A study of a global warming event that happened 93 million years ago suggests that the Earth can recover from high carbon dioxide emissions faster than thought, but that this process takes around 300,000 years after emissions decline.Scientists from Oxford University studied rocks from locations including Beachy Head, near Eastbourne, and South Ferriby, North Lincolnshire, to investigate how chemical weathering of rocks ‘rebalanced’ the climate after vast amounts of carbon dioxide (CO2) were emitted during more than 10,000 years of volcanic eruptions.
In chemical weathering CO2 from the atmosphere dissolved in rainwater reacts with rocks such as basalt or granite, dissolving them so that this atmospheric carbon then flows into the oceans, where a large proportion is ‘trapped’ in the bodies of marine organisms.
The team tested the idea that, as CO2 warms the planet, the reactions involved in chemical weathering speed up, causing more CO2 to be ‘locked away’, until, if CO2 emissions decline, the climate begins to cool again. The Oxford team looked at evidence from the ‘Ocean Anoxic Event 2’ in the Late Cretaceous when volcanic activity spewed around 10 gigatonnes of CO2 into the atmosphere every year for over 10,000 years. The researchers found that during this period chemical weathering increased, locking away more CO2 as the world warmed and enabling the Earth to stabilise to a cooler climate within 300,000 years, up to four times faster than previously thought.
A report of the research is published in Nature Geoscience.
‘Looking at this event is rather like imagining what the Earth would be like if humans disappeared tomorrow,’ said Dr Philip Pogge von Strandmann of Oxford University’s Department of Earth Sciences, who led the research. ‘Volcanic CO2 emissions in this period are similar to, if slightly slower than, current manmade emissions so that we can imagine a scenario in which, after human CO2 emissions ceased, the planet’s climate would start to recover and cool down. The bad news is that it’s likely this would take around 300,000 years.’
Reconstructing a record of past chemical weathering is challenging because of how plants and animals take carbon out of the environment. To get around this the team used a recently-developed technique involving studying lithium isotopes in marine limestone (this lithium could only come from weathering and is not changed by biological organisms).
The Ocean Anoxic Event 2 is believed to have been caused by a massive increase in volcanic activity in one of three regions: the Caribbean, Madagascar, or the Solomon Islands. The event saw the temperature of seawater around the equator warm by about 3 degrees Celsius. It is thought that this warming caused around 53% of marine species to go extinct. Animals like turtles, fish, and ammonites were amongst those severely affected.
‘Everyone remembers the mass extinction of land animals caused by the K-T meteorite impact 30 million years later, thought to be responsible for the demise of the dinosaurs, but in many ways this was just as devastating for marine life,’ said Dr Pogge von Strandmann. ‘Whilst nutrients from weathering caused a population boom of some species near the surface of the oceans, it also led to a loss of oxygen to the deeper ocean, killing off over half of all marine species and creating a ‘dead zone’ of decaying animals and plants. It’s a scenario we wouldn’t want to see repeated today.
‘Our research is good news, showing that the Earth can recover up to four times faster than we thought from CO2 emissions, but even if we stopped all emissions today this recovery would still take hundreds of thousands of years. We have to start doing something soon to remove CO2 from the atmosphere if we don’t want to see a repeat of the kind of mass extinctions that global warming has triggered in the past.’
The research was supported by the UK’s Natural Environment Research Council.
Note : The above story is based on materials provided by University of Oxford.
A team of palaeontologists has discovered the fossilised remains of a 72m-year-old dinosaur tail in a desert in northern Mexico, according to the country’s National Institute for Anthropology and History (INAH).
Unusually well preserved, the five-metre (16ft) tail (above) was the first ever found in Mexico, said Francisco Aguilar, INAH’s director in the border state of Coahuila.
The team, made up of palaeontologists and students from INAH and the National Autonomous University of Mexico, identified the fossil as a hadrosaur, or duck-billed dinosaur. The tail, found near the small town of General Cepeda, probably made up half the dinosaur’s length, Aguilar said.
Palaeontologists found the 50 vertebrae of the tail completely intact after spending 20 days in the desert slowly lifting a sedimentary rock covering the creature’s bones.
Strewn around the tail were other fossilised bones, including one of the dinosaur’s hips, INAH said.
Dinosaur tail finds are relatively rare, according to INAH. The new discovery could improve understanding of the hadrosaur family and aid research on diseases that afflicted dinosaur bones, which resembled those of humans, Aguilar said.
Scientists have already determined that dinosaurs suffered from tumours and arthritis, for example.
Dinosaur remains have been found in many parts of the state of Coahuila, in addition to Mexico’s other northern desert states.
“We have a very rich history of paleontology,” Aguilar said.
He noted that during the Cretaceous period, which ended about 65m years ago, much of what is now central northern Mexico was on the coast. This has enabled researchers to unearth remains of both marine and land-based dinosaurs.
The presence of the remains was reported to INAH by locals in June 2012. After initial inspections, excavation began earlier this month. The remains of the tail will be transferred to General Cepeda for cleaning and further investigation.
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Note : The above story is based on materials provided by Reuters
By directing energy beams at tiny crystals found in a Martian meteorite, a Western University-led team of geologists has proved that the most common group of meteorites from Mars is almost 4 billion years younger than many scientists had believed – resolving a long-standing puzzle in Martian science and painting a much clearer picture of the Red Planet’s evolution that can now be compared to that of habitable Earth.
In a paper published today in the journal Nature, lead author Desmond Moser, an Earth Sciences professor from Western’s Faculty of Science, Kim Tait, Curator, Mineralogy, Royal Ontario Museum, and a team of Canadian, U.S., and British collaborators show that a representative meteorite from the Royal Ontario Museum (ROM)’s growing Martian meteorite collection, started as a 200 million-year-old lava flow on Mars, and contains an ancient chemical signature indicating a hidden layer deep beneath the surface that is almost as old as the solar system.
The team, comprised of scientists from ROM, the University of Wyoming, UCLA, and the University of Portsmouth, also discovered crystals that grew while the meteorite was launched from Mars towards Earth, allowing them to narrow down the timing to less than 20 million years ago while also identifying possible launch locations on the flanks of the supervolcanoes at the Martian equator.
More details can be found in their paper titled, “Solving the Martian meteorite age conundrum using micro-baddeleyite and launch-generated zircon.”
Moser and his group at Western’s Zircon & Accessory Phase Laboratory (ZAPLab), one of the few electron nanobeam dating facilities in the world, determined the growth history of crystals on a polished surface of the meteorite. The researchers combined a long-established dating method (measuring radioactive uranium/lead isotopes) with a recently developed gently-destructive, mineral grain-scale technique at UCLA that liberates atoms from the crystal surface using a focused beam of oxygen ions.
Moser estimates that there are roughly 60 Mars rocks dislodged by meteorite impacts that are now on Earth and available for study, and that his group’s approach can be used on these and a much wider range of heavenly bodies.
“Basically, the inner solar system is our oyster. We have hundreds of meteorites that we can apply this technique to, including asteroids from beyond Mars to samples from the Moon,” says Moser, who credits the generosity of the collectors that identify this material and make it available for public research.
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Note : The above story is based on materials provided by University of Western Ontario
In 2006 the island of Java, Indonesia was struck by a devastating earthquake followed by the onset of a mud eruption to the east, flooding villages over several square kilometers and that continues to erupt today. Until now, researchers believed the earthquake was too far from the mud volcano to trigger the eruption. Geophysicists at the University of Bonn, Germany and ETH Zurich, Switzerland use computer-based simulations to show that such triggering is possible over long distances. The results have been published in Nature Geoscience.
On May 27, 2006 the ground of the Indonesian island Java was shaking with a magnitude 6.3 earthquake. The epicenter was located 25 km southwest of the city of Yogyakarta and initiated at a depth of 12 km. The earthquake took thousands of lives, injured ten thousand and destroyed buildings and homes. 47 hours later, about 250 km from the earthquake hypocenter, a mud volcano formed that came to be known as “Lusi,” short for “Lumpur Sidoarjo.” Hot mud erupted in the vicinity of an oil drilling-well, shooting mud up to 50 m into the sky and flooding the area. Scientists expect the mud volcano to be active for many more years.
Eruption of mud volcano has natural cause
Was the eruption of the mud triggered by natural events or was it human-made by the nearby exploration-well? Geophysicists at the University of Bonn, Germany and at ETH Zürich, Switzerland investigated this question with numerical wave-propagation experiments. “Many researchers believed that the earthquake epicenter was too far from Lusi to have activated the mud volcano,” says Prof. Dr. Stephen A. Miller from the department of Geodynamics at the University of Bonn. However, using their computer simulations that include the geological features of the Lusi subsurface, the team of Stephen Miller concluded that the earthquake was the trigger, despite the long distance.
The overpressured solid mud layer was trapped between layers with different acoustic properties, and this system was shaken from the earthquake and aftershocks like a bottle of champagne. The key, however, is the reflections provided by the dome-shaped geology underneath Lusi that focused the seismic waves of the earthquakes like the echo inside a cave. Prof. Stephen Miller explains: “Our simulations show that the dome-shaped structure with different properties focused seismic energy into the mud layer and could very well have liquified the mud that then injected into nearby faults.”
Previous studies would have underestimated the energy of the seismic waves, as ground motion was only considered at the surface. However, geophysicists at the University of Bonn suspect that those were much less intense than at depth. The dome-like structure “kept” the seismic waves at depth and damped those that reached the surface. “This was actually a lower estimate of the focussing effect because only one wave cycle was input. This effect increases with each wave cycle because of the reducing acoustic impedance of the pressurizing mud layer.” In response to claims that the reported highest velocity layer used in the modeling is a measurement artifact, Miller says „that does not change our conclusions because this effect will occur whenever a layer of low acoustic impedance is sandwiched between high impedance layers, irrespective of the exact values of the impedances. And the source of the Lusi mud was the inside of the sandwich. ”
It has already been proposed that a tectonic fault is connecting Lusi to a 15 km distant volcanic system. Prof. Miller explains “This connection probably supplies the mud volcano with heat and fluids that keep Lusi erupting actively up to today,” explains Miller.
With their publication, scientists from Bonn and Zürich point out, that earthquakes can trigger processes over long distances, and this focusing effect may apply to other hydrothermal and volcanic systems. Stephen Miller concludes: “Being a geological rarity, the mud volcano may contribute to a better understanding of triggering processes and relationships between seismic and volcanic activity.” Miller also adds „maybe this work will settle the long-standing controversy and focus instead on helping those affected.” The island of Java is part of the so called Pacific Ring of Fire, a volcanic belt which surrounds the entire Pacific Ocean. Here, oceanic crust is subducted underneath oceanic and continental tectonic plates, leading to melting of crustal material at depth. The resulting magma uprises and is feeding numerous volcanoes.
Note : The above story is based on materials provided by Universität Bonn.
U.S. Geological Survey This 2005 image shows a concentration of grains of zircon taken from sand deposits, where it occurs with other heavy minerals such as magnetite and ilmenite
The Yarlung-Tsangpo River in southern Asia drops rapidly through the Himalaya Mountains on its way to the Bay of Bengal, losing about 7,000 feet of elevation through the precipitously steep Tsangpo Gorge.
For the first time, scientists have direct geochemical evidence that the 150-mile long gorge, possibly the world’s deepest, was the conduit by which megafloods from glacial lakes, perhaps half the volume of Lake Erie, drained suddenly and catastrophically through the Himalayas when their ice dams failed at times during the last 2 million years.
“You would expect that if a three-day long flood occurred, there would be some pretty significant impacts downstream,” said Karl Lang, a University of Washington doctoral candidate in Earth and space sciences.
In this case, the water moved rapidly through bedrock gorge, carving away the base of slopes so steep they already were near the failure threshold. Because the riverbed through the Tsangpo Gorge is essentially bedrock and the slope is so steep and narrow, the deep flood waters could build enormous speed and erosive power.
As the base of the slopes eroded, areas higher on the bedrock hillsides tumbled into the channel, freeing microscopic grains of zircon that were carried out of the gorge by the fast-moving water and deposited downstream.
Uranium-bearing zircon grains carry a sort of geochemical signature for the place where they originated, so grains found downstream can be traced back to the rocks from which they eroded. Lang found that normal annual river flow carries about 40 percent of the grains from the Tsangpo Gorge downstream. But grains from the gorge found in prehistoric megaflood deposits make up as much as 80 percent of the total.
He is the lead author of a paper documenting the work published in the September edition of Geology. Co-authors are Katharine Huntington and David Montgomery, both UW faculty members in Earth and space sciences.
The Yarlung-Tsangpo is the highest major river in the world. It begins on the Tibetan Plateau at about 14,500 feet, or more than 2.5 miles, above sea level. It travels more than 1,700 miles, crossing the plateau and plunging through the Himalayas before reaching India’s Assam Valley, where it becomes the Brahmaputra River. From there it continues its course to the Ganges River delta and the Bay of Bengal.
0. Karl Lang/UW During a 2011 field trip, a regional assistant gathers samples from a deposit left by a catastrophic flood on the Yarlang-Tsangpo River in 200
At the head of the Tsangpo Gorge, the river makes a sharp bend around Namche Barwa, a 25,500-foot
Lang matched zircons in the megaflood deposits far downstream with zircons known to come only from Namche Barwa, and those signature zircons turned up in the flood deposits at a much greater proportion than they would in sediments from normal river flows. Finding the zircons in deposits so far downstream is evidence for the prehistoric megafloods and their role in forming the gorge.
Lang noted that a huge landslide in early 2000 created a giant dam on the Yiggong River, a tributary of the main river just upstream from the Gorge. The dam failed catastrophically in June 2000, triggering a flood that caused numerous fatalities and much property damage downstream.
That provided a vivid, though much smaller, illustration of what likely occurred when large ice dams failed millions of years ago, he said. It also shows the potential danger if humans decide to build dams in that area for hydroelectric generation.
“We are interested in it scientifically, but there is certainly a societal element to it,” Lang said. “This takes us a step beyond speculating what those ancient floods did. There is circumstantial evidence that, yes, they did do a lot of damage.”
The process in the Tsangpo Gorge is similar to what happened with Lake Missoula in Western Montana 12,000 to 15,000 years ago. That lake was more than 10,000 feet lower in elevation than lakes associated with the Tsangpo Gorge, though its water discharge was 10 times greater. Evidence suggests that Lake Missoula’s ice dam failed numerous times, unleashing a torrent equal to half the volume of Lake Michigan across eastern Washington, where it carved the Channeled Scablands before continuing down the Columbia River basin.
“This is a geomorphic process that we know shapes the landscape, and we can look to eastern Washington to see that,” Lang said.
The work was funded by the National Science Foundation and the UW Quaternary Research Center.
peak that is the eastern anchor of the Himalayas. Evidence indicates that giant lakes were impounded behind glacial dams farther inland from Namche Barwa at various times during the last 2.5 million years ago.
Note : The above story is based on materials provided by University of Washington. The original article was written by Vince Stricherz.
Global warming five million years ago may have caused parts of Antarctica’s large ice sheets to melt and sea levels to rise by approximately 20 metres, scientists report today in the journal Nature Geoscience.
The researchers, from Imperial College London, and their academic partners studied mud samples to learn about ancient melting of the East Antarctic ice sheet. They discovered that melting took place repeatedly between five and three million years ago, during a geological period called Pliocene Epoch, which may have caused sea levels to rise approximately ten metres.
Scientists have previously known that the ice sheets of West Antarctica and Greenland partially melted around the same time. The team say that this may have caused sea levels to rise by a total of 20 metres.
The academics say understanding this glacial melting during the Pliocene Epoch may give us insights into how sea levels could rise as a consequence of current global warming. This is because the Pliocene Epoch had carbon dioxide concentrations similar to now and global temperatures comparable to those predicted for the end of this century.
Dr Tina Van De Flierdt, co-author from the Department of Earth Science and Engineering at Imperial College London, says: “The Pliocene Epoch had temperatures that were two or three degrees higher than today and similar atmospheric carbon dioxide levels to today. Our study underlines that these conditions have led to a large loss of ice and significant rises in global sea level in the past. Scientists predict that global temperatures of a similar level may be reached by the end of this century, so it is very important for us to understand what the possible consequences might be.”
The East Antarctic ice sheet is the largest ice mass on Earth, roughly the size of Australia. The ice sheet has fluctuated in size since its formation 34 million years ago, but scientists have previously assumed that it had stabilised around 14 million years ago.
The team in today’s study were able to determine that the ice sheet had partially melted during this “stable” period by analysing the chemical content of mud in sediments. These were drilled from depths of more than three kilometres below sea level off the coast of Antarctica.
Analysing the mud revealed a chemical fingerprint that enabled the team to trace where it came from on the continent. They discovered that the mud originated from rocks that are currently hidden under the ice sheet. The only way that significant amounts of this mud could have been deposited as sediment in the sea would be if the ice sheet had retreated inland and eroded these rocks, say the team.
The academics suggest that the melting of the ice sheet may have been caused in part by the fact that some of it rests in basins below sea level. This puts the ice in direct contact with seawater and when the ocean warms, as it did during the Pliocene, the ice sheet becomes vulnerable to melting.
Carys Cook, co-author and research postgraduate from the Grantham Institute for Climate Change at Imperial, adds: “Scientists previously considered the East Antarctic ice sheet to be more stable than the much smaller ice sheets in West Antarctica and Greenland, even though very few studies of East Antarctic ice sheet have been carried out. Our work now shows that the East Antarctic ice sheet has been much more sensitive to climate change in the past than previously realised. This finding is important for our understanding of what may happen to the Earth if we do not tackle the effects of climate change.”
The next step will see the team analysing sediment samples to determine how quickly the East Antarctic ice sheet melted during the Pliocene. This information could be useful in the future for predicting how quickly the ice sheet could melt as a result of global warming.
Note : The above story is based on materials provided by Imperial College London. The original article was written by Colin Smith.
A sinkhole, also known as a sink-hole, sink, swallow hole, shakehole, swallet or doline, is a natural depression or hole in the Earth’s surface which may have various causes. Some are caused by karst processes—for example, the chemical dissolution of carbonate rocks or suffosion processes in sandstone. Others are formed as a result of the collapse of old mine workings close to the surface.
\Sinkholes may vary in size from 1 to 600 m (3.3 to 2,000 ft) both in diameter and depth, and vary in form from soil-lined bowls to bedrock-edged chasms. Sinkholes may be formed gradually or suddenly, and are found worldwide. The different terms for sinkholes are often used interchangeably.
Formation
Natural processes
Sinkholes may capture surface drainage from running or standing water, but may also form in high and dry
Sinkholes near the Dead Sea, formed when underground salt is dissolved by freshwater intrusion, due to continuing sea level drop.
places in certain locations.
The formation of sinkholes involves natural processes of erosion or gradual removal of slightly soluble bedrock (such as limestone) by percolating water, the collapse of a cave roof, or a lowering of the water table. Sinkholes often form through the process of suffosion. Thus, for example, groundwater may dissolve the carbonate cement holding the sandstone particles together and then carry away the lax particles, gradually forming a void.
Occasionally a sinkhole may exhibit a visible opening into a cave below. In the case of exceptionally large sinkholes, such as the Minyé sinkhole in Papua New Guinea or Cedar Sink at Mammoth Cave National Park in Kentucky, an underground stream or river may be visible across its bottom flowing from one side to the other.
Sinkholes are common where the rock below the land surface is limestone or other carbonate rock, salt beds, or other rocks that can naturally be dissolved by circulating ground water. As the rock dissolves, spaces and caverns develop underground. These sinkholes can be dramatic, because the surface land usually stays intact until there is not enough support. Then, a sudden collapse of the land surface can occur.
Artificial processes
Sinkholes also form from human activity, such as the rare but still occasional collapse of abandoned mines
Sinkhole formed by rainwater leaking through pavement and carrying soil into a ruptured sewer pipe.
and salt cavern storage in salt domes in places like Louisiana, Mississippi and Texas. More commonly, sinkholes occur in urban areas due to water main breaks or sewer collapses when old pipes give way. They can also occur from the overpumping and extraction of groundwater and subsurface fluids.
Sinkholes can also form when natural water-drainage patterns are changed and new water-diversion systems are developed. Some sinkholes form when the land surface is changed, such as when industrial and runoff-storage ponds are created; the substantial weight of the new material can trigger an underground collapse of supporting material, thus causing a sinkhole.
Occurrence
Sinkholes are frequently linked with karst landscapes. In such regions, there may be hundreds or even thousands of sinkholes in a small area so that the surface as seen from the air looks pock-marked, and there are no surface streams because all drainage occurs subsurface. Examples of karst landscapes dotted with numerous enormous sinkholes are Khammouan Mountains (Laos) and Mamo Plateau (Papua New Guinea). The largest known sinkholes formed in sandstone are Sima Humboldt and Sima Martel in Venezuela.
The most impressive sinkholes form in thick layers of homogenous limestone. Their formation is facilitated by high groundwater flow, often caused by high rainfall; such rainfall causes formation of the giant sinkholes in Nakanaï Mountains, on the New Britain island in Papua New Guinea. On the contact of limestone and insoluble rock below it, powerful underground rivers may form, creating large underground voids.In such conditions the largest known sinkholes of the world have formed, like the 662-metre (2,172 ft) deep Xiaozhai Tiankeng (Chongqing, China), giant sótanos in Querétaro and San Luis Potosí states in Mexico and others.
Unusual processes have formed the enormous sinkholes of Sistema Zacatón in Tamaulipas (Mexico), where more than 20 sinkholes and other karst formations have been shaped by volcanically heated, acidic groundwater. This has produced not only the formation of the deepest water-filled sinkhole in the world—Zacatón—but also unique processes of travertine sedimentation in upper parts of sinkholes, leading to sealing of these sinkholes with travertine lids.The state of Florida in the United States is known for having frequent sinkhole collapses, especially in the central part of the state. The Murge area in southern Italy also has numerous sinkholes. Sinkholes can be formed in retention ponds from large amounts of rain.
Local names of sinkholes
Large and visually unusual sinkholes have been well-known to local people since ancient times. Nowadays sinkholes are grouped and named in site-specific or generic names. Some examples of such names are listed below.
Black holes – This term refers to a group of unique, round, water-filled pits in the Bahamas. These formations seem to be dissolved in carbonate mud from above, by the sea water. The dark color of the water is caused by a layer of phototropic microorganisms concentrated in a dense, purple colored layer at 15 to 20 m (49 to 66 ft) depth; this layer “swallows” the light. Metabolism in the layer of microorganisms causes heating of the water, the only known case in the natural world where microorganisms create significant thermal effects. Most impressive is the Black Hole of Andros.
Blue holes – This name was initially given to the deep underwater sinkholes of the Bahamas but is often used for any deep water-filled pits formed in carbonate rocks. The name originates from the deep blue color of water in these sinkholes, which in turn is created by the high lucidity of water and the great depth of sinkholes; only the deep blue color of the visible spectrum can penetrate such depth and return back after reflection.
Cenotes – This refers to the characteristic water-filled sinkholes in the Yucatán Peninsula, Belize and some other regions. Many cenotes have formed in limestone deposited in shallow seas created by the Chicxulub meteorite’s impact.
Sótanos – This name is given to several giant pits in several states of Mexico.
Tiankengs – These are extremely large sinkholes, typically deeper and wider than 250 m (820 ft), with mostly vertical walls, most often created by the collapse of underground caverns. The term means sky hole in Chinese; many of this largest type of sinkhole are located in China.
Tomo – This term is used in New Zealand karst country to describe pot holes.
Note : The above story is reprinted from materials provided by Wikipedia
Diplodocus’ peg-like teeth were constantly replaced
Teeth from sauropod dinosaurs – the largest land animals that ever lived – reveal the feeding habits of these giants.
Researchers report that Diplodocus’ teeth were replaced as often as once a month throughout the dinosaur’s life.
In contrast, the teeth of Camarasaurus, another sauropod, show less frequent replacement, but bulkier growth.
This suggests that Diplodocus fed off low-lying vegetation while Camarasaurus ate upper-canopy plants.
Michael D’Emic, from Stony Brook University, New York, and co-workers used the daily layers of dentin, laid down as the dinosaur teeth grew, to determine the working lifetime and replacement rates of these massive herbivores’ teeth.
Dr D’Emic explains “A nearly 100-foot-long sauropod would have had a fresh tooth in each position about every one to two months, sometimes less.” These huge plant-eaters ate enormous quantities of vegetation, and their teeth suffered heavy wear.
The results are reported in the journal PLoS ONE.
Dr Emily Rayfield, reader in palaeobiology at the University of Bristol, commented “Diplodocus had peg-like teeth that stuck forward and out from its long narrow jaw, while Camarasaurus had a shorter jaw with a stronger bite. Their teeth wore down as they cropped vegetation.”
Dinosaurs replaced their teeth constantly throughout their life with new tooth crowns sitting deep in the jaw ready to erupt beneath each working tooth. This contrasts with mammals like us, which only replace their teeth once after birth (milk teeth and adult teeth).
The results indicate that Diplodocus and Camarasaurus had different approaches to feeding, allowing them to co-exist in the same ecosystem, with Diplodocus grazing plants at ground level and Camarasaurus taking the higher-lying vegetation.
Was T-Rex predator or scavenger, or both?
T-Rex and the one that got away
Earlier this week, a different dinosaur dental examination was described in the Proceedings of the National Academy of Sciences journal. A tooth of the carnivorous giant, Tyrannosaurus rex, found in the back bone of a duck-billed dinosaur, a type of hadrosaur, has been used to infer the eating habits of T.Rex.
The study, led by Dr David Burnham at the University of Kansas, demonstrates that the hadrosaur back bone had re-healed around the embedded T.Rex tooth, showing that it escaped from the T.Rex and continued to live for some time afterwards.
Importantly, this observation feeds into a long-standing debate over whether T.Rex was a scavenger or a predator, with the authors suggesting it supports the picture of T.Rex as a predator, and not simply a carrion scavenger.
It demonstrates once more the methods used by scientists to piece together the behaviour of ancient animals from fossil fragments.
Dr Paul Barrett, dinosaur researcher at the Natural History Museum in London, added “When we look at the ecology of living animals, we see that carnivores generally eat whatever they can get hold of.
“Hyenas, that we think of as specialist scavengers, hunt quite a bit; lions, that we think of as hunters, steal carcasses from other animals.
“There is no reason to think that T.Rex, as a big carnivore, would do anything other than it would need to, to survive at the cheapest possible cost.”
Note : The above story is reprinted from materials provided by BBC News. The original article was written bySimon Redfern
Hancock Gorge, Karijini national park, Pilbara, home to some of the planet’s most ancient rock formations. Photograph: Anne Montfort/Photononstop/Cor
Scientists analysing Australian rocks have discovered traces of bacteria that lived a record-breaking 3.49bn years ago, a mere 1bn years after Earth formed.
If the find withstands the scrutiny that inevitably faces claims of fossils this old, it could move scientists one step closer to understanding the first chapters of life on Earth. The discovery could also spur the search for ancient life on other planets.
These traces of bacteria “are the oldest fossils ever described. Those are our oldest ancestors,” said Nora Noffke, a biogeochemist at Old Dominion University in Norfolk, Virginia, who was part of the group that made the find and presented it in November at a meeting of the Geological Society of America. Unlike dinosaur bones, the newly identified fossils are not petrified body parts. They’re textures on the surfaces of sandstone thought to be sculpted by once-living organisms.
Today, similar patterns decorate parts of Tunisia’s coast, created by thick mats of bacteria that trap and glue together sand particles. Sand that is stuck to the land beneath the mats and thus protected from erosion can over time turn into rock that can long outlast the living organisms above it.
Finding the earliest remnants of this process required a long, hard look at some of the planet’s oldest rocks, located in Western Australia’s Pilbara region. This ancient landscape was once shoreline. Rocks made from sediment piled up billions of years ago are now exposed and available for examination. Relatively pristine in condition, such outcrops, along with others in South Africa, have long been a popular place to look for traces of life from the Archean eon, which ended 2.5bn years ago.
There are older rocks on Earth, said Maud Walsh, a biogeologist at Louisiana State University in Baton Rouge. “But these are the best-preserved sedimentary rocks we know of, the ones most likely to preserve the really tiny structures and chemicals that provide evidence for life.”
Last year, another team of researchers published the discovery of microscopic fossils in Pilbara’s Strelley Pool Formation, about 3.4bn years old. “It’s not just finding this stuff that’s interesting,” says Alan Decho, a geobiologist at the University of South Carolina’s Arnold School of Public Health. “It’s showing that the life had some organisation to it.” Ridges that crisscross the rocks like strands in a spider web hint that primitive bacteria linked up in sprawling networks. Like their modern counterparts, they may have lived in the equivalent of microbial cities that hosted thousands of kinds of bacteria, each specialised for a different task and communicating with the others via chemical signals.
Many of the textures seen in the Australian rocks had already shown up in 2.9bn-year-old rocks from South Africa, reported on by Noffke and colleagues in 2007.
Still, old Australian rocks have proved deceptive before. As early as 1980, rippling layers within the Strelley Pool were thought to be the handiwork of bacteria. But such stromatolites, which are different from the structures that Noffke studies, can also be the work of natural, non-living processes. For instance, water flowing along a seafloor can create similar structures under the right conditions. So can spraying jets of liquid loaded with particles onto a surface, as scientists at Oxford University demonstrated in laboratory experiments.
That’s why Noffke and her colleagues corroborated their story by measuring the carbon that makes up the textured rocks. About 99% of carbon in non-living stuff is carbon-12, a lighter version of the element than the carbon-13 that accounts for most of the remaining 1%. Microbes that use photosynthesis to make their food contain even more carbon-12 and less carbon-13. That bias, a signature of “organic” carbon that comes from a living being, showed up in the Australian rock.
“It’s always nice to have a number of different lines of evidence, and you definitely want to see organic carbon,” says geomicrobiologist John Stolz of Duquesne University in Pittsburgh.
What wasn’t preserved: any proteins or fats or body fossils that would clinch the case for life and identify what types of bacteria left behind this organic carbon. Most microbial mats today contain lots of photosynthetic cyanobacteria, which make the food that sustains the other bacteria. Named after the blue-green pigment they use for this process, called phycocyanin, cyanobacteria also make oxygen and are given the credit for creating Earth’s atmosphere about 2.4bn years ago.
Cyanobacteria living in microbial mats nearly 3.5bn years ago could shake up the history of the air we all breathe.
“Studying this kind of past life is really about learning how the Earth got to be the way it is today,” says Michael Tice, a geobiologist at Texas A&M University.
Ultimately, the fossils found on Earth could help those looking for the building blocks of life on Mars, where Nasa’s Curiosity rover has recently found evidence for ancient waterways. Remnants of life on the red planet might even be better preserved than they are here on Earth, says Harvard University paleontologist Andrew Knoll. That’s because old terrestrial rocks tend to get banged around by the movement of tectonic plates and cooked by the extreme heat of the planet’s depths. Mars, a planet that’s nearly dead geologically, lacks such tectonic activity.
Though no signs of ancient Martian microbes have been found, fossil hunters may now have something new to start looking for.
• This article was amended on 9 January 2013 to delete a reference to the archaeologically productive Pilbara region: the age of the fossils found would better suit the field of palaeontology. A missing fragment of a quote from geobiologist Alan Decho has also been reinstated.
Note : The above story is reprinted from materials provided by guardian.co.uk. The original article was written by Devin Powell for the Washington Post
CT scans of the hadrosaur bones. A) the two tail bones fused together and B) showing the cross-section of the Tyrannosaurus rex tooth buried in the bone (the white oval at the bottom of the picture). Scale bars are 1 cm. Modified from DePalma et al. 2013.
For too long there has been an apparently unending debate about the basic manner in which Tyrannosaurus and its near relatives obtained their food. Were these animals dedicated predators, hunting down and killing their prey before consuming it, or scavengers, too slow and poorly equipped to catch live prey, but instead limited to taking already dead meals, perhaps using their size to bully smaller carnivores from their meals.
Despite the press this has had and the evocative language that often appears in association with this question (‘deadly’ on the predatory size and inevitably ‘skulking’ on the scavenging one) the truth has been known to scientists for some time – they did both. Certainly tyrannosaurs scavenged when food was available, but they were clearly capable predators (or at least there was no truly strong evidence to suggest they were not) and some tentative evidence pointed towards animals that might have been injured by them.
However, this doesn’t mean that new evidence is not welcome and now a rather exciting and pretty definitive case has come forwards. A pair of bones from the tail of a hadrosaurian dinosaur (more often know as duck-bills) have been found that are fused together and with a huge chunk of amorphous bone joining them. In short, the site of some major injury or infection has caused this unusual growth to occur. However, it is what lies inside that is the real delight – a Tyrannosaurus tooth.
Carnivorous dinosaurs actually shed their teeth quite often – like sharks they continually grew new teeth and the old ones would eventually fall out. So while finding shed teeth in or around carcasses of other dinosaurs is quite common, and in other cases we have found teeth embedded into bones, the question is how do we know this didn’t happen when scavenging a carcass, but was a real strike on a living animal?
In the study by DePalma and colleagues, the tooth is buried deep within the mass of bone and is completely covered by it. The shape and texture of the bone growth is indicative of a major injury occurring to the hadrosaur and the obvious and entirely reasonable interpretation for this is that a bite from a tyrannosaur left the tooth in there.
It’s unlikely that this was an accident: large predators don’t usually bite prey species very hard for no reason (and indeed probably rarely get close enough to do so except when going after them) so it’s entirely justifiable to chalk this up to an attempted attack. “Attempted” is the key word here: the animal survived the incident and lived for many months or even years based on the amount of bone that had built up over the tooth.
This is also not a major surprise, few predators are successful much more than about half the time they try and hunt prey and of course many failed efforts would leave only a slight graze that would not show up on the bones, or be so bad as to kill the animal perhaps a few hours or days later where healing may not show. This doesn’t show that Tyrannosaurus was a poor predator, merely that this hadrosaur got very lucky but lived to honk the tale for some time at least. Perhaps we are luckier still to find such an event marked in the fossil record, but this is hopefully the final, final nail in the ‘scavenging only’ idea and we can move onto some more detailed analysis of the behaviour of these giant carnivores.
A geothermal plant in California. Water injection may prime cracks, making them vulnerable to triggering by tremors from distant earthquakes. Photograph: Getty
Pumping water underground at geothermal power plants can lead to dangerous earthquakes even in regions not prone to tremors, according to scientists. They say that quake risk should be factored into decisions about where to site geothermal plants and other drilling rigs where water is pumped underground – for example in shale gas fracking.
Prof Emily Brodsky, who led a study of earthquakes at a geothermal power plant in California, said: “For scientists to make themselves useful in this field we need to be able to tell operators how many gallons of water they can pump into the ground in a particular location and how many earthquakes that will produce.”
It is already known that pumping large quantities of water underground can induce minor earthquakes near to geothermal power generation and fracking sites. However, the new evidence reveals the potential for much larger earthquakes, of magnitude 4 or 5, related to the weakening of pre-existing undergrounds faults through increased fluid pressure.
The water injection appears to prime cracks in the rock, making them vulnerable to triggering by tremors from earthquakes thousands of miles away. Nicholas van der Elst, the lead author on one of three studies published on Thursday in the journal Science, said: “These fluids are driving faults to their tipping point.”
Prof Brodsky said they found a clear correlation between the amount of water extracted and injected into the ground, and the number of earthquakes.
The analysis of the Californian site showed that for a net injection of 500m gallons of water into the ground per month, there is an earthquake on average every 11 days.
“The problem is we can only predict how many earthquakes will occur but not their size and so with this knowledge then it has to be decided what is an acceptable size and frequency of earthquakes for a particular area,” said Brodsky.
Because of the increase in the exploitation of geothermal power for renewable energy, and hydraulic fracturing or “fracking” to release natural gas, it is important to understand the chances of a large earthquake occurring at these sites, particularly if they are in densely populated regions.
Another key feature of the research shows that sites experiencing sustained pumping of water into the ground for a period of decades or more are more susceptible to large tremors triggered by earthquakes occurring in other parts of the world.
Large earthquakes in Chile in 2010, Japan in 2011 and Sumatra in 2012 all set off mid-size tremors in the central United States near to sites of water injection, with the largest induced earthquake of magnitude 5.7 destroying 14 homes and injuring two people. Van der Elst said: “The remote triggering by big earthquakes is an indication the area is critically stressed.”
Heather Savage, a co-author on the same study said: “It is already accepted that when we have very large earthquakes seismic waves travel all over the globe, but even though the waves are small when they reach the other side of the world, they still shake faults. This can trigger seismicity in seismically active areas such as volcanoes where there is already a high fluid pressure. But this is the first time the same has been recognised for areas with anthropogenically induced high fluid pressure.”
Scientists map the exact location of faults that occur naturally over most of the Earth’s crust. However, there are many underground faults that do not intersect the Earth’s surface, some of which could be very large. The fear is that one of these previously inactive faults could be triggered. Van der Elst added: “It is an important subject for the future that we understand about the disposal of fluids as they arise from many processes.”
Rather than completely stopping the pumping of wastewater into the ground at geothermal plants, Prof Brodsky suggests that careful observation and analysis at each pumping site may help predict the chances of an earthquake.
Note : The above story is reprinted from materials provided by guardian.co.uk. The original article was written by Natalie Starkey
This is an illustration of a skull of Diploducus alongside the research team’s CT scan-generated images of some teeth in the front of its jaws. Bone is transparent and teeth are yellow. The arrows show the direction of tooth replacement, which is back to front similar to a shark. (Credit: Image courtesy of Stony Brook University)
Rapid tooth replacement by sauropods, the largest dinosaurs in the fossil record, likely contributed to their evolutionary success, according to a research paper by Stony Brook University paleontologist Michael D’Emic, PhD, and colleagues. Published in PLOS ONE, the study also hypothesizes that differences in tooth replacement rates among the giant herbivores likely meant their diets varied, an important factor that allowed multiple species to share the same ecosystems for several million years.
Paleontologists have long wondered how sauropods digested massive amounts of foliage that would have been necessary for their immense sizes. In “Evolution of high tooth replacement rates in sauropod dinosaurs,” the team of paleontologists reveal that their new research into the microscopic structure of sauropod teeth shows the dinosaurs formed and replaced teeth faster than any other type of dinosaurs — more like sharks and crocodiles — and this process kept teeth fresh given the immense amount of wear they underwent from clipping off enormous volumes of food required for them.
“The microscopic structure of teeth and bones records aspects of an animal’s physiology, giving us a window into the biology of long-extinct animals,” said Dr. D’Emic, Research Instructor in the Department of Anatomical Sciences at Stony Brook University School of Medicine. “We determined that for the gigantic sauropods, each tooth took just a few months to form. Effectively, sauropods took a ‘quantity over quality’ approach.”
Dr. D’Emic explained that unlike mammals and some other dinosaurs, sauropods did not chew their food. They snipped food into smaller pieces before swallowing.
“At least twice during their evolution, sauropods evolved small, peg-like teeth that formed and replaced quickly,” said Dr. D’Emic. “This characteristic may have led to the evolutionary success of sauropods.”
The team developed a novel method to estimate sauropod tooth formation and replacement rate without
With computed tomography (CT) scanning and microscopic anatomical methods, they measured tooth formation time, replacement rate, crown volume and enamel thickness in sectioned teeth of Camarasaurus and Diplodocus, two dinosaurs from the Late Jurassic Formation of North America. The technology and method enabled the researchers to count the number of growth lines in each tooth. Growth lines are a fraction of the thickness of a human hair. A tally of the lines gives the formation of each tooth in days.
To find out how fast these teeth were replaced, D’Emic and colleagues subtracted the ages of successive teeth from one another. The results indicated that replacement in these animals was extremely fast.
“A nearly 100-foot-long sauropod would have had a fresh tooth in each position about every one to two months, sometimes less” said Dr. D’Emic.
The tooth replacement rate, size and shape data collected by the team indicates that despite their somewhat stereotyped body plan and large body size, sauropods exhibited varied approaches to feeding. The paper indicates that this variation “represents a potential factor that allowed multiple giant species such as Camarasurus and Diplodocus to partition the same ecosystem.”
Dr. D’Emic added that the research also contributes to a new view of sauropods, which were once thought to be more primitive than other dinosaur groups such as horned and duckbilled dinosaurs.
The paper co-authors include John Whitlock of Mount Aloysius College, Kathlyn Smith of Georgia Southern University, and Jeffrey Wilson and Daniel Fisher of the University of Michigan.
The dinosaur specimens used for the research were loaned to the paleontologists from the Yale Peabody Museum, Utah Museum of Natural History, Staatliches Museum für Naturkunde and the Iziko South African Museum.
This is a sketch of a skull of Diplodocus alongside an actual horse skull. Note the similarity in shape of the skulls. However, the dinosaur has few, puny teeth in the front of its jaw, illustrating the non-chewing eating process in sauropds in comparison to the grinding method of horses and other mammals.
destructively sampling the teeth by making microscopic sections. Using these estimates, the researchers could track the evolution of tooth formation and replacement rates through time in species whose fossil remains are too rare to section.
Sauropod Dinosaur Facts:
1. Sauropod dinosaurs were the largest animals that ever walked the land.
2. Familiar examples of sauropods are Diplodocus, Brachiosaurus, and Apatosaurus. Apatosaurus was formerly called “Brontosaurus.” These are genera (plural of genus) and should be italicized.
3. Sauropods had tiny heads for their bodies — even a 100-foot-long animal would have a head only slightly larger than that of a horse.
4. Along with their tiny heads, sauropods had tiny teeth, ranging from the diameter of a pencil to a wide marker and only a few inches long.
5. Sauropods did not chew their food, but clipped it and swallowed it, where it was broken down in their digestive system.
6. In living animals, daily incremental lines are laid down in teeth. These lines are thinner than a human hair. The total number of lines indicates how long it took for the tooth to form.
7. Most animals have only one or two replacement teeth in a given socket (or tooth position), but sauropods had up to nine.
8. Sauropod teeth formed quickly — in just a few months.
9. Sauropods replaced their teeth more quickly than most animals, including other dinosaurs. A new tooth was replaced in each tooth position every month or so.
10. Sauropods twice evolved small teeth that formed and replaced quickly.
Note : The above story is reprinted from materials provided by Stony Brook University, via Newswise.
University of Adelaide research has shown new evidence that dinosaurs were warm-blooded like birds and mammals, not cold-blooded like reptiles as commonly believed.
In a paper published in PLoS ONE, Professor Roger Seymour of the University’s School of Earth and Environmental Sciences, argues that cold-blooded dinosaurs would not have had the required muscular power to prey on other animals and dominate over mammals as they did throughout the Mesozoic period.
“Much can be learned about dinosaurs from fossils but the question of whether dinosaurs were warm-blooded or cold-blooded is still hotly debated among scientists,” says Professor Seymour.
“Some point out that a large saltwater crocodile can achieve a body temperature above 30°C by basking in the sun, and it can maintain the high temperature overnight simply by being large and slow to change temperature.
“They say that large, cold-blooded dinosaurs could have done the same and enjoyed a warm body temperature without the need to generate the heat in their own cells through burning food energy like warm-blooded animals.”
In his paper, Professor Seymour asks how much muscular power could be produced by a crocodile-like dinosaur compared to a mammal-like dinosaur of the same size.
Saltwater crocodiles reach over a tonne in weight and, being about 50% muscle, have a reputation for being extremely powerful animals.
But drawing from blood and muscle lactate measurements collected by his collaborators at Monash University, University of California and Wildlife Management International in the Northern Territory, Professor Seymour shows that a 200 kg crocodile can produce only about 14% of the muscular power of a mammal at peak exercise, and this fraction seems to decrease at larger body sizes.
“The results further show that cold-blooded crocodiles lack not only the absolute power for exercise, but also the endurance, that are evident in warm-blooded mammals,” says Professor Seymour.
“So, despite the impression that saltwater crocodiles are extremely powerful animals, a crocodile-like dinosaur could not compete well against a mammal-like dinosaur of the same size.
“Dinosaurs dominated over mammals in terrestrial ecosystems throughout the Mesozoic. To do that they must have had more muscular power and greater endurance than a crocodile-like physiology would have allowed.”
His latest evidence adds to that of earlier work he did on blood flow to leg bones which concluded that the dinosaurs were possibly even more active than mammals.
Note: The above story is reprinted from materials provided by University of Adelaide.
Researchers recently discovered the crown of a T. rex tooth lodged in the fossilized spine of a plant-eating hadrosaur that seems to have survived the attack. (Credit: Illustration by University of Kansas alumnus Robert DePalma II of The Palm Beach Museum of Natural History)
Tyrannosaurus rex has long been popular with kids and moviemakers as the most notorious, vicious killing machine to roam the planet during the age of the dinosaurs.
So, it may come as a shock that for more than a century some paleontologists have argued that T. rex was a scavenger, not a true predator — more like a vulture than a lion. Indeed, a lack of definitive fossil proof of predation in the famous theropod has stirred controversy among scientists — until now.
“T. rex is the monster of our dreams,” said David Burnham, preparator of vertebrate paleontology at the Biodiversity Institute at the University of Kansas. “But ever since it was discovered in Montana and named in the early 1900s, there’s been a debate about whether these large carnivores were scavengers or predators. Most people assume they were predators, but the scientific evidence for predation has been really elusive. Yes, we’ve found lots of dinosaur skeletons with tooth marks that had been chewed up by something. But what did that really prove? Yes, these large carnivores fed on other dinosaurs — but did they eat them while they were alive or dead? That’s where the debate came in. Where was the evidence for hunt and kill?”
Now, Burnham is part of a team that has unearthed “smoking gun” physical proof that T. rex was indeed a predator, hunter and killer. In the Hell Creek Formation of South Dakota, Burnham and colleagues discovered the crown of a T. rex tooth lodged in the fossilized spine of a plant-eating hadrosaur that seems to have survived the attack. The team describes the find in the current issue of the Proceedings of the National Academy of Sciences.
Burnham’s KU co-authors are Bruce Rothschild and the late Larry Martin, along with former KU student Robert DePalma II of The Palm Beach Museum of Natural History and Peter Larson of the Black Hills Institute of Geological Research.
“Robert DePalma was a student here at KU doing his master’s thesis in the Hell Creek formation,” said Burnham. “He found a specimen that represents the tail of one of these hadrosaurs. It had a distorted-looking bone growth. He came to me and said, ‘What do you think is causing this?’ So we cleaned it and could see a tooth embedded in one of these duck-billed dinosaur vertebrae. Then we went to Lawrence Memorial Hospital and used a CT machine to scan the bones — and we saw all of the tooth.”
Previous evidence for predation included T. rex fossil discoveries with preserved stomach contents that included the bones of a young ceratopsian (e.g., Triceratops or one of its kin). However, there was no evidence to conclude whether the ceratopsian was alive or dead when the T. rex made a snack of it.
By contrast, Burnham said the tooth was definitive evidence of hunting, after carefully measuring its length and the size of its serrations to ensure that it came from the mouth of a T. rex.
“Lo and behold, the tooth plotted out just exactly with T. rex — the only known large theropod from the Hell Creek formation,” he said. “We knew we had a T. rex tooth in the tail of a hadrosaur. Better yet, we knew the hadrosaur got away because the bone had begun to heal. Quite possibly it was being pursued by the T. rex when it was bitten. It was going in the right direction — away. The hadrosaur escaped by some stroke of luck. The better luck is finding this fossil with the preserved evidence.”
Because T. rex regularly shed its teeth, the predator went away hungry, but otherwise no worse for the encounter. It would have grown a new tooth to replace the one left behind in the hadrosaur’s tail. This could have been a typical example of T. rex’s hunting efforts, even if it didn’t result in a meal.
“To make an analogy to modern animals, when lions go attack a herd of herbivores, they go after the sick and the slow,” Burnham said. “Most of the time, hadrosaurs traveled in packs. This hadrosaur may have been a little slower, or this T. rex may have been a little faster — at least fast enough to almost catch a duck-billed dinosaur.”
This concrete proof of T. rex’s predation continues a long relationship between KU paleontologists and the theropod, which lived in North America during the Late Cretaceous, some 65 million years ago. KU graduate Barnum Brown discovered the first documented remains of the dinosaur in Wyoming in 1900.
Note : The above story is reprinted from materials provided by University of Kansas.
This image shows the skull of the newly announced Nasutoceratops from Grand Staircase-Escalante National Monument (GSENM), which encompasses 1.9 million acres of high desert terrain in south-central Utah.Credit: Rob Gaston
A remarkable new species of horned dinosaur has been unearthed in Grand Staircase-Escalante National Monument, southern Utah. The huge plant-eater inhabited Laramidia, a landmass formed when a shallow sea flooded the central region of North America, isolating western and eastern portions for millions of years during the Late Cretaceous Period.
The newly discovered dinosaur, belonging to the same family as the famous Triceratops, was announced today in the British scientific journal, Proceedings of the Royal Society B.
The study, funded in large part by the Bureau of Land Management and the National Science Foundation, was led by Scott Sampson, when he was the Chief Curator at the Natural History Museum of Utah at the University of Utah. Sampson is now the Vice President of Research and Collections at the Denver Museum of Nature & Science.
Additional authors include Eric Lund (Ohio University; previously a University of Utah graduate student), Mark Loewen (Natural History Museum of Utah and Dept. of Geology and Geophysics, University of Utah), Andrew Farke (Raymond Alf Museum), and Katherine Clayton (Natural History Museum of Utah).
Horned dinosaurs, or “ceratopsids,” were a group of big-bodied, four-footed herbivores that lived during the Late Cretaceous Period. As epitomized by Triceratops, most members of this group have huge skulls bearing a single horn over the nose, one horn over each eye, and an elongate, bony frill at the rear. The newly discovered species, Nasutoceratops titusi, possesses several unique features, including an oversized nose relative to other members of the family, and exceptionally long, curving, forward-oriented horns over the eyes.
The bony frill, rather than possessing elaborate ornamentations such as hooks or spikes, is relatively unadorned, with a simple, scalloped margin. Nasutoceratops translates as “big-nose horned face,” and the second part of the name honors Alan Titus, Monument Paleontologist at Grand Staircase-Escalante National Monument, for his years of research collaboration.
For reasons that have remained obscure, all ceratopsids have greatly enlarged nose regions at the front of the face. Nasutoceratops stands out from its relatives, however, in taking this nose expansion to an even greater extreme. Scott Sampson, the study’s lead author, stated, “The jumbo-sized schnoz of Nasutoceratops likely had nothing to do with a heightened sense of smell — since olfactory receptors occur further back in the head, adjacent to the brain — and the function of this bizarre feature remains uncertain.”
This image shows an artist rendition of Nasutoceratops.Credit: Lukas Panzarin
Paleontologists have long speculated about the function of horns and frills on horned dinosaurs. Ideas have
ranged from predator defense and controlling body temperature to recognizing members of the same species. Yet the dominant hypothesis today focuses on competing for mates—that is, intimidating members of the same sex and attracting members of the opposite sex. Peacock tails and deer antlers are modern examples. In keeping with this view, Mark Loewen, a co-author of the study claimed that, “The amazing horns of Nasutoceratops were most likely used as visual signals of dominance and, when that wasn’t enough, as weapons for combatting rivals.”
A Treasure Trove of Dinosaurs on the Lost Continent of Laramidia
This is an image of a drawing of the skull of the Nasutoceratops found in Grand Staircase-Escalante National Monument (GSENM), which encompasses 1.9 million acres of high desert terrain in south-centralUtah. Credit: Sammantha Zimmerman
Nasutoceratops was discovered in Grand Staircase-Escalante National Monument (GSENM), which encompasses 1.9 million acres of high desert terrain in south-central Utah. This vast and rugged region, part of the National Landscape Conservation System administered by the Bureau of Land Management, was the last major area in the lower 48 states to be formally mapped by cartographers. Today GSENM is the largest national monument in the United States. Sampson proclaimed that, “Grand Staircase-Escalante National Monument is the last great, largely unexplored dinosaur boneyard in the lower 48 states.”
For most of the Late Cretaceous, exceptionally high sea levels flooded the low-lying portions of several continents around the world. In North America, a warm, shallow sea called the Western Interior Seaway extended from the Arctic Ocean to the Gulf of Mexico, subdividing the continent into eastern and western landmasses, known as Appalachia and Laramidia, respectively. Whereas little is known of the plants and animals that lived on Appalachia, the rocks of Laramidia exposed in the Western Interior of North America have generated a plethora of dinosaur remains. Laramidia was less than one-third the size of present day North America, approximating the area of Australia.
Most known Laramidian dinosaurs were concentrated in a narrow belt of plains sandwiched between the seaway to the east and mountains to the west. Today, thanks to an abundant fossil record and more than a century of collecting by paleontologists, Laramidia is the best known major landmass for the entire Age of Dinosaurs, with dig sites spanning from Alaska to Mexico. Utah was located in the southern part of Laramidia, which has yielded far fewer dinosaur remains than the fossil-rich north. The world of dinosaurs was much warmer than the present day; Nasutoceratops lived in a subtropical swampy environment about 100 km from the seaway.
Beginning in the 1960’s, paleontologists began to notice that the same major groups of dinosaurs seemed to be present all over this Late Cretaceous landmass, but different species of these groups occurred in the north (for example, Alberta and Montana) than in the south (New Mexico and Texas). This finding of “dinosaur provincialism” was very puzzling, given the giant body sizes of many of the dinosaurs together with the diminutive dimensions of Laramidia. Currently, there are five giant (rhino-to-elephant-sized) mammals on the entire continent of Africa. Seventy-six million years ago, there may have been more than two dozen giant dinosaurs living on a landmass about one-quarter that size. Co-author Mark Loewen noted that, “We’re still working to figure out how so many different kinds of giant animals managed to co-exist on such a small landmass?” The new fossils from GSENM are helping us explore the range of possible answers, and even rule out some alternatives.
During the past dozen years, crews from the Natural History Museum of Utah, the Denver Museum of Nature & Science and several other partner institutions (e.g., the Utah Geologic Survey, the Raymond Alf Museum of Paleontology, and the Bureau of Land Management) have unearthed a new assemblage of more than a dozen dinosaurs in GSENM. In addition to Nasutoceratops, the collection includes a variety of other plant-eating dinosaurs—among them duck-billed hadrosaurs, armored ankylosaurs, dome-headed pachycephalosaurs, and two other horned dinosaurs, Utahceratops and Kosmoceratops — together with carnivorous dinosaurs great and small, from “raptor-like” predators to a mega-sized tyrannosaur named Teratophoneus. Amongst the other fossil discoveries are fossil plants, insect traces, clams, fishes, amphibians, lizards, turtles, crocodiles, and mammals. Together, this diverse bounty of fossils is offering one of the most comprehensive glimpses into a Mesozoic ecosystem. Remarkably, virtually all of the identifiable dinosaur remains found in GSENM belong to new species, providing strong support for the dinosaur provincialism hypothesis.
Andrew Farke, a study co-author, noted that, “Nasutoceratops is one of a recent landslide of ceratopsid discoveries, which together have established these giant plant-eaters as the most diverse dinosaur group on Laramidia.”
Eric Lund, another co-author as well as the discoverer of the new species, stated that, “Nasutoceratops is a wondrous example of just how much more we have to learn about with world of dinosaurs. Many more exciting fossils await discovery in Grand Staircase-Escalante National Monument.”
Fact Sheet: Major Points of the Paper
(1) A remarkable new horned dinosaurs Nasutoceratops titusi, has been unearthed in Grand Staircase-Escalante National Monument, southern Utah.
(2) Nasutoceratops is distinguished by a number of unique features, including an oversized nose and elongate, forward-curving horns over the eyes.
(3) This animal lived in a swampy, subtropical setting on the “island continent” of western North America, also known as “Laramidia.”
(4) Nasutoceratops appears to belong to a previously unrecognized group of horned dinosaurs that lived on Laramidia, and provides strong evidence supporting the idea that distinct northern and southern dinosaur communities lived on this landmass for over a million years during the Late Cretaceous.
New Dinosaur Name: Nasutoceratops titusi.
The first part of the name, Nasutoceratops, can be translated as the “big-nosed horned face,” in reference to the oversized nose of this plant-eating dinosaur. The second part of the name honors Alan Titus, Monument Paleontologist at Grand Staircase-Escalante National Monument, for all of his work in support of paleontological research in GSENM.
Size Nasutoceratops was about 15 feet (5 meters) long and 2.5 tonnes.
Relationships Nasutoceratops belongs to a group of big-bodied horned dinosaurs called “ceratopsids,” the same family as the famous Triceratops. More specifically, they are members of the subset of ceratopsids known as “centrosaurines,” with Avaceratops being the closest known relative within this smaller subset of horned dinosaurs.
Anatomy
Nasutoceratops was a four-legged (quadrupedal) herbivore.
Like most other horned dinosaurs, Nasutoceratops had a large horn above each eye, although they are particularly elongate in this animal and forward facing, which is unusual. Rather than a large horn over the nose and an elaborately ornamented frill, both typical of centrosaurines, Nasutoceratops possessed a low, narrow, blade-like horn above the nose and relatively simple frill lacking well developed ornaments.
Age and Geography
Nasutoceratops lived during the Campanian stage of the Late Cretaceous period, which spanned from approximately 84 million to 70 million years ago. This animal lived about 76 million years ago.
During the Late Cretaceous, the North American continent was split in two by the Western Interior Seaway. Western North America formed an island continent called Laramidia, stretching from Mexico in the south to Alaska in the north.
Nasutoceratops lived in Utah at the same time that other, closely related horned dinosaurs lived in Alberta. This finding strong evidence of dinosaur provincialism on Laramidia—that is, the formation of northern and southern dinosaur assemblages during a part of the Late Cretaceous.
Discovery
Nasutoceratops was found in a geologic unit known as the Kaiparowits Formation, abundantly exposed in GSENM, southern Utah.
Nasutoceratops was first discovered by (then) University of Utah masters student Eric Lund in 2006. Additional specimens of this animal were found in subsequent years.
Nasutoceratops specimens are permanently housed in the collections and on public display at the Natural History Museum of Utah in Salt Lake City, Utah.
These discoveries are the result of a continuing collaboration between the Natural History Museum of Utah, the Denver Museum of Nature & Science, and the Bureau of Land Management.
Other
The fossil record of ceratopsid dinosaurs from the southern part of Laramidia has been very poorly known. The discovery of this new dinosaur in Utah helps to fill a major gap in our knowledge.
Nasutoceratops is part of a previously unknown assemblage dinosaurs discovered in GSENM over the past 12 years.
The skull of Nasutoceratops is on permanent display at the Natural History Museum of Utah.
The Bureau of Land Management manages more land—253 million acres—than any other federal agency, and manages paleontological resources using scientific principles and expertise.
In addition to serving as the Vice President of Research and Collections at the Denver Museum of Nature & Science, the paper’s lead author, Scott Sampson, is also the science advisor and on-air host of the hit PBS KIDS television series, Dinosaur Train.
Note : The above story is reprinted from materials provided by University of Utah
This artist’s rendering shows a solar system that is a much younger version of our own. Dusty disks, like the one shown here circling the star, are thought to be the breeding grounds of planets, including rocky ones like Earth. (Credit: NASA/JPL-Caltech)
It’s widely thought that Earth arose from violent origins: Some 4.5 billion years ago, a maelstrom of gas and dust circled in a massive disc around the sun, gathering in rocky clumps to form asteroids. These asteroids, gaining momentum, whirled around a fledgling solar system, repeatedly smashing into each other to create larger bodies of rubble — the largest of which eventually cooled to form the planets.
Countless theories, simulations and geologic observations support such a scenario. But there remains one lingering mystery: If Earth arose from the collision of asteroids, its composition should resemble that of meteoroids, the small particles that break off from asteroids.
But to date, scientists have found that, quite literally, something doesn’t add up: Namely, Earth’s mantle — the layer between the planet’s crust and core — is missing an amount of lead found in meteorites whose composition has been analyzed following impact with Earth.
Much of Earth is composed of rocks with a high ratio of uranium to lead (uranium naturally decays to lead over time). However, according to standard theories of planetary evolution Earth should harbor a reservoir of mantle somewhere in its interior that has a low ratio of uranium to lead, to match the composition of meteorites. But such a reservoir has yet to be discovered — a detail that leaves Earth’s origins hazy.
Now researchers in MIT’s Department of Earth, Atmospheric and Planetary Sciences have identified a “hidden flux” of material in Earth’s mantle that would make the planet’s overall composition much more similar to that of meteorites. This reservoir likely takes the form of extremely dense, lead-laden rocks that crystallize beneath island arcs, strings of volcanoes that rise up at the boundary of tectonic plates.
As two massive plates push against each other, one plate subducts, or slides, under the other, pushing material from the crust down into the mantle. At the same time, molten material from the mantle rises up to the crust, and is ejected via volcanoes onto Earth’s surface.
According to the MIT researchers’ observations and calculations, however, up to 70 percent of this rising magma crystallizes into dense rock — dropping, leadlike, back into the mantle, where it remains relatively undisturbed. The lead-heavy flux, they say, puts the composition of Earth’s mantle on a par with that of meteorites.
“Now that we know the composition of this flux, we can calculate that there’s tons of this stuff dropping down from the base of the crust into the mantle, so it is likely an important reservoir,” says Oliver Jagoutz, an assistant professor of geology at MIT. “This has a lot of implications for understanding how the Earth evolved through history.”
Jagoutz and his colleague Max Schmidt, of the Swiss Federal Institute of Technology in Zurich, have detailed their results in a paper published in Earth and Planetary Science Letters.
A mantle exposed
Measuring the composition of material that has dropped into the mantle is a nearly impossible task. Jagoutz estimates that such dense rocks would form at a depth of 40 to 50 kilometers below the surface, beyond the reach of conventional sampling techniques.
There is, however, one place on earth where such a depth of the crust and mantle is exposed: a region of northern Pakistan called the Kohistan arc. Forty million years ago, this island arc was crushed between India and Asia as the two plates collided.
“When India came in, it slammed into the arc, and the arc extended and rotated itself,” Jagoutz says. “Because of that, we now have a cross-section of the mantle-to-crust transition. This is the only place on Earth where this exists.”
On various trips from 2000 to 2007, Jagoutz trekked through the Kohistan arc region, collecting rocks from various parts of the arc’s crust and mantle. Bringing them back to the lab, he analyzed the rocks’ density and composition, discovering that some were “density-unstable” — much denser than the mantle. These denser rocks could potentially sink into the mantle, creating a hidden reservoir.
Adding up to an asteroid origin
The researchers measured the rocks’ composition, and found that the denser rocks contained much more lead than uranium — exactly the ratio predicted for the missing reservoir of material. Jagoutz then performed a mass balance (a simple conservation-of-mass calculation) to determine how much dense rock drops into the mantle, based on the composition of the region’s crust, rocks and mantle: Essentially, the mass of the Kohistan arc, minus whatever material drops into the mantle, should equal the material that comes out of the mantle.
Jagoutz and Schmidt solved the equation for 10 common elements. From their calculations, they found that 70 percent of the magma that rises from the mantle must ultimately drop back down, relatively heavy with lead. Applying this statistic to other island arcs in the world — such as the Andean volcanic belt and the Cascade Range — they found that the amount of material dropped into the mantle globally equals the composition and quantity of the so-called missing reservoir — a finding that suggests that Earth did indeed form from the collision of meteorites.
Bruce Buffett, a professor of earth and planetary science at the University of California at Berkeley, says a hidden reservoir in the mantle made of dense rocks is “interesting and plausible,” though he points out that there are other competing theories. For example, the subduction of oceanic crust into the mantle may contribute unknown material. Likewise, material may form from the cooling and solidifying of a large magma ocean.
“There are a large variety of options on the table to explain the complex structure we detect seismically at the bottom of the mantle,” says Buffett, who was not involved in the study. “The attractive aspect of [Jagoutz’s] idea is that it has testable consequences. This is how progress is made.”
“If we are right, one of the questions we have is: Why is the Earth capable of hiding something from us? Why is there never a volcano that brings up these rocks?” Jagoutz adds. “You’d think it’d come back up, but it doesn’t. It’s actually interesting.”
Note : The above story is reprinted from materials provided by Massachusetts Institute of Technology. The original article was written by Jennifer Chu.
The researchers studied the eruption of Redoubt in 2009
A change in the frequency of earthquakes may foretell explosive volcanic eruptions, according to a new study.
The seismic activity changes from steady drum beats to increasingly rapid successions of tremors.
These blend into continuous noise which silences just before explosion.
The study of tremors in the lead up to the 2009 eruption of Redoubt, a volcano in Alaska, appears in Journal of Volcanology and Geothermal Research.
Those quakes continuously rose in pitch like a volcanic glissando – a musical glide from one pitch to another.
Subterranean magma plumbing systems sit beneath volcanoes and feed pressurised molten rock toward the surface before eruptions.
As the magma flows through deep conduits and cracks, it generates small seismic tremors and earthquakes.
Scientists have noted earthquakes preceding volcanic eruptions before, for example drumbeat earthquakes were the first sign of renewed magmatic activity in Mount St Helens in April 2005.
But the new analysis of Alaska’s Redoubt volcano shows that the tremor glided to higher frequencies and then stopped abruptly less than a minute before eruption.
“The frequency of this tremor is unusually high for a volcano,” explained Alicia Hotovec-Ellis, a doctoral student involved in the study, from the University of Washington.
“Because there’s less time between each earthquake, there’s not enough time to build up enough pressure for a bigger one. After the frequency glides up to a ridiculously high frequency, it pauses and then it explodes.”
The earthquake noise sounds like a scream before eruption when the seismometer data are speeded up sixty times to make them audible. The authors suggest a simple model of brittle fracture may explain their results, although the precise details of what is going on underneath volcanoes before they erupt remain unclear.
Dr Marie Edmonds, from the University of Cambridge, who was not involved in the study, commented: “This work is probably the most intensive treatment of this phenomenon. If you can get an idea of what is causing these types of patterns then you have a route to prediction of volcanic eruptions.
“The question that arises is whether you can ever get these sorts of patterns without an eruption following?
“We had repetitive sequences of volcanic explosions in the Caribbean island of Montserrat in 1997 and 2003 which were preceded by similar tremors, with hybrid earthquakes that were periodic and then recurrence intervals decreased with time before the explosion. People are converging on a view on how magmas behave.”
Note : The above story is reprinted from materials provided by BBC News. The original article was written by Simon Redfern
New evidence suggests T rex was capable of bringing down live prey rather than simply scavenging dinosaur carcasses. Photograph: Corey Ford/Corbis
Threats to the fearsome reputation of Tyrannosaurs rex appeared to have been seen off on Monday by fresh evidence unearthed in the US.
The dinosaur’s feeding habits have long been debated by academics, with some claiming that T rex was less a ferocious hunter and more a lumbering slowcoach that scavenged the carcasses of beasts that had died at the claws of others.
The latest evidence comes from palaeontologists who found remnants of a prehistoric skirmish in a slab of rock at the Hell Creek Formation in South Dakota. The clash, which occurred around 66m years ago, involved a T rex and a large, plant-eating hadrosaur, and ended with the tooth of the former lodged firmly in the spine of the latter.
Scans of the tooth and two surrounding tail vertebrae showed clear signs of bone healing around the wound, taken as proof that the hadrosaur was alive at the time of the attack and survived for several months or even years afterwards.
“This is unambiguous evidence that T rex was an active predator,” the authors write in the journal Proceedings of the National Academy of Sciences. “Such evidence is rare in the fossil record for good reason – prey rarely escapes.”
Tyrannosaurs shed their teeth frequently as fresh sets came through. In this case a weaker rear tooth broke free as the T rex, which was not fully-grown, chomped on the hadrosaur’s tail. The hadrosaur is believed to have been an adult Edmontosaur, which grew to around 10 metres in length.
The tooth crown is embedded between two hadrosaur vertebrae and the bone has healed over. Photograph: David A Burnham
“We not only have a broken-off tooth embedded in the bone of another animal, but the bone has healed over
The remains join a large collection of fossils that tell their own partial stories about the dining habits of T rex. Previous discoveries reveal rake, puncture and chew marks on bones, while one specimen – an impressive half-metre of fossilised faeces – contained partly digested dinosaur bones. In all of these cases, it is hard to differentiate between predation and scavenging.
Palaeontologists expressed mixed reactions to the latest findings. Jack Horner at the Museum of the Rockies in Montana, who served as technical adviser on the Jurassic Park movies, told the Guardian: “This one piece of evidence does seem to suggest that a tyrannosaur bit a hadrosaur, but certainly doesn’t provide any indication of the sort of carnivore the rex actually was.”
In 2011, Horner and his team reported that T rex was probably an opportunistic carnivore like hyena, which take carrion and occasional live prey. “This paper certainly offers no evidence to refute that hypothesis,” Horner added.
Paul Barrett, a dinosaur researcher at the Natural History Museum in London, expressed exasperation that the debate was still ongoing. “The whole T rex scavenger or predator debate is pretty intractable and not particularly enlightening. Work on living carnivores, like big cats and wolves, clearly show they use both strategies depending on what’s available to them. They’ll generally make do with a meal from either source if it satisfies their dietary needs. Any other extinct carnivore, including T rex, is likely to have been the same,” he said.
“This paper shows without question that a T rex bit a living hadrosaur, but it can’t show if this was a regular behaviour or not, or even if this was hunting behaviour rather than some other kind of interaction,” he added.
But Sam Turvey, a senior research fellow at the Institute of Zoology in London, called it “important and convincing” new evidence. “Even though T rex may have fed on carcasses when the opportunity arose – a behaviour also seen in modern-day carnivorous large mammals such as lions – the new findings provide strong evidence that these iconic dinosaurs were fully capable of being active predators, and help to dismiss the ecologically unrealistic hypothesis that they were restricted to a scavenging lifestyle,” he said.
the wound, and a nasty wound it was too,” said David Burnham at Palm Beach Museum of Natural History in Florida.
Note : The above story is reprinted from materials provided by guardian.co.uk. The original article was written by Ian Sample, science correspondent .
Redoubt Volcano’s active lava dome as it appeared on May 8, 2009. The volcano is in the Aleutian Range about 110 miles south-southwest of Anchorage, Alaska. (Credit: Chris Waythomas, Alaska Volcano Observatory)
It is not unusual for swarms of small earthquakes to precede a volcanic eruption. They can reach a point of such rapid succession that they create a signal called harmonic tremor that resembles sound made by various types of musical instruments, though at frequencies much lower than humans can hear.
A new analysis of an eruption sequence at Alaska’s Redoubt Volcano in March 2009 shows that the harmonic tremor glided to substantially higher frequencies and then stopped abruptly just before six of the eruptions, five of them coming in succession.
“The frequency of this tremor is unusually high for a volcano, and it’s not easily explained by many of the accepted theories,” said Alicia Hotovec-Ellis, a University of Washington doctoral student in Earth and space sciences.
Documenting the activity gives clues to a volcano’s pressurization right before an explosion. That could help refine models and allow scientists to better understand what happens during eruptive cycles in volcanoes like Redoubt, she said.
The source of the earthquakes and harmonic tremor isn’t known precisely. Some volcanoes emit sound when magma — a mixture of molten rock, suspended solids and gas bubbles — resonates as it pushes up through thin cracks in Earth’s crust.
But Hotovec-Ellis believes in this case the earthquakes and harmonic tremor happen as magma is forced through a narrow conduit under great pressure into the heart of the mountain. The thick magma sticks to the rock surface inside the conduit until the pressure is enough to move it higher, where it sticks until the pressure moves it again.
Each of these sudden movements results in a small earthquake, ranging in magnitude from about 0.5 to 1.5, she said. As the pressure builds, the quakes get smaller and happen in such rapid succession that they blend into a continuous harmonic tremor.
“Because there’s less time between each earthquake, there’s not enough time to build up enough pressure for a bigger one,” Hotovec-Ellis said. “After the frequency glides up to a ridiculously high frequency, it pauses and then it explodes.”
She is the lead author of a forthcoming paper in the Journal of Volcanology and Geothermal Research that describes the research. Co-authors are John Vidale of the UW and Stephanie Prejean and Joan Gomberg of the U.S. Geological Survey.
Hotovec-Ellis is a co-author of a second paper, published online July 14 in Nature Geoscience, that introduces a new “frictional faulting” model as a tool to evaluate the tremor mechanism observed at Redoubt in 2009. The lead author of that paper is Ksenia Dmitrieva of Stanford University, and other co-authors are Prejean and Eric Dunham of Stanford.
The pause in the harmonic tremor frequency increase just before the volcanic explosion is the main focus of the Nature Geoscience paper. “We think the pause is when even the earthquakes can’t keep up anymore and the two sides of the fault slide smoothly against each other,” Hotovec-Ellis said.
She documented the rising tremor frequency, starting at about 1 hertz (or cycle per second) and gliding upward to about 30 hertz. In humans, the audible frequency range starts at about 20 hertz, but a person lying on the ground directly above the magma conduit might be able to hear the harmonic tremor when it reaches its highest point (it is not an activity she would advise, since the tremor is closely followed by an explosion).
Scientists at the USGS Alaska Volcano Observatory have dubbed the highest-frequency harmonic tremor at Redoubt Volcano “the screams” because they reach such high pitch compared with a 1-to-5 hertz starting point. Hotovec-Ellis created two recordings of the seismic activity. A 10-second recording covers about 10 minutes of seismic sound and harmonic tremor, sped up 60 times. A one-minute recording condenses about an hour of activity that includes more than 1,600 small earthquakes that preceded the first explosion with harmonic tremor.
Upward-gliding tremor immediately before a volcanic explosion also has been documented at the Arenal Volcano in Costa Rica and Soufrière Hills volcano on the Caribbean island of Montserrat.
“Redoubt is unique in that it is much clearer that that is what’s going on,” Hotovec-Ellis said. “I think the next step is understanding why the stresses are so high.”
The work was funded in part by the USGS and the National Science Foundation.
Note : The above story is reprinted from materials provided by University of Washington. The original article was written by Vince Stricherz.
The crater of the Indonesian volcano Tombora (diameter about 7 km). Its eruption turned 1815 in to a “year without a summer” in Europe. The sulfate traces it left behind in the Greenland and Antarctic ice, served as a comparison for the current model study. (Credit: NASA)
How severely have volcanoes contaminated the atmosphere with sulfur particles in past millennia? To answer this question, scientists use ice cores, among others, as climate archives. But the results differ, particularly in some major volcanic major events of the past, depending on whether the cores come from Antarctica or Greenland. Atmospheric scientists from the GEOMAR Helmholtz Centre for Ocean Research Kiel and the Max Planck Institute for Meteorology in Hamburg have now found an explanation that could significantly improve the interpretation of ice cores.
Their study was just published in the current issue of the Journal of Geophysical Research Atmosphere.
Storms, cold, poor harvests — the year 1816 was a “year without a summer” in European history. The reason was the eruption of the Indonesian volcano Tambora a year earlier. It had thrown huge amounts of sulfur compounds into the stratosphere (at altitudes of 15-50 km) where they spread around the entire globe and significantly weakened solar radiation for several years afterwards. Such intense volcanic eruptions are quite common in Earth’s history. To better understand their impact on the climate and the atmosphere, scientists try to reconstruct those eruptions accurately. Important archives of information are ice cores from Greenland and Antarctica because the sulfur particles ejected from the volcano fall back to the surface. A portion of that fallout is trapped in the ice of the polar regions and can be analyzed even thousands of years afterwards. The former aerosol contamination of the atmosphere is derived from it using a simple ratio calculation.
But this method has its limitations. “Volcanic aerosols in the stratosphere absorb infrared radiation, thereby heating up the stratosphere, and changing the wind conditions subsequently,” said Dr. Matthew Toohey, atmospheric scientist at GEOMAR Helmholtz Centre for Ocean Research Kiel. Using an atmospheric model, he has now tested the effects of this phenomenon. “We have found that the deposition of sulfur compounds in the Antarctic after very large volcanic eruptions in the tropics may be lower than previously thought,” the atmospheric researcher summarizes the findings of the study which has just been published in the current issue of the international “Journal of Geophysical Research — Atmosphere.”
For the study, Dr. Toohey and his colleagues from GEOMAR and the Max Planck Institute for Meteorology in Hamburg have used an aerosol-climate model to track 70 different eruption scenarios while analyzing the distribution of the sulfur particles. It was based on real volcanic eruptions during the past 200,000 years in Central America, which had been investigated in the framework of the Collaborative Research Project 574. “In our calculations, we could clearly see the differences in distribution and deposition between the northern and southern hemispheres,” explains co-author and director of the working group, Dr. Kirstin Krüger. The spatial deposition of sulfur particles in the bipolar ice cores, as calculated in the model, agrees well with the actually measured deposits of large volcanic eruptions, such as Pinatubo in 1991 or even of Tambora of 1815.
“If we know how volcanic sulfur particles affect the atmospheric winds, we can have a much improved interpretation of the traces of volcanic activities in the ice cores,” says Dr. Toohey. For one, there are better estimates of the strength of an outbreak. And secondly, the previously undetermined traces of volcanic eruptions that could not be assigned to any particular event or volcano eruption, can now be clearly traced to their origin.
“In any case, the results of our model study give a clear indication that the bipolar variability of sulfate deposits must be taken into consideration if the traces of large volcanic eruptions are to be deduced from ice cores,” says Dr. Krüger, “Several research groups that deal with this issue have already contacted us to verify their data through our model results.”
Note : The above story is reprinted from materials provided by Helmholtz Centre for Ocean Research Kiel (GEOMAR).
