The Reed Flute Cave is a landmark and tourist attraction in Guilin, Guangxi, China. It is a natural limestone cave with multicolored lighting and has been one of Guilin’s most interesting attractions for over 1200 years.
It is over 180 million years old. The cave got its name from the type of reed growing outside, which can be made into melodious flutes. Reed Flute Cave is filled with a large number of stalactites, stalagmites and rock formations in weird and wonderful shapes. Inside, there are more than 70 inscriptions written in ink, which can be dated back as far as 792 AD in the Tang Dynasty.
These aged inscriptions tell us that it has been an attraction in Guilin since ancient times. It was rediscovered in the 1940s by a group of refugees fleeing the Japanese troops. Nowadays, multicolored lightning artificially illuminates the cave.
Highlights of Reed Flute Cave
Limestone formations:The cave is filled with a large number of stalactites, stalagmites, and rock formations in weird and wonderful shapes. Illuminated by the colored lights, the cave looks like a dazzling underground palace. That’s why the cave is also known as ‘Nature’s Art Palace’. The most liked formations are Rose Dawn over Lion Peaks and Crystal Palace.
Historic inscriptions:Inside the cave there are more than 70 inscriptions written in ink, which can be dated back as far as 792 AD in the Tang Dynasty (618–907). These aged inscriptions tell us that it has been an attraction in Guilin since ancient times. Millions of tourists have visited Reed Flute Cave since its official opening as a tourist attraction in 1962.
Reed Flute Cave Tours
The cave is about 240 meters long and a tour lasts about one hour. Along the U-shaped route, visitors will have ample time see the oddly-shaped rocks and stone pillars while the guide narrates interesting stories about them.
You might easily see the difference in color between the D-color and Z-color diamonds, which represent the extreme ends of the GIA Color Scale. But the color differences between H and N may not be so apparent to you. Credit: GIA
If you’re asking, “What is the most important C?”, chances are you’re already well into the process of purchasing a diamond engagement ring. When it comes to diamond quality, the answer is simple, but not necessarily straightforward.
“Which is the most important of the 4Cs?” – well, it depends. It depends on your taste and budget, and what you and your partner deem most important. Like buying a car, a house, or anything else, your choices when buying a diamond will be determined by your budget. The goal is to get the best diamond quality you can afford. But there will be trade offs. Knowing your preferences is the first step in defining what’s most important to you, and where you’ll compromise. So, what are your diamond priorities?
Is Diamond Size Important?
How do diamond sizes compare? This image shows the carat (ct) weight and average diameter for various round brilliant cut diamonds. Credit: GIA
Diamond size is measured in carat weight. Small differences in carat weight can sometimes mean price differences of hundreds—even thousands—of dollars, depending on the size and overall diamond quality.
If the appearance of size is important, you can create the illusion of size by picking the right diamond shape. Fancy shapes tend to look bigger for their carat weight, especially elongated shapes such as a ovals, rectangles, and marquise. An engagement ring with a narrow band and a bezel or halo setting can also accentuate a diamond’s size.
If size were the only thing that mattered, you could, theoretically, buy a five-carat diamond for a few dollars. Of course, it would not be gem quality. It would be so heavily included that you couldn’t see through it, and its color might be brown or gray. Its cut quality would be irrelevant, since light doesn’t pass through it at all. The diamond would certainly be big, but friends, family, and your fiancée might be hard pressed to recognize it as diamond.
That’s why it’s important to know that carat weight alone isn’t everything. Diamond quality is determined by a combination of all the 4Cs.
Is Diamond Color Important?
You might easily see the difference in color between the D-color and Z-color diamonds, which represent the extreme ends of the GIA Color Scale. But the color differences between H and N may not be so apparent to you. Credit: GIA
Subtle differences in diamond color can dramatically affect diamond value. Two diamonds of the same clarity, weight, shape and cutting style can differ in value based on color alone. Even the slightest hint of color can make a difference in what you may pay for the diamond.
GIA determines the degree of colorlessness in a diamond by comparing it under controlled lighting and viewing conditions to a set of masterstones of established color grades. The GIA D-to-Z diamond color grading scale, or diamond color chart, begins with the letter D, representing colorlessness, and continues with increasing presence of color to the letter Z, for light yellow, light brown or light gray. The 23 color grades on the GIA Color Scale are subdivided into five subcategories: colorless (D-F); near colorless (G-J); faint (K-M); very light (N-R); and light (S-Z). Each letter grade has a clearly defined narrow range of color appearance.
The more colorless the diamond, the more rare it is, which is why you’ll spend top dollar on a D-color diamond. Once set in a mounting and worn on a hand or dangling from an ear, it’s less likely that you can easily see the difference between a D and G color diamond.
As you shop, look at diamonds with different color grades. You might be surprised at the range of color that you find acceptable. You might find (as some do) that a diamond with a little color (J or K for example) has some warmth that you like.
Remember that a diamond is made up of tiny reflective surfaces, so its color appearance will be influenced by its surroundings. This includes natural and artificial light, the color of the clothing you’re wearing, and even the color of the metal in which the diamond is set. White metals, like platinum, can accentuate diamonds with higher color grades of H and better. At about J, K, or L, the contrast starts to become noticeable if the metal is very white (platinum). The slightly yellowish body color of diamonds with a lower color grade is less noticeable when they are set in yellow gold.
Is Diamond Clarity Important?
In this group, can you tell which diamond has the highest clarity grade and which one has the lowest? Without a 10× loupe and seen from a distance, a diamond’s overall clarity may be difficult to see. Answer: The 1.03 ct Asscher cut diamond (second from the left) has the highest clarity: VVS2. The 1.01 ct marquise shaped diamond (second from the right) has the lowest clarity: SI1. Credit: Robert Weldon/GIA
Flawless diamonds are so rare that it’s possible to spend a lifetime in the jewelry industry without ever seeing one. At the other end of the diamond clarity scale are diamonds with inclusions that can be easily seen by the unaided eye. Between the two extremes are diamonds with inclusions visible only under 10× magnification. Stones in this middle range make up the bulk of the retail market.
Do you wander through the day carrying a 10× jewelers’ loupe examining people’s diamonds? No one else does either.
The GIA Clarity Scale, or diamond clarity chart, has 11 clarity grades: Flawless (FL), Internally Flawless (IF), two categories of Very, Very Slightly Included (VVS), two categories of Very Slightly Included (VS), two categories of Slightly Included (SI), and three categories of Included (I). A diamond’s clarity grade is determined by the size, number, position, nature, and color or relief of any inclusions or blemishes.
A diamond with no inclusions visible under 10× magnification, is graded IF: the very rare end of the clarity scale and therefore the priciest. As you move down the scale, it’s unlikely you’ll see the very tiny inclusions of a VS2 or SI1 diamond. And unless examined closely, some people won’t even notice the inclusions of an I1 diamond.
Look at diamonds with different clarity grades to narrow down your preferences. Note where surface reaching blemishes are located. If you have your heart set on an emerald cut diamond, you may want to consider the highest clarity grade you can afford, since the traditional step-cut faceting style tends to make inclusions more obvious in lower clarity diamonds.
Is Diamond Cut Important?
These round brilliant cut diamonds show how cut quality affects visual appearance. GIA cut grades, (left to right): Excellent, Good, Poor. Credit: Kevin Schumacher/GIA
Every diamond quality factor matters to someone. If you’re looking for sparkle and those unmistakable flashes of color and light that telegraph “diamond” across a crowded room, then a diamond’s cut quality is very important.
This diamond quality factor refers to how skillfully the diamond was cut. A diamond’s cut grade represents a range of proportion sets and diamond appearances – all of which combine to deliver the magnificent return of light that’s only possible with a diamond.
GIA developed the cut grading system for standard round brilliant cut diamonds based on thousands of observations of actual diamonds by jewelers and consumers like you. While the GIA Cut Grading Scale contains five grades going from Excellent to Poor, it’s important to keep in mind that each grade represents a range. Diamonds with different face-up appearances may have the same cut grade. And because the grades were established by determining what most people preferred in each range, a given cut grade may not necessarily deliver the diamond that you prefer.
Lighting has a dramatic affect on a diamond’s appearance. Here is the same diamond under (left to right) diffused/fluorescent lighting, under incandescent or spot lighting, and a combination of spot and diffused lighting. Credit: Eric Welch/GIA
ake your time in finding your preference. As with color, a diamond’s highly reflective surface causes light to affect its face-up appearance. Look at diamonds in three different kinds of light:
Diffused lighting: common in many offices, the overhead light source is generally white with no spots of bright light. You don’t see many flashes of color (fire) in the diamond under this type of lighting, but you can easily see a pattern of light and dark areas caused by reflections within the diamond (scintillation).
Spot lighting: this is becoming more common as people adopt LED light sources and ubiquitous in jewelry stores. You will see lots of fire, obscuring the pattern you saw in diffused light. Direct sunlight, the most common lighting condition is a form of spot lighting—one single spot source. Make sure to view the diamond outside to make sure that it “performs” as you expect it to.
Combination of spot and diffused lighting: you should still see the pattern in the diamond easily, with the addition of fire. This env is often the most pleasing overall.
As with color and clarity, the higher the cut grade, the more expensive the diamond when all other factors are the same.
The Most Important Diamond Quality Factor of All
Now that you’ve taken the time to figure out your diamond priorities, there’s one more factor to consider: cleanliness. A diamond is like a collection of tiny mirrors reflecting light and its surroundings. Its color, clarity, and cut will matter little if the diamond is dirty. You will need to keep your diamond clean (free from oil and dirt) if you want it to sparkle as much as it did when you first saw it.
Ready to start looking at diamonds? Before you head into a jewelry store, brush up on the lingo with this guide to common engagement ring terms and make your shopping a little easier.
Thanks to a precise combination of factors the prints have survived; the ground they walked had the right texture sediment to hold the print and subsequent sediment layers dried over the top to protect them. Credit: iStock
FOR just a few precious days every year a few lucky people can glance 66 million years into the past as the surf rolls back low enough on the Kimberley coast to reveal the wonderland of dinosaur footprints on its rocky ocean platforms.
The tide will be that low again in mid-July and a team of researchers, lead by University of Queensland’s Steve Salisbury, will again make its pilgrimage to Broome to build on their thrilling body of research.
It’s a massive project; they have 50 sites to study, each the size of a large quarry and each with a different dinosaur story.
It is also very exciting, Dr Salisbury says, because they are inching closer to creating a very accurate picture of how the Kimberley dinosaurs lived millions of years ago.
They have identified up to 20 species along a 200km stretch of coast, from the giant bird-claw-like imprint of the carnivorous Theropod to the stumpy Sauropod print and the distinctive four stubby-fingers and fat three-toed foot of the Stegosaurs.
Thanks to a precise combination of factors the prints have survived; the ground they walked had the right texture sediment to hold the print and subsequent sediment layers dried over the top to protect them.
The Kimberley sites are of global significance. According to researcher Dr Tony Tholborn (2012), nowhere else in the world have the comings and goings of dinosaurs moulded the landscape to the extent it has here.
However, this was not coastal cliff 130 million years ago when the dinosaurs trod it, but swampy sandy lagoons.
And there’s no doubt these were big animals. As Dr Salisbury clambered the slippery rock platforms on his 2015 expedition he could barely contain his excitement when he discovered what could be the largest dinosaur track in the world.
It was made by a Sauropod which could have stood up to eight metres at the hip and was estimated at 35m long. In comparison an Asian elephant is 6.5m long and just 2.7m high.
The sheer size of the dinosaurs is part of their appeal to so many people, Dr Salisbury says.
“They are colossal animals that really inspire the imagination—they are pretty spectacular,” he says.
“To think that things like this once existed and then to be able to see evidence whether its fossil bones or tracks, really inspires the imagination.
“Not just for little kids but big kids as well,” he says.
DNA found in the sediments and rocks will be studied to identify what animals and plants were present and evolved after the impact. Credit: iStock
Sixty-six million years ago an asteroid smashed into Earth releasing energy equivalent to 100 million nuclear bombs and creating a massive dust cloud that blocked out the sun for more than a year.
These events caused the famous mass extinction of dinosaurs, and it stopped photosynthesis by destroying many plants, and significant marine and terrestrial organisms in the food chain.
Now, WA scientists are part of an international team working to understand how life recovered and evolved following this catastrophic impact.
Curtin University’s geomicrobiologist Associate Professor Marco Coolen is currently in Mexico to sample the impact site of the Chicxulub Impact Crater in the Gulf of Mexico.
The crater is massive, covering 180km in diameter—the distance from Perth to Bunbury—and 30km deep, nearly 3.5 times the height of Mount Everest.
Upon impact, gigantic amounts of pulverized rock exploded into the atmosphere and landed back on Earth forming an ‘ejecta layer’ that can be found all over the world, A/Prof Coolen says.
“No fossil remains of dinosaurs have been found above this ejecta layer, however, avian dinosaurs—that evolved into modern birds—survived the extinction,” he says.
As part of the research A/Prof Coolen will collect more than 1000m of cores of the marine sediment and rock from the site and send the frozen samples back to Perth to study.
DNA found in the sediments and rocks will be studied to identify what animals and plants were present and evolved after the impact.
“We hope to find information about species such as plankton that do not leave behind fossils that can be studied by eye or under a microscope, and can only be identified via molecular fossils left behind such as DNA and lipid biomarkers.”
World leading molecular fossil expert Kliti Grice and her team will analyse lipid biomarkers and their isotopic compositions, to reveal what the environmental conditions were like at the time.
“This way we can make connections between past ecosystems and environments and identify reasons for why certain species adapted or disappeared,” John Curtin Distinguished Professor Grice says.
The researchers will be looking, and may also find ‘diamondoids’—diamond-shaped molecules that represent very high temperatures and can reveal more about the heating of water within the earth’s crust.
“We expect the microbes that re-colonised the crater rocks are related to bacteria such as geysers that live on the surface of the planet today, A/Prof Coolen says.
This is a Hawaii-Emperor seamount chain. Credit: University of Sydney
The physical mechanism causing the unique, sharp bend in the Hawaiian-Emperor seamount chain has been uncovered in a collaboration between the University of Sydney and the California Institute of Technology (Caltech).
Led by a PhD candidate at the University of Sydney’s School of Geosciences, researchers used the Southern Hemisphere’s most highly integrated supercomputer to reveal flow patterns deep in the Earth’s mantle — just above the core — over the past 100 million years. The flow patterns explain how the enigmatic bend in the Hawaiian-Emperor seamount chain arose.
True to the old adage — as above, so below — the Sydney-US collaboration found the shape of volcanic seamount chains (chains of mostly extinct volcanoes), including Hawaii, is intimately linked to motion near the Earth’s core.
The findings of PhD candidate Rakib Hassan and fellow researchers including Professor Dietmar Müller from the University’s EarthByte Group, are being published in Nature.
Mr Hassan explained: “Until now, scientists believed the spectacular 60° bend in the Hawaiian seamount chain — not found in any other seamount chains — was related to a change in plate motion combined with a change in flow direction in the shallow mantle, the layer of thick rock between the Earth’s crust and its core.
“These findings suggest the shape of volcanic seamount chains record motion in the deepest mantle, near the Earth’s core. The more coherent and rapid the motion deep in the mantle, the more acute its effects are on the shape of seamount chains above,” he said.
Although solid, the mantle is in a state of continuous flow, observable only over geological timescales. Vertical columns of hot and buoyant rock rising through the mantle from near the core are known as mantle plumes. Volcanic seamount chains such as Hawaii were created from magma produced near the surface by mantle plumes. Moving tectonic plates sit above the mantle and carry newly formed seamounts away from the plume underneath — the oldest seamounts in a chain are therefore furthest away from the plume.
“We had an intuition that, since the north Pacific experienced a prolonged phase where large, cold tectonic plates uninterruptedly sank into the mantle, the flow in the deepest mantle there would be very different compared to other regions of the Earth,” Mr Hassan said.
One of the most contentious debates in geoscience has centred on whether piles of rock in the deep mantle — to which plumes are anchored — have remained stationary, unaffected by mantle flow over hundreds of millions of years.
The new research shows the shapes of these piles have changed through time and their shapes can be strongly dependent on rapid, coherent flow in the deep mantle.
Between 50-100 million years ago, the edge of the pile under the north Pacific was pushed rapidly southward, along with the base of Hawaii’s volcanic plume, causing it to tilt. The plume became vertical again once the motion of its base stopped; this dramatic start-stop motion resulted in the seamount chain’s sharp bend.
Using Australia’s National Computational Infrastructure’s supercomputer Raijin, the team created high-resolution three-dimensional simulations of mantle evolution over the past 200 million years to understand the coupling between convection in the deep Earth and volcanism.
Mr Hassan said the simulations were guided by surface observations — similar to meteorologists applying past measurements to predict the weather.
“These simulations required millions of central processing unit (CPU) hours on the supercomputer over the course of the project,” he said.
Professor Müller concluded: “Our results help resolve a major enigma of why volcanic seamount chains on the same tectonic plate can have very different shapes.
“It is now clear that we first need to understand the dynamics of the deepest ‘Underworld’, right above the core, to unravel the history of volcanism at Earth’s surface,” said Professor Müller.
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Reference:
Rakib Hassan, R. Dietmar Müller, Michael Gurnis, Simon E. Williams, Nicolas Flament. A rapid burst in hotspot motion through the interaction of tectonics and deep mantle flow. Nature, 2016; 533 (7602): 239 DOI: 10.1038/nature17422
This is one of 60 micrometeorites extracted from 2.7 billion year old limestone, from the Pilbara region in Western Australia. These micrometeorites consist of iron oxide minerals that formed when dust particles of meteoritic iron metal were oxidised as they entered Earth’s atmosphere, indicating that the ancient upper atmosphere was surprisingly oxygen-rich. Credit: Andrew Tomkins
Using the oldest fossil micrometeorites — space dust — ever found, Monash University-led research has made a surprising discovery about the chemistry of Earth’s atmosphere 2.7 billion years ago.
The findings of a new study published today in the journal Nature — led by Dr Andrew Tomkins and a team from the School of Earth, Atmosphere and Environment at Monash, along with scientists from the Australian Synchrotron and Imperial College, London — challenge the accepted view that Earth’s ancient atmosphere was oxygen-poor. The findings indicate instead that the ancient Earth’s upper atmosphere contained about the same amount of oxygen as today, and that a methane haze layer separated this oxygen-rich upper layer from the oxygen-starved lower atmosphere.
Dr Tomkins explained how the team extracted micrometeorites from samples of ancient limestone collected in the Pilbara region in Western Australia and examined them at the Monash Centre for Electron Microscopy (MCEM) and the Australian Synchrotron.
“Using cutting-edge microscopes we found that most of the micrometeorites had once been particles of metallic iron — common in meteorites — that had been turned into iron oxide minerals in the upper atmosphere, indicating higher concentrations of oxygen than expected,” Dr Tomkins said.
“This was an exciting result because it is the first time anyone has found a way to sample the chemistry of the ancient Earth’s upper atmosphere,” Dr Tomkins said.
Imperial College researcher Dr Matthew Genge — an expert in modern cosmic dust — performed calculations that showed oxygen concentrations in the upper atmosphere would need to be close to modern day levels to explain the observations.
“This was a surprise because it has been firmly established that the Earth’s lower atmosphere was very poor in oxygen 2.7 billion years ago; how the upper atmosphere could contain so much oxygen before the appearance of photosynthetic organisms was a real puzzle,” Dr Genge said.
Dr Tomkins explained that the new results suggest the Earth at this time may have had a layered atmosphere with little vertical mixing, and higher levels of oxygen in the upper atmosphere produced by the breakdown of CO 2 by ultraviolet light.
“A possible explanation for this layered atmosphere might have involved a methane haze layer at middle levels of the atmosphere. The methane in such a layer would absorb UV light, releasing heat and creating a warm zone in the atmosphere that would inhibit vertical mixing,” Dr Tomkins said.
“It is incredible to think that by studying fossilised particles of space dust the width of a human hair, we can gain new insights into the chemical makeup of Earth’s upper atmosphere, billions of years ago.” Dr Tomkins said.
Dr Tomkins outlined next steps in the research.
“The next stage of our research will be to extract micrometeorites from a series of rocks covering over a billion years of Earth’s history in order to learn more about changes in atmospheric chemistry and structure across geological time. We will focus particularly on the great oxidation event, which happened 2.4 billion years ago when there was a sudden jump in oxygen concentration in the lower atmosphere.”
Reference:
Andrew G. Tomkins, Lara Bowlt, Matthew Genge, Siobhan A. Wilson, Helen E. A. Brand, Jeremy L. Wykes. Ancient micrometeorites suggestive of an oxygen-rich Archaean upper atmosphere. Nature, 2016; 533 (7602): 235 DOI: 10.1038/nature17678
Researchers at NMSU are analyzing samples from Mount McLoughlin in southern Oregon, as part of a three-year grant from the National Science Foundation to study the origins of magma in the Cascade Arc. (Courtesy photo) MAY16
In 1980, an eruption of Mount St. Helens shook the Pacific Northwest in one of the most spectacular displays of volcanism in United States history.
Despite being one of the most well known volcanoes in the lower 48 states, Mount St. Helens is actually part of a chain of volcanoes that dot the west coast, from northern California through the southern coast of Canada. It’s a region called the Cascade Arc, and researchers in New Mexico State University’s Department of Geological Sciences have received a three-year grant from the National Science Foundation to investigate it.
Specifically, the team is analyzing the chemical composition of erupted lavas from several sites along the southern Cascades, from northern California to central Oregon, in an effort to better understand the origins of the magma, or molten rock, gathering beneath the volcanoes.
“The idea is that we can use what has erupted at the surface to get back to what’s happening at great depth,” said Emily Johnson, principal investigator on this project, and assistant professor of volcanology and igneous petrology in NMSU’s College of Arts and Sciences.
So what exactly is happening miles beneath this volcanic arc?
“This part of North America is right along a plate boundary,” Johnson said. “Earth’s surface is made up of different plates that can either separate, come together or slide past one another. In the case of the Cascades, we have an oceanic plate that’s colliding with the North American, continental, plate.”
When these plates collide, Johnson explained, the dense oceanic plate sinks beneath North America in a process called subduction. As the slab sinks, pressure and temperature increase and fluids are released from the slab, causing the mantle underneath the crust to melt and rise to the surface, forming a volcano.
With the southern Cascades being a relatively understudied portion of the arc, this research will help determine the origins of these magmas, and when volcanoes like Oregon’s Mount McLoughlin, and some smaller cinder cones in California, last erupted. This will offer indications as to when and how they may erupt in the future.
“It’s really interesting to look at the magmas that are erupted and how variable they can be over very short spatial scales,” Johnson said. “You think volcanoes that erupt within several kilometers of one another would perhaps be related at depth to some larger magmatic system. Then you analyze the composition and you realize these are completely unrelated magma batches that erupted very close to one another.”
One likely cause of this variation is the extra material being dragged down with the oceanic plate, including water, seafloor sediments, carbon dioxide and other trace elements. This material is added in variable amounts to the magmas, and directly impacts the nature of an eruption.
“Very gas-rich magmas tend to make very explosive eruptions, whereas gas-poor magmas have more docile, effusive eruptions,” Johnson said. “So our results will impact our understanding of the style of volcanism and how future volcanism may be.”
Johnson’s team is also analyzing seafloor sediments from a drill core obtained just offshore of the Cascades, allowing them to look directly at the descending material before it melts into magma.
While not a direct focus of Johnson’s research, her work in determining the amount of sediment being dragged with the sinking slab can impact how scientists study the potential for big earthquakes in the southern Cascades.
“You can think of sediment as being really water-rich, kind of slippery,” Johnson said. “That can actually lubricate that fault zone, and that will have implications for how those earthquakes may occur, how they would slip.”
While these west coast hazards may be a distant concern to New Mexico residents, Johnson explained that Las Cruces, too, has a volcanic past.
“The Organ Mountains are part of this very old caldera system that erupted about 35-36 million years ago,” she said. “The northern part of the Organ Mountains represents the magma that cooled inside the crust and never erupted. The southern part of the Organ Mountains is actually the volcanic rocks that erupted explosively.”
Johnson and her research group are studying the Organs in order to better understand what caused a sequence of large, explosive eruptions to occur in the region, and how the magma changed between those eruptions.
A fossil found in Maryland was identified by a University of Pennsylvania doctoral student as belonging to a new species of ancient dog. The hyena-like canine, with massive jaws capable of crushing bone, would have lived approximately 12 million years ago, at a time when massive sharks like megalodon swam in the oceans. Credit: Illustration of Cynarctus from “Dogs, Their Fossil Relatives and Evolutionary History.” Reprinted and used with permission of the publisher and Mauricio Antón, author of the illustration and copyright owner [2008]; Courtesy of University of PennsylvaniaA doctoral student at the University of Pennsylvania has identified a new species of fossil dog. The specimen, found in Maryland, would have roamed the coast of eastern North America approximately 12 million years ago, at a time when massive sharks like megalodon swam in the oceans.
The newly named species is Cynarctus wangi, named for Xiaoming Wang, curator at the Natural History Museum of Los Angeles County and an expert on mammalian carnivores. This coyote-sized dog was a member of the extinct subfamily Borophaginae, commonly known as bone-crushing dogs because of their powerful jaws and broad teeth.
“In this respect they are believed to have behaved in a similar way to hyenas today,” said the study’s lead author, Steven E. Jasinski, a student in the Department of Earth and Environmental Science in Penn’s School of Arts & Sciences and acting curator of paleontology and geology at the State Museum of Pennsylvania in Harrisburg.
Fossils from terrestrial species from this region and time period are relatively rare, thus the find helps paleontologists fill in important missing pieces about what prehistoric life was like on North American’s East Coast.
“Most fossils known from this time period represent marine animals, who become fossilized more easily than animals on land,” Jasinski said. “It is quite rare we find fossils from land animals in this region during this time, but each one provides important information for what life was like then.”
Jasinski, who is advised by Peter Dodson, a professor of paleontology in the Department of Earth and Environmental Science and professor of anatomy in the School of Veterinary Medicine, collaborated on the paper with Steven C. Wallace, a professor at East Tennessee State University and curator at the East Tennessee State University National History Museum at the Gray Fossil Site.
Their work was published in the Journal of Paleontology.
When Jasinski and Wallace first began their investigation of the specimen, which had been found by an amateur collector along the beach under the Choptank Formation in Maryland’s Calvert Cliffs region and was then held by the Smithsonian Institution, they presumed it was a known species of borophagine dog, a species called marylandica that was questionably referred to as Cynarctus, a fossil of which had been found in older sediment in the same area. But when they compared features of the occlusal surfaces, where the top and bottom teeth meet, of the previously known and the new specimens, they found notable differences. They concluded that the specimen represented a distinct species new to science.
“It looks like it might be a distant relative descended from the previously known borophagine,” Jasinski said.
Borophagine dogs were widespread and diverse in North America from around 30 million to about 10 million years ago. The last members went extinct around 2 millions of years ago during the late Pliocene. C. wangi represents one of the last surviving borophagines and was likely outcompeted by ancestors of some of the canines living today: wolves, coyotes and foxes.
Despite its strong jaws, the researchers believe C. wangi wouldn’t have been wholly reliant on meat to sustain itself.
“Based on its teeth, probably only about a third of its diet would have been meat,” Jasinski said. “It would have supplemented that by eating plants or insects, living more like a mini-bear than like a dog.”
Although C. wangi represents the first known carnivore from the Choptank Formation, some of the animals that it would have lived beside are known. These include the ancient pigs Desmathyus and Prosthenops, the horned artiodactyl Prosynthetoceras, an ancient elephant-like animal known as a gomphothere, and perhaps the ancient horse Merychippus.
“This new dog gives us useful insight into the ecosystem of eastern North America between 12 and 13 million years ago,” Jasinski said.
The study was supported in part by the National Science Foundation (EAR-0958985), East Tennessee State University, the State Museum of Pennsylvania and the University of Pennsylvania.
Reference:
Steven E. Jasinski, Steven C. Wallace. A Borophagine canid (Carnivora: Canidae: Borophaginae) from the middle Miocene Chesapeake Group of eastern North America. Journal of Paleontology, 2016; 89 (06): 1082 DOI: 10.1017/jpa.2016.17
Fig.1 Holotype of Protovis himalayensis, in frontal-lateral view (A) and dorsal view of horncores (B) , and cross-sectional shapes at four intervals along left horn. Credit: WANG Xiaoming
Modern wild sheep, Ovis, is widespread in the mountain ranges of the Caucasus through Himalaya, Tibetan Plateau, Tianshan-Altai, eastern Siberia, and the Rocky Mountains in North America. In Eurasia, fossil sheep are known by a few isolated records at a few Pleistocene sites in North China, eastern Siberia, and western Europe, but are so far absent from the Tibetan Plateau.
In a paper published May 4 in the Journal of Vertebrate Paleontology, paleontologists from the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP), Chinese Academy of Sciences, Natural History Museum of Los Angeles County and La Brea Tar Pits and Museum at Los Angeles reported a new genus and species of fossil sheep from the Pliocene of Zanda Basin in Tibet. This finding extends the fossil record for the sheep into the Pliocene of the Tibetan Plateau, suggesting that the Tibetan Plateau, possibly including Tianshan-Altai, represents the ancestral home range(s) of mountain sheep and that these basal stocks were the ultimate source of all extant species, which is consistent with the Out-of-Tibet hypothesis regarding the origins of Ice Age megaherbivores.
New fossil materials were collected from IVPP locality ZD0712 in Guanjingtai, Zanda County, Tibetan Autonomous Region in western Himalaya during the 2006 and 2007 field seasons. The holotype specimen (IVPP V18928), forming the main basis of this new species, is a nearly complete male left and right horncores. With a total horncore upper curve length of 443 mm, it is similar in size to some extant species of Ovis.
This new extinct sheep, Protovis himalayensis, has a combination of features distinguishable from other species such as Ovis, Pseudois and Tossunnoria. Smaller than the living argali, it shares with Ovis posterolaterally arched horncores and partially developed sinuses and possesses several transitional characters leading to Ovis.
Situated between the Himalayas and Ayilariju ranges, Zanda Basin was formed in a tectonically active region, and throughout the basin development, basement outcrops from residual topography and surrounding mountains offered plenty of rugged terrain and gentle hills along the shores of the paleo-Zanda lake. The locality of Protovis is not far from one of the paleo-islands formed by metamorphic basement rock, and these cliffs probably provided protection from predators in times of danger.
Carbon isotopes on fossil mammalian herbivores from Zanda Basin indicate that C3 vegetation formed the dominant plant community during the Pliocene. It is likely that Protovis, too, had a C3 diet, as do the modern bovids within the Tibetan Plateau.
Ancestral sheep in the Tibetan Plateau, occupying a similar range as the extant argali, were adapted to high-elevation, cold environments during the Pliocene, when conditions elsewhere (including the high Arctic regions) were much warmer. These ancestral stocks evolved rapidly to morphological conditions similar to that of living Ovis. By the time the Ice Age arrives around 2.6 million years ago, Ovis possessed a competitive advantage for surviving in freezing environments and spread rapidly to regions surrounding the Plateau and beyond. Most sheep species survived along their Pleistocene route of dispersal, offering a highly consistent pattern of zoogeography.
“With the present discovery of a primitive sheep in the Himalaya, we thus offer another example of our previous out-of-Tibet hypothesis—ancestral sheep were adapted to high-elevation cold environments in the Pliocene, and during the Pleistocene they began to disperse outside their ancestral home range in Tibet to northern China, northern Siberia, and western Asia”, said lead author Dr. WANG Xiaoming, a visiting professor of Institute of Vertebrate Paleontology and Paleoanthropology (IVPP), Chinese Academy of Sciences, and a senior curator of Natural History Museum of Los Angeles County, “The sheep thus joined several other mammals, such as big cats, arctic foxes, hypercarnivorous hunting dogs, and woolly rhinoceros in their expansion out of Tibet during the Ice Age and gave rise to elements of the Pleistocene megafauna”.
“Both this new fossil datum and the existing molecular phylogeny suggest that the Tibetan Plateau, possibly including Tianshan-Altai, represents the ancestral home range(s) of mountain sheep”, said study coauthor Dr. LI Qiang of the IVPP, “Fortunately, wild sheep were able to take refuge in mountain ranges, possibly an important contributing factor in protection against early human hunting, and they have largely survived the end-Pleistocene extinction that befell many of their megafaunal contemporaries.”
Reference:
Xiaoming Wang et al. Out of Tibet: an early sheep from the Pliocene of Tibet, , genus and species nov. (Bovidae, Caprini), and origin of Ice Age mountain sheep , Journal of Vertebrate Paleontology (2016). DOI: 10.1080/02724634.2016.1169190
Fingal’s Cave is a sea cave on the uninhabited island of Staffa, in the Inner Hebrides of Scotland, known for its natural acoustics. The National Trust for Scotland owns the cave as part of a National Nature Reserve. It became known as Fingal’s Cave after the eponymous hero of an epic poem by 18th-century Scots poet-historian James Macpherson.
Meaning & History
From Scottish Gaelic Fionnghall meaning “white stranger”, derived from fionn “white, fair” and gall “stranger”. This was the name of the hero in James Macpherson’s epic poem ‘Fingal’ (1762), which he claimed to have based on early Gaelic legends about Fionn mac Cumhail.
Formation
Fingal’s Cave is formed entirely from hexagonally jointed basalt columns within a Paleocene lava flow, similar in structure to the Giant’s Causeway in Northern Ireland and those of nearby Ulva.
In all these cases, cooling on the upper and lower surfaces of the solidified lava resulted in contraction and fracturing, starting in a blocky tetragonal pattern and transitioning to a regular hexagonal fracture pattern with fractures perpendicular to the cooling surfaces. As cooling continued these cracks gradually extended toward the centre of the flow, forming the long hexagonal columns we see in the wave-eroded cross-section today. Similar hexagonal fracture patterns are found in desiccation cracks in mud where contraction is due to loss of water instead of cooling.
Composition of Earth’s mantle revisited thanks to research at Argonne’s Advanced Photon Source. Credit: Argonne National Laboratory
Researchers have compiled the first global set of observations of the movement of the Earth’s mantle, the 3000-kilometre-thick layer of hot silicate rocks between the crust and the core, and have found that it looks very different to predictions made by geologists over the past 30 years.
The team, from the University of Cambridge, used more than 2000 measurements taken from the world’s oceans in order to peer beneath the Earth’s crust and observe the chaotic nature of mantle flow, which forces the surface above it up and down. These movements have a huge influence on the way that the Earth looks today — the circulation causes the formation of mountains, volcanism and other seismic activity in locations that lie in the middle of tectonic plates, such as at Hawaii and in parts of the United States.
They found that the wave-like movements of the mantle are occurring at a rate that is an order of magnitude faster than had been previously predicted. The results, reported in the journal Nature Geoscience, have ramifications across many disciplines including the study of oceanic circulation and past climate change.
“Although we’re talking about timescales that seem incredibly long to you or me, in geological terms, the Earth’s surface bobs up and down like a yo-yo,” said Dr Mark Hoggard of Cambridge’s Department of Earth Sciences, the paper’s lead author. “Over a period of a million years, which is our standard unit of measurement, the movement of the mantle can cause the surface to move up and down by hundreds of metres.”
Besides geologists, the movement of the Earth’s mantle is of interest to the oil and gas sector, since these motions also affect the rate at which sediment is shifted around and hydrocarbons are generated.
Most of us are familiar with the concept of plate tectonics, where the movement of the rigid plates on which the continents sit creates earthquakes and volcanoes near their boundaries. The flow of the mantle acts in addition to these plate motions, as convection currents inside the mantle — similar to those at work in a pan of boiling water — push the surface up or down. For example, although the Hawaiian Islands lie in the middle of a tectonic plate, their volcanic activity is due not to the movement of the plates, but instead to the upward flow of the mantle beneath.
“We’ve never been able to accurately measure these movements before — geologists have essentially had to guess what they look like,” said Hoggard. “Over the past three decades, scientists had predicted that the movements caused continental-scale features which moved very slowly, but that’s not the case.”
The inventory of more than 2000 spot observations was determined by analysing seismic surveys of the world’s oceans. By examining variations in the depth of the ocean floor, the researchers were able to construct a global database of the mantle’s movements.
They found that the mantle convects in a chaotic fashion, but with length scales on the order of 1000 kilometres, instead of the 10,000 kilometres that had been predicted.
“These results will have wider reaching implications, such as how we map the circulation of the world’s oceans in the past, which are affected by how quickly the sea floor is moving up and down and blocking the path of water currents,” said Hoggard. “Considering that the surface is moving much faster than we had previously thought, it could also affect things like the stability of the ice caps and help us to understand past climate change.”
Reference:
M. J. Hoggard, N. White, D. Al-Attar. Global dynamic topography observations reveal limited influence of large-scale mantle flow. Nature Geoscience, 2016; DOI: 10.1038/ngeo2709
Note: The above post is reprinted from materials provided by University of Cambridge. The original story is licensed under a Creative Commons Licence.
The layers on this 2.7 billion-year-old rock, a stromatolite from Western Australia, show evidence of single-celled, photosynthetic life on the shore of a large lake. The new result suggests that this microbial life thrived despite a thin atmosphere. Credit: Roger Buick/University of Washington
The idea that the young Earth had a thicker atmosphere turns out to be wrong. New research from the University of Washington uses bubbles trapped in 2.7 billion-year-old rocks to show that air at that time exerted at most half the pressure of today’s atmosphere.
The results, published online May 9 in Nature Geoscience, reverse the commonly accepted idea that the early Earth had a thicker atmosphere to compensate for weaker sunlight. The finding also has implications for which gases were in that atmosphere, and how biology and climate worked on the early planet.
“For the longest time, people have been thinking the atmospheric pressure might have been higher back then, because the sun was fainter,” said lead author Sanjoy Som, who did the work as part of his UW doctorate in Earth and space sciences. “Our result is the opposite of what we were expecting.”
The idea of using bubbles trapped in cooling lava as a “paleobarometer” to determine the weight of air in our planet’s youth occurred decades ago to co-author Roger Buick, a UW professor of Earth and space sciences. Others had used the technique to measure the elevation of lavas a few million years old. To flip the idea and measure air pressure farther back in time, researchers needed a site where truly ancient lava had undisputedly formed at sea level.
Their field site in Western Australia was discovered by co-author Tim Blake of the University of Western Australia. There, the Beasley River has exposed 2.7 billion-year-old basalt lava. The lowest lava flow has “lava toes” that burrow into glassy shards, proving that molten lava plunged into seawater. The team drilled into the overlying lava flows to examine the size of the bubbles.
A stream of molten rock quickly cools from top and bottom, and bubbles trapped at the bottom are smaller than those at the top. The size difference records the air pressure pushing down on the lava as it cooled, 2.7 billion years ago.
Rough measurements in the field suggested a surprisingly lightweight atmosphere. More rigorous x-ray scans from several lava flows confirmed the result: The bubbles indicate that the atmospheric pressure at that time was less than half of today’s.
Earth 2.7 billion years ago was home only to single-celled microbes, sunlight was about one-fifth weaker, and the atmosphere contained no oxygen. But this finding points to conditions being even more otherworldly than previously thought. A lighter atmosphere could affect wind strength and other climate patterns, and would even alter the boiling point of liquids.
“We’re still coming to grips with the magnitude of this,” Buick said. “It’s going to take us a while to digest all the possible consequences.” Other geological evidence clearly shows liquid water on Earth at that time, so the early atmosphere must have contained more heat-trapping greenhouse gases, like methane and carbon dioxide, and less nitrogen.
The new study is an advance on the UW team’s previous work on “fossilized raindrops” that first cast doubt on the idea of a far thicker ancient atmosphere. The result also reinforces Buick’s 2015 finding that microbes were pulling nitrogen out of Earth’s atmosphere some 3 billion years ago.
“The levels of nitrogen gas have varied through Earth’s history, at least in Earth’s early history, in ways that people just haven’t even thought of before,” said co-author David Catling, a UW professor of Earth and space sciences. “People will need to rewrite the textbooks.”
The researchers will next look for other suitable rocks to confirm the findings and learn how atmospheric pressure might have varied through time.
While clues to the early Earth are scarce, it is still easier to study than planets outside our solar system, so this will help understand possible conditions and life on other planets where atmospheres might be thin and oxygen-free, like that of the early Earth.
Som is CEO of Seattle-based Blue Marble Space, a nonprofit that focuses on interdisciplinary space science research, international awareness, science education and public outreach. He currently does astrobiology research at NASA’s Ames Research Center in California.
Reference:
Sanjoy M. Som, Roger Buick, James W. Hagadorn, Tim S. Blake, John M. Perreault, Jelte P. Harnmeijer, David C. Catling. Earth’s air pressure 2.7 billion years ago constrained to less than half of modern levels. Nature Geoscience, 2016; DOI: 10.1038/NGEO2713
Note: The above post is reprinted from materials provided by University of Washington. The original item was written by Hannah Hickey.
Skeleton of Qinglongtriton, with photo (top) and interpretive drawing (bottom). Credit: Jia and Gao, 2016. CC-BY
Salamanders are fairly adorable, but often forgotten, animals. Because their skeletons are pretty delicate, the fossil record for this group is spotty, with many ancient forms known only from vertebrae or jaw bones. As has happened for many other vertebrate groups (including birds, mammals, and small dinosaurs), exquisitely preserved fossils from the Mesozoic of China are filling previous gaps in evolutionary history. The latest such salamander discovery was announced today in PLOS ONE.
Qinglongtriton gangouensis is named on the basis of 46 nearly complete skeletons from the Tiaojishan Formation of Hebei Province, China. With such a large sample, the fossils of Qinglongtriton capture many of the details of growth and variation in this animal. For instance, the animal was neotenic–meaning that it retained “juvenile” features such as external gill filaments into adulthood. A parallel example occurs today in axolotls and mudpuppies. Qinglongtriton probably would have been pretty recognizable as a salamander, and at its longest measured around 27 cm from tip to tail (just over 10 inches).
The rocks in which the fossils were discovered date to around 160 million years ago, near the close of the Jurassic Period and just a touch older than famous North American dinosaurs such as Stegosaurus and Brontosaurus. When placed into its evolutionary context, Qinglongtriton ends up as one of the oldest and earliest diverging salamandroids. Salamandroids include everything from mudpuppies to newts to tiger salamanders. They are colloquially known as “advanced salamanders,” for a host of anatomical features that contrast with the primitive condition for amphibians. Their closest relatives are the cryptobranchoids, which include the giant salamanders and others. In conjunction with Beiyanerpeton (another salamandroid from the same rocks as Qinglongtriton), and the Jurassic cryptobranchoid Pangerpeton, the split between the two major groups of modern salamanders can be dated to no later than the Late Jurassic.
So, the fossil record for salamanders is just a little bit better now, and we know more about their history than we did previously. Qinglongtriton and its friends point the way to the potential for even older salamanders–they’re just another expedition away!
Reference:
Jia Jia et al. A New Basal Salamandroid (Amphibia, Urodela) from the Late Jurassic of Qinglong, Hebei Province, China, PLOS ONE (2016). DOI: 10.1371/journal.pone.0153834
Power plants burned coal that released sulfur into the atmosphere, but coal use has declined. Today, coal plants use scrubbers to remove sulfur, or burn low-sulfur western coal. This has led to a large decrease in sulfur emissions, and less atmospheric deposition of sulfate to agricultural fields–and consequently, declining sulfate concentrations in rivers. Groundwater can be another source of sulfur in rivers when it comes in contact with underground coal or pyrite seams. In this sample from an Illinois mine, pyrite is visible as gold flecks in the center of the coal. Credit: Debra Levey Larson
With the move from burning coal to natural gas and low-sulfur coal and an increase in the use of scrubbers, only about 25 percent as much atmospheric sulfur is available today, compared to 40 years ago.
Sulfur balances in agricultural fields are now negative, with more removed each year in crop harvests and leaching than is added from fertilizers and deposition.
Fields with tile drainage move sulfate quickly to surface waters, contributing to the low levels in the soil.
Rivers in agricultural watersheds have declining sulfate concentrations, a direct response to declining atmospheric deposition.
Farmers may need to apply sulfur fertilizer at some point in the future, particularly on fields with less soil organic matter.
URBANA, Ill. – Air pollution legislation to control fossil fuel emissions and the associated acid rain has worked – perhaps leading to the need for sulfur fertilizers for crop production. A University of Illinois study drawing from over 20 years of data shows that sulfur levels in Midwest watersheds and rivers have steadily declined, so much so that farmers may need to consider applying sulfur in the not too distant future.
“We don’t think there are actual sulfur deficiencies yet, but clearly more sulfur is coming out of the soil and water than what is going in,” says U of I biogeochemist Mark David. “As the Clean Air Act and amendments have taken effect there has been a reduction in sulfur emissions from coal combustion, so that the amount of atmospheric sulfur deposited each year is only 25 percent of what it used to be. At some point, farmers are going to have to fertilize with sulfur.”
David says farmers whose fields have fine-textured soils that are high in organic matter have less of a concern. “For many, it could be 10 or 20 years from now, but for some, particularly those farming on poorer soils, it’ll be sooner. Farmers whose fields have poorer soil or notice a yield reduction may want to have their soil tested for sulfate. If it registers low, they can consider applying fertilizer.”
David explains that sulfur in soil comes from two main sources. It’s in the air from fossil fuel combustion and in groundwater where water has come in contact with coal or pyrite seams. It comes out of the soil through tile-drained fields and it is taken up into plants as they grow and are then harvested. Most fields in Illinois do not receive fertilizers containing sulfur. Some in the Embarras and Kaskaskia watersheds apply ammonium sulfate, which adds not just nitrogen, but also sulfur.
In their study, David and his team analyzed data from three rivers in east-central Illinois at times when the flow was high and low from the field drainage tiles and the rivers. Sulfate concentrations were greatest in the Salt Fork River, followed by the Embarras, and then the Kaskaskia Rivers.
“As we go from northeast to southwest across this part of Illinois, the sulfate that we think is from groundwater near coal seams, decreases. In the Tuscola and Atwood areas, we don’t think there are any groundwater sulfate inputs. When we looked at a whole variety of fields with tile drainage systems, we found that some had very low sulfate concentrations – just a few milligrams per liter. One farm in our study had applied bed ash from a power plant. We saw high concentrations of sulfate in that field. There’s no doubt that it boosted the level of sulfur. But over the next three or four years most of it had washed out through the tile system,” co-author and U of I agronomist Lowell Gentry says.
The long-term nature of the study allowed the team to do watershed balances and look at the inputs and outputs of the sulfur “budget” for the area.
“That balance is negative, with greater outputs from harvest and leaching, than inputs from atmospheric deposition and fertilizers, so what is missing is coming from the soil. There is a lot of sulfur in soil in organic forms and that’s being slowly depleted. At some point, there won’t be enough to keep up with what the crop needs. That’s when farmers will need to add fertilizer,” Gentry says.
David began his career in the 1980s studying the effects of acid rain – a main ingredient of which is sulfur. “Back then no one ever thought about fertilizing with sulfur because there was always plenty of atmospheric sulfur available from burning coal.”
The samples David collected over the past two decades were primarily used to track nitrates that enter the rivers via drainage tiles in agricultural fields, and eventually reach the Gulf of Mexico. He says that unlike nitrate, “sulfate is not a problem in Midwestern streams and rivers. It’s not like other chemicals that cause problems downstream and in the Gulf.”
David believes that this is the first study looking at long-term trends in sulfur in agricultural areas. “Most of the studies about atmospheric deposition in sulfur have been in forested watersheds in the northeast where lakes were acidified, such as in the Adirondack Mountains in New York and in streams in the Appalachian Mountains, areas that were sensitive to acid rain. Sulfate is more of a problem in the northeast in forest soils,” he says.
Arches National Park is a US National Park in eastern Utah. The park is located on the Colorado River 4 miles (6 km) north of Moab, Utah. It is known for containing over 2,000 natural sandstone arches, including the world-famous Delicate Arch, in addition to a variety of unique geological resources and formations.
The park is located just outside Moab, Utah, and is 76,679 acres (119.811 sq mi; 31,031 ha; 310.31 km2) in area. Its highest elevation is 5,653 feet (1,723 m) at Elephant Butte, and its lowest elevation is 4,085 feet (1,245 m) at the visitor center. Forty-three arches are known to have collapsed since 1977. The park receives 10 inches (250 mm) of rain a year on average.
Administered by the National Park Service, the area was originally named a National Monument on April 12, 1929. It was redesignated as a National Park on November 12, 1971.
Geology
The national park lies atop an underground evaporite layer or salt bed, which is the main cause of the formation of the arches, spires, balanced rocks, sandstone fins, and eroded monoliths in the area. This salt bed is thousands of feet thick in places, and was deposited in the Paradox Basin of the Colorado Plateau some 300 million years ago when a sea flowed into the region and eventually evaporated. Over millions of years, the salt bed was covered with debris eroded from the Uncompahgre Uplift to the northeast. During the Early Jurassic (about 210 Ma) desert conditions prevailed in the region and the vast Navajo Sandstone was deposited. An additional sequence of stream laid and windblown sediments, the Entrada Sandstone (about 140 Ma), was deposited on top of the Navajo. Over 5000 feet (1500 m) of younger sediments were deposited and have been mostly eroded away. Remnants of the cover exist in the area including exposures of the Cretaceous Mancos Shale. The arches of the area are developed mostly within the Entrada formation.
The weight of this cover caused the salt bed below it to liquefy and thrust up layers of rock into salt domes. The evaporites of the area formed more unusual salt anticlines or linear regions of uplift. Faulting occurred and whole sections of rock subsided into the areas between the domes. In some places, they turned almost on edge. The result of one such 2,500-foot (760 m) displacement, the Moab Fault, is seen from the visitor center.
As this subsurface movement of salt shaped the landscape, erosion removed the younger rock layers from the surface. Except for isolated remnants, the major formations visible in the park today are the salmon-colored Entrada Sandstone, in which most of the arches form, and the buff-colored Navajo Sandstone. These are visible in layer cake fashion throughout most of the park. Over time, water seeped into the surface cracks, joints, and folds of these layers. Ice formed in the fissures, expanding and putting pressure on surrounding rock, breaking off bits and pieces. Winds later cleaned out the loose particles. A series of free-standing fins remained. Wind and water attacked these fins until, in some, the cementing material gave way and chunks of rock tumbled out. Many damaged fins collapsed. Others, with the right degree of hardness and balance, survived despite their missing sections. These became the famous arches.
Although the park’s terrain appears rugged and durable, it is the exact opposite. More than 700,000 visitors each year threaten the fragile high desert ecosystem. The problem lies within the soil’s crust which is composed of cyanobacteria, algae, fungi, and lichens that grow in the dusty parts of the park. Factors that make Arches National Park sensitive to visitor damage include: semiarid region, and the scarce, unpredictable rainfall, lack of deep freezing, and lack of plant litter which results in soils that have both a low resistance to, and slow recovery from, compressional forces such as foot traffic. Methods of indicating effects on the soil are cytophobic soil crust index, measuring of water infiltration, and t-tests that are used to compare the values from the undisturbed and disturbed areas.
Photo
Credit:National Park ServiceCredit:National Park ServiceCredit:National Park ServiceCredit:National Park ServiceCredit:National Park ServiceCredit:National Park ServiceCredit:National Park ServiceCredit:National Park ServiceCredit:National Park ServiceCredit:National Park ServiceCredit:National Park ServiceCredit:National Park ServiceCredit:National Park ServiceCredit:National Park Service
Researchers have found that the dehydration of chlorite is likely crucial in explaining the high electrical conductivity observed in the Earth’s mantle. Credit: Johan Swanepoel via Getty Images
A team of scientists, including one at Lawrence Livermore National Laboratory (LLNL), has found that the dehydration of chlorite is likely to be crucial in explaining the anomalously high electrical conductivity observed in the Earth’s mantle.
The high electrical conductivity (EC) in the mantle wedge regions between depths of 40 and 100 km is often attributed to the aqueous fluid released from descending slabs. It is well known that mantle silicate minerals are electrical insulators with large electronic band gaps of around 7.5 to 9.5 electron volts (eV) at room temperature.
Laboratory-based measurements of the electrical conductivity of hydrous phases and aqueous fluids are significantly lower and cannot readily explain the geophysically observed high electrical conductivity. The released aqueous fluid also rehydrates the mantle wedge and stabilizes a suite of hydrous phases, including serpentine and chlorite.
The new research, appearing in the May 6 edition of the journal Science Advances, shows that the EC of chlorite is similar to other hydrous silicate minerals. The EC has a weak or no-pressure dependence but varies significantly with temperature.
“We have measured the electrical conductivity of a natural chlorite at pressures and temperatures relevant for the subduction zone setting,” said Davide Novella, a geophysicist at LLNL. “In our experiment, we observed two distinct conductivity enhancements when chlorite is heated to temperatures beyond its thermodynamic stability field. The initial increase in electrical conductivity can be attributed to chlorite dehydration and the release of aqueous fluids. This is followed by a unique, subsequent enhancement of electrical conductivity.”
The team found that the further increase in EC is related to the growth of an interconnected network of highly conductive and chemically impure magnetite mineral phases.
“The dehydration of chlorite and associated processes are likely to be crucial in explaining the anomalously high electrical conductivity observed in mantle wedges,” Novella said. “Chlorite dehydration in the mantle wedge provides an additional source of aqueous fluid above the slab and also could be responsible for the fixed depth (120 ± 40 km) of melting at the top of the subducting slab.”
Reference:
G. Manthilake et al. Dehydration of chlorite explains anomalously high electrical conductivity in the mantle wedges, Science Advances (2016). DOI: 10.1126/sciadv.1501631
Mosasaurus hoffmannii holotype jaw fragments (great animal from Maastricht specimen), Muséum national d’histoire naturelle, Paris. Credit: FunkMonk/Wikipedia
Mosasaurs — an extinct group of aquatic reptiles that thrived during the Late Cretaceous period — possibly were “endotherms,” or warm-blooded creatures, a paper co-written by a UA professor suggests.
Dr. Alberto Perez-Huerta’s paper on endothermic mosasaurs — co-written with now-graduated doctoral student Dr. T. Lynn Harrell Jr. and Dr. Celina Suarez of the University of Arkansas — was published in a March issue of Palaeontology, a journal published by the Palaeontological Association.
Mosasurs were large aquatic reptiles that went extinct at the end of the Cretaceous period, about 66 million years ago. The paper focuses on a debate in the paleontological community over how mosasaurs employed “thermaregulation,” or how they controlled their body heat — whether mosasaurs were endotherms (warm-blooded) or ectotherms, cold-blooded creatures taking their body temperature from the surrounding sea.
A paper published in 2010 suggested that mosasaurs were ectotherms, but Harrell and Perez-Huerta thought otherwise.
“There was a paper published in Science in 2010 reporting the thermoregulation in marine reptiles at the time of the dinosaurs focusing on the iconic extinct taxa: ichthyosaurs, plesiosaurs and mosasaurs,” said Perez-Huerta, a UA associate professor of geology. “This conclusion bothered me a bit because there was not a warm-blooded member organism used for comparison, and we know that size can matter in terms of thermoregulation.”
The study by Harrell (lead author), Perez-Huerta and Suarez used an oxygen isotope analysis on mosasaurs fossils in the collection of UA’s Alabama Museum of Natural History and compared them to fossils of known cold-blooded animals, such as fish and turtles, from the same period, as well as the bones of such contemporary warm-blooded organisms represented by birds — “true” endotherms.
“Lynn came up with good ideas for two chapters of his dissertation, already published as well,” Perez-Huerta said. “We discussed looking for endothermy in mosasaurs given his knowledge on this group of extinct marine reptiles, the large collections of these fossil organisms in the Alabama Museum of Natural History and the scientific controversy related to the Science paper.”
The study states that mosasurs’ body-temperatures compared to the temperatures of modern, warm-blooded sea birds, suggesting that mosausurs were indeed warm-blooded. The study found that this tendency toward higher body temperature held despite the size of the particular mosasur genus or species — body size (gigantothermy) didn’t matter.
“The findings of the present study support that mosasaurs were able to maintain a higher internal temperature independent of the ambient seawater temperature and were likely endotherms, with values closer to contemporaneous fossil and modern birds and higher than fish and turtles,” the researchers said. “Although there are small differences of body temperature among mosasaur genera, these are independent of size, and thus inferred body mass, suggesting that mosasaurs were not gigantotherms.”
Perez-Huerta noted that the study was possible thanks to the Alabama Museum of Natural History’s extensive collection.
“This research study was the ‘perfect storm’ because Lynn is a very good vertebrate paleontologist, amazing collections at the natural-history museum — one of the best in North America for mosasaurs,” Perez-Huerta said. “There are great outcroppings containing mosasaur fossils in Alabama. This research could not have been possible with the great fossil collections housed at the history museum on the University’s campus, and the collaboration of their staff to facilitate our access.”
Reference:
T. Lynn Harrell, Alberto Pérez-Huerta, Celina A. Suarez. Endothermic mosasaurs? Possible thermoregulation of Late Cretaceous mosasaurs (Reptilia, Squamata) indicated by stable oxygen isotopes in fossil bioapatite in comparison with coeval marine fish and pelagic seabirds. Palaeontology, 2016; 59 (3): 351 DOI: 10.1111/pala.12240
A map of ancient human migration. The black numbers indicate how many years ago the migrations took place. Credit: Wikipedia
“Forget this image,” says Dimitra Papagianni, pointing at the depiction of human evolution projected behind her: an ape crouched on all fours, followed by the early hominids carrying rock tools and spears, walking ultimately to the modern human form. While the image is iconic, Papagianni explains that the casual saunter from species to species doesn’t do justice to the 2-million-year epic story of how modern humans beat out their Neanderthal cousins to survive and thrive in the bitterly cold lands of modern day Europe.
Last Wednesday Papagianni, a researcher from the Centre for Archaeology of Human Origins at the University of Southampton, gave the inaugural seminar for the newly minted Center for Climate and Life at Columbia University and the Lamont-Doherty Earth Observatory. In her talk, titled “The Neanderthal Paradox,” she explained the differences between the Neanderthals, a species that went extinct, and the ancient humans, our tropical-adapted forebears that would defy all odds and usurp Neanderthals as they migrated from Africa and into the chilly north. It was a talk that wove together culture, climate change, genetics and evolution. Overall, it was an apt introduction to usher in this new division of Climate and Life.
Though they were closely related, Neanderthals and ancient humans were different species. Papagianni compared the skull of a Neanderthal to that of a human. The difference is clear. “Think of the skull of a human as a soccer ball, and the skull of a Neanderthal as a football,” she says. This sports analogy goes a step further. Like a soccer player, humans are lean and well-suited to running. Neanderthals have stocky statures and barrel chests, more like the stereotypical football player. Because of this, Neanderthals were better adapted to colder weather than ancient humans who originated in the tropical climates of Africa.
“What you likely know about Neanderthals,” Papagianni says, “it’s that they’re supposed to be stupid.” This is a tough rap, but archaeological research suggests they were advanced enough to make clothes and build fires, which would have been critical to survive the cold weather. They also used stone tools. Additionally, based on the size of their skulls, the brains housed with them were likely large enough to warrant some form of language capability. This language hypothesis is supported by modern experiments that show learning how to make and wield stone tools required some form of verbal instruction.
Papagianni laughed as she described the experiment. Groups of graduate students attempted to learn how to make stone tools with and without verbal cues. Even after hours of work, fashioning a working Neanderthal-style tool from stone was near impossible without some form of verbal instruction.
Given their adaptation to cold climes and their advanced, albeit under-appreciated, skills, how were Neanderthals beaten out by their human counterparts? The answer lies in a combination of culture and genetics that enabled the successful radiation of humans.
Humans had diets higher in energy-rich meat that could support smaller stomachs and bigger brains. They invented tools with multiple uses that could adapt to different circumstances. They had more advanced language capabilities to pass on these skills. They were smarter; one could almost say they had more culture. “And if you’re smart and you can speak,” Papagianni quips, “you want to go to Europe.”
So the humans migrated north. This is where the genetic factors come into play. Neanderthal communities became fractured. As they grew more and more isolated, their gene pool evaporated into a spattering of puddles. This so called genetic bottleneck can lead to the demise of a species when genetic diversity gets prohibitively low.
Papagianni explained the current theories for how humans were able to persist in the North at the expense of Neanderthals, but she ended on an ongoing research question: Why did humans leave Africa in the first place? Their migration could have been sparked by competition, climate change or simply a great hallmark of human nature, curiosity. Over the past 2 million years, humans have proven to be a remarkably successful species. In fact, humans are the only species on the planet with a global distribution. In order to figure out how we might fare in the future with a changing planet, it’s critical to get insight from our past. The research of Papagianni, as well as the new Center for Climate and Life, will yield this essential insight into Earth’s past and future, and our place within it.
The new trace fossil is dated from 8 million years ago and consists of two vertical and parallel shafts linked to each other through a horizontal and C-shaped gallery. Credit: Image courtesy of Universidad de Barcelona
Lepeichnus giberti is the name of the new trace fossil of the upper Miocene, very complex and exceptionally preserved, found in the town of Lepe (Huelva) and introduced in the magazine’s Palaeogeography, Palaeoclimatology, Palaeoecology article.
The new work is signed by the experts Zain Belaústegui, Jordi Martinell and Rosa Domènech, members of the PaleoNeoMar group from the Department of Earth and Ocean’s Dynamics and the Institute for Research on Biodiversity of UB (IRBio); Fernando Muñiz (University of Huelva) and Maria Gabriela Mangano and Luis A. Buatois (University of Saskatchewan, Canada).
Chasing fossils’ prints from the past
Ichnology is a palaeontology discipline which studies trace fossils or prints which have been left by the organisms’ activity in the past. The importance of the ichnofossils lies within three main points: most of them are preserved in situ -they provide direct information from the paleoenvironment in which they were generated; they represent the record of the produced animal’s behaviour (palaeontology and paleoecology) which is usually linked to the paleoenvironment, and they are often the only record of certain organisms- such as the ones with soft bodies- whose body characteristics enable their no-fossilization.
According to Dr. Zain Belaústegui (UB-IRBio), the main author of the article, “in general, Lepeichnus giberti is a new and exceptional ichnotaxon which consists of two vertical and parallel shafts connected to each other by a horizontal and C-shaped gallery, from which a hook-shaped branch is ratified. This morphological pattern is extremely regular and it always happens again in all studied specimens.
“The exceptional character of the L. giberti -he continues- is due to the -first- findings of the fossil records of each of the evolution stages of a fossil trace, from its origins to the final phase. This has enabled us to describe with a lot of more details how the generation process was 6 million years ago, i.e. its ichnogeny. Actually, 9 different and consecutive ichnogenetic phases have been identified within the L. giberti ichnogeny.”
“It is as if we would currently monitor a burrowing organism and took a series of pictures of its burrowing process… This is exactly what we have seen with L. giberti, but instead of pictures, these stages have been kept as fossils” says Belaústegui.
An exceptionally preserved ichnofossil
Ichnotaxons are the terms used by the ichnologists in order to list and classify these trace fossils with defined traits. The preserving state of the L. giberti is exceptional: the sandy silt which filled these burrows — after being abandoned by their organisms -and the following ferruginization of its walls has helped the preservation of the most delicate details (such as the scars probably done by the organism’s appendix). This sandy silt has also helped to its collection; around 90 complete samples with its intact three-dimensional morphology have been collected.
“Everything -said Belaústegui- has enabled us proposing by comparing it to modern burrows. The presence of different sized samples (from 1 to 10 cm of maximum width) and identic morphology have been seen, something which would mean that the producing organism would have the same burrowing behaviour in both young and adult phases. In the restoration and preparation process for the thin layers and sections of the L. giberti specimen, the participation of Dr. Alejandro Gallardo, technic of the mentioned Department of the Faculty of Earth Sciences of the University of Barcelona, should be mentioned.
A sea-linked paleoenvironment
6 million years ago the area where the fossil lies was a bay which was not very deep and was protected from waves and storms, probably affected by tides and with depths rich in organic fields and nutrients. “These would be the ideal conditions to gather big communities of the species (probably a swimming crustacean) which the Lepeichnus dag, because we have found around 93 burrows per square meter. Other organisms, such as anemones, another kind of crustaceans, and even cetaceans would have lived in this area” says Belaústegui.
At this moment there is no knowledge of any current organism which digs a burrow with the same characteristics of L. giberti’s. However, a great amount of the morphological traits noticed in modern upogebiid burrows -a kind of crustacean that digs burrows in the sea bottom- are similar to Lepeichnus’s.
“Since the similarities are not total -says Belaústegui- we present this kind of decapodes as the probable producers of L.giberti. The fact that there isn’t any identical analogue would be due to Lepeichnus being an already extinct burrowing behaviour upogebiid.”
Ichnogeny: a new concept in the world of Ichnology
The ichnotaxons are quite common within the fossil records but less than the ones related to animals or plants. The exceptional degree of preservation and fossilization of the different evolution stages of the L. giberti has enabled us proposing the new term “ichnogeny” -of great interest within the Ichnology field.
This new term describes the origins and evolution of a modern or fossil bioturbation structure (burrows, prints, traces, etc. produced in soft non-cemented substrates) or bioerosion (holes, bite marks, etc. produced in hard cemented substrates). Like the authors say, ichnogeny (creation and development of a fossil trace) can be a process depending (or not) on ontogeny (origins and evolution of an organism).
“Let’s imagine, for instance, a footprint. The formation process of the footprint, its ichogeny (first the heel, then the sole and last the toes) is the same, be it a baby, teenager, adult or old person. In this scenario, ontogeny and inchogeny are independent from each other. However, it could be possible for them to be related. For instance, now they are known as “flies” (Symplecta genre) that have different burrowing behaviours according to the particular ontogenetic state they are in (larva, pupa or adult). In any of the cases, each inchogeny will be the same, the larva will always generate a certain kind of trace in the same way, and the same happens with pupa and so on” says Belaústegui.
The palaeontology richness in the south of the Iberian Peninsula
The new fossil Lepeichnus giberti pays homage to the town of Lepe -a place with great ichnology interest where ichnofossil was found- and in memory of Dr. Jordi Maria de Gibert Atienza, member of the PaleoNeoMar group of the UB and distinguished leader of the country’s ichnology research. The first indicators of this ichnotaxon were found in 1955 by Dr. Fernando Muñiz (University of Huelva) during his doctoral thesis, and he preliminary presented it by himself (without giving it an official name) during the Spanish Society Palaeontology Sessions in 1999.
It is worth remembering that in 2010, due to the ichnology importance in Lepe, the research group PaleoNeoMar of the UB and Dr. Fernando Muñis organized an international conference in this town- about crustacean bioturbation (Workshop on Crustacean Bioturbation — Lepe 2010). And again, in May 2016, this area will be visited by the participants of ICHNIA, the international conference for Ichnology with the greatest projection worldwide, which will be held from the 6th to 9th of May in the Global Naturtejo Geopark of Idanha-a-Nova (Portugal).
Reference:
Zain Belaústegui, Fernando Muñiz, M. Gabriela Mángano, Luis A. Buatois, Rosa Domènech, Jordi Martinell. Lepeichnus giberti igen. nov. isp. nov. from the upper Miocene of Lepe (Huelva, SW Spain): Evidence for its origin and development with proposal of a new concept, ichnogeny. Palaeogeography, Palaeoclimatology, Palaeoecology, 2016; 452: 80 DOI: 10.1016/j.palaeo.2016.04.018
Prepared skulls of newly discovered specimens of Atopodentatus unicus, (A) in dorsal view (IVPP V20291), (B) in ventral view (IVPP V20292). Scale bar, 2 cm. Credit: IVPP
Some strange creatures cropped up in the wake of one of Earth’s biggest mass extinctions 252 million years ago. In 2014, scientists discovered a bizarre fossil–a crocodile-sized sea-dwelling reptile, Atopodentatus unicus, that lived 242 million years ago in what today is southwestern China. Its head was poorly preserved, but it seemed to have a flamingo-like beak. However, in a paper published May 6 in Science Advances, Dr. LI Chun, Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) of the Chinese Academy of Sciences, and his international team described two new specimens and revealed what was really going on–that “beak” is actually part of a hammerhead-shaped jaw apparatus, which it used to feed on plants on the ocean floor. It’s the earliest known example of an herbivorous marine reptile.
These two newly discovered specimens of Atopodentatus were collected from the Middle Triassic (Anisian) Guanling Formation of Luoping County, Yunnan Province, southwestern China. The new specimens clearly demonstrate that rather than being downturned, the rostrum was developed into a “hammerhead” with pronounced lateral processes formed by the premaxillae and maxillae in the upper jaw and mirrored by the dentary in the lower jaw, said the team.
“We confirm the presence of fine and densely packed needle-shaped teeth in the ramus of the dentaries and maxillae, but the premaxillary teeth are arranged along the anterior edge of the element and are more robust and peg-like in form”, said lead author LI Chun.
The wide jaw of Atopodentatus was shaped like a hammerhead, and along the edge, it had peg-like teeth. Then, further into its mouth, it had bunches of needle-like teeth. “That arrangement wouldn’t have been too useful for chewing prey”, said study co-author Olivier Rieppel, Field Museum of Natural History, “It’s more likely that Atopodentatus used its front teeth to nip algae or other plants from rocky surfaces and then, with its mouth closed, forced mouthfuls of water through its side teeth, which acted as a filter trapping the plants and letting the water back out, like how whales filter-feed with their baleen”.
Atopodentatus is thus the oldest known vegetarian among marine reptiles. It is older than other marine animals that ate plants with a filter-feeding system by about eight million years, said the team.
Atopodentatus appeared during the Triassic Period relatively soon after the biggest mass extinction of species in Earth’s history, illustrating that life recovered and diversified more quickly than previously thought. Other oddball creatures also swam the seas at the time, including a reptile called Dinocephalosaurus whose neck comprised half of its 17-foot (5.25 meters) length.
“Atopodentatus, about 9 feet (2.75 meters) long, lived in a shallow sea in China’s Yunnan province alongside fish and other marine reptiles, said study co-author CHENG Long, Wuhan Centre of China Geological Survey, “When thinking of hammerhead creatures, sharks may come to mind. But Atopodentatus’ hammerhead feature differed in location and function from the sharks, whose eyes are on the end of lateral extensions on their head.”
“Overall, the creature is so unusual that it’s difficult to tell where it fits on the reptile family tree”, said Dr. Nicholas Fraser, co-corresponding author of the study, National Museums Scotland, “Because its fossils are relatively complete, paleontologists will probably need to unearth fossils of yet-to-be-discovered relatives to better figure this out. In the meantime, Atopodentatus seems to be most closely related to the plesiosaurs, the typically long-necked marine reptiles that often were top predators in dinosaur-era oceans.”
