Home Blog Page 201

New geological epoch marked by human impact are clear

Artificial spheroids (left: carbonaceous; centre: plastic; right: metallic) and their respective compositional spectra present in the anthropocene sediments in the Urola Estuary (Basque Coast Geopark). Taken from the Master’s Dissertation on the Quarternary Period by Aintzane Goffard (2015). Credit: UPV/EHU

The Anthropocene, which is regarded as having begun halfway through the 20th century, is marked by the expansion of new materials, such as aluminium, cement, plastic, ash from the combustion of hydrocarbons, and radioisotopes originating from atomic tests around the planet, in addition to high greenhouse gas emissions and the unprecedented global spread of invasive species.

An international group of scientists is exploring whether human activity has brought the planet to a new geological epoch: the Anthropocene. The basic questions raised in their work are as follows: To what extent are human activities recorded as quantifiable signs in geological strata? And is the world of the Anthropocene clearly different from the relatively stable Holocene, which has lasted 11,700 years and which has made the development of human civilisation possible?

The Holocene epoch is a time during which human societies have advanced by gradually domesticating the earth’s surface in order to increase food production, build urban settlements, and make use of the planet’s water, and its mineral and energy resources. The Anthropocene epoch currently being proposed is, however, characterised as a time of rapid, environmental changes caused by the accelerated growth of the human population and the sharp increase in consumption following the “Great Acceleration” halfway through the 20th century. The authors of the work maintain that “for a long time we humans have been causing an impact on the environment, but a rapid global distribution of new materials (including aluminium, cement and plastics) has taken place recently, and these materials are leaving their mark in the sediments. The burning of fossil fuels has dispersed particles in the form of ash all over the planet, coinciding with the peaking in the distribution of radioisotopes resulting from the testing of nuclear bombs in the atmosphere. All these indications show that the the concept of the Anthropocene is a reality”.

This study, produced by 24 members of the Anthropocene Working Group and including Alejandro Cearreta, a lecturer at the UPV/EHU’s Faculty of Science and Technology, shows that the human species has modified System Earth sufficiently to generate a series of signs that are already evident in the sediments and ice and that these signs are sufficiently distinctive to justify the recognition of an Anthropocene epoch in the Table of Geological Ages. In the course of 2016, the Anthropocene Working Group will be gathering further evidence on this new geological epoch; it is expected to contribute towards drawing up the recommendations on possibly making it official and, in this case, on how it could be defined and characterised.

Reference:
Waters, C.N.; Zalasiewicz, J.; Summerhayes, C.; Barnosky, A.D.; Poirier, C.; Ga?uszka, A; Cearreta, A.; Edgeworth, M; Ellis, E.; Ellis, M.A.; Jeandel, C.; Leinfelder, R.; McNeill, J.R.; Richter, D. deB.; Steffen, W.; Syvitski, J.; Vidas, D.; Wagreich, M.; Williams, M.; Zhisheng, A.; Grinevald, J.; Odada, E.; Oreskes, N. & Wolfe, A.P. (2016). The Anthropocene is functionally and stratigraphically distinct from the Holocene. Science 351 (6269): aad2622.1-aad2622.10. DOI: 10.1126/science.aad2622

Note: The above post is reprinted from materials provided by University of the Basque Country .

Diamonds used to ‘probe’ ancient Earth

Diamonds used to 'probe-GeologyPage
A cluster of the Witwatersrand diamonds. Credit: Wits University

Diamonds dug up from ancient rock formations in the Johannesburg area, between 1890 and 1930 — before the industrialisation of gold mining — have revealed secrets of how Earth worked more than 3.5 billion years ago.

The three diamonds, which were extracted from the 3 billion-year-old Witwatersrand Supergroup — the rock formation that is host to the famous Johannesburg gold mines — were investigated by Dr. Katie Smart, Prof. Susan Webb and Prof. Lewis Ashwal from Wits University, Prof Sebastian Tappe from the University of Johannesburg, and Dr. Richard Stern from the University of Alberta (Edmonton, Canada), to study when modern-style plate tectonics began to operate on planet Earth. The diamonds were generously provided by Museum Africa, located in Johannesburg, with the assistance of curator Katherine James.

“Because diamonds are some of the the hardest, most robust material on Earth, they are perfect little time capsules and have the capacity to tell us what processes were occurring extremely early in Earth’s history,” says Dr Katie Smart, a Lecturer at the Wits School of Geoscience and the lead researcher on the paper, Early Archaean tectonics and mantle redox recorded in Witwatersrand diamonds, that was published in the journal, Nature Geoscience, in January.

Earth is approximately 4.5 billion years old, and while a rock record exists from about 4 billion years ago, the complex preservational history of the most ancient rocks exposed on Earth’s surface has led to a heated debate amongst Geoscientists on when plate tectonics began operating on Earth. Many researchers believe plate tectonics began in the Archaean (the Eon that took place from 4 to 2.5 billion years ago), although the exact timing is highly contested.

While the diamonds of this study were found in 3 billion-year-old sedimentary rocks, diamond formation occurred much deeper, within Earth’s mantle. Additionally, based on the nitrogen characteristics of the diamonds, they also formed much earlier, around 3.5 billion years ago. Transport of the diamonds to the surface of Earth by kimberlite-like volcanism, followed by their voyage across the ancient Earth surface and into the Witwatersrand basin, occurred between 3.5 and 3 billion years ago.

By using an ion probe to analyse the carbon and nitrogen isotope compositions of the Witwatersrand diamonds, which have been pristinely preserved for more than three billion years, Smart and her team found that plate tectonics was likely in operation on Earth as early as 3.5 billion years ago.

“We can use the carbon and nitrogen isotope compositions of the diamonds to tell us where the source material involved in the formation of the Witwatersrand diamonds over 3 billion years ago came from,” says Smart.

“The nitrogen isotope composition of the Witwatersrand diamonds indicated a sedimentary source (nitrogen derived from Earth’s surface) and this tells us that the nitrogen incorporated in the Witwatersrand diamonds did not come from Earth’s mantle, but that it was rather transported from Earth’s surface into the upper mantle through plate tectonics. This is important because the nitrogen trapped in the Witwatersrand diamonds indicates that plate tectonics, as we recognise it today, was operating on ancient Archaean Earth, and actively transported material at Earth’s surface deep into the mantle.”

Earth as a planet is unique because of the dynamic process of plate tectonics that constantly transports surface material into Earth’s mantle, which extends between 7 km to over 2800km below Earth’s surface. The process is driven by both convection cells within Earth’s mantle and the character of crustal plates at Earth’s surface, where newly formed oceanic crustal plates are formed at spreading centres at mid-ocean ridges and then pushed apart. Older, cooler and more dense crust at convergent plate margins is then pulled into, or sinks, into the mantle at subduction zones. The subduction of crustal plates into the mantle can also carry sediments and organic material deep into Earth’s interior.

The plate tectonic process is vital for shaping Earth as we know it, as the activity of plate tectonics causes earthquakes, volcanic eruptions, and is responsible for constructing Earth’s landscapes, such as deep sea trenches and building of mountains on the continents.

“Various researchers have tried to establish when exactly plate tectonics started on Earth, but while there are many investigations of ancient rocks on Earth’s surface — like the 3.5 billion year old Barberton Greenstone Belt here in South Africa, or the 4 billion year old Acasta Gneiss in northwest Canada — we are looking at the problem from a different viewpoint — by investigating minerals derived from Earth’s mantle,” says Smart.

“We are not the first research group to study diamonds in order to tell when plate tectonics began, but our study of confirmed Archaean diamonds has suggested that plate tectonics was in operation by at least 3.5 billion years.”

About the research:

  • Researchers acquired three Witwatersrand diamonds from Museum Africa. These diamonds were cut by laser and saws to create thin diamond plates.
  • Diamonds sometimes contain “inclusions” of minerals, which can be used to date the diamonds using radiogenic isotopes. Diamonds themselves cannot be directly dated, and it is assumed that the diamond and diamond inclusion formed together at the same time. The oldest diamond inclusion known has been dated to be 3.5 billion years old.
  • The age of the Wits diamonds is confirmed due to their derivation from the 3 billion-year-old Witwatersrand sediments, and are likely 3.5 billion years old based on the nitrogen characteristics of the diamonds.
  • The goal of the study was to complete carbon and nitrogen isotope analyses of the diamond plates using an Ion Microprobe.
  • The specimens were analyzed by Dr. Richard Stern and Dr. Katie Smart at the Canadian Centre for Isotopic Microanalysis at the University of Alberta, Edmonton, Alberta using a state of the art Cameca IMS1280 ion microprobe. An ion microprobe analyses geologic specimens using SIMS (Secondary Ion Mass Spectrometry) at a very fine spatial resolution, and in the case of this study, achieved spatial resolution of < 20 microns (1 micron is 1/1000th of a millimeter). Stern fired a beam of ions (usually cesium or oxygen ions) at the surface of the diamonds, which causes the specimen to produce secondary ions whose masses are resolved by a mass analyser.
  • The final product is a stable isotope ratio: in this case carbon (13C/12C) and nitrogen (15N/14N) isotope compositions plus nitrogen contents of the Witwatersrand diamonds were determined. Due to the sensitivity and spatial resolution required for the study, there are only a few labs worldwide that can complete these complex analyses.
  • The results showed that the source of the nitrogen involved in the formation of the Witwatersrand diamonds was likely sedimentary and derived ultimately from Earth’s surface. Importantly, this indicates that the nitrogen must have been transported into Earth’s mantle through plate tectonics much earlier than 3.5 billion years ago.

About the Witwatersrand Diamonds

The green Witwatersrand diamonds were found in the Witwatersrand conglomerate, where the gold was found that led to the establishment of the city of Johannesburg.

A number of these diamonds were found between 1890 and 1930, when men were still mining by hand and pick axes. After the industrialisation of the mines in the 1930s, most of the diamonds in the conglomerate were crushed to dust. For this reason, the Witwatersrand diamonds are extremely rare.

The Witwatersrand conglomerate is known to be at least three billion years old. The diamonds that are found in the conglomerate are known as “placer” diamonds. These diamonds did not originate in the conglomerate, but were transported from their original kimberlite sources by secondary means, such as rivers.

Most diamonds are believed to be younger than three billion years old, but as the Witwatersrand conglomerate is known to be three billion years old, the diamonds found in the conglomerate must have been formed more than 3 billion years ago. Thus, they can be referred to as “confirmed ancient diamonds.”

Reference:
Katie A. Smart, Sebastian Tappe, Richard A. Stern, Susan J. Webb, Lewis D. Ashwal. Early Archaean tectonics and mantle redox recorded in Witwatersrand diamonds. Nature Geoscience, 2016; DOI: 10.1038/ngeo2628

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

Discovery leads to largest titanosaur in Argentina

Discovery leads to largest-GeologyPage
The head of the titanosaur sticks out into the hallway at the American Museum of Natural History in New York. Credit: Brian Harkin/The New York Times

Four years ago, a rancher in the Patagonia region of Argentina came upon an old bone sticking out of his desert property near La Flecha.

With recent news of exciting dinosaur finds in that country in mind, he scratched around some more. Then he went to a local museum to ask paleontologists to come look for more fossils.

Many important dinosaur discoveries are made by nonexperts in just this casual way. The rancher’s find soon led to the exposure of skeletal remains of six of the biggest titanosaurs. These herbivores lived about 100 million years ago, in the Late Cretaceous Period, on all continents, including Antarctica. They seemed especially plentiful in southern lands.

Now, the most imposing one of these dinosaurs from the far south of South America, assembled from 84 fossil pieces excavated from the rancher’s land, is the newest eyeful of ancient life on display at the American Museum of Natural History in Manhattan. The hulking skeleton cast made its debut as a permanent attraction on Friday. Museum officials and scientists called it a must-see addition to the ranks of such popular icons as the institution’s great blue whale and the fierce Tyrannosaurus rex.

“There’s nothing like finding a great new fossil, especially such a huge one,” said Michael J. Novacek, the museum’s senior vice president, provost of science and a curator of paleontology.

The new research is expected to yield insights into the physiology of dinosaurs and how they were able to grow and function as such large creatures.

“Paleontology has become less geological and more biological in the last 20 years or so,” said Mark A. Norell, chairman of the paleontology division at the museum and a leading dinosaur researcher. He cited the field’s new “geochemical tools” for determining diet, growth patterns and locomotion. “All of us are simply biologists who work on fossils,” he added.

The exhibit is not only a centerpiece for the museum’s fossil collections but also the start of a wide range of dinosaur programs for the year, including symposiums and another exhibition, “Dinosaurs Among Us,” opening March 21. It will highlight the signal developments in remarkable research supporting a close relationship between dinosaurs and birds that are alive today.

The Patagonian skeleton was not an easy fit in its New York home. At 122 feet in length, it was a bit too long for the gallery. Part of its 39-foot-long neck extends through an opening in a wall toward the elevator banks, as if to welcome visitors to the fossil floors.

This titanosaur was a young adult, gender undetermined. Its appetite for all kinds of vegetation must have been prodigious. Based on bone sizes, researchers estimated that this individual weighed 70 tons — as much as 10 African elephants, the heaviest land animals today. Think of its possible heft if it were fully grown. Think of it satisfying its huge appetite by stretching its long neck to graze far and wide. With only a few shifts in position, it might have mowed the equivalent of all the grass in Yankee Stadium in a morning.

Weight was also a factor in preparing the skeleton cast for display, a task undertaken by Research Casting International in Canada. The actual mineralized fossils were too heavy to mount. Instead, all “bones” are made from lightweight fiberglass based on digital copies of the original fossils.

Much of the grueling excavation leading to the discovery was done by teams led by José Luis Carballido and Diego Pol, paleontologists at Paleontological Museum Egidio Feruglio in Argentina. They began excavating for months at a time after the rancher’s visit. Sometimes it took a week of digging to isolate a single femur or a forelimb. Thighs and upper arms are critical to judging the size and weight of a dinosaur.

Pol said the excavations revealed that at least six of these giant individuals, all young adults, had died at the site of what had been a flood plain near a river. Their deaths had happened at three distinct times, anywhere from a few years to centuries apart. Like many herding animals, they may have become isolated from the group and died of stress and hunger near their watering hole.

“That’s when we realized this was a once-in-a-lifetime discovery,” Pol said. Dinosaurs are the big game to fossil hunters, and these were some of the biggest plant-eating dinosaurs ever found.

The size and distinctive shape of an eight-foot femur of one specimen astonished scientists. This appeared to be a previously unknown titanosaur species, yet unnamed. Pol said a report that is being prepared may soon propose a formal species name.

In a bravura moment, Pol had his picture taken stretched out on the ground beside the femur, about the size of a living room couch. The photograph caught the attention of paleontologists at the natural history museum in New York, where Pol had done his Ph.D. research. “Maybe we can get that thing,” one said. “That would look great for a renovated dinosaur gallery” another said.

Early last year, Novacek signed the deal with the Argentine museum to build the full-size skeleton cast for permanent display in New York.

On a visit a few days before the titanosaur’s unveiling, workers were applying finishing touches as Norell paused at the entrance, under the watchful eye and toothy jaw of the star attraction.

“I guarantee you are going to remember this first impression,” Norell said. “Seeing something like this, you don’t quite have anything to compare its size and aspect with.”

He was right. The dinosaur was inexpressibly strange and big. Once again, we are reminded of what we know: Dinosaurs mostly were big, an engaging mystery and a challenge.

The titanosaur’s arrival at the museum may inspire new understanding of these incredible creatures. It is exciting enough to walk a corridor to the fossil galleries in anticipation of meeting it, and spending some time with old friends of fond memory.

Novacek is not bothered by some skepticism that the specimens are from the biggest dinosaur discovered so far, and that these may soon be eclipsed in size by new excavations.

“Every time we find the biggest dinosaur,” he said, “we soon find a bigger one in the next dig.”

Note: The above post is reprinted from materials provided by Pittsburgh Post-Gazette. The original article was written by John Noble Wilford.

Scientists detect deep carbon emissions associated with continental rifting

Scientists detect deep carbon-GeologyPage
Lake Magadi, an alkaline lake that contans soda, is located in southern Kenya. Credit: University of New Mexico

Scientists at the University of New Mexico conducted research to effectively study carbon emissions through fault systems in the East African Rift (EAR) in an effort to understand carbon emissions from Earth’s interior and how it affects the atmosphere.

Carbon dioxide (CO2) from Earth’s interior is thought to be released into the atmosphere mostly via degassing from active volcanoes. CO2 can also escape along faults away from active volcanic centers. However, such tectonic degassing is poorly constrained, and to date has been largely unmeasured.

The research, funded by the National Science Foundation (NSF) Tectonics Program, is directed by UNM Professor Tobias Fischer and is part of a continued effort to better quantify global emissions of CO2 from Earth’s interior.

Led by UNM Ph. D. student Hyunwoo Lee, the lead author of the paper titled, Massive and prolonged deep carbon emissions associated with continental rifting published in Nature Geosciences, the scientists set out to measure diffuse CO2 flux from the Magadi-Natron basin in the East African Rift (EAR) between Kenya and Tanzania.

“CO2 is the main source of the greenhouse effect,” said Lee. “Natural carbon emissions come from volcanoes and are derived from magma. Mostly, people have thought the major sources of magmatic emissions have come through active volcanic events. Our research is the first attempt to quantify magmatic CO2 gases from non-volcanic and continental rift regions.”

The EAR is the world’s largest active continental rift and is comprised through distinct western and eastern sectors. Several active volcanoes emit large volumes of CO2 including Nyiragongo in the Congo and Oldoinyo Lengai in Tanzania. Additionally, significant amounts of CO2 are stored in large anoxic lakes in this region.

“To measure diffuse CO2 flux, we used an EGM-4 CO2 gas analyzer with a cylindrical accumulation chamber” Lee said. “The gas samples were then diverted from the chamber into pre-evacuated glass vials in order to carry out gas chemistry and carbon isotope analyses in our laboratories at UNM.”

Additional gas samples collected along fault zones in the Magadi-Natron basin showed an elevated CO2 flux and provided further evidence that faults act as permeable pathways facilitating the ascent of deeply-derived CO2. This particular study area represented a conservative 10 percent of the entire Natron-Magadi region.

The data from all samples were then compared to gas data from the active volcano Oldoinyo Lengai and found to have carbon isotope compositions that indicated a strong magmatic contribution to the observed CO2.

James Muirhead, a doctoral student at the University of Idaho, focused on the relationship between the structure of the faults and the gas they released, including what controls carbon dioxide flow from depth and what volumes of gas the faults release.

Combing the CO2 flux data and fault structures with carbon isotopic analyses, conducted at UNM’s Center for Stable Isotopes (CSI), the research generated interesting data allowing the scientists to quantify the massive and prolonged deep carbon emissions through faults.

“We found that about 4 megatonnes per year of mantle-derived CO2 is released in the Magadi-Natron Basin, at the border between Kenya and Tanzania,” Lee said. “Seismicity at depths of 15 to 30 kilometers detected during our project implies that extensional faults in this region may penetrate the lower crust. Thus, the ultimate source of the CO2 is the lower crust or the mantle, consistent with the carbon isotopes measured in the gas.”

The findings suggest that CO2 is transferred from upper mantle or lower crustal magma bodies along these deep faults. Extrapolation of the measurements to the entire Eastern branch of the rift system implies a huge CO2 flux 71 megatonnes per year, comparable to emissions from the entire global mid-ocean ridge system of 53 to 97 megatonnes per year.

“It is often argued that large volcanic eruptions instantly transfer significant amounts of CO2 and other gases into the atmosphere where they affect the global climate over a few years,” Fischer said. “On human time-scales, continental rifting is extremely slow at spreading rates of mm’s per year but on geologic time-scales, rifting can be considered a catastrophic continental break-up event.”

“Widespread continental rifting and super-continent breakup could produce massive, long-term CO2 emissions and contribute to prolonged greenhouse conditions like those of the Cretaceous,” Lee added.

Large-scale rifting events could play a previously unrecognized role in heating up the atmosphere and perhaps ending global ice ages.

“It is important to note, however, even when including the newly quantified CO2 emissions from the EAR in the global CO2 budget, natural emissions are dwarfed by emissions from fossil fuel use which were 36 giga tons of CO2 in 2013,” Fischer said. “This comparison shows that humanity is currently emitting the equivalent of 500 East African Rifts in CO2 to the atmosphere per year.”

Cindy Ebinger, a professor of earth and environmental sciences at the University of Rochester, coordinated field activities near the Kenya-Tanzania border and analyzed earthquake patterns within the rift zone.

“The unique coupling of gas chemistry and earthquake studies made it possible to discover the escape of gas along permeable fault zones that serve as conduits to the surface,” said Ebinger. “The work also allowed us to document the process of crustal growth through the formation of igneous rocks from magma in early-stage continental rift zones.”

Lee says the scientists plan to measure diffuse CO2 flux and collect gas samples from other areas in the EAR to better constrain how much it releases deep carbon to try to better constrain how much deeply derived CO2 comes from natural systems.

“Because some geological settings, for example fault zones, have never been paid attention to, global CO2 flux from natural systems are obviously underestimated,” he said. “Although there are still many ongoing studies to find better ways to quantify CO2 flux from active volcanoes, we expect this study to trigger more research on CO2 output from non-volcanic areas.”

Reference:
Hyunwoo Lee, James D. Muirhead, Tobias P. Fischer, Cynthia J. Ebinger, Simon A. Kattenhorn, Zachary D. Sharp, Gladys Kianji. Massive and prolonged deep carbon emissions associated with continental rifting. Nature Geoscience, 2016; DOI: 10.1038/ngeo2622

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

Nearing the limits of life on Earth

In University Valley, there is a layer of dry permafrost soil overlaying ice-rich permanently frozen ground. The ice in the permafrost is formed not by liquid water, but by frozen water vapor; the absence of liquid water, makes the soil less likely to be able to sustain life. Credit: Jackie Goordial

It took Jackie Goordial over 1000 Petri dishes before she was ready to accept what she was seeing. Or not seeing. Goordial, a post-doctoral fellow in the Department of Natural Resource Sciences at McGill University has spent the past four years looking for signs of active microbial life in permafrost soil taken from one of the coldest, oldest and driest places on Earth: in University Valley, located in the high elevation McMurdo Dry Valleys of Antarctica, where extremely cold and dry conditions have persisted for over 150,000 years. The reason that scientists are looking for life in this area is that it is thought to be the place on Earth that most closely resembles the permafrost found in the northern polar region of Mars at the Phoenix landing site.

“I’ve been trying to cheer her up by telling her that not finding life is important too,” says Lyle Whyte, Goordial’s supervisor. “Going into the study, we were sure that we would detect a functioning and viable microbial ecosystem in the permafrost soils of University Valley as we and others have done in Arctic and Antarctic permafrost, including in other sites at lower elevations in Antarctica. It is hard for both of us to believe that we may have reached a cold and arid threshold where even microbial life cannot actively exist.”

Drilling for microbes in Antarctica

What brought the researchers to University Valley was a NASA ASTEP (astrobiology science and technology for exploring planets) project to test the IceBite auger, a permafrost drill designed to drill into Martian permafrost. The average daily air temperature in the Antarctic summer of 2013, when Goordial collected the permafrost samples which she tested both on the spot and later in the lab, was ? 14 °C and it never rose above 0 °C, making the permafrost difficult to drill.

The McGill team analyzed samples from two permafrost boreholes which reached a depth of just 42 cm and 55 cms below the surface. This may not sound like a lot, but drilling into permafrost to get soil samples for testing is very difficult.

“Anytime you drill into frozen ground and it has some ice in it the drilling process creates friction which melts the ice. The hole will refreeze within seconds if the drilling is interrupted, freezing the drill bit into the hole” says Whyte.” I remember drilling in the Arctic and losing a drill bit in one of the holes we had made, just because it froze into the ice before we could get it out.”

“Previous studies in the lower dry valleys of Antarctica and in subglacial lakes were giving us the impression that microbial life was rich in the cold regions. But this is finally Mars!” says Chris McKay of NASA’s Ames Research Centre. “University Valley has the coldest driest soil we can find on Earth. And life is really having a hard time of it there. This is certainly the training ground for the search for evidence of life on Mars and an extremely important result for NASA’s astrobiology effort.”

All the tests came out negative

The research team carried out a variety of tests, both in the field (where they failed to find evidence of carbon dioxide or methane — a gas used by all living things — in the soil) and then back in the lab at McGill in Montreal. They sent soil samples for DNA testing, looking for matches with particular genes known to be found in microbes and fungi; they tried to stimulate microbial growth on a wide variety of substances and then count the cells produced; and they used highly sensitive radiorespiration activity assays, which involve feeding the soil microorganisms a food source which has been labelled with radioactive carbon, which can then be used to detect if the microorganisms are active.

The tests failed to show any signs of active life.

“We couldn’t detect any microbial activity within these samples,” says Whyte. “Any, very limited traces we were able to find of microbial life in these samples are most likely the remnants of microbes that are dormant or are slowly dying off. Given the continuous dryness and subfreezing temperatures, and the lack of available water, even in summer, it is unlikely that any microbial communities can grow in these soils.”

Goordial adds, “We don’t know if there is activity beyond our limits of detection. All we can say for sure is that after using all the current methods of testing available to us, the samples are unlike any other permafrost we have encountered to date on Earth”

Implications for the search for life on Mars

“If conditions are too cold and dry to support active microbial life on an analogous climate on Earth, then the colder dryer conditions in the near surface permafrost on Mars are unlikely to contain life.” Says Whyte. “Additionally, if we cannot detect activity on Earth, in an environment which is teeming with microorganisms, it will be extremely unlikely and difficult to detect such activity on Mars.”

On a positive note however, the researchers add that this suggests that any microorganisms that may be transported to Mars from Earth by mistake are unlikely to be able to survive on the Martian surface, something that is of current concern for planetary protection.

Reference:
Jacqueline Goordial et al. Nearing the cold-arid limits of microbial life in permafrost of an upper dry valley, Antarctica. The ISME Journal, January 2016 DOI: 10.1038/ismej.2015.239

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

Earth’s largest dinosaurs are discovered in Argentina

Earth's largest dinosaurs-GeologyPage
A reconstruction of the gigantic new titanosaurian dinosaur species Notocolossus gonzalezparejasi in southern Mendoza Province, Argentina. Notocolossus is shown threatening a pair of much smaller, carnivorous abelisaurid dinosaurs. Credit: Taylor Maggiacomo/Carnegie Museum of Natural History and Carnegie Mellon University

A series of fossil discoveries have revealed giant dinosaurs that, head to tail, extended a third of a football field and weighed as much as a dozen elephants or the largest humpback whale.

And a Pittsburgh paleontologist was on one team to study newly discovered fossils of two such titanosaurs — gigantic creatures that likely shook the ground with each step in what is now modern-day Argentina. Those behemoths were 82 to 92 feet and up to 66 tons — 132,000 pounds.

“You’d definitely feel vibrations when lots of them were moving, just like a herd of buffalo shakes the ground,” said Matthew Lamanna, assistant curator of vertebrate paleontology at Carnegie Museum of Natural History. “But they definitely walked rather than ran. I don’t think titanosaurs could move very quickly.”

The dinosaurs known as Notocolossus gonzalezparejasi roamed the outskirts of Patagonia during the Cretaceous Period about 86 million years ago. Their necks were long enough to eat from the ground to the tree tops, with similarly long tails other creatures likely strived to stay clear of.

Mr. Lamanna, who holds a Ph.D. in paleontology, worked on the team led by Bernardo Gonzalez Riga of the National University of Cuyo in the Mendoza Province of Argentina, who first spotted a fossil partially sticking up from rocks nearly a decade ago in a desert full of fossils of the world’s largest dinosaurs.

Details about the fossil discoveries were published Monday in the journal Scientific Reports.

Despite their huge dimensions, Notocolossus dinosaurs would seem like Danny Devitos standing beside Arnold Schwarzenegger when compared with the largest titanosaur also recently discovered. It is still without a name and details on this latter species have yet to be published.

But that titanosaur found in the Patagonia region of Argentina will be the focus of the Nature television documentary “Raising the Dinosaur Giant,” scheduled for broadcast on WQED at 8 p.m. Feb. 17. For now, it represents the largest known creature to walk on Earth at 122 feet long with a couch-sized thigh bone notably longer than host Sir David Attenborough, according to a PBS photograph of him reclined beside it.

That dinosaur existed about 100 million years ago and would stretch from the goal line to beyond the 40 yard line on a football field.

“They almost certainly are different species since that dinosaur is at least 10 million years older [than Notocolossus] and comes from different rocks,” said Mr. Lamanna, who also helped a Drexel University team dig up and study the fossils of the giant titanosaur Dreadnoughtus schrani announced in September 2014. The Dreadnought fossils are more complete than those of Notocolossus. But Dreadnoughtus was similar in size at up to 65 tons and 85 feet long, despite not being fully mature.

“People might be suffering from giant titanosaur fatigue by now,” Mr. Lamanna said, given the string of fossil finds. “But one of the cool things is that there was not one but many species of giant titanosaurs and most of them come from Argentina.”

Mr. Lamanna, with a research focus on Southern Hemisphere dinosaurs, said Mr. Gonzalez Riga summoned him about six years ago to help analyze the fossils he discovered roughly a quarter mile apart in the same rock layer. The two dinosaur specimens had identical tail bones revealing the same species. Fossil also include back, forelimb and pelvis bones, with a complete ankle and foot from the smaller specimen.

That find helps explain how the tree-trunk-like ankles and feet, containing few bones and tiny toes, evolved to support such massive weight. Elephants also have small toes but many foot bones, revealing two evolutionary paths in foot development for Earth’s largest animals, Mr. Lamanna said.

Mr. Gonzalez Riga said titanosaurs were the heaviest terrestrial creatures that ever lived. “But the hind feet of these dinosaurs — which are critical for understanding how they stood and moved — were not completely known until now,” he said. “Now we have new evidence that helps to solve this mystery.”

Titanosaur bones, especially their vertebrae, were infused with air, making them lightweight but strong. The dinosaurs also lived during one of the hottest periods in the past 600 million years, fostering the growth of lush foliage almost from pole to pole. Titanosaurs had communal nesting areas and fossilized footprints reveal they moved in herds.

One theory holds that, similar to an arms race, plant-eating dinosaurs needed to grow ever larger to thwart attacks from ever larger predatory dinosaurs. “I think it’s safe to say we haven’t found the biggest dinosaur yet,” Mr. Lamanna said.

Stay tuned. Mr. Gonzalez Riga has a lab full of titanosaur fossils he’s collected. “Hopefully, with this wealth of new and exciting fossils to study, we’ll finally be able to understand more about giant titanosaurs, the biggest creatures that ever lived on land,” Mr. Lamanna said.

Reference:
Bernardo J. González Riga et al. A gigantic new dinosaur from Argentina and the evolution of the sauropod hind foot, Scientific Reports (2016). DOI: 10.1038/srep19165

Note: The above post is reprinted from materials provided by Pittsburgh Post-Gazette. The original article was written by David Templeton.

Extinct crustacean Dollocaris was all eyes

An artist’s reconstruction of a Dollocaris, a visual predator of the Jurassic seas, in an image provided by the science journal Nature Communication on January 18, 2016

A tiny but scary-looking marine critter that died out with the dinosaurs, caught prey with the aid of two monstrous eyes—each a quarter of its body length, scientists said Tuesday.

The giant peepers were composed of 18,000 lenses each—a record only ever surpassed by modern-day dragonflies, a team wrote in the science journal Nature Communications.

The sophisticated organs belonged to Dollocaris ingens, an extinct arthropod which lived about 160 million years ago, during the Jurassic geological period better known for the rise and fall of the dinosaurs.

An arthropod is an animal with an exoskeleton and segmented body—including groups like today’s insects, spiders and crustaceans.

D. ingens, a swimmer, would have had a crab-like shell, with three pairs of clawed, segmented legs with which to catch tiny shrimps, and eight pairs of stubby swimming appendages.

It would have been about five to 20 centimetres (two to eight inches) long, and each eye about a quarter of that.

For the study, experts used special microscopes and scans to examine fossilised D. ingens eyes dug up in southeast France.

It is extremely rare to find well-preserved samples of internal eye structure.

The first compound eyes, made up of many individual units like those of ants, are thought to have appeared in the Cambrian period some 500 million years ago—revolutionising animal development, according to study co-author Jean Vannier from France’s University of Lyon.

“To see and be seen changed everything—with eyes you could become a more effective hunter, while prey became more easily detectable,” he explained.

“All this led to a new dynamic—for some to better protect themselves, for others to become better at detection, and new evolutionary pressures.”

Their examinations confirmed that C. ingens was a “visual hunter,” said Vannier.

Its eyes shared features with those of modern-day insects and crustaceans.

“It is clear that its huge, panoramic, multi-faceted acute eyes were crucial to scanning its environment and to detecting potential moving prey,” the study authors wrote.

It was probably not a very dexterous swimmer, and more likely an “ambush predator” pouncing on prey from a concealed position.

While this line of animals disappeared, its eye type continued independently in other animals.

Reference:
Exceptional preservation of eye structure in arthropod visual predators from the Middle Jurassic, Nature Communications, DOI:10.1038/ncomms10320

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

Explosive underwater volcanoes were a major feature of ‘Snowball Earth’

Extensive underwater volcanism during ridge spreading led to rapid alteration of volcanic deposits and major changes in ocean chemistry. Credit: Gary Hincks

Around 720-640 million years ago, much of the Earth’s surface was covered in ice during a glaciation that lasted millions of years. Explosive underwater volcanoes were a major feature of this ‘Snowball Earth’, according to new research led by the University of Southampton.

Many aspects of this extreme glaciation remain uncertain, but it is widely thought that the breakup of the supercontinent Rodinia resulted in increased river discharge into the ocean. This changed ocean chemistry and reduced atmospheric CO2 levels, which increased global ice coverage and propelled Earth into severe icehouse conditions.

Because the land surface was then largely covered in ice, continental weathering effectively ceased. This locked the planet into a ‘Snowball Earth’ state until carbon dioxide released from ongoing volcanic activity warmed the atmosphere sufficiently to rapidly melt the ice cover. This model does not, however, explain one of the most puzzling features of this rapid deglaciation; namely the global formation of hundreds of metres thick deposits known as ‘cap carbonates’, in warm waters after Snowball Earth events.

The Southampton-led research, published in Nature Geoscience, now offers an explanation for these major changes in ocean chemistry.

Lead author of the study Dr Tom Gernon, Lecturer in Earth Science at the University of Southampton, said: “When volcanic material is deposited in the oceans it undergoes very rapid and profound chemical alteration that impacts the biogeochemistry of the oceans. We find that many geological and geochemical phenomena associated with Snowball Earth are consistent with extensive submarine volcanism along shallow mid-ocean ridges.”

During the breakup of Rodinia, tens of thousands of kilometres of mid-ocean ridge were formed over tens of millions of years. The lava erupted explosively in shallow waters producing large volumes of a glassy pyroclastic rock called hyaloclastite. As these deposits piled up on the sea floor, rapid chemical changes released massive amounts of calcium, magnesium and phosphorus into the ocean.

Dr Gernon explained: “We calculated that, over the course of a Snowball glaciation, this chemical build-up is sufficient to explain the thick cap carbonates formed at the end of the Snowball event.

“This process also helps explain the unusually high oceanic phosphorus levels, thought to be the catalyst for the origin of animal life on Earth.”

Reference:
T. M. Gernon, T. K. Hincks, T. Tyrrell, E. J. Rohling, M. R. Palmer. Snowball Earth ocean chemistry driven by extensive ridge volcanism during Rodinia breakup. Nature Geoscience, 2016; DOI: 10.1038/ngeo2632

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

Man-made heat put in oceans has doubled since 1997, study finds

This image provided by Lawrence Livermore National Laboratory shows Pacific and Atlantic meridional sections showing upper-ocean warming for the past six decades (1955-2011). Red colors indicate a warming (positive) anomaly and blue colors indicate a cooling (negative) anomaly. The amount of global-warming triggered heat energy absorbed by the seas has doubled since 1997, a new study showed. Scientists have long known that more than 90 percent of the heat energy from man-made global warming goes into the world’s oceans instead of the ground. And they’ve seen ocean heat content rise in recent years. But a new study using ocean observing data that goes back to the British research ship Challenger in the 1870s, includes high-tech modern underwater monitors and computer models, tracked how much man-made heat has been buried in the oceans in the past 150 years. Credit: Timo Bremer/Lawrence Livermore National Laboratory via AP

The amount of man-made heat energy absorbed by the seas has doubled since 1997, a new study says.

Scientists have long known that more than 90 percent of the heat energy from man-made global warming goes into the world’s oceans instead of the ground. And they’ve seen ocean heat content rise in recent years. But the new study, using ocean-observing data that goes back to the British research ship Challenger in the 1870s and including high-tech modern underwater monitors and computer models, tracked how much man-made heat has been buried in the oceans in the past 150 years.

The world’s oceans absorbed approximately 150 zettajoules of energy from 1865 to 1997, and then absorbed about another 150 in the next 18 years, according to a study published Monday in the journal Nature Climate Change.

To put that in perspective, if you exploded one atomic bomb the size of the one that was dropped on Hiroshima every second for a year, the total energy released would be 2 zettajoules. So since 1997, Earth’s oceans have absorbed man-made heat energy equivalent to a Hiroshima-style bomb being exploded every second for 75 straight years.

“The changes we’re talking about, they are really, really big numbers,” said study co-author Paul Durack, an oceanographer at the Lawrence Livermore National Lab in California. “They are nonhuman numbers.”

Because there are decades when good data wasn’t available and computer simulations are involved, the overall figures are rough but still are reliable, the study’s authors said. Most of the added heat has been trapped in the upper 2,300 feet, but with every year the deeper oceans also are absorbing more energy, they said.

But the study’s authors and outside experts say it’s not the raw numbers that bother them. It’s how fast those numbers are increasing.

“After 2000 in particular the rate of change is really starting to ramp up,” Durack said.

This means the amount of energy being trapped in Earth’s climate system as a whole is accelerating, the study’s lead author Peter Gleckler, a climate scientist at Lawrence Livermore, said.

Because the oceans are so vast and cold, the absorbed heat raises temperatures by only a few tenths of a degree, but the importance is the energy balance, Gleckler and his colleagues said. When oceans absorb all that heat it keeps the surface from getting even warmer from the heat-trapping gases spewed by the burning of coal, oil and gas, the scientists said.

The warmer the oceans get, the less heat they can absorb and the more heat stays in the air and on land surface, the study’s co-author, Chris Forest at Pennsylvania State University, said.

“These finding have potentially serious consequences for life in the oceans as well as for patterns of ocean circulation, storm tracks and storm intensity,” said Oregon State University marine sciences professor Jane Lubchenco, the former chief of the National Oceanic and Atmospheric Administration.

One outside scientist, Kevin Trenberth, climate analysis chief at the National Center for Atmospheric Research, also has been looking at ocean heat content and he said his ongoing work shows the Gleckler team “significantly underestimates” how much heat the ocean has absorbed.

Jeff Severinghaus at the Scripps Institute of Oceanography praised the study, saying it “provides real, hard evidence that humans are dramatically heating the planet.”

Reference:
Peter J. Gleckler, Paul J. Durack, Ronald J. Stouffer, Gregory C. Johnson & Chris E. Forest. Industrial-era global ocean heat uptake doubles in recent decades, DOI:10.1038/nclimate2915

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

Landslide researcher digs into the past

Geology professor Alison Duvall, left, observes as Sean LaHusen collects a sample of wood to be used in a carbon dating test. Credit: ADAM BOOTH/Portland State University

Growing up in Ridgefield, Sean LaHusen could see a prominent example of America’s shifting landscape. He didn’t realize he was looking at a possible career.

But for more than a year, LaHusen’s workplace has been defined by geomorphology: specifically, mud in motion. The University of Washington doctoral student is researching the area around the Oso landslide that killed 43 people on March 22, 2014.

LaHusen was the lead author of a paper published recently in the journal Geology. It examined the frequency of slides along that stretch of the Stillaguamish River in Northwest Washington.

Researchers used airborne lasers and dug woody debris from centuries-old slopes to show that the pace of slides is much faster than people thought.

It’s all part of trying to determine when it might happen again.

“The only way to forecast is to look into the past and see how these hill slopes fall apart,” LaHusen said.

Rather than occurring every few thousand years, as some people thought, slopes in the Oso area have been collapsing every 500 years or so. And over the last 2,000 years, the slides have been occurring at an even faster rate — about every 140 years.

His own environment was a factor in the study, LaHusen said. “I was inspired by the landscape of the Pacific Northwest. It is such a dynamic landscape: not just landslides, but volcanic activity.

“Growing up, we had a view of Mount St. Helens: a cool spot. I ended up climbing it a few times,” he said.

He wasn’t thinking about geology when he enrolled at Western Washington University, however. The 2009 Ridgefield High honor graduate was looking at a different branch of science, even though his dad, Rick LaHusen, worked for 30 years at the U.S. Geological Survey’s volcano observatory in Vancouver.

Appreciating outdoors

There certainly were family influences, though.

“I’m not in geology because my dad works for the USGS,” the University of Washington researcher said. “I’m a scientist who is interested in the environment because of my upbringing. I grew up with a deep appreciation of the outdoors. My folks would always take me out backpacking and skiing, which had a pretty profound impact on how I wanted to spend my life.

“I also got a respect for the scientific method, and the process of learning about our environment.”

“Of course, I am terribly proud of Sean,” Rick LaHusen said in an email message. “As Sean said, and must be emphasized, he has been forging his own career path.

“We did enjoy many adventures together, camping, mountain biking, skiing, climbing, hiking and backpacking in the Pacific Northwest,” said the retired hydrologist, who now is a volunteer at the Cascades Volcano Observatory. “Consequently, we share a great appreciation for the incredibly beautiful and dynamic landscapes in Washington and Oregon.”

It all was a factor in the younger LaHusen originally choosing environmental science as his major.

“A prerequisite was Geology 101. I had a fantastic teacher. I took a couple of her courses and it clicked for me. I changed to geology. The next year, I took a geomorphology course. It’s a study of landscapes and land forms and how the surface of the Earth changes,” he said.

“It’s very tangible; it changes on human scale. A lot of geology operates on time scales that are hard to grasp: millions and billions of years. We can see geomorphic processes in a human lifetime. It affects human societies,” he said, noting that the Oso mudslide “killed 43 people in one event, which is catastrophic.”

When he decided to pursue graduate studies at the University of Washington, he committed to landslide research. A few weeks later, the Oso slide struck.

LaHusen and his adviser, assistant professor Alison Duvall, set out to determine the dates of more than two dozen major slides along a 3.7-mile stretch of the Stillaguamish River near the Oso site.

Expensive, difficult

It’s interesting that nobody had studied it before, he said, although “Dating landslides can be tough. It’s not cheap and it’s not easy. It costs $300 per sample to run radiocarbon dating” of wood samples.

In obtaining those samples, “I’m basically bush-whacking,” LaHusen said. “I look for areas when a river cuts a gully, where a landslide deposit has been exposed naturally.”

He digs into the gully wall and looks for remnants of trees that were buried in mud centuries ago.

For specimens used in the recently published study, “We dug back really far into the gully wall — a meter, at least — to make sure the tree hadn’t just fallen into the gully.”

Slide deposits get smoother as they get older, so another important research tool was lidar (light detection and ranging).

A laser mounted on an airplane fires laser pulses to the ground, said Adam Booth, an assistant geology professor at Portland State University.

“It reflects off objects and returns to the plane,” said Booth, a co-author of the study. “The end product is a 3-D representation of the surface of the Earth.”

It’s much more revealing than aerial photography.

“From photos, all you see is the tops of vegetation,” Booth said. “For this study, some of that energy penetrates vegetation and bounces off the Earth’s surface. With lidar, you can see an image of what the ground looks like.”

Duvall and LaHusen were able to obtain woody debris from several old slide areas, but not all of them. By combining data from the radiocarbon-dated samples and the lidar imagery, researchers established a roughness-age scale.

“The roughness analysis helps extend (their findings) to places where they didn’t have access or were not able to find datable materials,” Booth said.

LaHusen and Duvall also are part of the university’s M-9 Project, studying the risks from a magnitude-9 earthquake along the Cascadia subduction zone.

They’re hoping to use the techniques from the Oso study to look at landslides in Washington that were triggered by a massive quake in 1700.

Scientists hope to learn whether they can develop simulations to predict which places in Washington are most vulnerable to earthquake-generated landslides.

Note: The above post is reprinted from materials provided by Columbian. The original article was written by  Tom Vogt, Columbian Science, Military & History Reporter .

Newly discovered pliosaur terrorised ancient Russian seas

The Mesozoic played host to some of the most dangerous predators to ever swim the Earth’s oceans. Among these, pliosaurs were lethal hunters, and some of the largest predators ever on this planet. They were the shorter-necked cousins of the plesiosaurs, which are often spoken of in reference to their superficial similarity to the Loch Ness Monster, which we’re definitely not going to do here. Together, pliosaurs and plesiosaurs form a group known as Sauropterygia, which existed in the oceans from the Triassic right until the end of the Cretaceous, when they went extinct along with the non-avian dinosaurs and other vertebrate groups. This actually makes sauropterygians the longest living group of marine-adapted tetrapods (animals with four limbs), which is quite an impressive feat!

New discoveries show that perhaps this evolutionary success can be attributed to the ecological diversity that this group possessed, and in particular an ability to adapt to different feeding styles.

Valentin Fischer from the University of Oxford and an international team of researchers have discovered a new pliosaur from western Russia, named Makhaira rossica. The name dreives from the Latinized Ancient Greek word ‘mákhaira’, which describes a blade with a curved outline, as well as the Latin word ‘rossica’, which means Russian. The specimen comprises a fragmentary skeleton of a sub-adult animal, found within a series of limestone nodules along the banks of the Volga River.

Makhaira comes from a period in Earth’s geological history, known as the earliest part of the Cretaceous, where our knowledge of vertebrate life is relatively poor due to the way in which fossils are differentially preserved through time. Sadly, this lack of knowledge means that our understanding of how faunas changed from the latest part of the Jurassic period into the first part of the Cretaceous is relatively poor compared to other important geological boundaries.

Analysis of the evolutionary placement of this new species places it as the most basal member of a group known as Brachaucheninae, which survived through the Cretaceous. However, the new species is different in being a little smaller than some of its more advanced relatives.

The weirdest feature of the new beasty has to be the teeth. The teeth occur in pairs, and have a trihedral form, meaning they had three peaks on each alveolus, and the edges of the teeth were adorned with wicked serrations. They were also very large, similar even to some teeth from theropod dinosaurs roaming the lands at the time!

The morphology of these teeth suggest that they were equipped just for one thing – devouring other large animals! This form of feeding is known as macrophagy, and was a common form of predation at the time for giant marine crocodyliforms (the ancestors of modern crocodiles) called metriorhynchids. Importantly, this feeding style previously seemed to have been lost in the early evolution of other brachauchenine pliosaurs, but now appears to have been present in at least one species from this group. This shows that Early Cretaceous pliosaurs were still well adapted to hypercarnivory, and retained a high feeding diversity at the beginning of the Cretaceous, and not lost from their Jurassic ancestors.

Recently, Alessandro Chiarenza, a colleague of mine at Imperial College London, reported on what appeared to be the oldest metriorhynchid remains currently known, from a fossil site in Sicily. Based on a single fossilised tooth from a period known as the Aptian, later on in the Cretaceous than when Makhaira was found, these remains extended the duration of metriorhynchids, and their eventual extinction, by several millions of years. However, the morphology of the teeth of Makhaira wasn’t known at the time of publishing the crocodyliform fossils, and it seems that it is actually impossible to distinguish between these and the teeth of some metriorhynchids. This means that the Sicilian tooth cannot be referred unequivocally to either a metriorhynchid or a pliosaur – the teeth of some species is just too similar to say for certain! What does this imply though? Well, it seems that the fate of metriorhynchids is still a mystery concealed by the fossil record, and is only something that future study of these fossils, their other monstrous counterparts, and discovery of new fossils can hope to solve!

Reference:
Valentin Fischer et al. Peculiar macrophagous adaptations in a new Cretaceous pliosaurid, Royal Society Open Science (2015). DOI: 10.1098/rsos.150552

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

‘Cave of forgotten dreams’ may hold earliest painting of volcanic eruption

Spray-shaped drawings in an inner gallery of the Chauvet cave may depict a volcanic eruption. Left: general view; right: traced detail, with an overlaid charcoal painting of a giant deer species removed (lower right). Credit: D. Genty (left)/V. Feruglio/D. Baffier (right)/CC BY 4.0

Mysterious paintings in one of the world’s most famous caves could mark the oldest-known depiction of a volcanic eruption. Spray-shaped images in Chauvet cave in France were painted at around the same time as nearby volcanoes spewed lava high into the sky, reports a paper published this month in PLoS ONE.

Chauvet-Pont D’Arc cave, in southern France, is one of the world’s oldest and most impressive cave-art sites. Discovered in 1994 and popularized in the Werner Herzog documentary ‘Cave of Forgotten Dreams’, Chauvet contains hundreds of paintings that were made as early as 37,000 years ago.

Fearsome animals such as woolly rhinoceroses, cave lions and bears dominate Chauvet’s imagery. But one of its innermost galleries — named after a giant deer species, Megaloceros, that is depicted there — also contains a series of mysterious spray-shaped drawings, partly covered by the Megaloceros painting. A nearby gallery holds similar spray imagery, as does a wall near the cave’s original entrance, but researchers have not determined what the images represent.

The depictions are unique to Chauvet, notes Sebastien Nomade, a geoscientist at the University of Paris-Saclay in Gif-Sur-Yvette, France, who led the study. The Bas-Vivarais volcanic field, a well-known site containing more than a dozen extinct volcanoes, lies just 35 kilometres from the cave, but only eruptions that happened before humans occupied Chauvet had been dated, Nomade says.

Lava light show

In the hope of calculating the dates of younger eruptions, Nomade visited Bas-Vivarais in 2012 and sampled rock from three volcanic centres. By measuring the levels of different isotopes of radioactive argon gas, his team determined that the region had been lit up by a series of eruptions between about 19,000 years and 43,000 years ago. The events would have been dramatic ‘strombolian’ eruptions, Nomade says — named after those typical of the Stromboli volcano in Italy — with lava spewing 200-plus metres into the sky and flowing down the volcanoes’ slopes. Each cone would have erupted once or twice before going extinct.

Hunter-gatherers living in the region at the time must have seen the eruptions, Nomade says, noting that the 35 kilometres between the Chauvet cave and Bas-Vivarais would have offered a safe vantage point. “You just have to climb the small hill on top of Chauvet, and looking north you see the volcanoes. During the night you could see them glowing and you could hear the sound of the volcanic eruption.”

Meanwhile, radiocarbon dating suggests that humans occupied the Megaloceros gallery between 36,000 and 37,000 years ago, and charcoal used to paint the Megaloceros that overlays the spray-like paintings is at least 34,000–36,000 years old. “There’s no way anybody could prove that it is a volcano that they depicted, but for us it’s the hypothesis which is the most probable,” says Nomade, whose team includes two rock-art experts who have previously studied the Megaloceros gallery.

A matter of record

If Nomade and his team are correct, Chauvet’s volcano imagery would represent the earliest record of any eruption. Other, younger examples include a mysterious 8,600-year-old mural found on a wall at the Neolithic site of Çatalhöyük in central Turkey, which may be a map depicting a nearby volcano that erupted at around that time. And the poet Pliny the Younger famously documented the ad 79 eruption of Vesuvius (which took the life of his uncle, Pliny the Elder).

Axel Schmitt, a geoscientist at Heidelberg University in Germany whose team studied the eruption near Çatalhöyük, says that the dating of the eruptions near Chauvet is solid. But it will be difficult to get more precise dates from the volcanic basalt rock in the Bas-Vivarais, he says. “You have to be lucky to find the right sample.”

“I think they make a pretty good case that it’s potentially a depiction of the kind of volcano that one sees on the landscape,” says Michael Petraglia, an archaeologist at the University of Oxford, UK. Depictions of natural events in rock art are rare, he notes, but this could be because they are too abstract or because researchers simply haven’t looked. “Maybe there’s more of this out there than we have realized.”

Note: The above post is reprinted from materials provided by Nature. The original article was written by Ewen Callaway.

Human-made climate change suppresses the next ice age

Landscape shaped by Permafrost dynamics near Spitzbergen. Credit: Alfred-Wegener-Institute/Jaroslav Obu

Humanity has become a geological force that is able to suppress the beginning of the next ice age, a study now published in the scientific journal Nature shows. Cracking the code of glacial inception, scientists of the Potsdam Institute for Climate Impact Research found the relation of insolation and CO2 concentration in the atmosphere to be the key criterion to explain the last eight glacial cycles in Earth history. At the same time their results illustrate that even moderate human interference with the planet’s natural carbon balance might postpone the next glacial inception by 100,000 years.

“Even without human-made climate change we would expect the beginning of a new ice age no earlier than in 50,000 years from now — which makes the Holocene as the present geological epoch an unusually long period in between ice ages,” explains lead author Andrey Ganopolski. “However, our study also shows that relatively moderate additional anthropogenic CO2-emissions from burning oil, coal and gas are already sufficient to postpone the next ice age for another 50.000 years. The bottom line is that we are basically skipping a whole glacial cycle, which is unprecedented. It is mind-boggling that humankind is able to interfere with a mechanism that shaped the world as we know it.”

For the first time, research can explain the onset of the past eight ice ages by quantifying several key factors that preceded the formation of each glacial cycle. “Our results indicate a unique functional relationship between summer insolation and atmospheric CO2 for the beginning of a large-scale ice-sheet growth which does not only explain the past, but also enables us to anticipate future periods when glacial inception might occur again,” Ganopolski says.

Humanity as a geological force

Using an elaborate Earth system model simulating atmosphere, ocean, ice sheets and global carbon cycle at the same time, the scientists analyzed the effects of further human-made CO2-emissions on the ice volume on the Northern Hemisphere. “Due to the extremely long life-time of anthropogenic CO2 in the atmosphere, past and future emissions have a significant impact on the timing of the next glacial inception,” co-author Ricarda Winkelmann says. “Our analysis shows that even small additional carbon emissions will most likely affect the evolution of the Northern Hemisphere ice sheets over tens of thousands of years, and moderate future anthropogenic CO2-emissions of 1000 to 1500 Gigatons of Carbon are bound to postpone the next ice age by at least 100,000 years.”

The quest for the drivers of glacial cycles remains one of the most fascinating questions of Earth system analysis and especially paleoclimatology, the study of climate changes throughout the entire history of our planet. Usually, the beginning of a new ice age is marked by periods of very low solar radiation in the summer, like at current times. However, at present there is no evidence for the beginning of a new ice age: “This is the motivation for our study. Unravelling the mystery of the mechanisms driving past glacial cycles also facilitates our ability to predict the next glacial inception,” Winkelmann says.

“Like no other force on the planet, ice ages have shaped the global environment and thereby determined the development of human civilization. For instance, we owe our fertile soil to the last ice age that also carved out today’s landscapes, leaving glaciers and rivers behind, forming fjords, moraines and lakes. However, today it is humankind with its emissions from burning fossil fuels that determines the future development of the planet,” co-author and PIK-Director Hans Joachim Schellnhuber says. “This illustrates very clearly that we have long entered a new era, and that in the Anthropocene humanity itself has become a geological force. In fact, an epoch could be ushered in which might be dubbed the Deglacial.”

Reference:
A. Ganopolski, R. Winkelmann, H. J. Schellnhuber. Critical insolation–CO2 relation for diagnosing past and future glacial inception. Nature, 2016; 529 (7585): 200 DOI: 10.1038/nature16494

Note: The above post is reprinted from materials provided by Potsdam Institute for Climate Impact Research (PIK).

Bone-crushing prehistoric reptile the largest marine crocodile ever discovered

Machimosaurus rex had bullet-shaped teeth shaped with blunt tips and wrinkles, thought to have been used to crush carapaces of marine turtles. Credit: Davide Bonadonna

A five-foot-long skull discovered in war-torn Tunisia has led to the identification of a new species.

University of Alberta PhD student Tetsuto Miyashita is among seven scientists to report the largest crocodile ever known to swim the Earth’s seas. Named Machimosaurus rex, the new species was the largest and the last survivor of crocodiles that lived in oceans during the dinosaur age. The crocodile’s skull was more than five feet long, with its total body measuring about 35 feet.

With a body length of about 35 feet, Machimosaurus rex was larger than any other known crocodiles known from oceans of the dinosaur age. Machimosaurus had bullet-shaped teeth shaped with blunt tips and wrinkles, thought to have been used to crush carapaces of marine turtles. “These teeth weren’t for cutting or piercing flesh,” says Miyashita, “they were built for crushing bones.”

Machimosaurus rex was not only the largest but also the last of its kind. Its closest relatives lived more than 30 million years earlier in the sea that is today’s England. Marine crocodiles were formidable predators during the Jurassic Period, but many of them went extinct when these habitats were lost across today’s Europe. Machimosaurus rex survived in the remaining shallow sea habitat in northern Africa.

In 2014, a team of Italian and Tunisian scientists unearthed the specimen from 130-million-year-old rocks some 30 miles south of Tataouine, Tunisia. “We have been digging in that area since 2011 because the rocks there are nothing like other places,” says Federico Fanti, assistant professor at the University of Bologna and lead author on the study. “Globally, good fossils are rare from this age—130 million years ago.”

Miyashita received a Skype call from Fanti after the dig and was shown a photograph of the crocodile skull in the ground. “There was a neck attached to it, and then the back, and the tail, and the limbs sticking out sideways. The whole crocodile was there,” says Miyashita.

Then he realized that an object that looked like a toothpick in the photo was actually a hammer. “That gave me the sense of how big this animal was,” he says. “I could tell the whole length of the skull must be about my height, 5.5 feet. That’s larger than the skull of T. rex.”

Miyashita was invited to join the dig after the first team had only managed to collect the skull. Tataouine—where George Lucas filmed his Star Wars movies—is pinched by Libya to the east and Algeria to the west. Like Lucas’s planet Tatooine in the films, it is a remote, sparsely populated desert province. Since the Arab Spring in 2012, the region’s security has been unstable.

The Fanti-Miyashita duo was set to return to southern Tunisia in early 2015 to retrieve the rest of the body from the ground, but political turmoil in the region derailed their plan. After being grounded in Italy for a week, Fanti and Miyashita decided to fly to Tunisia anyway.

The skull from the 2014 dig greeted the two in Tunis. They had only three days to clean up the giant skull and just one day to study it. “We had to work very hard to finish what would normally take weeks of work,” Miyashita recalls. “But that was enough for us to be convinced it’s a new species.”

Fanti and Miyashita remain hopeful to dig up the rest of Machimosaurus rex someday. A series of setbacks has forced the two to postpone the next expedition several times already. Barely a week after their return from Tunis, gunmen attacked Bardo National Museum in that city, killing 22 and wounding 42.

“Sometimes we are reminded that our endeavour to unlock the ancient mysteries is only possible through peace, freedom and sheer goodwill of people,” Miyashita says. “We were touched by the kindness and hospitality of Tunisians when we were there. Nothing could make me happier than us working together again to get to that big monster.”

The new study was published in the journal Cretaceous Research.

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

Researchers track tyrannosaur’s trail

Just outside the tiny town of Glenrock, Wyoming the footprints of a 66-million-year-old monster are cemented in stone. This fossil trackway was brought to light with the help of University of Alberta paleontologist Scott Persons, who first viewed the tracks as a 13-year-old while visiting the Glenrock Paleon Museum. Credit: Scott Persons

Just outside the tiny town of Glenrock, Wyoming the footprints of a 66 million-year-old monster are cemented in stone. This fossil trackway was brought to light with the help of University of Alberta paleontologist Scott Persons, who first viewed the tracks as a 13-year-old while visiting the Glenrock Paleon Museum.

“The Paleon is an unusual place. It’s not a big museum, but it doesn’t have to be because it’s got the badlands for a backyard,” explains Persons. The working museum has dinosaurs on display, but also provides opportunities to experience paleontology in action. “Before Glenrock, for me paleontology was dinosaurs in books and their skeletons in display halls and behind glass cases. This was the first time I got my hands dirty in the field and in a fossil preparation laboratory.”

The museum’s curator, Sean Smith, showed Scott another first: the fossil tracks of a tyrannosaur. “Sean led me out to a sandstone slope and started brushing away at an indented spot. At first, it looked like a prehistoric pothole,” Persons recalls. “But soon, I could see the imprints of three big toes each with sharp claw tips. It was so cool my jaw dropped. Then, Sean pointed up slope, and there were two more!”

The Glenrock tracks, as it turns out, are one of a kind. Years after his initial visit to the Paleon, Persons—now a doctoral student in paleontology—reached out to the museum and urged them to pursue formal scientific description of the trackway. With his help, a research paper on the rare footprints has just been published in the peer-reviewed journal Cretaceous Research.

Based on the sharp claws and other traits, such as the imprint of a small fourth claw at the rear of the best track, the footprints can be definitively identified as those of a carnivorous dinosaur—a big one. Given the trackway’s age and geography, the only candidate for the prints’ maker is a species of tyrannosaurid.

“The tracks are just a bit too small to belong to a full grown T. rex,” Persons explains. “But they could very well be the tracks of an adolescent Tyrannosaurus rex, or they could belong to the closely-related smaller tyrannosaur Nanotyrannus. We really can’t say which.”

Either way, the tracks are unique. While several instances of isolated tyrannosaur footprints have been found before, the Glenrock trackway is only the second multi-step tyrannosaur tracksite known to science, and the first to belong to T. rex or Nanotyrannus.

“Having a trail of tracks is important,” says Persons. “With it, you can calculate an estimate of how fast the tyrannosaur was walking.” That estimation, between 4.5 and 8 km/h, put the tyrannosaur at a slow trot and confirms, contrary to some previous speculation, that tyrannosaurs were no slower than many other large carnivorous dinosaurs. It also shows that, even when walking, tyrannosaurs moved faster and covered more ground in a single step than the large herbivores, such as the duckbilled dinosaurs, which they coexisted with and presumably hunted.

The tyrannosaur tracks are expected to help put Glenrock and its museum on the map. “The tracks are still in the field,” says Persons. “If you go to Glenrock, today, visit the Plaeon Museum, and are up for a little hike, you can see the prints just like I did.” To help preserve a record of the tracks, casts of the footprints have also been made and are on public display in the Glenrock Paleon Museum.

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

Hotspots of small swimming marine organisms may contribute to mixing

New research using high-fidelity numerical simulations is revealing details about how “hotspots” of small swimming organisms might contribute to the mixing of ocean waters. The research is depicted in this animated GIF. Credit: Shiyan Wang and Arezoo Ardekani

New research findings suggest small marine organisms swimming in concentrated “hotspots” likely contribute to the mixing of water needed to distribute nutrients for ocean species.

The ocean consists of a top nutrient-depleted layer that is well mixed by turbulence created primarily by wind, tides and other mechanisms, and a bottom unmixed nutrient-rich layer. In between is a layer called the pycnocline marked by a sharp change in density, said Arezoo Ardekani, an assistant professor of mechanical engineering at Purdue University.

“We are trying to learn about the potential contribution of marine organisms to the mixing processes that transport water from this nutrient-rich bottom region through the pycnoline layer and to the nutrient-depleted region,” she said.

Ocean mixing is critical for distributing nutrients to the nutrient-depleted layer.

“Some marine organisms move vertically between the top and bottom layers during the day and night through a process called diel vertical migration,” she said.

While it is known that wind and waves are the primary cause of ocean mixing, one unknown factor is whether swimming organisms contribute to this vital mixing. Previous research has suggested the organisms transport volumes of fluid and nutrients with them, a concept known as Darwinian drift. However, some scientists argue that the drifted fluid can re-stratify in marine environments and may not cause mixing.

The Purdue researchers used high-fidelity numerical simulation (animated gif available) of a “simplified swimming model” to determine whether the small ocean organisms such as zooplankton swimming in concentrated hotspots contribute to the mixing.

“So there are local hotspots where this mixing can be comparable to the turbulent mixing in the mid-ocean,” Ardekani said. “The mixing induced by horizontally swimming organisms is one hundred times weaker than the contribution of vertically swimming organisms.”

The hotspots may be especially important in the mid-ocean, where the majority of energy from waves and wind is dissipated prior to contributing to mixing.

Findings were detailed in a paper published in December in the journal Scientific Reports published by the Nature Publishing Group. The paper was authored by doctoral student Shiyan Wang and Ardekani.

https://news.uns.purdue.edu/images/2016/ardekani-animation.gif
New research using high-fidelity numerical simulations is revealing details about how “hotspots” of small swimming organisms might contribute to the mixing of ocean waters. The research is depicted in this animated GIF. Credit: Purdue University image/Shiyan Wang and Arezoo

Reference:
Shiyan Wang et al. Biogenic mixing induced by intermediate Reynolds number swimming in stratified fluids, Scientific Reports (2015). DOI: 10.1038/srep17448

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

Charting the growth of one of the world’s oldest babies

This is a life reconstruction of baby Chasmosaurus, by paleo artist Michael Skrepnick. Credit: Michael Skrepnick

The discovery of a juvenile Chasmosaurus–one of the rarest dinosaur discoveries–made headlines around the world in late 2013: Professor Philip Currie from the University of Alberta and his colleagues have now published the results of their scientific findings in an alpha-level taxonomic description in the Journal of Vertebrate Paleontology.

“For the first time ever, we have a complete skeleton of a baby ceratopsid,” says Currie of the roughly 75-million-year-old dinosaur found in 2010 in Dinosaur Provincial Park in Alberta, Canada. “We’ve only had a few isolated bones before to give us an idea of what these animals should look like as youngsters, but we’ve never had anything to connect all the pieces. All you need is one specimen that ties them all together. Now we have it!”

Currie notes that the discovery allows for the refinement of previous findings and provides the opportunity to fill in gaps in the evolution of other horned dinosaurs, such as Triceratops.

“One of the greatest benefits is that we can now look at the different body proportions for Chasmosaurus as it grew up,” Currie explains. “We now have an anchor point with the baby that we can compare with all other specimens of this species, and from that comparison can calculate the dimensions, body weights, and ages for all other ceratopsid species. We can start filling in missing pieces.”

Currie says this new publication holds incredible value not only for paleoecological studies but also for understanding the life history, biomass, population structure, growth rates, variation, and physiology of these animals. “Unless you’ve got that basic anatomical information, you’re kind of shooting in the dark with all of these other calculations.”

He says the biggest surprises came in the comparisons of shapes and relative proportions with adult Chasmosaurus. “There was no doubt in our minds that a baby would have had a much shorter frill relative to its skull length than an adult. But what we couldn’t see is that it also has a different shape. Now with a full skull of a juvenile in which the bones actually articulate with each other, we can see that in Chasmosaurus, the back of the frill isn’t broad and squared off the same way that it is in an adult. In fact, the frill narrows towards the back. And instead of being flat on top from one side to the other, the frill is arched and has a ridge running down the middle of it,” says Currie. “It is very different than I expected.”

Currie and his co-authors Michael Ryan (Cleveland Museum of Natural History), Rob Holmes (University of Alberta), and Clive Coy (University of Alberta), worked with paleo-artist Michael Skrepnick to create a life reconstruction of what the animal might have looked like.

“Alberta has long been known as one of the centres for ceratopsian research,” says Michael Ryan, one of the world’s top ceratopsian dinosaur researchers and Curator of Vertebrate Paleontology at the Cleveland Museum of Natural History. “The discovery and publication of the baby Chasmosaurus cements Alberta’s leadership in this area.” Ryan is also one of Currie’s former students.

What are the next steps for these researchers and this dinosaur? “We still haven’t plumbed the depths of the anatomical description,” says Currie, noting that the specimen will provide scientists with unparalleled opportunities to study the growth, changes, and variation of a single species. “Over the next few years, I will assign different parts of the body to different students who will then focus on growth changes and their implications within ceratopsids.”

Currie also has immediate plans to examine the brain case through advanced CT scanning in Japan. In fact, the baby will be on exhibit in Tokyo at the National Museum of Nature and Science later this year, the first opportunity anyone outside Alberta will have to see it. The baby dinosaur has previously been exhibited at Dinosaur Provincial Park and at the University of Alberta.

Reference:
Philip J. Currie, Robert B. Holmes, Michael J. Ryan, Clive Coy. A juvenile chasmosaurine ceratopsid (Dinosauria, Ornithischia) from the Dinosaur Park Formation, Alberta, Canada. Journal of Vertebrate Paleontology, 2016; e1048348 DOI: 10.1080/02724634.2015.1048348

Note: The above post is reprinted from materials provided by University of Alberta. The original item was written by Jennifer Pascoe.

A day in the life of an ammonite

A reconstruction of an ammonite Asteroceras. Credit: Nobu Tamura

Several years ago, back when I was working as the lab and collections manager for the St. George Dinosaur Discovery Site in St. George, Utah, we constructed a temporary exhibit with hundreds of ammonite shells from all over the world. One of our museum volunteers, an older French lady volunteering as a museum greeter and docent, refused to look at or go near the cabinet of ammonite shells. Confused, I asked her for her thoughts on the display. She shuddered, “Ack, they look like little snakes, coiled and ready to attack.”

Aware of her ophidiophobia, I tried to explain to her that ammonites have absolutely nothing to do with snakes. But she wouldn’t hear any of it. To me, the ammonites were beautiful fossils, exquisite and intricate, perfectly coiled, some with an iridescent patina increasing their aesthetic beauty. The variation was great from one shell to the next.

But I was (and arguably am still) poorly educated about ammonites, other than my basic knowledge that they were the shells of extinct cephalopods, with only their living relative Nautilus to remind us of what they may have looked like millions of years ago. Ammonites are fascinating, and like any other extinct organism, have a lot to tell us about the history of the planet we live on.

Paleontologists that study ammonites are like all paleontologists: they are working with a limited dataset based on what was preserved in the fossil record, and are restricted to interpreting what they have as best they can. But a new study published today in PLOS ONE provides a clearer picture of ammonites, particularly regarding their growth, their sexual behaviors, and their environment.

The new study, conducted by authors Patrick Zell and Wolfgang Stinnesbeck from Universität Heidelberg in Germany, examined a collection of 169 specimens of Salinites grossicostatum from the Tithonian La Caja Formation in Coahuila, Mexico, collected between 1986–1994 by Stinnesbeck. The specimens are three-dimensional and well-preserved, and yield a great deal of information on both external and internal characters, allowing Zell and Stinnesbeck to evaluate several morphological variables that can tell us about ontogeny, dimorphism, and even habitat preference for these ammonites.

The study found four distinct age stages (embryonic, neanic, juvenile, and mature). Embryonic stages have stronger variation in septal spacing, with a trend of crowding of septa as embryos, which the authors interpret to be related to hatching. As young ammonites transition to post-embryonic stages, Zell and Stinnesbeck observed a decrease in the distance between septa, and even note differential growth between males and females during the juvenile stage.

Sexual dimorphism in ammonites has lead to distinction in naming the smaller form the microconch and the larger form the macroconch, with many regarding the macroconchs as the female form to better accommodate egg production. This sexual variation has caused taxonomic confusion in the past, as previous studies had considered many dimorphic ammonites two distinct species; only more recently has it be recognized that they represented dimorphism, owing mainly to the fact that the two distinct forms were so often found together.

The presence of mature specimens of S. grossicostatum in the La Caja Formation is notably fewer in number than juveniles, but macroconchs and microconchs are found in approximately equal numbers, according to the authors of this study. The authors do note a geographic distribution pattern related to size, and infer that macroconchs (females), once having reached sexual maturity, may have migrated to shallow water environments after mating and fertilization in order to lay their eggs, where the microconchs (males) remained in what is interpreted as the outer shelf to uppermost slope environments. Some macroconchs after laying eggs, may have returned to the mating area for a possible second mating event. A similar distribution pattern is seen in other ammonites, as well as observed behavior in Nautilus, corroborating this potential behavior in the fossils.

Going back to the distance between septa seen in the shells of ammonites, there is an observed pattern of septal crowding that indicates the end of shell growth in mature ammonites, as once an ammonite reaches the end of growth it is producing less shell. This pattern is also observed by the authors regarding S. grossicostatum, with the last 12 septa in macroconchs being crowded together, and the last 4 septa in microconchs crowding together. Why the difference in the number of septa between macro- and microconchs? Well, Zell and Stinnesbeck interpret this disparity as a shorter life span for microconchs (sorry, dudes), whereas macroconchs have a prolonged lifespan to allow for migration and egg deposition.

Seasonal changes, such as temperature, oxygen availability, etc., and other life factors such as diseases, stress from predation, etc., can produce spikes in the variability of septal distances in ammonite shells. This study published in PLOS ONE proposes that some of the variability seen in S. grossicostatum can be due to environmental factors, and correlates known climatic changes seen in the geologic record to variation in septal distances seen in S. grossicostatum. Specifically, an oceanic upwelling in the La Caja Ocean could have provided nutrient-rich conditions for S. grossicostatum for much of the year, but during monsoonal seasons may have limited upwelling, and thus, food sources. An abundance of juvenile Salinites grossicostatum may be related to these upwelling episodes, as well as noted variation in septal distances in juvenile and mature specimens.

This new study by Zell and Stinnesbeck, out today in PLOS ONE, is a clear and comprehensive snapshot of ammonite morphology, growth, and behavior, and shows that fossils contain a trove of information, not just about the organism itself, but the habitat it lived in as well.

Reference:
Patrick Zell et al. Paleobiology of the Latest Tithonian (Late Jurassic) Ammonite Salinites grossicostatum Inferred from Internal and External Shell Parameters, PLOS ONE (2016). DOI: 10.1371/journal.pone.0145865

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

Evidence of large volcanic activity in the Caribbean uncovered

Activity from Soufriere volcano on Montserrat island. Credit: NASA-JSC

Scientists from the University of Southampton have uncovered evidence of a previously unknown large volcanic eruption in the Caribbean Sea.

By studying ash layers, known as tephras, in marine sediments they identified an eruption that took place on Guadeloupe 2.4 million years ago.

The research, published in the journal Geology, indicates this eruption is the largest documented volcanic event in the region since that time.

Lead author, Professor Martin Palmer, at the University of Southampton, said: “Volcanic eruptions are relatively common in this area of world, but while they are very disruptive for the local community, as seen on Montserrat over the past 20 years, they do not generally have a major impact on neighboring islands. While a large eruption of the scale that we have identified would represent an important hazard to human populations in the wider region if it occurred today, it is very important to note that our research suggests that such events are rare in the Lesser Antilles – there is no indication that another large eruption is imminent.”

The research team analysed a sediment core recovered by the Integrated Ocean Drilling Program (IODP) Expedition at a site 30km southwest of Montserrat and 75km west of Guadeloupe in the northeastern Caribbean Sea. This is close to several volcanically active islands in the Lesser Antilles. The core contained an unusually thick (18 cm) tephra that was deposited 2.4 million years ago.

By analysing the isotopes, trace elements and grain morphology of the tephra, together with volcanological models, the researchers were able to identify the origin and magnitude of the large VEI (Volcanic Explosivity Index) 6 eruption. In comparison, the largest Montserrat eruptions since 1995 had a VEI of 3-4.

Professor Palmer added: “Reconstructing the magnitude of past volcanic eruptions is important to inform predictions about future eruptions and hazards. This is difficult to accomplish from records on land – old eruptions are often eroded away, buried beneath later eruptions, or obscured by vegetation and soil. Most volcanoes are close to the oceans, so much of the erupted material falls into seawater and accumulates on the seafloor.

“It is important to continue these types of study as they allow scientists to build a more complete picture of conditions required to generate unusually large eruptions in settings where they are normally much smaller.”

Reference:
Martin R. Palmer et al. Discovery of a large 2.4 Ma Plinian eruption of Basse-Terre, Guadeloupe, from the marine sediment record, Geology (2015). DOI: 10.1130/G37193.1

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

Bones of hunted mammoth show early human presence in Arctic

Excavations of the carcass from channel deposits unit. In this photo, Sergey Gorbunov is excavating the mammoth carcass. This material relates to a paper that appeared in the Jan. 15, 2016, issue of Science, published by AAAS. The paper, by V.V. Pitulko at Russian Academy of Sciences in St. Petersburg, Russia, and colleagues was titled, “Early human presence in the Arctic: Evidence from 45,000-year-old mammoth remains.” Credit: Pitulko et al., Science (2016)

The remains of a mammoth that was hunted down about 45,000 years ago have revealed the earliest known evidence of humans in the Arctic.

Marks on the bones, found in far northern Russia, indicate the creature was stabbed and butchered. The tip of a tusk was damaged in a way that suggests human activity, perhaps to make ivory tools.

With a minimal age estimate of 45,000 years, the discovery extends the record of human presence in the Arctic by at least about 5,000 years.

The site in Siberia, near the Kara Sea, is also by far the northernmost sign of human presence in Eurasia before 40,000 years ago, Vladimir Pitulko of the Russian Academy of Science in St. Petersburg and co-authors reported in a paper released Thursday by the journal Science.

They also briefly report evidence of human hunting at about the same time from a wolf bone found well to the east. That suggests a widespread occupation, although the population was probably sparse, they said.

Daniel Fisher, a mammoth expert at the University of Michigan who did not participate in the study, said the markings on the mammoth bone strongly indicate human hunting. It makes sense to conclude that the hunters were from our own species rather than Neanderthals, John Hoffecker of the University of Colorado at Boulder commented in an email.

But Robert Park, an archaeologist at the University of Waterloo in Canada who has studied the bones of hunted animals in the far north, called the evidence for human hunting “pretty marginal.” The beast had been found with remains of its fat hump, while hunters would be expected to take the fat for food and fuel, he said. And the skeleton shows far less butchering than one would expect, he said.

Park emphasized he’s not ruling out the idea that the mammoth was hunted.

If people were living this far north that long ago, he said, it implies they had not only the technical abilities to carry out mammoth hunts, but also a social organization complex enough to share the food from the relatively rare kills.

Reference:
“Early human presence in the Arctic: Evidence from 45,000-year-old mammoth remains,” Science, DOI: 10.1126/science.aad0554

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

1...200201202...342Page 201 of 342

Related Articles

All