million-year-old carnivorous dinosaur distantly related to Tyrannosaurus rex has been discovered in Argentine Patagonia by a team of paleontologists.

The four-meter-long (13-foot-long) theropod was discovered in February 2018 in the central Argentine province of Rio Negro.

Scientists have christened it Tralkasaurus cuyi, the National University of La Matanza’s Scientific Disclosure Agency said on Thursday.

Tralkasaurus means “thunder reptile” in the indigenous Mapuche language common in Patagonia. Cuyi relates to the place the fossil remains were found, El Cuy.

Tralkasaurus would have been dwarfed by its distant cousin Tyrannosaurus rex which could grow to 14 meters in length.

“The size of the Tralkasaurus body is smaller than other carnivores in its group—the abelisaurids,” said Dr Federico Agnolin, an investigator from the Argentine Museum of Natural Sciences.

Other abelisaurids usually measured seven to 11 meters.

This “demonstrates that the group of abelisaurid theropods encompassed a much wider ecological niche than we thought,” said Mauricio Cerroni, another researcher.

The team found a skull, teeth, ribs and part of the hip and tail.

Just like Tyrannosaurus, it was a short-necked and muscular biped with four claws on each of its hind legs, and arms that were very short in comparison to the rest of its body. The bones of its extremities were light and hollow.

“This new discovery helps us to define the ecological habits of carnivorous dinosaurs as well as herbivores,” said Cerroni.

According to the researchers, Tralkasaurus possibly fed on small herbivore dinosaurs called iguanodonts that have been found nearby by the same team of researchers.

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

5,200-year-old grains in the eastern Altai Mountains redate trans-Eurasian crop exchange

A photo of the stone men (Chimulchek Culture) in the steppe area of Altai Mountains. These figures are characteristic of the peoples who lived in the area around the time of occupation at Tongtian. These specific examples are located at the Chimulchek site (ca. 4000 years old) and not far from Tongtian Cave. Ceramic sherds from the cave suggest that the occupants in the cave shared similar cultural traits to other people in the region. Credit: Jianjun Yu
A photo of the stone men (Chimulchek Culture) in the steppe area of Altai Mountains. These figures are characteristic of the peoples who lived in the area around the time of occupation at Tongtian. These specific examples are located at the Chimulchek site (ca. 4000 years old) and not far from Tongtian Cave. Ceramic sherds from the cave suggest that the occupants in the cave shared similar cultural traits to other people in the region. Credit: Jianjun Yu

Most people are familiar with the historical Silk Road, but fewer people realize that the exchange of items, ideas, technology, and human genes through the mountain valleys of Central Asia started almost three millennia before organized trade networks formed. These pre-Silk Road exchange routes played an important role in shaping human cultural developments across Europe and Asia, and facilitated the dispersal of technologies such as horse breeding and metal smelting into East Asia. One of the most impactful effects of this process of ancient cultural dispersal was the westward spread of northeast Asian crops and the eastward spread of southwest Asian crops. However, until the past few years, a lack of archaeobotanical studies in Central Asia left a dearth of data relating to when and how this process occurred.

This new study, led by scientists from the Chinese Academy of Sciences and the Max Planck Institute for the Science of Human History, provides details of recently recovered ancient grains from the far northern regions of Inner Asia. Radiocarbon dating shows that the grains include the oldest examples of wheat and barley ever recovered this far north in Asia, pushing back the dates for early farming in the region by at least a millenium. These are also the earliest domesticated plants reported from the northern half of Central Asia, the core of the ancient exchange corridor. This study pulls together sedimentary pollen and ancient wood charcoal data with archaeobotanical remains from the Tiangtian archaeological site in the Chinese Altai Mountains to reveal how humans cultivated crops at such northern latitudes. This study illustrates how adaptable ancient crop plants were to new ecological constraints and how human cultural practices allowed people to survive in unpredictable environments.

The Northern Dispersal of Cereal Grains

The ancient relatives of wheat and barley plants evolved to grow in the warm and dry climate of the eastern Mediterranean and southwest Asia. However, this study illustrates that ancient peoples were cultivating these grasses over five and a half thousand kilometers to the northeast of where they originally evolved to grow. In this study, Dr. Xinying Zhou and his colleagues integrate paleoenvironmental proxies to determine how extreme the ecology was around the archaeological cave site of Tangtian more than five millennia ago, at the time of its occupation. The site is located high in the Altai Mountains on a cold,dry landscape today; however, the study shows that the ecological setting around the site was slightly warmer and more humid at the time when people lived in and around this cave.

The slightly warmer regional conditions were likely the result of shifting air masses bringing warmer, wetter air from the south. In addition to early farmers using a specific regional climate pocket to grow crops in North Asia, analysis showed that the crops they grew evolved to survive in such northern regions. The results of this study provide scholars with evidence for when certain evolutionary changes in these grasses occurred, including changes in the programed reliance of day length, which signals to the plant when to flower, and a greater resistance to cold climates.

The Trans-Eurasian Exchange and Crop Dispersal

The ancient dispersal of crops across Inner Asia has received a lot of attention from biologists and archaeologists in recent years; as Dr. Spengler, one of the study’s lead authors, discusses in his recent book Fruit from the Sands, these ancient exchange routes shaped the course of human history. The mingling of crops originating from opposite ends of Asia resulted in the crop-rotation cycles that fueled demographic growth and led to imperial formation. East Asian millets would become one of the most important crops in ancient Europe and wheat would become one of the most important crops in East Asia by the Han Dynasty. While the long tradition of rice cultivation in East Asia made rice a staple of the Asian kitchen, Chinese cuisine would be unrecognizable without wheat-based food items like steamed buns, dumplings, and noodles. The discovery that these plants dispersed across Eurasia earlier than previously understood will have lasting impacts on the study of cultivation and labor practices in ancient Eurasia, as well as the history cultural contact and shifts in culinary systems throughout time.

These new discoveries provide reason to question these views, and seem to suggest that mixed small-scale human populations made major contributions to world history through migration and cultural and technological exchange. “This study not only presents the earliest dates for domesticated grains in far North Asia,” says Professor Xiaoqiang Li, director of the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, “it represents the earliest beginning of a trans-Eurasian exchange that would eventually develop into the great Silk Road.”

Dr. Xinying Zhou, who headed the study and directs a research team at the IVPP in Beijing, emphasizes that “this discovery is a testament to human ingenuity and the amazing coevolutionary bond between people and the plants that they maintain in their cultivated fields.”

Reference:
Xinying Zhou, Jianjun Yu, Robert Nicholas Spengler, Hui Shen, Keliang Zhao, Junyi Ge, Yige Bao, Junchi Liu, Qingjiang Yang, Guanhan Chen, Peter Weiming Jia, Xiaoqiang Li. 5,200-year-old cereal grains from the eastern Altai Mountains redate the trans-Eurasian crop exchange. Nature Plants, 2020; DOI: 10.1038/s41477-019-0581-y

Note: The above post is reprinted from materials provided by Max Planck Institute for the Science of Human History.

Boom and bust for ancient sea dragons

This very complete specimen of the ichthyosaur Suevoleviathan is from the Early Jurassic of Germany. Many excellently preserved ichthyosaur fossils are known from this time and have been collected from the UK and Germany. Mary Anning from Lyme Regis is intimately associated with fossil collection and found the first recognized ichthyosaur fossils in 1810. Credit: Dr Ben Moon & Dr Tom Stubbs
This very complete specimen of the ichthyosaur Suevoleviathan is from the Early Jurassic of Germany. Many excellently preserved ichthyosaur fossils are known from this time and have been collected from the UK and Germany. Mary Anning from Lyme Regis is intimately associated with fossil collection and found the first recognized ichthyosaur fossils in 1810. Credit: Dr Ben Moon & Dr Tom Stubbs

Ichthyosaurs were fish-like reptiles that first appeared about 250 million years ago and quickly diversified into highly capable swimmers, filling a broad range of sizes and ecologies in the early Mesozoic oceans. However, this rapid pace didn’t last long and an evolutionary bottleneck 200 million years ago, through which only one lineage of ichthyosaurs survived, led to much slower evolution in much of their long history.

Dr Ben Moon, who led the research, published in the journal Communications Biology, said: “Ichthyosaurs are a fascinating group of animals to work on because they evolved so many adaptations for living in water very quickly: a fish-like body and tail fin, giving birth to live young rather than laying eggs, and lots of different feeding styles.

“Because of this we expected to see a rapid evolution early after ichthyosaurs first appeared, but we were staggered by just how big this early burst was and how relatively short it was.”

There are over 100 known species of ichthyosaur from between 250-90 million years ago in the Mesozoic Era, when the infamous dinosaurs ruled the land and the seas were full of marine reptiles, the top predators that filled comparable roles to dolphins, orcas, and sharks in modern seas.

The study used state-of-the-art computational methods and looked at two types of data, one covering skull size and the other including many features of ichthyosaurs’ skeleton. All methods show an ‘early burst’ of evolution in ichthyosaurs, with high rates and rapid variation soon after the appearance of the group, that quickly diminishes later on.

Co-author Dr Tom Stubbs said: “Ichthyosaurs really dominated early in the Triassic (252-201 million years ago), rapidly evolving in an ocean with few predators soon after the largest known mass extinction in Earth’s history. However, the seas quickly became more crowded and competitive, and ichthyosaurs lost their top position in the Jurassic (201-145 million years ago) to other marine reptiles like plesiosaurs and pliosaurs.

“It may well have been the ichthyosaurs’ decreasing evolutionary rates which made them less able to adapt quickly, and therefore less diverse and competitive, allowing other marine reptiles to take over as the top predators.”

Despite slower evolution and going through a bottleneck at the end of the Triassic period, ichthyosaurs remained a common group but had less variation between them. These are perhaps best known ichthyosaurs, found in several UK locations, including Lyme Regis in Dorset, and first collected by Mary and Joseph Anning.

Dr Ben Moon added: “Even though ichthyosaurs were evolving more slowly in their last 100 million years, they are still known from many species, but with less variety between them.

“It’s possible that we might find more ichthyosaurs out there that buck this trend, but it seems that this lack of variety was eventually the cause of their extinction when global conditions became less favourable around 90 million years ago. Ichthyosaurs were simply unable to adapt.”

Reference:
Benjamin C. Moon, Thomas L. Stubbs. Early high rates and disparity in the evolution of ichthyosaurs. Communications Biology, 2020; 3 (1) DOI: 10.1038/s42003-020-0779-6

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

Extinct giant turtle had horned shell of up to three meters

A graphic reconstruction of the giant turtle Stupendemys geographicus: male (front) and female individual (left) swimming in freshwater. Credit: Artwork: Jaime Chirinos
A graphic reconstruction of the giant turtle Stupendemys geographicus: male (front) and female individual (left) swimming in freshwater. Credit: Artwork: Jaime Chirinos

The tropical region of South America is one of the world’s hot spots when it comes to animal diversity. The region’s extinct fauna is unique, as documented by fossils of giant rodents and crocodylians -including crocodiles, alligators, caimans and gavials — that inhabited what is today a desert area in Venezuela. Five to ten million years ago, this was a humid swampy region teeming with life. One of its inhabitants was Stupendemys geographicus, a turtle species first described in the mid-1970s.

Giant turtle 100 times heavier than its closest relative

Researchers of the University of Zurich (UZH) and fellow researchers from Colombia, Venezuela, and Brazil have now reported exceptional specimens of the extinct turtle recently found in new locations across Venezuela and Colombia. “The carapace of some Stupendemys individuals reached almost three meters, making it one of the largest, if not the largest turtle that ever existed,” says Marcelo Sánchez, director of the Paleontological Institute and Museum of UZH and head of the study. The turtle had an estimated body mass of 1,145 kg — almost one hundred times that of its closest living relative, the big-headed Amazon river turtle.

Males carried horns on their carapace

In some individuals, the complete carapace showed a peculiar and unexpected feature: horns. “The two shell types indicate that two sexes of Stupendemys existed — males with horned shells, and females with hornless shells,” concludes Sánchez. According to the paleobiologist, this is the first time that sexual dimorphism in the form of horned shells has been reported for any of the side-necked turtles, one of the two major groups of turtles world-wide.

Despite its tremendous size, the turtle had natural enemies. In many areas, the occurrence of Stupendemys coincides with Purussaurus, the largest caimans. This was most likely a predator of the giant turtle, given not only its size and dietary preferences, but also as inferred by bite marks and punctured bones in fossil carapaces of Stupendemys.

Turtle phylogeny thoroughly revised

Since the scientists also discovered jaws and other skeleton parts of Stupendemys, they were able to thoroughly revise the evolutionary relationships of this species within the turtle tree of life. “Based on studies of the turtle anatomy, we now know that some living turtles from the Amazon region are the closest living relatives,” says Sánchez. Furthermore, the new discoveries and the investigation of existing fossils from Brazil, Colombia and Venezuela indicate a much wider geographic distribution of Stupendemys than previously assumed. The animal lived across the whole of the northern part of South America.

Reference:
E-A. Cadena, T. M. Scheyer, J. D. Carrillo-Briceño, R. Sánchez, O. A Aguilera-Socorro, A. Vanegas, M. Pardo, D. M. Hansen, M. R. Sánchez-Villagra. The anatomy, paleobiology and evolutionary relationships of the largest side-necked extinct turtle. Science Advances, 2020 DOI: 10.1126/sciadv.aay4593

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

Heat transport property at the lowermost part of the Earth’s mantle

Calculated lattice thermal conductivity of MgSiO3 postperovskite (PPv) and bridgmanite (Brg) under the Earth’s lowermost mantle conditions. Credit: Ehime University
Calculated lattice thermal conductivity of MgSiO3 postperovskite (PPv) and bridgmanite (Brg) under the Earth’s lowermost mantle conditions. Credit: Ehime University

Lattice thermal conductivities of MgSiO3 bridgmanite and postperovskite (PPv) phases under the Earth’s deepest mantle conditions have been determined by quantum mechanical computer simulations. Researchers at Ehime University found a substantial increase in the conductivity associated with the phase change. This indicates that the PPv phase boundary is the boundary not only of the mineralogy but also the thermal conductivity. The effect of anisotropy on the conductivity of PPv in the heat transport properties at the lowermost mantle was also found to be minor.

Heat transport in the deep Earth controls its thermal evolution. Determination of the thermal conductivity of the lower mantle is one of the central issues for a better understanding of deep Earth phenomena, such as the style of mantle convection, the evolution of the magnetic field, and inner core growth. However, it is poorly understood because deep mantle pressure and temperature conditions are quite difficult to replicate in laboratory experiments. In the new study, the researchers determined the thermal conductivity of MgSiO3 postperovskite, the most abundant mineral at the bottom of the mantle, which is transformed from MgSiO3 bridgmanite,under the lowermost mantle conditions based on quantum mechanical computations without any empirical parameters.

The scientists found a jump in the thermal conductivity associated with the phase transition, indicating that the postperovskite phase boundary is the boundary not only of the mineralogy but also the thermal conductivity (Figure 1). The phase change produces larger lateral variation in heat flux across the core-mantle boundary (CMB). Also, they examined the effects of anisotropy on the thermal conductivity of the CMB heat flux and found that it to be minor with the crystal orientation of postperovskite. This may explain how seismic anisotropy observed at the base of the mantle is developed.

Reference:
Haruhiko Dekura et al. Lattice Thermal Conductivity of MgSiO 3 Postperovskite Under the Lowermost Mantle Conditions From Ab Initio Anharmonic Lattice Dynamics, Geophysical Research Letters (2019). DOI: 10.1029/2019GL085273

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

As groundwater depletes, arid American West is moving east

Horseshoe Bend, Arizona
Horseshoe Bend, Arizona

Even under modest climate warming scenarios, the continental United States faces a significant loss of groundwater — about 119 million cubic meters, or roughly enough to fill Lake Powell four times or one quarter of Lake Erie, a first-of-its-kind study has shown.

The results, published today in Nature Communications, show that as warming temperatures shift the balance between water supply and demand, shallow groundwater storage can buffer plant water stress — but only where shallow groundwater connections are present, and not indefinitely. As warming persists, that storage can be depleted — at the expense of vital connections between surface water, such as rivers, streams and water reservoirs underground.

“Even with a 1.5 degrees Celsius warming case, we’re likely to lose a lot of groundwater,” said Reed Maxwell, professor of hydrology at the Colorado School of Mines, who co-authored the paper with Laura Condon of the University of Arizona and Adam Atchley of Los Alamos National Laboratory. “The East Coast could start looking like the West Coast from a water standpoint. That’s going to be a real challenge.”

Most global circulation models don’t take into account the lateral movement of water in the subsurface. Typically, they only include limited up-and-down movement, such as rain percolating from vegetation into the soil and roots pulling up water from the ground. In addition, these models tend to limit their scope to mere meters above or below ground.

This new study goes beyond that to simulate how water moves in the subsurface and connects with the land surface.

“We asked what would the response look like if we included the entire complexity of subsurface water movement in a large-scale simulation, and we think this is the first time this has been done,” said Condon, lead author of the paper and assistant professor of hydrology and atmospheric sciences at the University of Arizona.

The calculations revealed a direct response of shallow groundwater storage to warming that demonstrates the strong and early effect that even low to moderate warming may have on groundwater storage and evapotranspiration.

In the western U.S., changes in groundwater storage may remain masked for a long time, the study revealed, because the groundwater there is already deep, and dropping levels would not have as great an effect on surface waters. Additionally, the region’s vegetation is already largely water limited and adapted to being disconnected from deep groundwater sources.

However, the eastern U.S. will be much more sensitive to a lowering of the water table. Groundwater and surface water are more closely linked, and depleting the groundwater will be more disruptive to vegetation, streams and rivers. Many of the systems that have been put in place in the western U.S. for handling and managing water shortage are lacking in the eastern part of the country, as well.

The study revealed that regions in the eastern U.S. may reach a tipping point sooner rather than later, when vegetation starts to lose access to shallow groundwater as storage is depleted with warming.

“Initially, plants might not be experiencing stress because they still have existing shallow groundwater available, but as we continue to have warmer conditions, they can compensate less and less, and changes are more dramatic each year,” Condon said. “In other words, shallow groundwater is buffering the response to warming, but when it’s depleted, it can’t do that anymore.”

The study’s simulations were set up to keep precipitation patterns the same and only increase atmospheric temperatures according to projections ranging from 1.5 to 4 degrees Celsius. Even with a modest 1.5 degrees Celsius of warming, 119 million cubic meters of storage were lost from groundwater — or four times the volume of Lake Powell, the largest reservoir in the Upper Colorado basin. At 4 degrees Celsius, groundwater losses were projected at 324 million cubic meters — roughly 10 times the volume of Lake Powell or enough to fill nearly three-quarters of Lake Erie.

“We are facing a crisis in global groundwater storage,” Condon said. “Huge groundwater reservoirs are drying up at an alarming rate, and that’s a problem because they nourish major growing regions around the world.”

Reference:
Laura E. Condon, Adam L. Atchley, Reed M. Maxwell. Evapotranspiration depletes groundwater under warming over the contiguous United States. Nature Communications, 2020; 11 (1) DOI: 10.1038/s41467-020-14688-0

Note: The above post is reprinted from materials provided by University of Arizona. Original written by Daniel Stolte.

NASA flights detect millions of Arctic methane hotspots

The image shows a thermokarst lake in Alaska. Thermokarst lakes form in the Arctic when permafrost thaws. Credit: NASA/JPL-Caltech
The image shows a thermokarst lake in Alaska. Thermokarst lakes form in the Arctic when permafrost thaws. Credit: NASA/JPL-Caltech

Knowing where emissions are happening and what’s causing them brings us a step closer to being able to forecast the region’s impact on global climate.

The Arctic is one of the fastest warming places on the planet. As temperatures rise, the perpetually frozen layer of soil, called permafrost, begins to thaw, releasing methane and other greenhouse gases into the atmosphere. These methane emissions can accelerate future warming—but to understand to what extent, we need to know how much methane may be emitted, when and what environmental factors may influence its release.

That’s a tricky feat. The Arctic spans thousands of miles, many of them inaccessible to humans. This inaccessibility has limited most ground-based observations to places with existing infrastructure—a mere fraction of the vast and varied Arctic terrain. Moreover, satellite observations are not detailed enough for scientists to identify key patterns and smaller-scale environmental influences on methane concentrations.

In a new study, scientists with NASA’s Arctic Boreal Vulnerability Experiment (ABoVE), found a way to bridge that gap. In 2017, they used planes equipped with the Airborne Visible Infrared Imaging Spectrometer—Next Generation (AVIRIS—NG), a highly specialized instrument, to fly over some 20,000 square miles (30,000 square kilometers) of the Arctic landscape in the hope of detecting methane hotspots. The instrument did not disappoint.

“We consider hotspots to be areas showing an excess of 3,000 parts per million of methane between the airborne sensor and the ground,” said lead author Clayton Elder of NASA’s Jet Propulsion Laboratory in Pasadena, California. “And we detected 2 million of these hotspots over the land that we covered.”

The paper, titled “Airborne Mapping Reveals Emergent Power Law of Arctic Methane Emissions,” was published Feb. 10 in Geophysical Research Letters.

Within the dataset, the team also discovered a pattern: On average, the methane hotspots were mostly concentrated within about 44 yards (40 meters) of standing bodies of water, like lakes and streams. After the 44-yard mark, the presence of hotspots gradually became sparser, and at about 330 yards (300 meters) from the water source, they dropped off almost completely.

The scientists working on this study don’t have a complete answer as to why 44 yards is the “magic number” for the whole survey region yet, but additional studies they’ve conducted on the ground provide some insight.

“After two years of ground field studies that began in 2018 at an Alaskan lake site with a methane hotspot, we found abrupt thawing of the permafrost right underneath the hotspot,” said Elder. “It’s that additional contribution of permafrost carbon—carbon that’s been frozen for thousands of years—that’s essentially contributing food for the microbes to chew up and turn into methane as the permafrost continues to thaw.”

Scientists are just scratching the surface of what is possible with the new data, but their first observations are valuable. Being able to identify the likely causes of the distribution of methane hotspots, for example, will help them to more accurately calculate this greenhouse gas’s emissions across areas where we don’t have observations. This new knowledge will improve how Arctic land models represent methane dynamics and therefore our ability to forecast the region’s impact on global climate and global climate change impacts on the Arctic.

Elder says the study is also a technological breakthrough.

“AVIRIS-NG has been used in previous methane surveys, but those surveys focused on human-caused emissions in populated areas and areas with major infrastructure known to produce emissions,” he said. “Our study marks the first time the instrument has been used to find hotspots where the locations of possible permafrost-related emissions are far less understood.”

Reference:
More information on ABoVE can be found here: https://above.nasa.gov/ Clayton D. Elder et al. Airborne Mapping Reveals Emergent Power Law of Arctic Methane Emissions, Geophysical Research Letters (2020). DOI: 10.1029/2019GL085707

Note: The above post is reprinted from materials provided by Jet Propulsion Laboratory.

One single primitive turtle resisted mass extinction in the northern hemisphere

A reconstruction of Laurasichersis relicta which lived in the northen hemisphere 66 millons years ago. Credit: José Antonio Peñas (SINC)
A reconstruction of Laurasichersis relicta which lived in the northen hemisphere 66 millons years ago. Credit: José Antonio Peñas (SINC)

Sixty-six million years ago, in the emerged lands of Laurasia—now the northern hemisphere—a primitive land tortoise, measuring about 60 cm, managed to survive the event that killed the dinosaurs. It was the only one to do so in this area of the world, according to a Spanish palaeontologist who has analysed its peculiar fossils, found in France.

All turtle species we know of today are descendants of two lineages that separated during the Jurassic, more than 160 million years ago. But their members were not the only ones that existed. There had been many groups of primitive tortoises before them, in an earlier evolutionary position.

Some of these ancient reptiles managed to survive at a time when dinosaurs dominated the Earth. However, virtually all of the early groups of turtles disappeared after an asteroid impact that took place 66 million years ago and wiped out 70% of life on the planet.

Only the so-called “horned turtles” or meiolaniids managed to hold out, more specifically in Gondwana, the current southern hemisphere, according to fossils found in Oceania and South America. Their last representatives managed to co-exist relatively recently with humans, who hunted them to extinction. No other primitive turtle had appeared in the records of the last 66 million years.

After 10 years of study, the palaeontologist Adán Pérez García, from the Evolutionary Biology Group of the National University of Distance Education (UNED, Spain), now confirms that, in the northern hemisphere, on the ancient continent called Laurasia, a primitive land turtle also survived the mass extinction of the late Cretaceous period.

This was Laurasichersis relicta, an extinct turtle genus and species that corresponds to a new form, with very peculiar anatomical characteristics, and whose lineage evolved independently from that of the Gondwana tortoises, from which it separated 100 million years earlier.

“The reason why Laurasichersis survived the great extinction, while none of the other primitive North American, European or Asian land turtles managed to do so, remains a mystery,” Pérez García, the sole author of the paper published in Scientific Reports magazine, has confided to Sinc.

All turtle species we know of today are descendants of two lineages that separated during the Jurassic, more than 160 million years ago. But their members were not the only ones that existed. There had been many groups of primitive tortoises before them, in an earlier evolutionary position.

Some of these ancient reptiles managed to survive at a time when dinosaurs dominated the Earth. However, virtually all of the early groups of turtles disappeared after an asteroid impact that took place 66 million years ago and wiped out 70% of life on the planet.

Only the so-called “horned turtles” or meiolaniids managed to hold out, more specifically in Gondwana, the current southern hemisphere, according to fossils found in Oceania and South America. Their last representatives managed to co-exist relatively recently with humans, who hunted them to extinction. No other primitive turtle had appeared in the records of the last 66 million years.

After 10 years of study, the palaeontologist Adán Pérez García, from the Evolutionary Biology Group of the National University of Distance Education (UNED, Spain), now confirms that, in the northern hemisphere, on the ancient continent called Laurasia, a primitive land turtle also survived the mass extinction of the late Cretaceous period.

This was Laurasichersis relicta, an extinct turtle genus and species that corresponds to a new form, with very peculiar anatomical characteristics, and whose lineage evolved independently from that of the Gondwana tortoises, from which it separated 100 million years earlier.

“The reason why Laurasichersis survived the great extinction, while none of the other primitive North American, European or Asian land turtles managed to do so, remains a mystery,” Pérez García, the sole author of the paper published in Scientific Reports magazine, has confided to Sinc.

A special turtle

The shell of the newly discovered turtle was just over 60 cm long during adulthood and, like other primitive reptiles, it could not retract its neck into its shell to conceal its head from predators. This physical limitation allowed it to develop other protective mechanisms such as an armor with large, mutually linked spikes, which were hard structures located on the neck, legs and tail.

Its peculiar shell is one of the most remarkable features of this reptile and one of the characteristics that make it unique. This complex structure was made up of numerous plates. “Although the number of plates is usually the same in most turtles, the ventral shell region of the new species was provided with a greater number of these elements than those known in any other turtle,” Pérez García stresses.

After the 10-km-diameter meteorite hit the Earth, the large dinosaurs ceased to be part of the landscape, but the turtle, which lived in humid environments with forest areas, coexisted with new predators. The latter quickly dominated the positions of the food chain that had remained available when most animals disappeared.

Reference:
Adán Pérez García. Surviving the cretaceouspaleogene mass extinction event: A terrestrial stem turtle in the cenozoic of Laurasia. Scientific Reports January 30th 2020

Note: The above post is reprinted from materials provided by Spanish Foundation for Science and Technology (FECYT).

New thalattosaur species discovered in Southeast Alaska

The fossil of Gunakadeit joseeae, which was found in Southeast Alaska. About two thirds of the tail had already eroded away when the fossil was discovered. Credit: University of Alaska Museum of the North
The fossil of Gunakadeit joseeae, which was found in Southeast Alaska. About two thirds of the tail had already eroded away when the fossil was discovered. Credit: University of Alaska Museum of the North

Scientists at the University of Alaska Fairbanks have identified a new species of thalattosaur, a marine reptile that lived more than 200 million years ago.

The new species, Gunakadeit joseeae, is the most complete thalattosaur ever found in North America and has given paleontologists new insights about the thalattosaurs’ family tree, according to a paper published today in the journal Scientific Reports. Scientists found the fossil in Southeast Alaska in 2011.

Thalattosaurs were marine reptiles that lived more than 200 million years ago, during the mid to late Triassic Period, when their distant relatives — dinosaurs — were first emerging. They grew to lengths of up to 3-4 meters and lived in equatorial oceans worldwide until they died out near the end of the Triassic.

“When you find a new species, one of the things you want to do is tell people where you think it fits in the family tree,” said Patrick Druckenmiller, the paper’s lead author and director and earth sciences curator at the University of Alaska Museum of the North. “We decided to start from scratch on the family tree.”

Prior to the discovery of Gunakadeit joseeae, it had been two decades since scientists had thoroughly updated thalattosaur interrelationships, Druckenmiller said. The process of re-examining a prehistoric animal’s family tree involves analyzing dozens and dozens of detailed anatomical features from fossil specimens worldwide, then using computers to analyze the information to see how the different species could be related.

Druckenmiller said he and collaborator Neil Kelley from Vanderbilt University were surprised when they identified where Gunakadeit joseeae landed.

“It was so specialized and weird, we thought it might be out at the furthest branches of the tree,” he said. Instead it’s a relatively primitive type of thalattosaur that survived late into the existence of the group.

“Thalattosaurs were among the first groups of land-dwelling reptiles to readapt to life in the ocean,” Kelley said. “They thrived for tens of millions of years, but their fossils are relatively rare so this new specimen helps fill an important gap in the story of their evolution and eventual extinction.”

That the fossil was found at all is a remarkable. It was located in rocks in the intertidal zone. The site is normally underwater all but a few days a year. In Southeast Alaska, when extreme low tides hit, people head to the beaches to explore. That’s exactly what Jim Baichtal, a geologist with the U.S. Forest Service’s Tongass National Forest, was doing on May 18, 2011, when low tides of -3.7 feet were predicted.

He and a few colleagues, including Gene Primaky, the office’s information technology professional, headed out to the Keku Islands near the village of Kake to look for fossils. Primaky saw something odd on a rocky outcrop and called over Baichtal, “Hey Jim! What is this?” Baichtal immediately recognized it as a fossilized intact skeleton. He snapped a photo with his phone and sent it to Druckenmiller.

A month later, the tides were forecasted to be almost that low, -3.1 feet, for two days. It was the last chance they would have to remove the fossil during daylight hours for nearly a year, so they had to move fast. The team had just four hours each day to work before the tide came in and submerged the fossil.

“We rock-sawed like crazy and managed to pull it out, but just barely,” Druckenmiller said. “The water was lapping at the edge of the site.”

Once the sample was back at the UA Museum of the North, a fossil preparation specialist worked in two-week stints over the course of several years to get the fossil cleaned up and ready for study.

When they saw the fossil’s skull, they could tell right away that it was something new because of its extremely pointed snout, which was likely an adaptation for the shallow marine environment where it lived.

“It was probably poking its pointy schnoz into cracks and crevices in coral reefs and feeding on soft-bodied critters,” Druckenmiller said. Its specialization may have been what ultimately led to its extinction. “We think these animals were highly specialized to feed in the shallow water environments, but when the sea levels dropped and food sources changed, they had nowhere to go.”

Once the fossil was identified as a new species, it needed a name. To honor the local culture and history, elders in Kake and representatives of Sealaska Corp. agreed the Tlingit name “Gunakadeit” would be appropriate. Gunakadeit is a sea monster of Tlingit legend that brings good fortune to those who see it. The second part of the new animal’s name, joseeae, recognizes Primaky’s mother, Joseé Michelle DeWaelheyns.

Reference:
Patrick S. Druckenmiller, Neil P. Kelley, Eric T. Metz, James Baichtal. An articulated Late Triassic (Norian) thalattosauroid from Alaska and ecomorphology and extinction of Thalattosauria. Scientific Reports, 2020; 10 (1) DOI: 10.1038/s41598-020-57939-2

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

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