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Paleo study shows how elevation may affect evolution

The rise of the Rockies extended from British Columbia to Nevada in three phases between 56 and 23 million years ago. The rising mountains dried out the interior, preparing mammals for a major climate change event 34 million years ago, researchers say. European mammals were not so prepared. Credit: Courtesy of Eronen et. al.

Paleontologists have documented how dramatic shifts in climate have led to dramatic shifts in evolution. One such event, the Grande Coupure, was a wipeout of many European mammal species 33.9 million years ago when global temperatures and precipitation declined sharply. What has been puzzling is that during the same transition between the Eocene and Oligocene periods, North American mammals fared much better. A new study explains why: the rise of the Rocky Mountains, already underway for millions of years, had predisposed populations to adapt to a cold, dry world.
‘Regional tectonically driven surface uplift resulted in large-scale reorganization of precipitation patterns, and our data show that the mammalian faunas adapted to these changes,’ write the study authors, including Christine Janis, professor of ecology and evolutionary biology at Brown University, in the Proceedings of the Royal Society B. ‘We suggest that the late Eocene mammalian faunas of North America were already ‘pre-adapted’ to the colder and drier global conditions that followed the EO climatic cooling.’

The data in the study led by Jussi Eronen of the Senckenberg Research Institutes in Germany and the University of Helsinki in Finland, come from the authors’ analysis of the fossil record of the two continents, combined with previous oxygen isotope data that reveal precipitation patterns, and tectonic models that show the growth of the Rocky Mountains. Specifically, the study shows that the rise of the range spread south in three phases from Canada starting more than 50 million years ago, down through Idaho, and finally into Nevada by 23 million years ago.

In the meantime, fossil mammal data show, precipitation in the interior regions dropped, and major shifts in mammal populations, such as an almost complete loss of primates, took place. Estimated rainfall based on plant fossils in Wyoming, for example, dropped from about 1,200 millimeters a year 56 million years ago to only 750 millimeters a year about 49 million years ago.

But across the region these correlated shifts occurred over tens of millions of years, leaving a well-adapted mix of mammals behind by the time of the Grand Coupure 34 million years ago.

In Europe, meanwhile, tectonic developments weren’t a major factor driving local climate. When the global climate change happened, that continent’s mammals were evolutionary sitting ducks. Other studies have already suggested that Europe’s mammals were largely overrun and outcompeted by Asian mammals that were already living in colder and drier conditions.

Eronen said the findings should elevate the importance of collaboration across disciplines, for instance by integrating geoscience with paleontology, in the analysis of broad evolutionary patterns.

‘Our results highlight the importance of regional tectonic and surface uplift processes on the evolution of mammalian faunas,’ they wrote.

Reference:
Jussi T. Eronen et al. Mountain uplift explains differences in Palaeogene patterns of mammalian evolution and extinction between North America and Europe. Proceedings of the Royal Society B., June 2015 DOI: 10.1098/rspb.2015.0136

Note: The above story is based on materials provided by Brown University.

Researchers discover deepest known high-temperature hydrothermal vents in Pacific Ocean

These delicate carbonate spires formed when scalding hot water emerged from sediments in the Pescadero Basin and came in contact with near-freezing seawater. Dense colonies of tubeworms grow on the sides of the spires. This group of spires is about five meters (15 feet) wide. Credit: MBARI

In spring 2015, MBARI researchers discovered a large, previously unknown field of hydrothermal vents in the Gulf of California, about 150 kilometers (100 miles) east of La Paz, Mexico. Lying more than 3,800 meters (12,500 feet) below the surface, the Pescadero Basin vents are the deepest high-temperature hydrothermal vents ever observed in or around the Pacific Ocean. They are also the only vents in the Pacific known to emit superheated fluids rich in both carbonate minerals and hydrocarbons. The vents have been colonized by dense communities of tubeworms and other animals unlike any other known vent communities in the in the eastern Pacific.
Like another vent field in the Gulf that MBARI discovered in 2012, the Pescadero Basin vents were initially identified in high-resolution sonar data collected by an autonomous underwater vehicle (AUV). MBARI’s yellow, torpedo-shaped seafloor-mapping AUV spent two days flying about 50 meters above the bottom of the Basin, using sound beams to map the depth and shape of the seafloor.

The AUV team, led by MBARI engineer David Caress, pored over the detailed bathymetric map they created from the AUV data and saw a number of mounds and spires rising up from the seafloor. Data from the AUV also showed slightly warmer water over some of the spires, which implied that they might be active hydrothermal-vent chimneys. A team of geologists led by David Clague then used a tethered underwater robot, the remotely operated vehicle (ROV) Doc Ricketts, to dive down to the seafloor, fly around the vents, and collect video and samples of rocks and hot water spewing from the chimneys.

Reflecting on the discovery, Clague commented, ‘Before the AUV survey of Pescadero Basin, all we knew was that this area was really deep and filled with sediment. I was hoping to find a few outcrops of lava on the seafloor. But we got lucky. The vent field was right on the edge of our survey area, along a fault at the western edge of the basin.’

The AUV and ROV dives showed that the new field extends for at least 400 meters (one quarter mile) along this fault. Within this area the researchers found at least three active hydrothermal chimneys up to 12 meters (40 feet) tall, as well as dozens of low mounds that are most likely collapsed chimneys.

After his ROV dive, Clague noted, ‘This site was not at all what I was expecting.’ For one thing, the fragments of chimneys that the ROV brought back to the surface were quite different from those collected at other vents in the area. The Pescadero chimneys consisted entirely of light-colored carbonate minerals instead of the dark sulfide minerals that are abundant in hydrothermal chimneys elsewhere in the Gulf.

The Pescadero Basin is only the second place in the world where carbonate chimneys (instead of ones made primarily of sulfides) have been found in the deep sea. The other known location is the ‘Lost City’ vent field in the middle of the Atlantic Ocean, at a spot on the Mid-Atlantic Ridge.

The geologists also noticed that their rock samples smelled like diesel. They hypothesize that hot hydrothermal fluids migrating upward through the thick sediments of the Pescadero Basin ‘cook’ organic matter in the sediment, converting it into petroleum-like hydrocarbons — a process that has been observed at several other vents in the Pacific. Hydrocarbons may provide nutrition for the unusual microbes that thrive at these vents.

After Clague’s initial ROV dive, MBARI biologist Robert Vrijenhoek made three follow-up dives in the Pescadero Basin. His goal was to determine how and why animal communities at the Pescadero vents differed from those at other vent fields in the Gulf. Clague’s and Vrijenhoek’s dives revealed at least three different types of hydrothermal vents in the southern Gulf of California — black smokers, carbonate chimneys, and hydrothermal seeps. Each environment supports its own unique animal community.

Black smokers form in active volcanic areas. One such area is on the Alarcón Rise, about 160 kilometers (100 miles) south of the Pescadero Basin, where MBARI researchers discovered several hydrothermal fields in 2012. On the Alarcón Rise, massive, dark-colored sulfide chimneys rise more than 37 meters (120 feet) above the lava-covered seafloor. These chimneys gush extremely hot fluids (over 350 degrees Celsius, 660 degrees Fahrenheit) rich in heavy metals and sulfides. When the superheated fluids come in contact with near-freezing seawater, these minerals precipitate, forming dark, smoke-like plumes of particles. The ‘black smoker’ chimneys are often colonized by giant tubeworms in the genus Riftia, which grow over two meters (six feet) long, as well as limpets, crabs, squat lobsters, and Alvinella palmworms.

In contrast, the carbonate chimneys in the Pescadero Basin emerge from a flat, muddy seafloor, and are smaller and more delicate than black smokers. They emit fluids that are slightly cooler (250-290 degrees Celsius) and do not form dark, smoke-like plumes. The Pescadero Basin fluids are, however, rich in oil-like hydrocarbons that form dark, oily crusts on the light colored carbonate chimneys. They also support a very different group of animals, including dense colonies of tubeworms in the genus Oasisia.

In the third type of vent environment, ‘hydrothermal seeps,’ much cooler (less than 30-60 degrees Celsius) water trickles out of lava flows interleaved with seafloor mud. These seeps support an entirely different community of animals, including anemones, tubeworms in the genera Lamellibrachia and Escarpia, and broad, white mats of bacteria. In contrast to the Pescadero and Alarcón vents, each of which hosted a single species of deep-sea clams, the seeps support at least four different types of clams.

One thing that all of these communities have in common is that the dominant tubeworms and clams host specialized intracellular bacteria (symbionts) that allow these animals to exploit potentially toxic chemicals in the vent fluids as sources of nutrition. Vrijenhoek and his collaborators are trying to figure out if the different vent communities in the Gulf are controlled by differences in water depth, geochemistry, symbiotic bacteria, or perhaps other unanticipated factors.

The discovery of the Pescadero Basin hydrothermal field is just the latest example of how MBARI’s extensive use of underwater robotics has accelerated the pace of scientific discovery in the deep sea. As Vrijenhoek noted, ‘In the 1990s, following the discovery of plumes of warm water over the Mid-Atlantic Ridge, researchers from four countries searched for seven years to find what eventually became known as the ‘rainbow vent field.’ They were limited by inaccurate and imprecise bathymetric maps. This spring it took us only two days to do the same thing in the Pescadero Basin, using MBARI’s high-precision seafloor-mapping AUV.’

Note: The above story is based on materials provided by Monterey Bay Aquarium Research Institute.

Large Quakes May Dampen Themselves

Snapshots of a 10-Hz rupture propagation and surface wave field. The bottom shot includes the effects of crustal variations, generating a strongly scattered wave field. Credit: Amit Chourasia, SDSC

Most models of ground motion during earthquakes have the earth shifting and grinding, then returning to essentially the same state as before once the temblor ends. But during earthquakes, especially large ones, the earth gets transformed. It crumbles and breaks apart, and in extreme cases even liquefies. These terrestrial transformations are known as nonlinear effects, and they may impact how much damage certain temblors can cause.
If a massive magnitude 8.0 earthquake rocked the San Andreas Fault, certain properties of the Southern California region’s shallow sediments might mean the quake would shake less than previously estimated. Kim Olsen, a geologist and earthquake expert at San Diego State University, recently was awarded a $57,000 grant from the U.S. Geological Survey to study these nonlinear effects.

Shake and rattle

It’s harder for an earthquake’s waves to transmit as much energy through this broken-up earth, meaning that the quake’s amplitude winds up being dampened in the process. This earthen breakup is more likely to occur in areas with unconsolidated sediment—clay, sand and gravel—and during large, powerful earthquakes. That means, somewhat counterintuitively, that the Big One might be so powerful that nonlinear effects near the fault limit the amplitude of certain waves, dramatically reducing the damage much further away.

“A 7.8 or 8.0 magnitude earthquake on the San Andreas might halve the amplitude of the shaking in certain parts of Los Angeles as a result of nonlinear effects,” Olsen explained.

Olsen and his colleagues in the San Diego Supercomputer Center—made up of researchers from SDSU and the University of California, San Diego—are using supercomputing technology to model earthquakes that incorporate these nonlinear effects.

Prize-winning code

This team of researchers recently won a $150,000 grand prize from the technology company NVIDIA in a competition to find real-world applications for the company’s accelerated graphics processing unit (GPU) technology.

Olsen and his SDSU colleague Steven Day created the code which, for the competition, was used to simulate high-frequency seismic waves in the range of 0-10 Hertz, the kind of waves that tend to cause the most damage to single-level and two-story homes. Their simulations could be used to test and potentially overhaul earthquake building codes to make homes safer, Olsen said

NVIDIA’s accelerated GPU technology allowed the simulation to run about five times faster than it would ordinarily. By incorporating the accelerated GPU, researchers can do their work more quickly and efficiently.

“We’re excited that we got this speed-up,” Olsen said. “Now we want to use it and get some results.”

Note : The above story is based on materials provided by San Diego State University.

Yorkshire’s oldest new addition to the ‘Jurassic World’

Experts from the University of Manchester have identified Britain’s oldest sauropod dinosaur from a fossil bone discovered on the Yorkshire coast. Credit: Jason Poole

Experts from the University of Manchester have identified Britain’s oldest sauropod dinosaur from a fossil bone discovered on the Yorkshire coast.

The vertebra (backbone) originates from a group of dinosaurs that includes the largest land animals to have ever walked on Earth. This new sauropod dinosaur, from the Middle Jurassic Period at about 176 million years old, was found near Whitby, Yorkshire, after it fell out of a cliff face. This find represents the earliest skeletal record of this type of dinosaur from the United Kingdom and adds to existing evidence from Yorkshire dinosaur tracks that this part of the country was once Britain’s very own ‘Jurassic World’.

Sauropods (often referred to as ‘brontosaurs’) include some of the largest plant-eating dinosaurs to have roamed the Earth and were a successful group for nearly 150 million years. They possessed distinctive long necks and tails, small heads, a large body and walked on all fours. Some species such as the Argentinosaurus grew up to 115 feet (35 metres) long and possibly weighed as much as 80 tonnes.

The fragmentary nature of the new find from Yorkshire means it is not possible to generate a new species of dinosaur. However, this fossil clearly belongs to this distinctive group of titanic sized animals, the sauropods. This dinosaur fossil is an extremely rare find, given the Middle Jurassic rocks of the world are only exposed in a few areas, such as China and Argentina where similar-aged dinosaur fossils originate.

Professor Phil Manning and his team from The University of Manchester used X-Ray Tomography to study the fossil bone, which is now held in the collections at the Yorkshire Museum in York (UK). They present their description of this new sauropod dinosaur in a paper published today in the journal PLOS ONE.

Professor Manning said: “Many scientists have worked on the amazing dinosaur tracks from the Middle Jurassic rocks of Yorkshire. It was a splendid surprise to come face-to-face with a fossil vertebra from the Jurassic rocks of Yorkshire that was clearly from a sauropod dinosaur

“This fossil offers the earliest ‘body fossil’ evidence for this important group of dinosaurs in the United Kingdom, but it is impossible to define a new species based upon this single bone.”

Whilst this is clearly frustrating for the team, there is possibly more of this Jurassic titan still to be discovered in the future and only then might it get a new species name. Until more bones are discovered the team have simply nicknamed Britain’s oldest sauropod dinosaur, ‘Alan’, after the finder of this prehistoric beastie (Alan Gurr).

Dr Victoria Egerton (co-author on the paper) added: “The Jurassic Park that was once Yorkshire clearly has much more to offer science in our understanding of the distribution and evolution of dinosaurs.”

Dr Mike Romano, another co-author on the paper said: “Dinosaur remains of Middle Jurassic age are generally rare, even on a global scale. So, to find a single distinctive vertebra of that age on the beach at Whitby, and one that represents a new taxon of sauropod dinosaurs, is indeed a (white) feather in the cap for Yorkshire.”

Reference:
Phillip L. Manning , Victoria M. Egerton , Mike Romano. A new sauropod dinosaur from the Middle Jurassic of the United Kingdom. PLOS ONE, June 1, 2015 DOI: 10.1371/journal.pone.0128107

Note: The above story is based on materials provided by Manchester University.

Laser from a plane discovers Roman goldmines in Spain

These are ancient goldmines in the Eria river valley, with channels and reservoirs for exploitation. The model generated with LiDAR data (left) allows these structures to be located on aerial photos (right). Credit: J. Fernández Lozano et al.

Hidden under the vegetation and crops of the Eria Valley, in León (Spain), there is a gold mining network created by the Romans two thousand years ago, as well as complex hydraulic works, such as river diversions, to divert water to the mines of the precious metal. Researchers from the University of Salamanca made the discovery from the air with an airborne laser teledetection system.

Las Médulas in León is considered to be the largest opencast goldmine of the Roman Empire, but the search for this metal extended many kilometres further south-east to the Erica river valley. Thanks to a Light Detection and Ranging (LiDAR) laser system attached to an aircraft, the ancient mining works of the area and the complex hydraulics system used by the Romans in the 1st century BC to extract gold (including channels, reservoirs and a double river diversion) have been discovered.

“The volume of earth exploited is much greater than previously thought and the works performed are impressive, having achieved actual river captures, which makes this valley extremely important in the context of Roman mining in the north-east of the Iberian Peninsula,” as Javier Fernández Lozano, geologist at the University of Salamanca and co-author of this study published in the Journal of Archaeological Science, said.

The specialists consider that the systems for the transport and storage of water were copied from those already existing in North Africa, where the Egyptians had been employing them for centuries. Some details of the methodology used appear in texts such as those of the Pliny the Elder, the Roman procurator in charge of overseeing mining in Hispania.

“We have established that the labour that went into extracting the resource until its exhaustion was so intensive that after removing the gold from surface sediments, operations continued until reaching the rocks with the auriferous quartz veins underneath,” explains Fernández Lozano.

The researcher stresses that the real discoverer was the LiDAR technology: “Unlike traditional aerial photography, this airborne laser detection system allows the visualisation of archaeological remains under vegetation cover or intensely ploughed areas.”

From aircraft or drones

LiDAR comprises a laser sensor which scans the ground from an aircraft or drone with geographical references provided by GPS ground stations. The data obtained is represented by point clouds, which are processed with a piece of software to construct a cartographic model where the forms are identified, such as old reservoirs or channels.

This technology was developed by NASA in the sixties to analyse the retreating sea ice in the Arctic and composition of the oceans. Since then their use has been extended to topography, cadastral mapping, geology and archaeology. According to the authors, the study of Roman mining in the Eria valley is the first piece of ‘geo-archaeology’ performed with LiDAR in Spain.

“Our intention is to continue working with this technique to learn more about mineral mining in the Roman Empire and clear up any mysteries such as why Rome abandoned such a precious resource as gold from one day to the next,” concludes the researcher.

Reference:
Javier Fernández-Lozano, Gabriel Gutiérrez-Alonso, Miguel Fernández-Morán. Using airborne LiDAR sensing technology and aerial orthoimages to unravel roman water supply systems and gold works in NW Spain (Eria valley, León). Journal of Archaeological Science, 2014. DOI:10.1016/j.jas.2014.11.003

Note: The above story is based on materials provided by Plataforma SINC.

Radiocarbon dates of mollusc shells show that modern humans occupied the Near East at least 45,900 years ago

Phorcus turbinatus shells. Top and side views of: (1) A complete specimen (inventory no.: RGM-606318a). (2) A shell of which the top was removed by Upper Palaeolithic people to aid flesh extraction (RGM-606318b). Scale bar is 1 cm.

New high precision radiocarbon dates of mollusk shells show that modern humans occupied the Near East at least 45,900 years ago and colonized Europe from there.
A multinational team, which included researchers from the University of York, analysed shells recovered at Ksâr ‘Akil, a site in Lebanon. Ksâr ‘Akil is one of the few sites in the Near East where modern human fossils are associated with Upper Palaeolithic (UP) tools.

The researchers radiocarbon-dated the shell carbonates of the mollusck species Phorcus turbinatus that was eaten by prehistoric humans. The analysis revealed that modern humans carrying UP tools occupied the eastern Mediterranean at least 45,900 years ago. This confirms UP modern human presence in the Levant prior to their arrival in Europe and suggests that it served as a corridor for the colonization of Europe by modern humans.

Dr Beatrice Demarchi, of the Department of Archaeology at York, and Sheila Taylor, of the University’s Department of Chemistry, were part of the team which studied around 3500 shells comprising 49 species. The researchers found that the best-preserved shells were those of mollusks gathered by prehistoric humans for consumption as food and they used new techniques to ensure that the samples had not been compromised during burial before radiocarbon dating them.

“One of these approaches is a technique called ‘intra-crystalline protein diagenesis’ which evaluates the integrity of amino acids preserved in the intra-crystalline structure of the shell carbonates” says Dr Demarchi. Amino acid analyses were undertaken at the University’s Natural Environment Research Council-recognised facility for amino acid analysis.

The study, which is published in Proceedings of the National Academy of Sciences (PNAS), has allowed the researchers to propose a robust new chronology for Ksâr ‘Akil. Their results confirm the presence of modern humans carrying a UP toolkit in the Levant prior to any modern human fossils in Europe.

The timing of the spread of modern humans out of Africa and into Eurasia is a topic of major debate among archaeologists, human paleontologists and geneticists. They have been seeking to establish when modern humans first arrived in Europe, the route they took and if the Levant serve as a corridor facilitating Upper Palaeolithic modern human dispersal.

The importance of Ksâr ‘Akil lies in the fact that there are two modern human fossils, nicknamed ‘Ethelruda’ and ‘Egbert’ by the original excavators, associated with Upper Palaeolithic toolkits from the site.

However, the new research shows that Egbert lived around 43,000 years ago and Ethelruda at least 45,900 years ago, possibly earlier. Therefore, Ethelruda pre-dates all European modern humans.

Marjolein Bosch, from the Max Planck Institute for Evolutionary Anthropology, the lead author of the study added: “Toolkits similar to those associated with Ethelruda and Egbert are also found in other sites in the Levant as well as in Europe. These similar toolkits and the earlier ages in the Near East suggest population dispersals from the Near East to Europe between 55,000 and 40,000 years ago.”

Reference:
Marjolein D. Bosch, Marcello A. Mannino, Amy L. Prendergast, Tamsin C. O’Connell, Beatrice Demarchi, Sheila M. Taylor, Laura Niven, Johannes van der Plicht, and Jean-Jacques Hublin. New chronology for Ksâr ‘Akil (Lebanon) supports Levantine route of modern human dispersal into Europe. Proceedings of the National Academy of Sciences, 2015; DOI: 10.1073/pnas.1501529112

Note: The above story is based on materials provided by University of York.

New evidence emerges on the origins of life

In the beginning, there were simple chemicals. And they produced amino acids that eventually became the proteins necessary to create single cells. And the single cells became plants and animals. Recent research is revealing how the primordial soup created the amino acid building blocks, and there is widespread scientific consensus on the evolution from the first cell into plants and animals. But it’s still a mystery how the building blocks were first assembled into the proteins that formed the machinery of all cells.

Now, two long-time University of North Carolina scientists — Richard Wolfenden, PhD, and Charles Carter, PhD — have shed new light on the transition from building blocks into life some 4 billion years ago.

“Our work shows that the close linkage between the physical properties of amino acids, the genetic code, and protein folding was likely essential from the beginning, long before large, sophisticated molecules arrived on the scene,” said Carter, professor of biochemistry and biophysics at the UNC School of Medicine. “This close interaction was likely the key factor in the evolution from building blocks to organisms.”

Their findings, published in companion papers in the Proceedings of the National Academy of Sciences, fly in the face of the problematic “RNA world” theory, which posits that RNA — the molecule that today plays roles in coding, regulating, and expressing genes — elevated itself from the primordial soup of amino acids and cosmic chemicals to give rise first to short proteins called peptides and then to single-celled organisms.

Wolfenden and Carter argue that RNA did not work alone; in fact, it was no more likely that RNA catalyzed peptide formation than it was for peptides to catalyze RNA formation.

The finding adds a new layer to the story of how life evolved billions of years ago.

Its name was LUCA

The scientific community recognizes that 3.6 billion years ago there existed the last universal common ancestor, or LUCA, of all living things presently on Earth. It was likely a single-cell organism. It had a few hundred genes. It already had complete blueprints for DNA replication, protein synthesis, and RNA transcription. It had all the basic components — such as lipids — that modern organisms have. From LUCA forward, it’s relatively easy to see how life as we know it evolved.

Before 3.6 billion years, however, there is no hard evidence about how LUCA arose from a boiling caldron of chemicals that formed on Earth after the creation of the planet about 4.6 billion years ago. Those chemicals reacted to form amino acids, which remain the building blocks of proteins in our own cells today.

“We know a lot about LUCA and we are beginning to learn about the chemistry that produced building blocks like amino acids, but between the two there is a desert of knowledge,” Carter said. “We haven’t even known how to explore it.”

The UNC research represents an outpost in that desert.

“Dr. Wolfenden established physical properties of the twenty amino acids, and we have found a link between those properties and the genetic code,” Carter said. “That link suggests to us that there was a second, earlier code that made possible the peptide-RNA interactions necessary to launch a selection process that we can envision creating the first life on Earth.”

Thus, Carter said, RNA did not have to invent itself from the primordial soup. Instead, even before there were cells, it seems more likely that there were interactions between amino acids and nucleotides that led to the co-creation of proteins and RNA.

Complexity from simplicity

Proteins must fold in specific ways to function properly. The first PNAS paper, led by Wolfenden, shows that both the polarities of the twenty amino acids (how they distribute between water and oil) and their sizes help explain the complex process of protein folding — when a chain of connected amino acids arranges itself to form a particular 3-dimensional structure that has a specific biological function.

“Our experiments show how the polarities of amino acids change consistently across a wide range of temperatures in ways that would not disrupt the basic relationships between genetic coding and protein folding,” said Wolfenden, Alumni Distinguished Professor of Biochemistry and Biophysics. This was important to establish because when life was first forming on Earth, temperatures were hot, probably much hotter than they are now or when the first plants and animals were established.

A series of biochemical experiments with amino acids conducted in Wolfenden’s lab showed that two properties — the sizes as well as the polarities of amino acids — were necessary and sufficient to explain how the amino acids behaved in folded proteins and that these relationships also held at the higher temperatures of Earth 4 billion years ago.

The second PNAS paper, led by Carter, delves into how enzymes called aminoacyl-tRNA synthetases recognized transfer ribonucleic acid, or tRNA. Those enzymes translate the genetic code.

“Think of tRNA as an adapter,” Carter said. “One end of the adapter carries a particular amino acid; the other end reads the genetic blueprint for that amino acid in messenger RNA. Each synthetase matches one of the twenty amino acids with its own adapter so that the genetic blueprint in messenger RNA faithfully makes the correct protein every time.”

Carter’s analysis shows that the two different ends of the L-shaped tRNA molecule contained independent codes or rules that specify which amino acid to select. The end of tRNA that carried the amino acid sorted amino acids specifically according to size.

The other end of the L-shaped tRNA molecule is called the tRNA anticodon. It reads codons, which are sequences of three RNA nucleotides in genetic messages that select amino acids according to polarity.

Wolfenden and Carter’s findings imply that the relationships between tRNA and the physical properties of the amino acids — their sizes and polarities — were crucial during the Earth’s primordial era. In light of Carter’s previous work with very small active cores of tRNA synthetases called Urzymes, it now seems likely that selection by size preceded selection according to polarity. This ordered selection meant that the earliest proteins did not necessarily fold into unique shapes, and that their unique structures evolved later.

Carter said, “Translating the genetic code is the nexus connecting pre-biotic chemistry to biology.”

He and Wolfenden believe that the intermediate stage of genetic coding can help resolve two paradoxes: how complexity arose from simplicity, and how life divided the labor between two very different kinds of polymers: proteins and nucleic acids.

“The fact that genetic coding developed in two successive stages — the first of which was relatively simple — may be one reason why life was able to emerge while the earth was still quite young,” Wolfenden noted.

An earlier code, which enabled the earliest coded peptides to bind RNA, may have furnished a decisive selective advantage. And this primitive system could then undergo a natural selection process, thereby launching a new and more biological form of evolution.

“The collaboration between RNA and peptides was likely necessary for the spontaneous emergence of complexity,” Carter added. “In our view, it was a peptide-RNA world, not an RNA-only world.”

The National Institutes of Health funded this work. Dr. Wolfenden holds a joint appointment in the department of chemistry in the College of Arts and Sciences at UNC-Chapel Hill.

Reference:
Richard Wolfenden, Charles A. Lewis Jr., Yang Yuan, and Charles W. Carter Jr. Temperature dependence of amino acid hydrophobicities. Proceedings of the National Academy of Sciences, 2015; DOI: 10.1073/pnas.1507565112

Note: The above story is based on materials provided by University of North Carolina Health Care.

Ancient algae found deep in tropical glacier

Pennate (elongated) diatoms found in an ice core from the Quelccaya Summit Dome Glacier were among many samples identified by scientists at Rice University, the University of Nebraska-Lincoln and Ohio State University. They suspect the freshwater diatoms, a type of algae, were blown there from nearby high-elevation ponds as far back as the sixth century. Credit: Images by Bruce Brinson/Rice University

The remains of tiny creatures found deep inside a mountaintop glacier in Peru are clues to the local landscape more than a millennium ago, according to a new study by Rice University, the University of Nebraska-Lincoln and Ohio State University.
The unexpected discovery of diatoms, a type of algae, in ice cores pulled from the Quelccaya Summit Dome Glacier demonstrate that freshwater lakes or wetlands that currently exist at high elevations on or near the mountain were also there in earlier times. The abundant organisms would likely have been transported in air currents to the glacier, where they were deposited on its surface, dead or alive, and ultimately became frozen within the glacial ice and persisted there for hundreds of years.

The study is the first to show the presence of diatoms in glacial ice from tropical regions. The diatoms offer useful information about conditions in and around the Andes when they were deposited on the ice.

The paper is the result of a unique collaboration among Rice chemists Ed Billups and Bruce Brinson, Ohio State climatologist Lonnie Thompson and lead author Sherilyn Fritz, a geoscientist at Nebraska. It appears this week in Arctic, Antarctic, and Alpine Research, a journal published by the University of Colorado-Boulder.

Of the four scientists, Billups, Brinson and even Thompson had something in common with the focus of their study: They were all, figuratively, fish out of water.

“I was the lucky latecomer to the group,” said Fritz, who studies diatoms from cores she and her students drill from South American lakebeds. “It’s only because Bruce was so observant and curious and did such a nice job on documenting the diatoms that it happened at all.”

Over a long and storied career, Thompson has collected ice cores from many of the world’s hard-to-reach locations, including Quelccaya in 2003. The cores contain a climate record that spans millennia, but Thompson’s ability to pull hard data from his samples was complicated by the sheer number he had preserved.

Thompson said the first record of diatoms in tropical glaciers “points to the potential of these archives for investigating how not just diatoms but other life forms such as ancient microbes survived, thrived and evolved under extreme conditions and under very different climatic regimes.”

The collaboration began when Thompson visited Rice for a conference and struck up a conversation with Billups, with whom he shares West Virginia roots.

“We got to talking,” said Billups of their first encounter. “He knew we were working on carbon materials and said, ‘You know, sometimes my ice is black, and I think that’s carbon.'” Billups, whose wide-ranging research includes the study of all forms of carbon, suspected wind currents carried fullerenes from forest fires to the mountaintop and offered to have a look.

Thompson sent ice core filtrates in silica filter paper that preserved the contents of water from three layers corresponding to the years 1161 to 1176, 807 to 837 and 460 to 511 A.D. (The earliest samples tested for the study were from about 540 feet below the surface of the 18,000-foot mountain.) “When I looked at the samples, I thought, ‘Whatever are we going to do with these?'” Billups recalled.

“We realized they weren’t appropriate for searching for fullerenes,” said Brinson, a Rice research scientist.

Brinson looked at the samples through a Rice electron microscope and quickly recognized their significance. Rather than fullerenes, they contained what the paper described as “a serendipitous byproduct”: an abundance of diatoms, the study of which is generally well outside the realm of either chemists or glaciologists.

“When we saw the first diatom and realized it possessed periodic nanoscale structure, we knew we were documenting irreplaceable snapshots in archeological time and space,” Brinson said.

“Thompson was very excited about this,” Billups said. “Diatoms are found in Arctic and Antarctic ice, but he said nobody’s ever found them in equatorial glaciers.”

Brinson hit the books and identified many of the diatoms, which ranged in size from a few to 70 microns in length. “I don’t have a biological background, but I knew they were unique,” he said. He also realized the team needed a specialist.

Thompson, who knew of Fritz’s work in South America, suggested they enlist her.

“There are diatoms in dust that is transported globally, and people have found them in glaciers in Antarctica and Greenland, so my first thought was they’d be like those,” Fritz said. “But these are beautifully preserved, and most of the ecology we know about indicates they’re not from global diatom dust sources.”

Fritz said the diatoms’ excellent condition suggested they hadn’t traveled far. “Most but not all of them are species you would find in very dilute freshwater, either lakes or wetlands, and there are lots of those in the tropical Andes at varied elevations,” she said. The presence of Volvox, green algae found in the two older samples, confirmed the diatoms’ freshwater source.

The study has Fritz thinking about gathering diatoms from lakes near the ice cap to see how diatom populations have changed over the centuries. “I’ve contemplated doing some more sampling, just because it’s an interesting question,” she said. She does plan to have her students take a closer look at the original samples, which Brinson sent her, “to do some quantitative counts, just to get a better sense of the relative abundance of things.”

The researchers wrote that continuing study of diatoms in relation to other materials found in the ice core record could provide valuable information about local or even global environmental change.

“I’m convinced there’s no end to what you can find in these glaciers,” Billups said.

“One thing is clear,” Thompson said. “The greatest scientific progress going forward will be made with increased collaboration among many different disciplines. Unfortunately, these valuable ice archives of our past are rapidly disappearing under the present climate conditions.”

Reference:
Lonnie G. Thompson et al. Diatoms at >5000 Meters in the Quelccaya Summit Dome Glacier, Peru. Arctic, Antarctic, and Alpine Research, June 2015 DOI: 10.1657/AAAR0014-075

Note: The above story is based on materials provided by Rice University.

The ebb and flow of Greenland’s glaciers

These icebergs are easily visible in the fjord from an area just outside of Ilulissat. They calved from Jakobshavn Isbrae (aka Ilulissat Glacier) earlier in the season, from the calving front which peaks at speeds of nearly 17 km/yr in mid summer. Credit: Ian Joughin, University of Washington

In northwestern Greenland, glaciers flow from the main ice sheet to the ocean in see-sawing seasonal patterns. The ice generally flows faster in the summer than in winter, and the ends of glaciers, jutting out into the ocean, also advance and retreat with the seasons.
Now, a new analysis shows some important connections between these seasonal patterns, sea ice cover and longer-term trends. Glaciologists hope the findings, accepted for publication in the June issue of the American Geophysical Union’s Journal of Geophysical Research-Earth Surface and available online now, will help them better anticipate how a warming Greenland will contribute to sea level rise.

“Rising sea level can be hard on coastal communities, with higher storm surges, greater flooding and saltwater encroachment on freshwater,” said lead author Twila Moon, a researcher at the National Snow and Ice Data Center (NSIDC). NSIDC is part of the Cooperative Institute for Research in Environmental Sciences (CIRES) at the University of Colorado Boulder.

“We know that sea level will go up in the future,” Moon said. “The challenge is to understand how quickly it will rise, and one element of that is better understanding how Greenland glaciers behave.”

Moon and colleagues from the University of Washington focused on 16 glaciers in northwest Greenland, collecting detailed information on glacier speed, terminus position (the “end” of the glacier in the ocean) and sea ice conditions, during the years 2009-2014.

Sea ice had an important influence on the glaciers: When the waters in front of the glacier were completely covered by sea ice, the ends of the glaciers often advanced out away from land; icebergs that might otherwise have broken off and floated away stayed attached. When sea ice broke up in the spring, the ends of the glaciers usually quickly retreated back toward land as icebergs broke away.

By contrast, seasonal swings in glacier speed had little to do with sea ice conditions or glacier terminus location. Rather, the speed (velocity) of ice flow is likely responding to changes in the surface melt on top of the ice sheet and the movement of meltwater through and under the ice sheet.

Over the longer-term, however, Moon and her colleagues found a tight relationship between the speed of glaciers and terminus location. When sea ice levels were especially low and glaciers’ toes (termini) retreated more than normal and then didn’t re-advance, the glaciers sped up, moving ice toward the sea more quickly. While low sea ice is likely not the full cause of the changes, it may be a visible indication of other processes, such as subsurface ice melt, that also affect terminus retreat, Moon said.

It’s important to recognize that the mechanisms driving seasonal glacier changes–in northwestern Greenland and around the world–are not necessarily the same ones driving longer-term trends, Moon said. Knowing the differences may help researchers better anticipate the impact of anomalously low sea ice years, for example.

“We do know we’re going to see sea ice reduction in this area, and it’s possible we can begin to estimate how that may affect glacier velocities,” Moon said. It’s also possible, she said, that researchers and communities interested in long-term glacial changes–the kind that affect sea levels–may not need to focus as much on seasonal advance and retreat of the rivers of ice.

“It may be that we need to instead pay more attention to these out-of-bounds events, these anomalous years of very low sea ice or very high melt that likely have the greatest influence on longer-term trends.”

Reference:
Ben Smith et al. Seasonal to multiyear variability of glacier surface velocity, terminus position, and sea ice/ice mélange in northwest Greenland. Journal of Geophysical Research-Earth Surface, June 2015 DOI: 10.1002/2015JF003494

Note: The above story is based on materials provided by American Geophysical Union.

Astronomers make real-time, 3D movies of plasma tubes drifting overhead

This is an artist’s impression of tubular plasma structures in the Earth’s magnetosphere, 600 kilometres above the ground. Credit: CAASTRO/Mats Bjorkland

By creatively using a radio telescope to see in 3D, astronomers have detected the existence of tubular plasma structures in the inner layers of the magnetosphere surrounding Earth.
“For over 60 years, scientists believed these structures existed but by imaging them for the first time, we’ve provided visual evidence that they are really there,” said Cleo Loi of the ARC Centre of Excellence for All-sky Astrophysics (CAASTRO) and School of Physics at the University of Sydney in Australia.

Ms Loi is the lead author on this research, undertaken as part of her award-winning undergraduate thesis and recently published in Geophysical Research Letters. In collaboration with international colleagues, she identified the structures.

“The discovery of the structures is important because they cause unwanted signal distortions that could, as one example, affect our civilian and military satellite-based navigation systems. So we need to understand them,” Ms Loi said.

The region of space around Earth occupied by its magnetic field, called the magnetosphere, is filled with plasma that is created by the atmosphere being ionised by sunlight.

The innermost layer of the magnetosphere is the ionosphere, and above that is the plasmasphere. They are embedded with a variety of strangely shaped plasma structures including, as has now been revealed, the tubes.

“We measured their position to be about 600 kilometres above the ground, in the upper ionosphere, and they appear to be continuing upwards into the plasmasphere. This is around where the neutral atmosphere ends, and we are transitioning to the plasma of outer space,” explained Ms Loi.

Using the Murchison Widefield Array (MWA), a radio telescope located in the Western Australian desert, Ms Loi found that she could map large patches of the sky and even exploit the MWA’s rapid snapshot capabilities to create a movie — effectively capturing the real-time motions of the plasma.

“We saw a striking pattern in the sky where stripes of high-density plasma neatly alternated with stripes of low-density plasma. This pattern drifted slowly and aligned beautifully with the Earth’s magnetic field lines, like aurorae,” Ms Loi said.

“We realised we may be onto something big and things got even better when we invented a new way of using the MWA.”

The MWA consists of 128 antenna ’tiles’ spread over an area roughly three by three kilometres that work together as one instrument — but by separating the signals from tiles in the east from the ones in the west, the astronomers gave the MWA the power to see in 3D.

“This is like turning the telescope into a pair of eyes, and by that we were able to probe the 3D nature of these structures and watch them move around,” said Ms Loi.

“We were able to measure the spacing between them, their height above the ground and their steep inclination. This has never been possible before and is a very exciting new technique.”

This ability adds yet another accolade to the MWA’s name after it had already proven its worth as a powerful precursor instrument to the Square Kilometre Array (SKA), and now the MWA’s 3D vision has the potential to provide many more in-depth analyses of the formation of plasma structures.

“It is to Cleo’s great credit that she not only discovered this but also convinced the rest of the scientific community. As an undergraduate student with no prior background in this, that is an impressive achievement,” said Ms Loi’s supervisor Dr Tara Murphy, also of CAASTRO and School of Physics at the University of Sydney.

“When they first saw the data, many of her senior collaborators thought the results were literally ‘too good to be true’ and that the observation process had somehow corrupted the findings, but over the next few months, Cleo managed to convince them that they were both real and scientifically interesting.”

Video

Reference:
S.T. Loi et al. Real-time imaging of density ducts between the plasmasphere and ionosphere. Geophysical Research Letters, 2015 DOI: 10.1002/2015GL063699

Note: The above story is based on materials provided by University of Sydney.

M8.5 Earthquake Hits Japan, May 30, 2015

Volcano erupts in Galapagos Islands, home to unique pink iguanas

Wolf Volcano, Isabela Island, Galapagos Credit: NASA Landsat 7

A volcano perched atop one of Ecuador’s Galapagos Islands erupted in the early hours of Monday, the local authorities said, potentially threatening a unique species of pink iguanas.
The roughly 1.7-kilometer (1.1-mile) high Wolf volcano is located on Isabela Island, home to a rich variety of flora and fauna typical of the archipelago that helped inspire Charles Darwin’s theory of evolution following his 1835 visit.

“The Wolf volcano is not located near a populated area. There is not risk for the human population. This is the only population of pink iguanas in the world,” Galapagos National Park said in a posting on Twitter.

The park posted pictures showing lava pouring down the sides of the Wolf volcano, the Galapagos’ highest point, while a dark plume estimated to be 10 km (6.4 miles) high, billowed overhead.

Wolf had been inactive 33 years, according to the park.

The lava is flowing down the volcano’s southern face while the iguanas, officially an endangered species, inhabit the opposite side, the Environment Ministry said in a statement, adding it expected the animals to escape harm.

The flow is likely to reach the sea, however, where it could harm marine life, the Geophysics Institute said separately. While populated areas of the island are safe from the eruption, the institute said some of the ash cloud could descend upon them.

In April, unusual seismic activity was also reported at the Sierra volcano on the same Isabela Island, the archipelago’s biggest, where yellow iguanas and giant turtles also live.

The eruption in Ecuador comes on the heels of eruptions in Chile, another South American country located on the so-called Pacific Ring of Fire.

Note : The above story is based on materials Reporting by Alexandra Valencia, writing by Alexandra Ulmer and Peter Murphy; editing by Marguerita Choy and G Crosse. “Reuters“

Curiosity rover adjusts route up Martian mountain

This May 10, 2015, view from Curiosity’s Mastcam shows terrain judged difficult for traversing between the rover and an outcrop in the middle distance where a pale rock unit meets a darker rock unit above it. The rover team decided not to approach this outcrop and identified an alternative. Credit: NASA/JPL-Caltech/MSSS

NASA’s Curiosity Mars rover climbed a hill Thursday to approach an alternative site for investigating a geological boundary, after a comparable site proved hard to reach.
The drive of about 72 feet (22 meters) up slopes as steep as 21 degrees brought Curiosity close to a target area where two distinctive types of bedrock meet. The rover science team wants to examine an outcrop that contains the contact between the pale rock unit the mission analyzed lower on Mount Sharp and a darker, bedded rock unit that the mission has not yet examined up close.

Two weeks ago, Curiosity was headed for a comparable geological contact farther south. Foiled by slippery slopes on the way there, the team rerouted the vehicle and chose a westward path.The mission’s strategic planning keeps multiple route options open to deal with such situations.

“Mars can be very deceptive,” said Chris Roumeliotis, Curiosity’s lead rover driver at NASA’s Jet Propulsion Laboratory, Pasadena, California. “We knew that polygonal sand ripples have caused Curiosity a lot of drive slip in the past, but there appeared to be terrain with rockier, more consolidated characteristics directly adjacent to these ripples. So we drove around the sand ripples onto what we expected to be firmer terrain that would give Curiosity better traction. Unfortunately, this terrain turned out to be unconsolidated material too, which definitely surprised us and Curiosity.”

In three out of four drives between May 7 and May 13, Curiosity experienced wheel slippage in excess of the limit set for the drive, and it stopped mid-drive for safety. The rover’s onboard software determines the amount of slippage occurring by comparing the wheel-rotation tally to actual drive distance calculated from analysis of images taken during the drive.

The rover was heading generally southward from near the base of a feature called “Jocko Butte” toward a geological contact in the eastern part of the “Logan Pass” area.

Routes to this contact site would have required driving across steeper slopes than Curiosity has yet experienced on Mars, and the rover had already experienced some sideways slipping on one slope in this area.

“We decided to go back to Jocko Butte, and, in parallel, work with the scientists to identify alternate routes,” Roumeliotis said.

The team spent a few days analyzing images from the rover and from NASA’s Mars Reconnaissance Orbiter to choose the best route for short-term and long-term objectives.

“One factor the science team considers is how much time to spend reaching a particular target, when there are many others ahead,” said Curiosity Project Scientist Ashwin Vasavada of JPL. “We used observations from NASA’s Mars Reconnaissance Orbiter to identify an alternative site for investigating the geological contact in the Logan Pass area. It’s a little mind-blowing to drive up a hill to a site we saw only in satellite images and then find it in front of us.”

Curiosity has been exploring on Mars since 2012. It reached the base of Mount Sharp last year after fruitfully investigating outcrops closer to its landing site and then trekking to the mountain. The main mission objective now is to examine successively higher layers of Mount Sharp.

Note: The above story is based on materials provided by NASA/Jet Propulsion Laboratory.

New technique harnesses everyday seismic waves to image Earth

This is a coverage map of the the seismic wave sensors in Long Beach that the researchers drew upon for their study. Credit: Courtesy of Nori Nakata.

A new technique developed at Stanford University harnesses the buzz of everyday human activity to map the interior of the Earth. “We think we can use it to image the subsurface of the entire continental United States,” said Stanford geophysics postdoctoral researcher Nori Nakata.

Using tiny ground tremors generated by the rumble of cars and trucks across highways, the activities within offices and homes, pedestrians crossing the street and even airplanes flying overhead, a team led by Nakata created detailed three-dimensional subsurface maps of the California port city of Long Beach.

The maps, detailed in a recent issue of the Journal of Geophysical Research, marks the first successful demonstration of an elusive Earth-imaging technique, called ambient noise body wave tomography. “It’s a technique that scientists have been trying to develop for more than 15 years,” said Nakata, who is the Thompson Postdoctoral Fellow at the School of Earth, Energy & Environmental Sciences.

The subsurface maps were created by applying a new signal processing technique to a particular type of seismic waves — energy waves that travel across the Earth’s surface and through its interior. Seismic waves can be generated naturally, during earthquakes and volcanic eruptions, for example, or by artificial means such as explosions.

There are two major types of seismic waves: surface waves and body waves. As their name suggests, surface waves travel along the surface of the Earth. Scientists have long been able to harness surface waves to study the upper layers of the planet’s crust, and recently they have even been able to extract surface waves from the so-called ambient seismic field. Also known as ambient noise, these are very weak but continuous seismic waves that are generated by colliding ocean waves, among other things.

Body waves, in contrast, travel through the Earth, and as a result can provide much better spatial resolution of the planet’s interior than surface waves. “Scientists have been performing body-wave tomography with signals from earthquakes and explosives for decades,” said study coauthor Jesse Lawrence, an assistant professor of geophysics at Stanford. “But you can’t control when and where an earthquake happens, and explosives are expensive and often damaging.”

For this reason, geophysicists have long sought to develop a way to perform body wave tomography without relying on earthquakes or resorting to explosives. This has proven challenging, however, because body waves have lower amplitudes than surface waves, and are therefore harder to observe.

“Usually you need to combine and average lots and lots of data to even see them,” Lawrence said.

In the new study, the Stanford team applied a new software processing technique, called a body-wave extraction filter. Nakata developed the filter to analyze ambient noise data gathered from a network of thousands of sensors that had been installed across Long Beach to monitor existing oil reservoirs beneath the city.

While experimenting with different types of filters for parsing and analyzing ambient noise, Nakata came up with an idea for a filter of his own that focused specifically on body waves. “When I saw the Long Beach data, I realized I had all of the pieces in my hand to isolate body- wave energy from ambient noise,” Nakata said. “I was excited, but at the same time I was skeptical my idea would work.”

The filter Nakata developed and then refined with help from his Stanford colleagues represents a new way of processing the ambient noise by comparing each observation to every other observation, which boosts the body-wave signal while reducing the noise.

Using its filter, the team was able to create maps that revealed details about the subsurface of Long Beach down to a depth of more than half a mile (1.1. kilometers). The body-wave maps were comparable to, and in some cases better than, existing imaging techniques.

One map, for example, clearly revealed the Newport-Inglewood fault, an active geological fault that cuts through Long Beach. This fault also shows up in surface-wave maps, but the spatial resolution of the body-wave velocity map was much higher, and revealed new information about the velocity of seismic waves traveling through the fault’s surrounding rocks, which in turn provides valuable clues about their composition and organization.

“This has been something of a holy grail in Earth imaging, and Nori’s work is a first-of-its-kind study,” said geophysicist Greg Beroza, the Wayne Loel Professor at Stanford, who was not involved in the study. “His groundbreaking achievement is sure to be widely emulated.”

Lawrence says the real power of the new technique will come when it is combined with surface wave tomography. “Primary waves, which are a type of body wave, are sensitive to compressional forces, whereas surface waves are more sensitive to shear, or sliding, forces,” Lawrence said. “To characterize the subsurface properly, one must measure both shear and compressional properties. Using one wave type and not the other is like trying to study a painting by looking at it through a frosted window.”

Now that ambient-noise body wave tomography has been shown to work, Nakata says he plans to apply his technique to much larger test areas.

Reference:
Nori Nakata, Jason P. Chang, Jesse F. Lawrence, Pierre Bou�. Body wave extraction and tomography at Long Beach, California, with ambient-noise interferometry. Journal of Geophysical Research: Solid Earth, 2015; 120 (2): 1159 DOI: 10.1002/2015JB011870

Note: The above story is based on materials provided by Stanford’s School of Earth, Energy & Environmental Sciences.

Little-known quake, tsunami hazards lurk offshore of Southern California

This map shows the California Borderland and its major tectonic features, as well as the locations of earthquakes greater than Magnitude 5.5. The dashed box shows the area of the new study. Large arrows show relative plate motion for the Pacific-North America fault boundary. The abbreviations stand for the following: BP = Banning Pass, CH = Chino Hills, CP = Cajon Pass, LA = Los Angeles, PS = Palm Springs, V = Ventura; ESC = Santa Cruz Basin; ESCBZ = East Santa Cruz Basin Fault Zone; SCI = Santa Catalina Island; SCL = San Clemente Island; SMB = Santa Monica Basin; SNI = San Nicolas Island. Credit: Mark Legg

While their attention may be inland on the San Andreas Fault, residents of coastal Southern California could be surprised by very large earthquakes — and even tsunamis — from several major faults that lie offshore, a new study finds.
The latest research into the little known, fault-riddled, undersea landscape off of Southern California and northern Baja California has revealed more worrisome details about a tectonic train wreck in the Earth’s crust with the potential for magnitude 7.9 to 8.0 earthquakes. The new study supports the likelihood that these vertical fault zones have displaced the seafloor in the past, which means they could send out tsunami-generating pulses towards the nearby coastal mega-city of Los Angeles and neighboring San Diego.

“We’re dealing with continental collision,” said geologist Mark Legg of Legg Geophysical in Huntington Beach, California, regarding the cause of the offshore danger. “That’s fundamental. That’s why we have this mess of a complicated logjam.”

Legg is the lead author of the new analysis accepted for publication in the Journal of Geophysical Research: Earth Surface, a journal of the American Geophysical Union. He is also one of a handful of geologists who have been trying for decades to piece together the complicated picture of what lies beyond Southern California’s famous beaches.

The logjam Legg referred to is composed of blocks of the Earth’s crust caught in the ongoing tectonic battle between the North American tectonic plate and the Pacific plate. The blocks are wedged together all the way from the San Andreas Fault on the east, to the edge of the continental shelf on the west, from 150 to 200 kilometers (90 to 125 miles) offshore. These chunks of crust get squeezed and rotated as the Pacific plate slides northwest, away from California, relative to the North American plate. The mostly underwater part of this region is called the California Continental Borderland, and includes the Channel Islands.

By combining older seafloor data and digital seismic data from earthquakes along with 4,500 kilometers (2,796 miles) of new seafloor depth measurements, or bathymetry, collected in 2010, Legg and his colleagues were able to take a closer look at the structure of two of the larger seafloor faults in the Borderland: the Santa Cruz-Catalina Ridge Fault and the Ferrelo Fault. What they were searching for are signs, like those seen along the San Andreas, that indicate how much the faults have slipped over time and whether some of that slippage caused some of the seafloor to thrust upwards.

What they found along the Santa Cruz-Catalina Ridge Fault are ridges, valleys and other clear signs that the fragmented, blocky crust has been lifted upward, while also slipping sideways like the plates along the San Andreas Fault do. Further out to sea, the Ferrelo Fault zone showed thrust faulting — which is an upwards movement of one side of the fault. The vertical movement means that blocks of crust are being compressed as well as sliding horizontally relative to each other-what Legg describes as “transpression.”

Compression comes from the blocks of the Borderland being dragged northwest, but then slamming into the roots of the Transverse Ranges — which are east-west running mountains north and west of Los Angeles. In fact, the logjam has helped build the Transverse Ranges, Legg explained.

“The Transverse Ranges rose quickly, like a mini Himalaya,” Legg said.

The real Himalaya arose from a tectonic-plate collision in which the crumpled crust on both sides piled up into fast-growing, steep mountains rather than getting pushed down into Earth’s mantle as happens at some plate boundaries.

As Southern California’s pile-up continues, the plate movements that build up seismic stress on the San Andreas are also putting stress on the long Santa Cruz-Catalina Ridge and Ferrelo Faults. And there is no reason to believe that those faults and others in the Borderlands can’t rupture in the same manner as the San Andreas, said Legg.

“Such large faults could even have the potential of a magnitude 8 quake,” said geologist Christopher Sorlien of the University of California at Santa Barbara, who is not a co-author on the new paper.

“This continental shelf off California is not like other continental shelves — like in the Eastern U.S.,” said Sorlien.

Whereas most continental shelves are about twice as wide and inactive, like that off the U.S. Atlantic coast, the California continental shelf is very narrow and is dominated by active faults and tectonics. In fact, it’s unlike most continental shelves in the world, he said. It’s also one of the least well mapped and understood. “It’s essentially terra incognita.”

“This is one of the only parts of the continental shelf of the 48 contiguous states that didn’t have complete … high-resolution bathymetry years ago,” Sorlien said.

And that’s why getting a better handle on the hazards posed by the Borderland’s undersea faults has been long in coming and slow to catch on, even among earth scientists, he said.

NOAA was working on complete high-resolution bathymetry of the U.S. Exclusive Economic Zone — the waters within 200 miles of shore — until the budget was cut, said Legg. That left out Southern California and left researchers like himself using whatever bits and pieces of smaller surveys to assemble a picture of what’s going on in the Borderland, he explained.

“We’ve got high resolution maps of the surface of Mars,” Legg said, “yet we still don’t have decent bathymetry for our own backyard.”

Reference:
Mark Legg, Monica D. Kohler, Natsumi Shintaku, Dayanthie Weeraratne. High-resolution mapping of two large-scale transpressional fault zones in the California Continental Borderland: Santa Cruz-Catalina Ridge and Ferrelo faults. Journal of Geophysical Research: Earth Surface, 2015; DOI: 10.1002/2014JF003322

Note: The above story is based on materials provided by American Geophysical Union.

Fossil ancestor shows sharks have a bony past

Professor John Long with the Gogo shark (Gogoselachus) fossil in 2005

Most people know that sharks have a distinctive, all-cartilage skeleton, but now a fossil from Western Australia has revealed a surprise ‘missing link’ to an earlier, more bony form of the fish.
Published today in the scientific journal PLOS One, research by Flinders University palaeontologist Professor John Long substantially strengthens the theory that the modern shark is less primitive than previously believed.

In testing fossil remains discovered by Professor Long in July 2005 at Gogo in the Kimberley in Western Australia, detailed CT scanning analysis has shown that the three-dimensional remnant skeleton contains a small proportion of bone as well as cartilage.

Professor Long said the fossil, which dates from the Devonian Period (380 million years old), reveals an ancient shark caught in evolutionary transition.

Because sharks and rays have entirely cartilaginous skeletons, Professor Long said it was traditionally thought that they were part of a primitive evolutionary pathway, and that bone in other fish was the more advanced condition.

But a series of discoveries in recent years has suggested that sharks are “more evolutionarily derived”, and are likely to be descended from bony ancestors.

“Our shark more or less nails that theory, because here we have a heavily mineralised type of cartilage in the skeleton, which contains remnant bone cells,” Professor Long said.

“It’s almost a missing link condition showing that early sharks had a lot more bone in their skeleton, and that just before modern sharks evolved they lost the bone, with only the soft cartilage remaining.”

Professor Long said the research indicates a direction in their evolution that shows that sharks to be much more specialised than previously thought.

The Gogo formation, which is the remains of a tropical reef now located far inland, has proved to be one of the most important sources of Devonian fossil fish in the world.

Professor Long said sharks are poorly known from the Devonian period, with research heavily reliant on fossil teeth. The rarity makes the Gogo shark all the more remarkable, Professor Long said.

“This is a partial articulated skeleton, with the jaws and shoulder and all the teeth and scales, but best of all, we have acid-etched the fossils out of the rock, so they are three-dimensional, uncrushed and perfect,” he said. “It’s the first time a shark of that age has been prepared in that manner.”

“This is a really interesting discovery,” said Professor Per Ahlberg, a palaeontologist at Uppsala University in Sweden, which was not involved in the study.

“The new Gogo shark shows what seems to be an early version of prismatic calcified cartilage: unlike the modern kind, the gaps between the prisms contain cells that resemble bone cells. This may help to explain the relationship between prismatic calcified cartilage and bone.”

The find also represented a breakthrough in that it was the first specimen of a shark discovered at the Gogo site in 60 years of investigation.

“It means that we can go back and find more sharks with continued collecting,” said Professor Long, who will head back to the site later this year.

Reference:
“First Shark from the Late Devonian (Frasnian) Gogo Formation, Western Australia Sheds New Light on the Development of Tessellated Calcified Cartilage.” PLoS ONE 10(5): e0126066. DOI: 10.1371/journal.pone.0126066

Note : The above story is based on materials provided by Flinders University.

Mammoths Reached the California Channel Islands Much Earlier Than Previously Thought

Skeleton of Columbian mammoth, Mammuthus columbi, in the George C. Page Museum at the La Brea Tar Pits, Los Angeles, California Credit: WolfmanSF, Wikipedia

Recently, U.S. Geological Survey researchers and partners working in California’s Channel Islands National Park discovered mammoth remains in uplifted marine deposits that date to about 80,000 years ago, confirming a long-held but never proven hypothesis that mammoths may have been on the Channel Islands long before the last glacial period 25,000 to 12,000 years ago.
“These are the first confidently dated fossils from the California Channel Islands showing that mammoths had been on the islands a long time, not just during the last glacial period,” said lead author and USGS research geologist Dan Muhs. “It supports an older hypothesis that mammoths could have swum from the mainland to the islands any time that conditions were favorable for such a journey, when sea level was low.”

This discovery on Santa Rosa Island, detailed in the online and print journal editions of Quaternary Research, shows that mammoths likely ventured to the islands during at least one earlier glacial period, when sea level was lower than present and the swimming distance from the mainland to the islands was minimal.

The older age of mammoths also challenges the hypothesis that climate change and sea level rise at the close of the last glacial period (about 12,000 years ago) were the causes of mammoth extinction on the Channel Islands. Earlier mammoth populations also would have had to contend with climate change and sea level rise, but apparently survived.

The newly discovered fossil mammoth remains are likely Mammuthus exilis, the pygmy mammoth. The Columbian mammoth immigrated to the islands from the California mainland by swimming and the pygmy mammoth evolved on the islands from this ancestral stock. Most mammoth remains previously reported on the Channel Islands date to the last glacial period, about 25,000 to 12,000 years ago.

Mammoths are iconic animals of the Pleistocene Ice Ages, both in North America and Eurasia. Fossil mammoths and other proboscideans (elephants and their relatives) have also been found on many islands of the Mediterranean.

Reference:
Daniel R. Muhsa, Kathleen R. Simmonsa, Lindsey T. Grovesb, John P. McGeehinc, R. Randall Schumanna, Larry D. Agenbroadd. Late Quaternary sea-level history and the antiquity of mammoths (Mammuthus exilis and Mammuthus columbi), Channel Islands National Park, California, USA. DOI:10.1016/j.yqres.2015.03.001

Note : The above story is based on materials provided by U.S. Geological Survey.

Dinosaurs were likely warm-blooded

A microscopic image of the thigh bone (femur) of a dinosaur shows concentric rings. Like tree rings, they formed each year in the dinosaur’s bones during the season when resources were scarce. The rings represent unrecorded time, so an annual growth rate (dashed line in graph) is an underestimate relative to the true growth rate during the favorable growing season. Credit: Scott Hartman

Dinosaurs grew as fast as your average living mammal, according to a research paper published by Stony Brook University paleontologist Michael D’Emic, PhD. The paper, to published in Science on May 29, is a re-analysis of a widely publicized 2014 Science paper on dinosaur metabolism and growth that concluded dinosaurs were neither ectothermic nor endothermic — terms popularly simplified as ‘cold-blooded’ and ‘warm-blooded’ — but instead occupied an intermediate category.
“The study that I re-analyzed was remarkable for its breadth — the authors compiled an unprecedented dataset on growth and metabolism from studies of hundreds of living animals,” said Dr. D’Emic, a Research Instructor in the Department of Anatomical Sciences as Stony Brook, when referring to “Evidence for mesothermy in dinosaurs.”

“Upon re-analysis, it was apparent that dinosaurs weren’t just somewhat like living mammals in their physiology — they fit right within our understanding of what it means to be a ‘warm-blooded’ mammal,” he said.

Dr. D’Emic specializes in bone microanatomy, or the study of the structure of bone on scales that are just a fraction of the width of a human hair. Based on his knowledge of how dinosaurs grew, Dr. D’Emic re-analyzed that study, which led him to the strikingly different conclusion that dinosaurs were more like mammals than reptiles in their growth and metabolism.

Dr. D’Emic re-analyzed the study from two aspects. First, the original study had scaled yearly growth rates to daily ones in order to standardize comparisons.

“This is problematic,” Dr. D’Emic explains, “because many animals do not grow continuously throughout the year, generally slowing or pausing growth during colder, drier, or otherwise more stressful seasons.

“Therefore, the previous study underestimated dinosaur growth rates by failing to account for their uneven growth. Like most animals, dinosaurs slowed or paused their growth annually, as shown by rings in their bones analogous to tree rings,” he explained.

He added that the growth rates were especially underestimated for larger animals and animals that live in very stressful or seasonal environments — both of which characterize dinosaurs.

The second aspect of the re-analysis with the original study takes into account that dinosaurs should be statistically analyzed within the same group as living birds, which are also warm-blooded, because birds are descendants of Mesozoic dinosaurs.

“Separating what we commonly think of as ‘dinosaurs’ from birds in a statistical analysis is generally inappropriate, because birds are dinosaurs — they’re just the dinosaurs that haven’t gone extinct.”

He explained that re-analyzing the data with birds as dinosaurs lends more support that dinosaurs were ‘warm-blooded,’ not occupants of a special, intermediate metabolic category.

According to Holly Woodward, Assistant Professor in the Center for Health Sciences at Oklahoma State University, Dr. D’Emic’s re-analysis is crucial to building research on the metabolism and development of dinosaurs.

“D’Emic’s study reveals how important access to the data behind published results is for hypothesis testing and advancing our understanding of dinosaur growth dynamics,” said Woodward.

Dr. D’Emic hopes that his study will also spur new research into when, why, and how pauses or slowdowns in growth are recorded in bones, which may have implications in the development of other species and in the study of bone diseases such as osteoporosis.

Video

References:

  1. M. D. D’Emic. Comment on “Evidence for mesothermy in dinosaurs”. Science, 2015 DOI: 10.1126/science.1260061
  2. J. M. Grady, B. J. Enquist, E. Dettweiler-Robinson, N. A. Wright, F. A. Smith. Evidence for mesothermy in dinosaurs. Science, 2014; 344 (6189): 1268 DOI: 10.1126/science.1253143

Note: The above story is based on materials provided by Stony Brook University.

Reconstruction of Arctic climate conditions in the Cretaceous period

Scientists at the Goethe University Frankfurt and at the Senckenberg Biodiversity and Climate Research Centre working together with their Canadian counterparts, have reconstructed the climatic development of the Arctic Ocean during the Cretaceous period, 145 to 66 million years ago. The research team comes to the conclusion that there was a severe cold snap during the geological age known for its extreme greenhouse climate. The study published in the professional journal Geology is also intended to help improve prognoses of future climate and environmental development and the assessment of human influence on climate change.

The Cretaceous, which occurred approximately 145 million to 66 million years ago, was one of the warmest periods in the history of Earth. The poles were devoid of ice and average temperatures of up to 35 degrees Celsius prevailed in the oceans. “A typical greenhouse climate; some even refer to it as a ‘super greenhouse’ ,” explains Professor Dr. Jens Herrle of the Goethe University and Senckenberg Biodiversity and Climate Research Centre, and adds: “We have now found indications in the Arctic that this warm era 112 to 118 million years ago was interrupted for a period of about 6 million years.”

In cooperation with his Canadian colleague Professor Claudia Schröder-Adams of the Carleton University in Ottawa, the Frankfurt palaeontologist sampled the Arctic Fjord Glacier and the Lost Hammer diapir locality on Axel Heiberg Island in 5 to 10 metre intervals. “In so doing, we also found so-called glendonites,” Herrle recounts. Glendonite refers to star-shaped calcite minerals, which have taken on the crystal shape of the mineral ikaite. “These so-called pseudomorphs from calcite to ikaite are formed because ikaite is stable only below 8 degrees Celsius and metamorphoses into calcite at warmer temperatures,” explains Herrle and adds: “Thus, our sedimentological analyses and age dating provide a concrete indication for the environmental conditions in the cretaceous Arctic and substantiate the assumption that there was an extended interruption of the interglacial period in the Arctic Ocean at that time.”

In two research expeditions to the Arctic undertaken in 2011 and 2014, Herrle brought 1700 rock samples back to Frankfurt, where he and his working group analysed them using geochemical and paleontological methods. But can the Cretaceous rocks from the polar region also help to get a better understanding of the current climate change? “Yes,” Herrle thinks, elaborating: “The polar regions are particularly sensitive to global climatic fluctuations. Looking into the geological past allows us to gain fundamental knowledge regarding the dynamics of climate change and oceanic circulation under extreme greenhouse conditions. To be capable of better assessing the current human-made climate change, we must, for example, understand what processes in an extreme greenhouse climate contribute significantly to climate change.” In the case of the Cretaceous cold snap, Herrle assumes that due to the opening of the Atlantic in conjunction with changes in oceanic circulation and marine productivity, more carbon was incorporated into the sediments. This resulted in a decrease in the carbon dioxide content in the atmosphere, which in turn produced global cooling.

The Frankfurt scientist’s newly acquired data from the Cretaceous period will now be correlated with results for this era derived from the Atlantic, “in order to achieve a more accurate stratigraphic classification of the Cretaceous period and to better understand the interrelationships between the polar regions and the subtropics,” is the outlook Herrle provides.

Reference:
J. O. Herrle, C. J. Schroder-Adams, W. Davis, A. T. Pugh, J. M. Galloway, J. Fath. Mid-Cretaceous High Arctic stratigraphy, climate, and Oceanic Anoxic Events. Geology, 2015; 43 (5): 403 DOI: 10.1130/G36439.1

Note: The above story is based on materials provided by Goethe-Universität Frankfurt am Main.

New study: Iceberg influx into Atlantic during ice age raised tropical methane emissions

Antarctica. Credit: Andrew Thurber, Oregon State University

A new study shows how huge influxes of fresh water into the North Atlantic Ocean from icebergs calving off North America during the last ice age had an unexpected effect – they increased the production of methane in the tropical wetlands.

 

Usually increases in methane levels are linked to warming in the Northern Hemisphere, but scientists who are publishing their findings this week in the journal Science have identified rapid increases in methane during particularly cold intervals during the last ice age.

These findings are important, researchers say, because they identify a critical piece of evidence for how the Earth responds to changes in climate.

“Essentially what happened was that the cold water influx altered the rainfall patterns at the middle of the globe,” said Rachael Rhodes, a research associate in the College of Earth, Ocean, and Atmospheric Sciences at Oregon State University and lead author on the study, which was funded by the National Science Foundation. “The band of tropical rainfall, which includes the monsoons, shifts to the north and south through the year.

“Our data suggest that when the icebergs entered the North Atlantic causing exceptional cooling, the rainfall belt was condensed into the Southern Hemisphere, causing tropical wetland expansion and abrupt spikes in atmospheric methane,” she added.

During the last ice age, much of North America was covered by a giant ice sheet that many scientists believe underwent several catastrophic collapses, causing huge icebergs to enter the North Atlantic – phenomena known as Heinrich events. And though they have known about them for some time, it hasn’t been clear just when they took place and how long they lasted.

Rhodes and her colleagues examined evidence from the highly detailed West Antarctic Ice Sheet Divide ice core (http://www.waisdivide.unh.edu). They used a new analytical method perfected in collaboration with Joe McConnell at the Desert Research Institute in Reno, Nevada, to make extremely detailed measurements of the air trapped in the ice.

“Using this new method, we were able to develop a nearly 60,000-year, ultra-high-resolution record of methane much more efficiently and inexpensively than in past ice core studies, while simultaneously measuring a broad range of other chemical parameters on the same small sample of ice,” McConnell noted.

Utilizing the high resolution of the measurements, the team was able to detect methane fingerprints from the Southern Hemisphere that don’t match temperature records from Greenland ice cores.

“The cooling caused by the iceberg influx was regional but the impact on climate was much broader,” said Edward Brook, an internationally recognized paleoclimatologist from Oregon State University and co-author on the study. “The iceberg surges push the rain belts, or the tropical climate system, to the south and the impact on climate can be rather significant.”

Concentrating monsoon seasons into a smaller geographic area “intensifies the rainfall and lengthens the wet season,” Rhodes said.

“It is a great example of how inter-connected things are when it comes to climate,” she pointed out. “This shows the link between polar areas and the tropics, and these changes can happen very rapidly. Climate models suggest only a decade passed between the iceberg intrusion and a resulting impact in the tropics.”

Reference:
Enhanced tropical methane production in response to iceberg discharge in the North Atlantic, DOI: 10.1126/science.1262005

Note : The above story is based on materials provided by Oregon State University.

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