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New Dinosaur Species With Spiky Backbone Discovered in Argentina

dinosaur, Earth History, Fossils 5:58 PM

New Dinosaur Species With Spiky Backbone Discovered in Argentina

A replica of the skull and neck of the "Bajadasaurus pronuspinax," a new species of sauropod discovered in Patagonia Pale...

Massive Bolivian Earthquake Reveals Mountains 660 Kilometers Below Earth's Surface

earth, Geology, Tectonic 11:02 AM

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<tr><td class="tr-caption" style="text-align: center;">Scientists aren't sure how high the underground mountains are, but said they could be bigger than anything above Earth's surface<br />
Credit: THE SUN</td></tr>
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<span style="font-family: "arial" , "helvetica" , sans-serif;"><span style="font-family: "georgia" , "times new roman" , serif;">Mountains buried 400 miles underground ‘could be BIGGER than Everest’ – and were only found after massive Bolivian Earthquake</span></span></h4>
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<span style="font-family: "arial" , "helvetica" , sans-serif;"><span style="font-family: "georgia" , "times new roman" , serif;">Most schoolchildren learn that the Earth has three (or four) layers: a crust, mantle and core, which is sometimes subdivided into an inner and outer core. That's not wrong, but it does leave out several other layers that scientists have identified within the Earth.</span><br />
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In a study published this week in Science, Princeton geophysicists Jessica Irving and Wenbo Wu, in collaboration with Sidao Ni from the Institute of Geodesy and Geophysics in China, used data from an enormous earthquake in Bolivia to find mountains and other topography on a layer located 660 kilometers (410 miles) straight down, which separates the upper and lower mantle. (Lacking a formal name for this layer, the researchers simply call it "the 660-km boundary.")<br />
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To peer deep into the Earth, scientists use the most powerful waves on the planet, which are generated by massive earthquakes. "You want a big, deep earthquake to get the whole planet to shake," said Irving, an assistant professor of geosciences.<br />
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<span style="font-family: "arial" , "helvetica" , sans-serif;">Big earthquakes are vastly more powerful than small ones -- energy increases 30-fold with every step up the Richter scale -- and deep earthquakes, "instead of frittering away their energy in the crust, can get the whole mantle going," Irving said. She gets her best data from earthquakes that are magnitude 7.0 or higher, she said, as the shockwaves they send out in all directions can travel through the core to the other side of the planet -- and back again. For this study, the key data came from waves picked up after a magnitude 8.2 earthquake -- the second-largest deep earthquake ever recorded -- that shook Bolivia in 1994.<br />
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"Earthquakes this big don't come along very often," she said. "We're lucky now that we have so many more seismometers than we did even 20 years ago. Seismology is a different field than it was 20 years ago, between instruments and computational resources."<br />
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Seismologists and data scientists use powerful computers, including Princeton's Tiger supercomputer cluster, to simulate the complicated behavior of scattering waves in the deep Earth.<br />
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The technology depends on a fundamental property of waves: their ability to bend and bounce. Just as light waves can bounce (reflect) off a mirror or bend (refract) when passing through a prism, earthquake waves travel straight through homogenous rocks but reflect or refract when they encounter any boundary or roughness.<br />
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"We know that almost all objects have surface roughness and therefore scatter light," said Wu, the lead author on the new paper, who just completed his geosciences Ph.D. and is now a postdoctoral researcher at the California Institute of Technology. "That's why we can see these objects -- the scattering waves carry the information about the surface's roughness. In this study, we investigated scattered seismic waves traveling inside the Earth to constrain the roughness of the Earth's 660-km boundary."<br />
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The researchers were surprised by just how rough that boundary is -- rougher than the surface layer that we all live on. "In other words, stronger topography than the Rocky Mountains or the Appalachians is present at the 660-km boundary," said Wu. Their statistical model didn't allow for precise height determinations, but there's a chance that these mountains are bigger than anything on the surface of the Earth. The roughness wasn't equally distributed, either; just as the crust's surface has smooth ocean floors and massive mountains, the 660-km boundary has rough areas and smooth patches. The researchers also examined a layer 410 kilometers (255 miles) down, at the top of the mid-mantle "transition zone," and they did not find similar roughness.<br />
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"They find that Earth's deep layers are just as complicated as what we observe at the surface," said seismologist Christine Houser, an assistant professor at the Tokyo Institute of Technology who was not involved in this research. "To find 2-mile (1-3 km) elevation changes on a boundary that is over 400 miles (660 km) deep using waves that travel through the entire Earth and back is an inspiring feat. ... Their findings suggest that as earthquakes occur and seismic instruments become more sophisticated and expand into new areas, we will continue to detect new small-scale signals which reveal new properties of Earth's layers."</span></div>
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<span style="font-family: "arial" , "helvetica" , sans-serif;"><span style="font-family: "georgia" , "times new roman" , serif;">What it means</span></span></h4>
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<span style="font-family: "arial" , "helvetica" , sans-serif;">The presence of roughness on the 660-km boundary has significant implications for understanding how our planet formed and continues to function. That layer divides the mantle, which makes up about 84 percent of the Earth's volume, into its upper and lower sections. For years, geoscientists have debated just how important that boundary is. In particular, they have investigated how heat travels through the mantle -- whether hot rocks are carried smoothly from the core-mantle boundary (almost 2,000 miles down) all the way up to the top of the mantle, or whether that transfer is interrupted at this layer. Some geochemical and mineralogical evidence suggests that the upper and lower mantle are chemically different, which supports the idea that the two sections don't mix thermally or physically. Other observations suggest no chemical difference between the upper and lower mantle, leading some to argue for what's called a "well-mixed mantle," with both the upper and lower mantle participating in the same heat-transfer cycle.<br />
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"Our findings provide insight into this question," said Wu. Their data suggests that both groups might be partially right. The smoother areas of the 660-km boundary could result from more thorough vertical mixing, while the rougher, mountainous areas may have formed where the upper and lower mantle don't mix as well.<br />
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In addition, the roughness the researchers found, which existed at large, moderate and small scales, could theoretically be caused by heat anomalies or chemical heterogeneities. But because of how heat in transported within the mantle, Wu explained, any small-scale thermal anomaly would be smoothed out within a million years. That leaves only chemical differences to explain the small-scale roughness they found.<br />
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What could cause significant chemical differences? The introduction of rocks that used to belong to the crust, now resting quietly in the mantle. Scientists have long debated the fate of the slabs of sea floor that get pushed into the mantle at subduction zones, the collisions happening found all around the Pacific Ocean and elsewhere around the world. Wu and Irving suggest that remnants of these slabs may now be just above or just below the 660-km boundary.<br />
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"It's easy to assume, given we can only detect seismic waves traveling through the Earth in its current state, that seismologists can't help understand how Earth's interior has changed over the past 4.5 billion years," said Irving. "What's exciting about these results is that they give us new information to understand the fate of ancient tectonic plates which have descended into the mantle, and where ancient mantle material might still reside."<br />
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She added: "Seismology is most exciting when it lets us better understand our planet's interior in both space and time."</span><br />
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</span><u><i><span style="font-family: "trebuchet ms" , sans-serif;">The above story is based on <a href="https://www.princeton.edu/news/2019/02/14/massive-1994-bolivian-earthquake-reveals-mountains-660-kilometers-below-our-feet" rel="nofollow" target="_blank">Materials</a> provided by <a href="http://www.princeton.edu/" rel="nofollow" target="_blank">Princeton University</a>. Original written by Liz Fuller-Wright.</span></i></u></div>
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Massive Bolivian Earthquake Reveals Mountains 660 Kilometers Below Earth's Surface

Scientists aren't sure how high the underground mountains are, but said they could be bigger than anything above Earth's surface ...

Mantle Plumes Can Destroy Diamonds

Diamonds, Earth History 7:37 PM

Mantle Plumes Can Destroy Diamonds

Examples of rough diamonds from the Letseng mine, Lesotho Kimberlites (pipe-like bodies) are the host rocks for the majority of dia...

Giant Dinosaur Trackway Discovered in Queensland

dinosaur, Earth History 6:09 PM

Giant Dinosaur Trackway Discovered in Queensland

The three dinosaur footprint types found at the site: the left footprints of a sauropod (outlined in blue). Credit: Swinburne University ...

Rare Spider Fossil Preserves 100-Million-Year-Old Glowing Eyes

Earth History, Fossils 5:42 PM

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<tr><td class="tr-caption" style="text-align: center;">Flint rock preserved characteristics of the spider fossils differently than the more common amber-preserved spiders. Glowing Spider Eyes, Revealed by Fossil Preserved in Rock</td></tr>
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</span> <span style="font-family: "arial" , "helvetica" , sans-serif;"><span style="font-family: "georgia" , "times new roman" , serif;">Usually, soft-bodied species like spiders aren't fossilized in rock like animals with bones and teeth. More often, ancient spiders and insects are more likely to be discovered preserved in amber.</span><br />
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Yet a new paper in the Journal of Systematic Palaeontology, co-written by a University of Kansas researcher, describes fossil spiders found in an area of Korean shale called the Lower Cretaceous Jinju Formation.<br />
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What's most remarkable: Two of the fossils from the extinct spider family Lagonomegopidae feature reflective eyes that enabled their nighttime hunting.<br />
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"Because these spiders were preserved in strange slivery flecks on dark rock, what was immediately obvious was their rather large eyes brightly marked with crescentic features," said Paul Selden, Gulf-Hedberg Distinguished Professor of Geology and director of the Paleontological Institute at KU's Biodiversity Institute and Natural History Museum. "I realized this must have been the tapetum -- that's a reflective structure in an inverted eye where light comes in and is reverted back into retina cells. This is unlike a straightforward eye where light goes through and doesn't have a reflective characteristic."<br />
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<span style="font-family: "arial" , "helvetica" , sans-serif;">Selden said that some contemporary spiders feature eyes with a tapetum, but the new paper is the first to describe the anatomical feature in a fossilized spider. The research team said the discovery provides evidence for lagonomegopid enlarged eyes being posterior medians.<br />
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"ln spiders, the ones you see with really big eyes are jumping spiders, but their eyes are regular eyes -- whereas wolf spiders at nighttime, you see their eyes reflected in light like cats," he said. "So, night-hunting predators tend to use this different kind of eye. This was the first time a tapetum had been in found in fossil. This tapetum was canoe-shaped -- it looks a bit like a Canadian canoe. That will help us place this group of spiders among other families."<br />
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Selden's collaborators were Tae-Yoon Park of the Korea Polar Research Institute and amateur fossil hunter Kye-Soo Nam of the Daejeon Science High School for the Gifted, who found the fossils preserved in the shale.<br />
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The description of the fossils boosts the number of known spiders from the Jinju Formation from one to 11. The KU researcher said the spiders, who lived between 110 and 113 million years ago, must somehow have been protected from deterioration to have become so well-preserved in the shale formation.<br />
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"This is so rare because they're very soft -- they don't have hard shells so they very easily decay," Selden said. "It has to be a very special situation where they were washed into a body of water. Normally, they'd float. But here, they sunk, and that kept them away from decaying bacteria -- it may have been a low-oxygen condition. These rocks also are covered in little crustaceans and fish, so there maybe was some catastrophic event like an algal bloom that trapped them in a mucus mat and sunk them -- but that's conjecture. We don't really know what caused this, but something killed off a lot of animals around the lake at one time or on an annual basis."<br />
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The discovery was made possible because of the unique geography of South Korea, where the shale containing the fossils was exposed during a construction project.<br />
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"It's all black shale, and in that area it's very hilly," Selden said. "South Korea doesn't have much flat land to build anything. So, they carve away the hillsides to make a flat area, and there are temporary excavations while they're cutting away and building a factory or whatever -- that's where they found these fossils."<br />
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According to Selden, the shale preserved the spider fossils in a manner that highlighted the reflectivity of the tapetum, a feature that may have been missed had the spiders been preserved in amber instead, as is more typical.<br />
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"Amber fossils are beautiful, they look wonderful, but they preserve things in a different way," he said. "Now, we want to go back and look at the amber fossils and see if we can find the tapetum, which stares out at you from rock fossils but isn't so obvious in amber ones because the mode of preservation is so different."<br />
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Beyond the novelty of discovering the first fossilized-spider tapetum, Selden said the spiders informed the scientific understanding of Cretaceous biodiversity.<br />
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"This is an extinct family of spiders that were clearly very common in the Cretaceous and were occupying niches now occupied by jumping spiders that didn't evolve until later," he said. "But these spiders were doing things differently. Their eye structure is different from jumping spiders. It's nice to have exceptionally well-preserved features of internal anatomy like eye structure. It's really not often you get something like that preserved in a fossil."</span><br />
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</span> <span style="font-family: "arial" , "helvetica" , sans-serif;"><u><i><span style="font-family: "trebuchet ms" , sans-serif;">The above story is based on <a href="http://news.ku.edu/2019/02/06/ancient-spider-fossils-surprisingly-preserved-rock-reveal-reflective-eyes" rel="nofollow" target="_blank">materials </a>provided by <a href="http://www.ku.edu/" rel="nofollow" target="_blank">The University of Kansas.</a></span></i></u></span></div>