Home Blog Page 194

Decline of crocodile ancestors was good news for early marine turtles

Decline of crocodile ancestors-GeologyPage

Marine turtles experienced an evolutionary windfall thanks to a mass extinction of crocodyliforms around 145 million years ago, say researchers.

Crocodyliforms comprise modern crocodiles and alligators and their ancient ancestors, which were major predators that thrived on Earth millions of years ago. They evolved into a variety of species including smaller ones that lived on land through to mega-sized sea-swimming species that were up to 12 metres long. However, around 145 million years ago crocodyliforms, along with many other species, experienced a severe decline – an extinction event during a period between two epochs known as the Jurassic/Cretaceous boundary.

Now a PhD student and his colleagues from Imperial College London and University College London have carried out an extensive analysis of 200 species of crocodyliforms from a fossil database. One of the findings of the study is that the timing of the extinction coincided with the origin of modern marine turtles. The team suggest that the ecological pressure may have been lifted from early marine turtle ancestors due to the extinction of many marine crocodyliforms, which were one of their primary predators.

Jon Tennant, lead author of the study from the Department of Earth Science and Engineering at Imperial, said: “This major extinction of crocodyliforms was literally a case of out with the old and in with the new for many species. Marine turtles, the gentle, graceful creatures of the sea, may have been one of the major winners from this changing of the old guard. They began to thrive in oceans around the world when their ferocious arch-predators went into terminal decline.”

In the study, published today in the journal Proceedings of the Royal Society B, the researchers point to evidence in the records of a dramatic extinction of crocodyliforms during the Jurassic/Cretaceous boundary. Up to 80 per cent of species on land and in marine environments were wiped out. This decline was primarily due to a drop in sea levels, which led to a closing off of shallow marine environments such as lagoons and coastal swamps. These were the homes and primary hunting grounds for many crocodyliforms.

The decimation of many marine crocodyliforms may also have laid the way for their ecological replacement by other large predatory groups such as modern shark species and new types of plesiosaurs. Plesiosaurs were long-necked, fat-bodied and small-headed ocean-going creatures with fins, which later went extinct around 66 million years ago.

Other factors that contributed to the decline of marine crocodyliforms included a change in the chemistry of ocean water with increased sulphur toxicity and a depletion of oxygen.

While primitive crocodyliform species on land also suffered major declines, the remaining species diversified into new groups such as the now extinct notosuchians, which were much smaller in size at around 1.5 metres in length. Eusuchians also came to prominence after the extinction, which led to today’s crocodiles.

To carry out the study on crocodyliforms the team used the Paleobiology Database, which is a professionally curated digital archive of all known fossil records. The team analysed almost 1,200 crocodyliform fossil records.

Scientists have known since the early 1970s about the Jurassic/Cretaceous boundary extinction from fossil records. However, researchers have focussed on other extinction events and as a consequence less has been done to understand in detail the effects of Jurassic/Cretaceous boundary extinction on species like crocodyliforms.

The next steps will see the analysis extended to other groups including dinosaurs, amphibians and mammals to learn more about the effects of the Jurassic/Cretaceous boundary on their biodiversity.

Reference:
Environmental drivers of crocodyliform extinction across the Jurassic/Cretaceous transition, Proceedings of the Royal Society B: Biological Sciences, DOI: 10.1098/rspb.2015.2840

Note: The above post is reprinted from materials provided by Imperial College London.

Geochemists show experimental verification of principle of detailed balance

Geochemists show experimental-GeologyPage
Comparison of the equilibrium dissolution and precipitation rates determined using 29Si isotope doping (Type 1 Experiment) with the far from equilibrium dissolution rate (Type 2 Experiment). The vertical arrow points to the average value for each set of experiments and the horizontal arrows indicate two standard deviations of the data.

Geochemists at Indiana University and Virginia Tech have developed and demonstrated a technique for assessing the validity of a principle that has long been important in thermodynamics and chemical kinetics but has proven resistant to experimental verification.

Called the principle of detailed balance, the concept is widely used in models to ensure the long-term safety of environmental projects such as storage sites for nuclear waste and for carbon dioxide.

“Even though this principle is the cornerstone of a great deal of chemistry and quantum mechanics, it is difficult to demonstrate,” said Chen Zhu, professor of geological sciences in the College of Arts and Sciences and an author of the study. “We have assumed that it works in many situations without experimental verification.”

The study, “A stable isotope doping method to test the range of applicability of detailed balance,” was published in Geochemical Perspectives Letters, a publication of the European Association of Geochemists. Co-authors are IU postdoctoral researcher Zhaoyun Liu and doctoral student Yilun Zhang; J. Donald Rimstidt of Virginia Tech; and Honglin Yuan of Northwest University in Xian, China.

The principle of detailed balance says that when a system is in a state of equilibrium, each process or reaction will be balanced by a reverse process or reaction occurring at the same rate. For example, if a solid is in equilibrium with a solution, it will precipitate back to solid form at the same rate that it dissolves.

The principle was introduced in the late 1800s and early 1900s, and it became a foundation for modern chemical kinetics. But demonstrating the rate of reverse processes is difficult, Rimstidt said, and experimental tests of the principle’s applicability are rare in the scientific literature.

Zhu and his colleagues take advantage of recent developments in analytical technology called MC-ICP-MS, for multiple collector-inductively coupled plasma-mass spectrometry. They created a novel experiment in which quartz, a mineral composed largely of a common isotope of silicon, was reacted with a solution that contained high concentrations of a stable but rare isotope of silicon.

By measuring the relative concentrations of the two isotopes in the solution over time, they were able to establish rates of dissolution and precipitation. The results showed that these rates were essentially the same at equilibrium, confirming that the principle of detailed balance was applicable.

And the principle matters, Zhu said, for a number of reasons. For example, it is used in models that predict the long-term performance of underground nuclear waste disposal projects and the movement of plumes of carbon dioxide captured from power-generation plants and stored underground or undersea. To meet safety requirements, such models must accurately predict what will happen over more than 10,000 years as geological conditions shift over time.

Verification of the principle of detailed balance in an experiment with quartz is significant, Rimstidt said, because quartz makes up about 20 percent of the Earth’s continental crust. He said the method can and should be used for additional investigations to confirm the principle’s applicability with other minerals using different isotopes.

Reference:
Z. Liu, J.D. Rimstidt, Y. Zhang, H. Yuan, C. Zhu. A stable isotope doping method to test the range of applicability of detailed balance. DOI: 10.7185/geochemlet.1608

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

Faults control the amount of water flowing into the Earth during continental breakup

Faults control the amount of-GeologyPage
Ocean Bottom Seismometer on the F/S Poseidon.

New light has been shed on the processes by which ocean water enters the solid Earth during continental breakup.

Research led by geoscientists at the University of Southampton, and published in Nature Geoscience this week, is the first to show a direct link on geological timescales between fault activity and the amount of water entering the Earth’s mantle along faults.

When water and carbon is transferred from the ocean to the mantle it reacts with a dry rock called peridotite, which makes up most of the mantle beneath the crust, to form serpentinite.

Dr Gaye Bayrakci, Research Fellow in Geophysics, and Professor Tim Minshull, from Ocean and Earth Science, with colleagues at the University of Southampton and six other institutions, measured the amount of water that had entered the Earth by using sound waves to map the distribution of serpentinite.

The sound waves travel through the crust and mantle and can be detected by sensitive instruments placed on the ocean floor. The time taken for the signals to travel from an acoustic seismic source to the seafloor instruments reveals how fast sound travels in the rocks, and the amount of serpentinite present can be determined from this speed.

The four-month experiment, which involved two research ships (the R/V Marcus Langseth and the F/S Poseidon), mapped an 80 by 20 km area of seafloor west of Spain called the Deep Galicia Margin where the fault structures were formed when North America broke away from Europe about 120 million years ago.

The results showed that the amount of serpentinite formed at the bottom of each fault was directly proportional to the displacement on that fault, which in turn is closely related to the duration of fault activity.

Dr Bayracki said: “One of the aims of our survey was to explore the relationship between the faults, which we knew already were there, and the presence of serpentinite, which we also knew was there but knew little about its distribution. The link between fault activity and formation of serpentinite was something we might have hoped for but did not really expect to see so clearly.

“This implies that seawater reaches the mantle only when the faults are active and that brittle processes in the crust may ultimately control the global amount of seawater entering the solid Earth.”

In other tectonic settings where serpentinite is present such as mid ocean ridges and subduction zones, the focused flow of seawater along faults provides a setting for diverse hydrothermal ecosystems where life-forms live off the chemicals stripped out of the rocks by the water as it flows into and then out of the Earth’s mantle.

The researchers were able to estimate the average rate at which seawater entered the mantle through the faults at the Deep Galicia Margin and discovered that rate was comparable to those estimated for water circulation in hot rock at mid-ocean ridges, where such life-forms are more common. These results suggest that in continental rifting environment there may have been hydrothermal systems, which are known to support diverse ecosystems.

Co-Author and Professor of Geology at the University of Birmingham Tim Reston commented: “Understanding the transport of water during deformation has broad implications, ranging from hydrothermal systems to earthquake mechanics. The new results suggest a more direct link between faulting and water movements than we previously suspected.”

Reference:
G. Bayrakci, T. A. Minshull, D. S. Sawyer, T. J. Reston, D. Klaeschen, C. Papenberg, C. Ranero, J. M. Bull, R. G. Davy, D. J. Shillington, M. Perez-Gussinye, J. K. Morgan. Fault-controlled hydration of the upper mantle during continental rifting. Nature Geoscience, 2016; DOI: 10.1038/ngeo2671

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

Leaf mysteries revealed through the computer’s eye

Leaf mysteries revealed-GeologyPage
This is an image of leaves in the Rosaceae family that is made up of herbs, shrubs and trees including rose, peach, strawberry, plums, cherries, apricots and others. These cleared leaves have “heat mapping” by the computer vision system that shows leaf attributes important to characterization and classification of the leaves into the Rosaceae family. Depth of color indicates importance of attributes. The heat map shows that many locations on the leaf edges are important as are many large vein intersections. Credit: Shengping Zhang

A computer program that learns and can categorize leaves into large evolutionary categories such as plant families will lead to greatly improved fossil identification and a better understanding of flowering plant evolution, according to an international team of researchers.

“Paleobotanists have collected many millions of fossil leaves and placed them in the world’s museums,” said Peter Wilf, professor of geosciences, Penn State. “They represent one of the most underused resources for understanding plant evolution. Variation in leaf shape and venation, whether living or fossil, is far too complex for conventional botanical terminology to capture. Computers, on the other hand, have no such limitation.”

When botanists identify modern plants, they look at the leaves, but rely mostly on the associated fruits, seeds and flowers to categorize the specimens. In fossil collections, fruits, seeds and flowers are usually much less common than leaves. Even with modern leaves it is a slow process figuring out which features are botanically informative. If a computer vision approach works on modern leaves, it could help in the classification of fossil leaves as well.

“Leaf characterization builds on an 1800’s system of description that we call leaf architecture,” said Wilf. “It looks at leaf teeth, margins, lobes, and venation patterns and uses specialized terminology to describe them. For the most part, this procedure tells us how to describe a leaf, not how to identify one and place it on the tree of life. Cracking the leaf code and accessing the evolutionary information in leaf architecture is the central problem I feel I must try to solve in my career as a paleobotanist.”

About nine years ago, Wilf learned of an article in the Proceedings of the National Academy of Sciences on a computer vision program that could determine whether or not an animal was in a photograph.

“A bell rang in my head,” said Wilf. “Instead of an animal, tell me if the image is of an oak leaf or not, or pick among several categories.”

He contacted Thomas Serre, now Manning Assistant Professor of Cognitive, Linguistic and psychological science, Brown University, who, as a graduate student at the Massachusetts Institute of Technology, was lead author of that work. The method worked well right off the bat, and after nine years of development and experiments using different vision algorithms, the team published their first paper from this work, also in the Proceedings of the National Academy of Sciences.

More than two of those years were required for a Penn State undergraduate team to vet and prepare the final dataset of more than 7500 images of cleared leaves, which are specimens that have been chemically bleached, stained and mounted on slides to reveal venation patterns. The largest collection they used is in the Smithsonian Institution’s National Museum of Natural History.

“The success of our computer vision approach suggests that this may be one of those tasks that are comparatively easier for computers because of computers’ ability to process and analyze large numbers of specimens, to discover novel visual features that may have phylogenetic significance,” said Serre.

The researchers currently have a 72 percent accuracy rate over 19 leaf families compared to about 5 percent for random chance. This project is not the first to computerize leaf identification. A popular app, Leafsnap: An Electronic Field Guide, matches the shape of an unknown leaf from a particular region and identifies it down to the species level. However, this current work is the first to analyze cleared leaves or leaf venation for thousands of species from around the world, to learn the traits of evolutionary groups above the species level such as plant families, or to directly visualize informative new characteristics. The variation among the hundreds to thousands of species in a family is many times greater than within a species, and yet, the computer algorithms could learn a set of features and apply it successfully. Because nearly all leaf fossils are of extinct species, family-level identification is usually the first target for paleobotanists.

“This approach is a key distinction between what we call image processing, where literally a computer expert programs a computer to see, as opposed to machine learning and computer vision, where the machine is not programmed to exhibit a particular behavior but rather it learns from examples,” said Serre. “Here, our examples were leaf images together with category labels corresponding to family and order.”

The researchers provide the computer program with half the photos already identified so that it can automatically learn a dictionary of special features such as vein intersections and tiny bumps and asymmetries that turn out to matter quite a bit in identifying leaves. The system also learns to disregard the typical problems of low image quality, insect bites and mounting defects. Then the algorithm receives unlabeled test photos and uses its dictionary to identify them. The researchers repeated this procedure 10 times, randomly choosing the training and test images. The results agreed with only 1 percent difference between the runs.

“It normally takes a trained person a few hours to describe one leaf according to the standard protocol, which uses about fifty terms, ” said Wilf. “The computer program is thousands of times faster, automatically generates a dictionary of more than 1,000 elements and then actually shows us what parts of the leaf are diagnostic.”

Instead of producing only a black box of results, the computer generates a “heat” map directly on the leaf image, identifying and rating areas of importance for correct identification. This approach generates a flood of previously hidden botanical information.

Wilf notes that leaf teeth in the rose family have always been considered distinctive, but the heat maps highlight previously unknown features of their tips. Leaves of the coffee family, with 13,000 living species, are very hard to identify when not attached to twigs, but the computer program found it one of the least problematic at 90 percent accuracy.

The ability of computer vision to classify leaves quickly and to generate vast quantities of new botanical knowledge will allow scientists to develop more accurate evolutionary pedigrees for plants and plant fossils.

Reference:
Peter Wilf, Shengping Zhang, Sharat Chikkerur, Stefan A. Little, Scott L. Wing, and Thomas Serre. Computer vision cracks the leaf code. PNAS, March 2016 DOI: 10.1073/pnas.1524473113

Note: The above post is reprinted from materials provided by Penn State. The original item was written by A’ndrea Elyse Messer.

Unlocking the secrets of Shark Bay’s stromatolites

Unlocking the secrets-GeologyPage
Dr Suosaari and her colleagues carried out their research by collecting samples from 45 stromatolites for microscopic and molecular analyses to work out how Shark Bay stromatolites formed. Credit: julie

Look at the world-renowned stromatolites protruding from saline seas at Hamelin Pool in Shark Bay and you could be forgiven for wondering what all the fuss is about.

They appear as strange-shaped columns of rock—a mere oddity. Yet this mundane appearance belies a fascinating structure whose fossilised remains hold records to the earliest life on Earth.

They not only provide a picture into life billions of years ago, the microbes which created them generated the oxygen that went on to help make the planet habitable to human life.

Despite their importance to our very existence, and many years of research, much about stromatolites remains disputed.

But Bush Heritage science development fellow Erica Suosaari is determined to unlock more of their secrets via research which has transformed the way we understand the modern stromatolites at Shark Bay.

By conducting such research, Dr Suosaari has categorised the stromatolites into different morphological types—some never before recorded—and mapped them into eight distinct provinces.

Understanding how the local environment affects stromatolite morphology will help scientists interpret the ancient stromatolite structures so prevalent throughout the rock record, Dr Suosaari says.

“It has been argued that modern stromatolites cannot be compared to ancient stromatolites because of the grainy internal fabrics, built primarily by cyanobacterial trapping and binding of sediment grains, whereas ancient structures are typically comprised of frameworks of microbially induced cements,” she says.

“But intense analyses of internal fabrics from Hamelin Pool stromatolites have uncovered mineral precipitation as a key constructional component, a feature shared with Precambrian (600+ million years ago) stromatolites that date back three billion years.”

Furthermore, the research determined the stromatolite-building microbial mats of Hamelin Pool are dominated by Entophysalis, with lineage to an ancient microbe Eoentophysalis, that had a hand in building stromatolites billions of years ago.

Dr Suosaari and her colleagues carried out their research by collecting samples from 45 stromatolites for microscopic and molecular analyses to work out how Shark Bay stromatolites formed.

Additionally, in collaboration with NASA Ames, they collected and analysed aerial images of the stromatolites captured via a drone.

The images were created using a specially adapted technology which provided pictures of stromatolites in extreme detail, without interference by water movement.

Dr Suosaari’s work demonstrates that modern day stromatolites are a truly fascinating window to ancient Precambrian times.

Note: The above post is reprinted from materials provided by Science Network WA.

Leicester City fans caused ‘earthquake’ after last minute winner

Leicester City fans caused --GeologyPage

Leicester City Football Club has been making a big impact on the Premier League this season, and their success is sending shockwaves, quite literally, through the city of Leicester.

Geology students at the University of Leicester have been monitoring large seismic signals detected by earthquake monitoring equipment installed at Hazel Community Primary School near the King Power Stadium.

The students discovered that the equipment was actually measuring small earthquakes produced by the sudden energy release by the elated Leicester fans when their team scored a goal at home matches.

Richard Hoyle, a first year student from Leeds studying geological science at the University of Leicester said: “A few days after we installed the equipment at the school and were analysing data collected, we noticed large peaks on the seismogram during football matches being held in the LCFC stadium nearby.

“A closer look showed us there was a strong correlation between the exact time Leicester scored at home and the occurrence of the large seismic signals. We concluded that our equipment was actually measuring small earthquakes produced by the sudden energy release by the cheering Leicester fans celebrating at the moment a goal was scored.”

Working with Paul Denton, a seismologist working for the British Geological Survey, the project, involving 20 students studying Geology and Geophysics at the University of Leicester, started off as an outreach project.

The students installed earthquake monitoring equipment at Hazel Community Primary School enabling them to detect, record and calculate the magnitudes of seismic signals coming from earthquakes around the world.

The equipment works in unison with a similar system in the basement of the University’s Department of Geology Bennett Building and another recently installed set in the New Walk Museum.

By measuring small earthquakes using this equipment, the students are then able to calibrate the calculation for the Leicester-goal-quakes.

During the match between Leicester and West Bromwich Albion on Tuesday 1 March, the equipment detected strong seismic signals during the first half when Leicester scored a goal which measured a magnitude 0.1. A much smaller signal was detected when the opposition scored – probably due to the smaller visiting crowds for an away game.

Richard said of the game against Norwich: “Our biggest signal detected so far came last Saturday (27 February) when Leicester scored the only goal in the match in the 89th minute and this registered a magnitude 0.3 -clearly the fans were very tense!

“This project gives us a fantastic opportunity to conduct a novel investigation for the remainder of the football season while also further engaging the school children while their home team is doing so well in the football tables.

“Besides naturally occurring earthquakes, we are now curious to discover which Leicester City footballer will generate the biggest seismic signal. Our money is on Vardy.”

Dr Stewart Fishwick, Senior Lecturer in Geophysics, University’s Department of Geology, said: “Having our equipment installed within the local primary school has given our students an excellent opportunity to engage with young minds and inspire them to take an interest in practical applications of Earth Sciences.

“Several of the students in our group are due to hold demonstration classes with years 5 & 6 to give them a better understanding of earthquakes and the way seismic waves move through the earth.”

Gillian Blatherwick, Head Teacher at Hazel Community Primary School, said: “We’re delighted at the opportunity for pupils to work with students from the University of Leicester as this is a fantastic opportunity for Hazel pupils to be inspired by first-hand experience of practical science in a real life context.”

The most powerful signal so far detected was produced during the LCFC Vs Norwich game when LCFC scored the only goal of the match at the 90th minute, winning them the game.


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

Scientists uncover history of ancient viruses as far back as 30 million years ago

Scientists uncover history of-GeologyPage
Representative image: Two rotaviruses: the one on the right is coated with antibodies that stop its attaching to cells and infecting them Credit: GrahamColm / Wikipedia

Researchers from Boston College, US, have revealed the global spread of an ancient group of retroviruses that affected about 28 of 50 modern mammals’ ancestors some 15 to 30 million years ago.

Retroviruses are abundant in nature and include human immunodeficiency viruses (HIV-1 and -2) and human T-cell leukemia viruses. The scientists’ findings on a specific group of these viruses called ERV-Fc, to be published in the journal eLife, show that they affected a wide range of hosts, including species as diverse as carnivores, rodents, and primates.

The distribution of ERV-Fc among these ancient mammals suggests the viruses spread to every continent except Antarctica and Australia, and that they jumped from one species to another more than 20 times.

The study also places the origins of ERV-Fc at least as far back as the beginning of the Oligocene epoch, a period of dramatic global change marked partly by climatic cooling that led to the Ice Ages. Vast expanses of grasslands emerged around this time, along with large mammals as the world’s predominate fauna.

“Viruses have been with us for billions of years, and exist everywhere that life is found. They therefore have a significant impact on the ecology and evolution of all organisms, from bacteria to humans,” says co-author Welkin Johnson, Professor of Biology at Boston College where his team carried out the research.

“Unfortunately, viruses do not leave fossils behind, meaning we know very little about how they originate and evolve. Over the course of millions of years, however, viral genetic sequences accumulate in the DNA genomes of living organisms, including humans, and can serve as molecular ‘fossils’ for exploring the natural history of viruses and their hosts.”

Using such “fossil” remnants, the team sought to uncover the natural history of ERV-Fc. They were especially curious to know where and when these pathogens were found in the ancient world, which species they infected, and how they adapted to their mammalian hosts.

To do this, they first performed an exhaustive search of mammalian genome sequence databases for ERV-Fc loci and then compared the recovered sequences. For each genome with sufficient ERV-Fc sequence, they reconstructed the sequences of proteins representing the virus that colonized the ancestors of that particular species. These sequences were then used to infer the natural history and evolutionary relationships of ERV-Fc-related viruses.

The studies also allowed the team to pinpoint patterns of evolutionary change in the genes of these viruses, reflecting their adaptation to different kinds of mammalian hosts.

Perhaps most interestingly, the researchers found that these viruses often exchanged genes with each other and with other viruses, suggesting that genetic recombination played a significant role in their evolutionary success.

“Mammalian genomes contain hundreds of thousands of ancient viral fossils similar to ERV-Fc,” says lead author William E. Diehl from the University of Massachusetts, who conducted the study while a post-doctoral researcher at Boston College.

“The challenge will now be to use ancient viral sequences for looking back in time, which may prove insightful for predicting the long-term consequences of newly emerging viral infections. For example, we could potentially assess the impact of HIV on human health 30 million years from now. The method will allow us to better understand when and why new viruses emerge and how long-term contact with them impacts the evolution of host organisms.”

Reference:
William E Diehl, Nirali Patel, Kate Halm, Welkin E Johnson. Tracking interspecies transmission and long-term evolution of an ancient retrovirus using the genomes of modern mammals. DOI: 10.7554/eLife.12704

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

How rivers of hot ash and gas move when a supervolcano erupts

How rivers of hot ash and-GeologyPage
Photographs scanned from Kodachrome slides show dark rocks embedded in layers of ash. The rocks were picked up and moved across the landscape by pyroclastic flows when the Silver Creek caldera, a supervolcano, erupted 18.8 million years ago. Credit: Greg A. Valentine

Supervolcanoes capable of unleashing hundreds of times the amount of magma that was expelled during the Mount St. Helens eruption of 1980 are found in populated areas around the world, including the western United States.

A new study is providing insight into what may happen when one of these colossal entities explodes.

The research focuses on the Silver Creek caldera, which sits at the intersection of California, Nevada and Arizona. When this supervolcano erupted 18.8 million years ago, it flooded parts of all three states with river-like currents of hot ash and gas called pyroclastic flows. These tides of volcanic material traveled for huge distances—more than 100 miles.

The new study suggests that pyroclastic flows from the ancient eruption took the form of slow, dense currents—and not fast-moving jets as some experts previously thought.

The research combines recent laboratory experiments with field data from the 1980s—some of it captured in colorful Kodachrome slides—to show that the rivers of ash and gas emanating from the Silver Creek caldera likely traveled at modest speeds of about 10 to 45 miles per hour.

“Intuitively, most of us would think that for the pyroclastic flow to go such an extreme distance, it would have to start off with a very high speed,” says study co-author Olivier Roche. “But this isn’t consistent with what we found.”

The research was conducted by Roche at Blaise Pascal University in France, David C. Buesch at the United States Geological Survey and Greg A. Valentine at the University at Buffalo. It will be published on Monday, March 7 in Nature Communications, and all information in this press release is embargoed until 5 a.m. U.S. Eastern Standard Time on that date.

Research on pyroclastic flows is important because it can help inform disaster preparedness efforts, says Valentine, a UB professor of geology and director of the Center for GeoHazards Studies in the UB College of Arts and Sciences.

“We want to understand these pyroclastic flows so we can do a good job of forecasting the behavior of these flows when a volcano erupts,” he says. “The character and speed of the flows will affect how much time you might have to get out of the way, although the only truly safe thing to do is to evacuate before a flow starts.”

New and vintage data come together to tell the story of a supervolcano

The new study favors one of two competing theories about how pyroclastic flows are able to cover long distances. One school of thought says the flows should resemble turbulent, hot, fast-moving sandstorms, made up mostly of gas, with few particles. The other theory states that the flows should be dense and fluid-like, with pressurized gas between ash particles. The new research supports this latter model, which requires sustained emissions from volcanoes, for many pyroclastic flows.

The findings were based on two sets of data: results from recent experiments that Roche ran to simulate the behavior of pyroclastic flows, and information that Buesch and Valentine gathered at the Silver Creek Caldera eruption site in the 1980s when they were PhD students at the University of California, Santa Barbara, supplemented by some more recent fieldwork.

“I always tell students that they should take good notes while they’re working in the field, because you never know when it could be useful,” says Valentine, who has a fat binder full of Kodachrome slides showing images he snapped around the Silver Creek caldera.

The data that he and Buesch collected included photographs and notes documenting the size, type and location of rocks that were lifted off the ground and moved short distances by pyroclastic flows during the ancient eruption.

Many of the rocks the pair observed were relatively large—too large to have been shifted by sandstorm-like pyroclastic flows, which do not pick up heavy objects easily. Denser flows, which can move sizable rocks more readily, likely accounted for the rock patterns Buesch and Valentine observed.

To figure out how fast these dense flows may have been moving when the Silver Creek caldera erupted 18.8 million years ago, the team relied on a model developed by Roche through experiments.

In his tests, Roche studied what happened when a gas and particle mixture resembling a dense pyroclastic flow traveled across a substrate of beads. He found that faster flows were able to lift and move heavier beads, and that there was a relationship between the velocity of a flow and the weight of the bead it was capable of lifting.

Based on Roche’s model, the scientists determined that the ancient pyroclastic flows from the supervolcano would have had to travel at speeds of about 5 to 20 meters per second (10 to 45 miles per hour) to pick up rocks as heavy as the ones that Buesch and Valentine saw. It’s unlikely that the flows were going much faster than that because larger rocks on the landscape remained undisturbed, Valentine says.

The findings could have widespread applicability when it comes to supereruptions, says Valentine, who notes that patterns of rock deposits around some other supervolcanoes heavily resemble those around the Silver Creek caldera.

Reference:
O. Roche et al. Slow-moving and far-travelled dense pyroclastic flows during the Peach Spring super-eruption, Nature Communications (2016). DOI: 10.1038/ncomms10890

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

World’s oldest chameleon found in amber fossil

World’s oldest chameleon-GeologyPage
Credit: Courtesy of David Grimaldi, additional photos by Kristen Grace, Florida Museum of Natural History

About 100 million years ago an infant lizard’s life was cut short when it crawled into a sticky situation.

The early chameleon was creeping through the ancient tropics of present-day Myanmar when it succumbed to the resin of a coniferous tree. Over time, the resin fossilized into amber, leaving the lizard remarkably preserved. Seventy-eight million years older than the previous oldest specimen on record, the dime-size chameleon along with 11 more ancient fossil lizards were pulled, encased in amber, from a mine decades ago, but it wasn’t until recently that scientists had the opportunity to analyze them.

In Jurassic Park, fictional scientists cloned dinosaurs with blood extracted from amber, but these real-life fossils hold snapshots of “missing links” in the evolutionary history of lizards that will allow scientists to gain a better understanding of where they fit on the tree of life, said Edward Stanley, a University of Florida postdoctoral student in herpetology at the Florida Museum of Natural History.

Of the 12 lizard specimens, three—a gecko, an archaic lizard and the chameleon—were particularly well-preserved. The new species will be named and described in a future study.

“These fossils tell us a lot about the extraordinary, but previously unknown diversity of lizards in ancient tropical forests,” said Stanley, co-author of a new study appearing online today in the journal Science Advances. “The fossil record is sparse because the delicate skin and fragile bones of small lizards do not usually preserve, especially in the tropics, which makes the new amber fossils an incredibly rare and unique window into a critical period of diversification.”

Stanley first encountered the amber fossils at the American Museum of Natural History after a private collector donated them. He knew the fossils were ancient, but it was a combination of luck and micro-CT technology that allowed him to identify the oldest chameleon.

“It was mind-blowing,” he said, to see the fossils for the first time. “Usually we have a foot or other small part preserved in amber, but these are whole specimens—claws, toepads, teeth, even perfectly intact colored scales. I was familiar with CT technology, so I realized this was an opportunity to look more closely and put the lizards into evolutionary perspective.”

A micro-CT scanner looked inside the amber without damaging the fossils, allowing study researchers to digitally piece together tiny bones and examine soft tissue. Scanned images of the detailed preservation provided insight into the anatomy and ecology of ancient lizards, Stanley said.

The amber gecko, for example, confirms the group already had highly advanced adhesive toe pads used for climbing, suggesting this adaptation originated earlier. As for the Southeast Asian chameleon, the find significantly pushes back the origins of the group and challenges long-held views that chameleons got their start in Africa. Stanley said it also reveals the evolutionary order of chameleons’ strange and highly derived features. The amber-trapped lizard has the iconic projectile tongue of modern chameleons, but had not yet developed the unique body shape and fused toes specially adapted for gripping that we see today.

Stanley said the fact that these incredibly ancient lizards have modern counterparts living today in the Old World tropics speaks to the stability of tropical forests.

“These exquisitely preserved examples of past diversity show us why we should be protecting these areas where their modern relatives live today,” Stanley said. “The tropics often act as a stable refuge where biodiversity tends to accumulate, while other places are more variable in terms of climate and species. However, the tropics are not impervious to human efforts to destroy them.”

Reference:
J. D. Daza et al. Mid-Cretaceous amber fossils illuminate the past diversity of tropical lizards, Science Advances (2016). DOI: 10.1126/sciadv.1501080

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

New micro-CT scanner allows inside view of even the tiniest fossils

New micro-CT scanner allows-GeologyPage
These girdled lizards from the Cordylidae family have diverse patterns of body armor scales that protect them, highlighted in blue. Credit: Florida Museum of Natural History scan by Edward Stanley

Encased in hard rock, the bones of many fossilized mammals are only partially visible for scientists to study. A poor attempt to take apart the rock and view the complete fossil may damage the bone, but micro-CT scanning technology has safeguarded the fate of these specimens, many of which are tens of millions of years old.

“You can essentially cut into the specimens in a non-destructive way with a micro-CT scanner,” said Jonathan Bloch, curator of vertebrate paleontology at the Florida Museum of Natural History. “And it allows you to look at the internal anatomy of fossil skulls.”

The new micro-CT scanner at the University of Florida’s Nanoscale Research Facility will allow Bloch and other scientists to closely view and study specimens as small as a micron (one millionth of a meter).

Holding a tiny Notharctus skull in his hand, Bloch explained the scanner can digitally recreate the 45-million-year-old lemur-like primate’s brain, which could give insight into how its body structure differs from modern primates.

“Once you have an image of the brain, you can follow nerves and blood vessels from the brain through the rest of the skull to determine where they go,” he said. “It allows us to test ideas about what these holes and grooves and things are on the surface of fossil bones.”

Florida Museum Associate Curator of Herpetology David Blackburn plans to use the scanner to merge together what looks like a series of puzzle pieces—fossilized frog bones from 25 million years ago—which he keeps ready for scanning in a small box in his office.

“These are parts that we think are all from the same species,” Blackburn said, holding up a bone about 1 centimeter long. “We don’t have a complete one, but we can virtually put it back together.”

“It’s such a great way of sharing our research,” Blackburn said. “We can virtually take specimens apart. We can zoom into any piece of it, we can go inside pieces of it.”

The scanner works a lot like a traditional X-ray machine one might use at a doctor’s office, but instead of taking an image from one direction, thousands of images are taken from different angles so they can be combined to produce a 3-D picture, Blackburn said.

Bones become visible in X-ray imaging because they are the densest part of an animal’s body, but some of Bloch’s work has involved “filling” empty spaces between bones to outline the size and shape of internal organs. The process is significant in understanding differences between the internal development of fossilized animals from millions of years ago and modern species—it enables scientists to make accurate physical comparisons and unlock their historic connections.

“For the first time, we’re allowed to segment out the shape of the brain inside the skull of these fossil animals without removing the rock or the bone itself,” Bloch said.

Another way to view internal anatomies with micro-CT scanning involves infusing a specimen with a chemical like iodine that makes soft tissues appear dense while still intact inside the animal—everything from muscles to nerves and blood vessels.

“We can reconstruct a frog’s muscles, see its nervous system, all of its internal organs,” Blackburn said. “Some of this is useful for describing new species, some is simply of interest to understanding basic biology.”

The new technology also allows scientists to study some of the smallest and most delicate biodiversity, such as the moth eyes and antennae studied by Akito Kawahara, an assistant curator at the Florida Museum’s McGuire Center for Lepidoptera and Biodiversity.

“When you are working with specimens this small, pieces might get lost,” Kawahara said. “Our research with micro-CT scanning will help us understand how these eyes and antennae vary without dissecting their structure.”

Kawahara said the technology will also help visitors better understand the organisms displayed at the museum.

“To be able to do that without harming any of these really small insects is a great benefit,” he said.

The technology may also benefit students in the classroom and members of the public through printed 3-D models of specimens, including the ancient tuatara lizard that is a sister to nearly all living lizard species. Blackburn has a 6-inch tuatara model in his office—about 10 times the size of the original species.

“One plan is to use the technology for generating data for classrooms,” Blackburn said. “We might bring the real specimen into an undergraduate class to show it in a lab, but we’re certainly not going to let a 5-year-old handle it during a public program. A model can be replaced.”

A 3-D specimen model will also allow scientists to complete statistical analyses and more accurately measure the size and shape of different body parts. This capability is important for Blackburn and Bloch, who often try to link the ancestries of fossils in the museum collections with living species.

Micro-CT technology has helped UF assistant anthropology professor Valerie DeLeon and her students research the development of primates and the use of mice as models for human biological behaviors. Like Blackburn, she says access to 3-D specimen models will help students better connect with science.

“A high school science teacher in Alaska could download these 3-D compatible files and print the models to use in their classroom,” DeLeon said. “And it’s all based on having the CT data to start with.”

“One of the really valuable aspects of the micro-CT scanner is it not only creates data for UF researchers to study right here and right now, but it creates this resource of data that will be available way beyond the borders of the university and have a lot of benefit to the research community as a whole,” DeLeon said.

Note: The above post is reprinted from materials provided by Florida Museum of Natural History.

99 million years old Lizards Trapped in Amber Give Clues to ‘lost ecosystem’

World’s oldest chameleon-GeologyPage
Various lizard specimens are shown preserved in ancient amber from present-day Myanmar in Southeast Asia, in this handout photo provided by the Florida Museum of Natural History on March 5, 2016. Credit: David Grimaldi/Florida Museum of Natural History/Handout via Reuters

A fossilized lizard found in Southeast Asia preserved in amber dates back some 99 million years, Florida scientists have determined, making it the oldest specimen of its kind and a “missing link” for reptile researchers.

The lizard is some 75 million years older than the previous record holder, according to researchers at the Florida Museum of Natural History, who announced the finding this week.

It was found decades ago in a mine along with other ancient, well-preserved reptile fossils, but the U.S. scientists were able to analyze the finds only recently.

“It was incredibly exciting to see these animals for the first time,” Edward Stanley, a member of the research team, said on Saturday. “It was exciting and startling, actually, how well they were preserved.”

Scientists believe the chameleon-like creature was an infant when it was trapped in a gush of sticky resin while darting through a tropical forest in what is now Myanmar, in Southeast Asia.

The creature’s entire body, including its eyes and colorful scales, is unusually well-preserved, Stanley said. The other reptiles trapped in the amber, including a gecko and an arctic lizard, were also largely intact.

Small reptiles have delicate bodies and typically deteriorate quickly, he said. Being encased in solid amber helped to lock the specimen together.

Stanley and other researchers used high-resolution digital X-ray technology to examine the creatures and estimate the age of the amber without breaking it.

The discovery will help researchers learn more about the “lost ecosystem, the lost world” to which the creatures belonged, Stanley said, and it may help researchers learn more about the creatures’ modern relatives.

“It’s kind of a missing link,” Stanley said.

Video

3D volume-rendered movies of the burmite lizards.

Reference:
Juan D. Daza, Edward L. Stanley, Philipp Wagner, Aaron M. Bauer and David A. Grimaldi. Mid-Cretaceous amber fossils illuminate the past diversity of tropical lizards. DOI: 10.1126/sciadv.1501080

Note: The above post is reprinted from materials provided by Reuters. The original article was written by Frank McGurty and Leslie Adler.

Penguin brains not changed by loss of flight

Penguin brains not-GeologyPage
This is an ancient penguin skull and endocast. Scale bar is 2.5 cm and letters indicate parts of the brain: ce, cerebellum; el, endosseus labyrinth; fl, floccular lobe; ol, optic lobe; os, occipital sinus impression; pb, pituitary bulb; t, telencephalon; w, wulst. Credit: Courtesy of James Proffitt

Losing the ability to fly gave ancient penguins their unique locomotion style. But leaving the sky behind didn’t cause major changes in their brain structure, researchers from The University of Texas at Austin suggest after examining the skull of the oldest known penguin fossil.

The findings were published in the Journal of Anatomy in February.

“What this seems to indicate is that becoming larger, losing flight and becoming a wing-propelled diver does not necessarily change the [brain] anatomy quickly,” said James Proffitt, a graduate student at the university’s Jackson School of Geosciences who led the research. “The way the modern penguin brain looks doesn’t show up until millions and millions of years later.”

Proffitt conducted the research with Julia Clarke, a professor in the Jackson School’s Department of Geological Sciences, and Paul Scofield, the senior curator of Natural History at the Canterbury Museum in Christchurch, New Zealand, where the skull fossil is from.

The skull is from a penguin that lived in New Zealand over 60 million years ago during the Paleocene epoch. According to Proffitt, it likely lived much like penguins today. But while today’s penguins have been diving instead of flying for tens of millions of years, the change was relatively new for the ancient penguin.

“It’s the oldest [penguin] following pretty closely after the loss of flight and the evolution of flightless wing-propelled diving that we know of,” Proffitt said.

The shape of bird skulls is influenced by the structure of the brain. To learn about early penguin brain anatomy, Proffitt used X-ray CT-scanning to digitally capture fine features of the skull’s anatomy, and then used computer modeling software to create a digital mold of the brain, called an endocast.

The researchers thought that loss of flight would impact brain structure–making the brains of ancient penguins and modern penguins similar in certain regions. However, after analyzing the endocast and comparing it to modern penguin brain anatomy, no such similarity was found, Proffitt said. The brain anatomy had more in common with skulls of modern relatives that both fly and dive such as petrels and loons, than modern penguins.

It’s difficult to know why modern penguins’ brains look different than their ancestors’ brains, Proffitt said. It’s possible that millions of years of flightless living created gradual changes in the brain structure. But the analysis shows that these changes are not directly related to initial loss of flight because they are not shared by the ancient penguin brain.

However, similarities in the brain shape between the ancient species and diving birds living today suggest that diving behavior may be associated with certain anatomical structures in the brain.

“The question now is do the old fossil penguins’ brains look that way because that’s the way their ancestors looked, or does it have something maybe to do with diving?” Proffitt said. “I think that’s an open question right now.”

Reference:
J. V. Proffitt, J. A. Clarke, R. P. Scofield. Novel insights into early neuroanatomical evolution in penguins from the oldest described penguin brain endocast. Journal of Anatomy, 2016; DOI: 10.1111/joa.12447

Note: The above post is reprinted from materials provided by University of Texas at Austin.

Cosmochemists find evidence of rare element in early solar system

Cosmochemists find-GeologyPage
This close-up picture shows a ceramic-like refractory inclusion (pink inclusion) still embedded into the meteorite in which it was found. Refractory inclusions are the oldest-known rocks in the solar system (4.5 billion years old). Analysis of the uranium isotope ratios of such inclusions demonstrates that a long-lived isotope of the radioactive element curium was present in the solar system when this inclusion was formed. Credit: Origins Lab at the University of Chicago

University of Chicago scientists have discovered evidence in a meteorite that a rare element, curium, was present during the formation of the solar system. This finding ends a 35-year-old debate on the possible presence of curium in the early solar system, and plays a crucial role in reassessing models of stellar evolution and synthesis of elements in stars. Details of the discovery appear in the March 4 edition of Science Advances.

“Curium is an elusive element. It is one of the heaviest-known elements, yet it does not occur naturally because all of its isotopes are radioactive and decay rapidly on a geological time scale,” said the study’s lead author, François Tissot, UChicago PhD’15, now a W.O. Crosby Postdoctoral Fellow at the Massachusetts Institute of Technology.

And yet Tissot and his co-authors, UChicago’s Nicolas Dauphas and Lawrence Grossman, have found evidence of curium in an unusual ceramic inclusion they called “Curious Marie,” taken from a carbonaceous meteorite. Curium became incorporated into the inclusion when it condensed from the gaseous cloud that formed the sun early in the history of the solar system.

Curious Marie and curium are both named after Marie Curie, whose pioneering work laid the foundation of the theory of radioactivity. Curium was only discovered in 1944, by Glenn Seaborg and his collaborators at the University of California, Berkeley, who, by bombarding atoms of plutonium with alpha particles (atoms of helium) synthesized a new, very radioactive element.

To chemically, and unambiguously, identify this new element, Seaborg and his collaborators studied the energy of the particles emitted during its decay at the Metallurgical Laboratory at UChicago (which later became Argonne National Laboratory). The isotope they had synthesized was the very unstable curium-242, which decays in a half-life of 162 days.

On Earth today, curium exists only when manufactured in laboratories or as a byproduct of nuclear explosions. Curium could have been present, however, early in the history of the solar system, as a product of massive star explosions that happened before the solar system was born.

“The possible presence of curium in the early solar system has long been exciting to cosmochemists, because they can often use radioactive elements as chronometers to date the relative ages of meteorites and planets,” said study co-author Nicolas Dauphas, UChicago’s Louis Block Professor in Geophysical Sciences.

Indeed, the longest-lived isotope of curium (247Cm) decays over time into an isotope of uranium (235U). Therefore, a mineral or a rock formed early in the solar system, when 247Cm existed, would have incorporated more 247Cm than a similar mineral or rock that formed later, after 247Cm had decayed. If scientists were to analyze these two hypothetical minerals today, they would find that the older mineral contains more 235U (the decay product of 247Cm) than the younger mineral.

“The idea is simple enough, yet, for nearly 35 years, scientists have argued about the presence of 247Cm in the early solar system,” Tissot said.

Long wait to detect curium

Early studies in the 1980s found large excesses of 235U in any meteoritic inclusions they analyzed, and concluded that curium was very abundant when the solar system formed. More refined experiments conducted by James Chen and UChicago alumnus Gerald Wasserburg, SB’51, SM’52, PhD’54, at the California Institute of Technology showed that these early results were spurious, and that if curium was present in the early solar system, its abundance was so low that state-of-the-art instrumentation would be unable to detect it.

Scientists had to wait until a new, higher-performance mass spectrometer was developed to successfully identify, in 2010, tiny excesses of 235U that could be the smoking gun for the presence of 247Cm in the early solar system.

“That was an important step forward but the problem is, those excesses were so small that other processes could have produced them,” Tissot noted.

Models predict that curium, if present, was in low abundance in the early solar system. Therefore, the excess 235U produced by the decay of 247Cm cannot be seen in minerals or inclusions that contain large or even average amounts of natural uranium. One of the challenges was thus to find a mineral or inclusion likely to have incorporated a lot of curium but containing little uranium.

With the help of study co-author Lawrence Grossman, UChicago professor emeritus in geophysical sciences, the team was able to identify and target a specific kind of meteoritic inclusion rich in calcium and aluminum. These CAIs (calcium, aluminum-rich inclusions) are known to have a low abundance of uranium and likely to have high curium abundance. One of these inclusions—Curious Marie— contained an extremely low amount of uranium,

“It is in this very sample that we were able to resolve an unprecedented excess of 235U,” Tissot said. “All natural samples have a similar isotopic composition of uranium, but the uranium in Curious Marie has six percent more 235U, a finding that can only be explained by live 247Cm in the early solar system.”

Thanks to this sample, the research team was able to calculate the amount of curium present in the early solar system and to compare it to the amount of other heavy radioactive elements such as iodine-129 and plutonium-244. They found that all these isotopes could have been produced together by a single process in stars.

“This is particularly important because it indicates that as successive generations of stars die and eject the elements they produced into the galaxy, the heaviest elements are produced together, while previous work had suggested that this was not the case,”
Dauphas explained.

The finding of naturally occurring curium in meteorites by Tissot and collaborators closes the loop opened 70 years ago by the discovery of man-made Curium and it provides a new constraint, which modelers can now incorporate into complex models of stellar nucleosynthesis and galactic chemical evolution to further understand how elements like gold were made in stars.

Reference:
“Origin of uranium isotope variations in early solar nebula condensates” by F.L.H. Tissot, N. Dauphas, and L. Grossman, Science Advances, March 4, 2016. DOI: Vol. 2, No. 3, March 4, 2016, DOI: 10.1126/sciadv.1501400.

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

Studies how Arctic soils are affected by precipitation, mainly snow

studies how Arctic soils-GeologyPage
Researchers dig a trench in permafrost. Credit: University of Delaware

Neil Sturchio, professor and chair of the University of Delaware’s Department of Geological Sciences, is exploring how the thawing of permafrost, a subsurface layer of soil that remains mostly frozen throughout the year, affects vegetation and the carbon cycle in the Toolik Lake area of the Alaska’s North Slope.

“There is a lot of carbon frozen in the Arctic soil’s permafrost layer. If this all thaws out, prevailing thought is that the carbon in the soil could be released to the atmosphere and potentially accelerate global warming,” said Sturchio.

Climate models predict 25-50 percent more precipitation in the Arctic region by the end of the century, mostly as fall and winter snow. However, extra snow can also mean extra moisture during warmer seasons like spring and summer.

In 2012, Sturchio and colleagues from several universities conducted a study to determine whether methane and carbon dioxide production in Arctic soils are affected by precipitation, mainly snow accumulation.

Specifically, they studied the long-term effects of projected changes in snow accrual on the methane emissions from moist acidic tundra, which covers over 25 percent of the Alaskan Arctic.

Snow fence experiment

During fieldwork, the scientists used an existing snow fence that had been in place for 18 years to explore what changes in average snow accumulation might mean for the Toolik Lake area. The researchers hypothesized that increased snow accumulation would result in wetter and warmer soils, greater thaw depth and an increase in the abundance of shrubs and tall, grass-like plants called sedges. They also predicted that these soil conditions would lead to increased methane emissions.

Typical winter snowfall depth in the area is about one foot. The snow fence, which stands approximately 9 feet high by 200 feet long, was built perpendicular to the wind direction so that snowdrifts would form behind the fence. This allowed the researchers to mimic various snowfall accumulations for the region, from below normal to average to much higher levels of winter precipitation.

In summer 2012, the researchers established four research plots and took biweekly soil measurements and soil gas samples during the growing season from late May through August. They monitored soil temperature and gas compositions at 10, 20, 35 and 50-centimeter depths; water moisture; oxygen saturation; the amounts and carbon isotope ratios of methane and carbon dioxide; and the thickness of unfrozen ground, known as thaw depth. They also characterized the plant species at peak season.

Snow blanket means longer growing season for plants

As they reviewed the data, the researchers discovered that in areas with increased winter precipitation, the ground didn’t freeze as deeply because the snow acted like a blanket, keeping the ground warmer than normal.

Their findings showed that higher snow accumulations resulted in increased soil temperatures and a deeper thawing of the permafrost, which, in turn, resulted in increased microbial activity, increased melting depth and more water content in the soil that led to increased production of methane and more plant growth.

In areas with reduced snow accumulation, however, the soil acted as a methane sink because of enhanced activity of methane-oxidizing bacteria.

The study results suggest that the amount of methane fluctuation was primarily in response to changes in the amount and type of vegetation present, as well as the temperature and moisture of the soil, rather than in how much carbon was in the soil.

When the snow melted, scientists noted a longer growing season for plants and shrubs. In areas with higher snow, the soil also collapsed when the ice that was occupying the soil’s pore space melted, causing depressions in the ground.

“It affected more than just the amount of methane produced, it changed the landscape and the types of plants that grew there. We started seeing woody plants — dwarf trees like birch and other shrubs — instead of just moss, lichens and grass. This is something you could predict would happen under climate change,” Sturchio explained.

More work is needed to better understand the interactions between soil and vegetation processes that affect the release of methane and to determine whether or not the Arctic tundra will act as a significant methane source or methane sink in the future.

“It’s safe to say a lot of things are changing in the Arctic. But depending on where you go, the climate change effects are somewhat different,” Sturchio said.

The researcher team recently published their findings in the journal Global Change Biology.

Co-authors on the work include the paper’s lead author Elena Blanc-Betes and the project’s principal investigator Miguel Gonzalez-Meler, from University of Illinois at Chicago; Jeffrey Welker from University of Alaska; and Jeffrey Chanton from Florida State University.

This work was funded in part by the Department of Energy, Terrestrial Ecosystem Science Program, and the National Science Foundation.

Reference:
Elena Blanc-Betes, Jeffrey M. Welker, Neil C. Sturchio, Jeffrey P. Chanton, Miquel A. Gonzalez-Meler. Winter precipitation and snow accumulation drive the methane sink or source strength of Arctic tussock tundra. Global Change Biology, 2016; DOI: 10.1111/gcb.13242

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

The ancient rotation of the Iberian Peninsula left a magnetic trace

The ancient rotation of-GeologyPage
This is an aerial photograph of the Truchillas river (Truchas, Leon), and detail of its volcanic rock. Credit: J. Fernandez Lozano et al.

The volcanic rock found in the south of Leon (Spain) experienced a rotation of almost 60º 300 million years ago, an example of what could have occurred across the entire Iberian Peninsula when, in that moment, it was still being formed. This fact is demonstrated by the magnetic signals of its minerals, currently being analysed by researchers from the universities of Salamanca and Utrecht (The Netherlands). This discovery improves our understanding of a now-disappeared mountain range that stood over what is now north-western Spain, France, and the southern United Kingdom.

The bathers that gather every summer on the banks of the rivers of the mountain ranges of La Cabrera and El Teleno in Leon (Spain) have little reason to suspect that the rocks that they can see near the water are of volcanic origin, over 460 million years old, when an emerging Iberian Peninsula was still on the coast of the continent of Gondwana, on the shore of the Rheic ocean.

Around 350 million years ago, that ancient ocean closed during the formation of the Pangea supercontinent, and the sediments deposited in it became a large mountain range that later acquired a curved shape, becoming part of what is now the Iberian Peninsula around 300 million years ago.

Now scientists at University of Salamanca have collected, in the Leonese towns located between Truchas and Ponferrada, 320 samples of volcanic rock and limestone, a record of that turbulent, volcanic period of our planet’s history.

After having analysed the samples in one of the most important Palaeomagnetism laboratories in the world, located at Utrecht University (The Netherlands), they have been able to reconstruct the history of these ancient rocks based on the magnetic signal of their mineral content. The results have been published in the journal ‘Tectonophysics’.

“These rocks were deposited on the ocean floor 440 million years ago near the south pole, and its components were oriented in the direction of the Earth’s magnetic field at the time (N-S),” explains to SINC Javier Fernandez Lozano, a geologist at the University of Salamanca and co-author of the research.

About 120 million years later, the collision of two continents occurred, between what is now the North and South of Europe. The result of this collision was what is known as the Variscan orogeny, the raising of a mountain range along the North-South axis, which left the rocks with a secondary magnetic signal, adapted to the new magnetic field of the Earth.

The changes in the direction of that magnetic field were preserved in their minerals, and indicate that shortly after that process, the rocks of these mountains experienced a rotation of almost 60º, until they ended up in with their current orientation,” notes Fernandez Lozano.

He points out that this magnetic signal can be associated with large-scale processes of mountain formation, and how these ranges can be curved until they create structures known as oroclines: “With a rock sample, we can analyse a process that has occurred on the tectonic plate level; and, specifically, offers new data that allows us to discover how this orogeny or large Variscan range and its curvature occurred. This information was preserved in the rocks of the British Isles, France, and North-West Spain, along more than 3,000 kilometres.

This study forms part of a long-debated geological problem: the Cantabrian orocline, an issue that a few years ago brought together specialists at an international congress held in Salamanca. An orocline is the curvature of a range or chain of mountains that was originally linear, and the Cantabrian orocline is recognizable 300 million years later in the geography of the Iberian Peninsula and surrounding areas.

Concretely, one can observe the arc formed by the Cantabrian range until it disappears into the continental shelf, and the curvature that continues onward towards the Iberian Range. Fernandez Lozano notes that the new research “goes beyond previous efforts, primarily focused on Asturias, in order to understand this orocline, and now we can find its traces further to the south, on the border between Leon and Zamora.”

“Thanks to studies like this one, we can continue to provide information on the causes and processes that gave birth to curved mountain ranges after the collision between two continents,” concludes the geologist.

Reference:
Javier Fernández-Lozano et al. New kinematic constraints on the Cantabrian orocline: A paleomagnetic study from the Peñalba and Truchas synclines, NW Spain, Tectonophysics (2016). DOI: 10.1016/j.tecto.2016.02.019

Note: The above post is reprinted from materials provided by FECYT – Spanish Foundation for Science and Technology.

The maximum earthquake magnitude for North Turkey

Seismogram2

Geoscientists and natural disaster management experts are well aware of the risk prevailing in the megacity of Istanbul: The Istanbul metropolitan region faces a high probability for a large earthquake in the near future. The question is: how large can such an earthquake be?

Scientists from the GFZ German Research Centre for Geosciences together with a colleague from the University of Southern California have examined the earthquake maxima along the North Anatolian Fault Zone and came to the astonishing conclusion that mega quakes of magnitude M8 are exclusively to be expected in the east of this earthquake region. On the other hand the maximum earthquake magnitude to be expected in northwestern Turkey including the Istanbul-Marmara region does not exceed M7.5.

Seismologist, Marco Bohnhoff, from the GFZ explains: “We have compiled a new catalogue on historical seismicity for the North Anatolian Fault Zone (NAFZ) dating back to 300 years BC, thus, covering a time period of 2300 years. It is interesting to notice that in the North West of Turkey an earthquake with a magnitude larger than 7.5 has never been observed. On the other hand in eastern Turkey magnitudes of up to M8 are well documented.”

The observations can be explained by the age of the fault zone. The NAFZ extends through northern Turkey along more than 900 km from the northern Aegean Sea almost towards the Caucasus. The fault reflects the tectonic boundary between the Anatolian plate and the Eurasian plate in the North. The Anatolian plate and with it the whole country of Turkey, moves towards the west and hereby interlocks with the Eurasian plate. The plate movement results in an accumulation of stress along the plate boundary that is released in large earthquakes with recurrence periods of several hundreds of years.

The just published new catalogue of historical earthquakes, together with further key parameters such as age, cumulative fault offset, slip rates and maximum length of coherent fault segments reveal a logical explanation.

Geoscientist Bohnhoff: “We were able to demonstrate that the smaller earthquake magnitudes in the west are closely linked to the earlier stage in fault-zone evolution there with an approx. age of eight million years. In comparison the eastern part of the NAFZ with an age of twelve to thirteen million years, is older and more mature. The largest M8 earthquakes solely occur along the older eastern part that also has longer consistent segments”.

This is due to the fact that continental transform faults such as the NAFZ have a life cycle. The rock does not fracture along the whole fault zone all at once but rather in sub-segments. In the run of millions of years some of these segments coalesce due to repeated activation during earthquakes. Thus, due to the older age in the east these longer uniform sections are capable of generating larger ruptures and, therefore, larger earthquakes can be found in the east as compared to the west where the segments are still comparatively small and have not coalesced.

For Istanbul this implies that: Earthquakes as large as M8 are not expected there before further fault evolution that may take several millennia. This is important to estimate upper bounds for the seismic hazard and risk of the city.

This, however, by no means reduces the general seismic hazard for the metropolitan region since the NAFZ is located only 20 km away from the historic city center below the seafloor of the Marmara Sea where an up to M 7.5 earthquake can cause a great threat to the local population and infrastructure.

The results of the newly published study are relevant for the estimation of expected maximum magnitudes in highly populated regions, as well as for the determination of seismic hazards and the accompanying risks and, last but not least, they provide important baselines for adapting building codes.

Reference:
Marco Bohnhoff et al. Maximum earthquake magnitudes along different sections of the North Anatolian fault zone, Tectonophysics (2016). DOI: 10.1016/j.tecto.2016.02.028

Note: The above post is reprinted from materials provided by Helmholtz Association of German Research Centres.

With Climate, Fertilizing Oceans Could Be Zero-Sum Game

With Climate-GeologyPage
Scientists on a research cruise in the central equatorial Pacific collected seafloor sediments showing that nutrient cycling in one part of the ocean may affect another region far away. Here, a researcher from Georgia Institute of Technology checks out newly retrieved mud. Credit: Pratigya Polissar/Lamont-Doherty Earth Observatory

Scientists plumbing the depths of the central equatorial Pacific Ocean have found ancient sediments suggesting that one proposed way to mitigate climate warming—fertilizing the oceans with iron to produce more carbon-eating algae—may not necessarily work as envisioned.

Plants need trace amounts of iron to perform photosynthesis, but certain parts of the oceans lack it, and thus algae are scarce. Recent shipboard experiments have shown that when researchers dump iron particles into such areas, it can boost growth.  The algae draw the greenhouse gas carbon dioxide from the air to help build their bodies, so fertilization on a large scale could, theoretically, reduce atmospheric CO2. Seafloor sediments show that during past ice ages, more iron-rich dust blew from chilly, barren landmasses into the oceans, apparently producing more algae in these areas and, presumably, a natural cooling effect. Some scientists believe that iron fertilization and a corresponding drop in CO2 is one reason why ice ages become icy and remain so.

But the researchers in the new study say that increased algae growth in one area can inhibit growth elsewhere. This is because ocean waters are always on the move, and algae also need other nutrients, such as nitrates and phosphates. Given heavy doses of iron, algae in one region may suck up all those other nutrients; by the time the water circulates elsewhere, it has little more to offer, and adding iron doesn’t do anything. The study appears today in the leading journal Nature.

“There’s only a limited amount of total nutrients in the oceans. So if there’s greater use in one area, it seems you’d have lesser concentrations in other areas,” said lead author Kassandra Costa, a doctoral student at Columbia University’s Lamont-Doherty Earth Observatory who led the analysis. “The basic message is, if you add to one place, you may subtract from another.”

Much of the equatorial Pacific’s near-surface water comes from the Southern Ocean. In the southerly latitudes, powerful winds circle Antarctica. This stirs things like a giant ladle, dredging large amounts of nitrates, phosphates and other nutrients from bottom waters where they tend to settle—so much so, that the nutrients can’t all be used up by resident algae. This makes the Southern Ocean an attractive place for potential artificial fertilization; experiments have shown that adding iron there does cause more algae to grow.

Much of this nutrient-rich water eventually sinks and circulates below the surface to the mid-Pacific; the journey takes a century or two. At the equator, the southern water meets with opposing currents from the north and rises, making the nutrients available to near-surface algae. But most of these nutrients pass on by; the mid-Pacific is too far from iron-rich dust sources on land for algae to make much use of them.

In 2012, Lamont scientists conducted a research cruise in this remote region, and took cores from the seabed. Costa and her colleagues analyzed sediments from the cores dating to the last ice age, some 17,000 to 26,000 years ago. As expected, they found two or three times more dust reaching the area compared to today, due to reduced plant cover in the cold, dry climate. Marine plant growth might have been expected to have increased accordingly, but it didn’t. The sediments showed that productivity stayed the same, or even declined. Their conclusion:  algae in the southerly latitudes, which also got dusted at the same time, snapped up the iron—along with most of the other nutrients. That left the Pacific algae high and dry.

“This shows how different parts of the system are connected,” said Lamont marine geochemist Jerry McManus, a coauthor on the paper. “If you push hard in one place, the system pushes back somewhere else.” This undercuts the idea that iron fertilization could be a major force in spurring and maintaining ice ages. He said. “That doesn’t mean it’s not an influence, but the global system may be self-regulating and [that] reduces the potential impact of fertilization,” he said. The study does not say so, but McManus adds that it also suggests “we should be very careful about thinking we can use artificial fertilization to combat climate change.”

Recently researchers have done a series of artificial iron fertilization experiments. These have ranged from a 2012 privately sponsored seeding off British Columbia said to have produced a 10,000-square-mile algae bloom, to a similar 2009 German cruise in the southwest Atlantic. Some earlier projects were done in the southern ocean—the place “where you get the most bang for your buck,” said McManus. Because iron is needed only in trace quantities, researchers have calculated that in some areas, each kilogram added could produce 100,000 kilograms of algae, at least locally.

The most recent experiments have sparked protests from environmental groups. Some scientists say iron dumping could alter marine ecosystems in unpredictable and possibly harmful ways. Another problem: for excess carbon to be truly locked away, it must sink to the seafloor when the algae die. Some studies have suggested that while algae may grow quickly when fertilized, much of the carbon they take up remains near the surface for hundreds of years, cycling through other marine creatures, or bleeding directly back into the air.

Phoebe Lam, an oceanographer at the University of California, Santa Cruz, who studies marine cycling of iron and carbon, said the paper “shows there are downstream consequences to anything you do in the ocean. It’s what the geoengineers don’t necessarily think of. It makes the idea of artificial iron fertilization require a discussion of much more subtlety.”

Sylvain Pichat, a marine geochemist at the University of Lyon, said the study “indeed shows that we need to think about the oceans and the climate system as a whole.”

Earlier this month, British researchers published a study showing how much still remains to be discovered: they observed that big icebergs increasingly calving off Antarctica are releasing vast trails of iron as they melt, triggering algae blooms for hundreds of miles—a possible mechanism that one could speculate might eventually push back against the manmade forces implicated in the calving.

Reference:

  1. Jeff Tollefson. Ocean-fertilization project off Canada sparks furore, Nature (2012). DOI: 10.1038/490458a
  2. K. M. Costa et al. No iron fertilization in the equatorial Pacific Ocean during the last ice age, Nature (2016). DOI: 10.1038/nature16453

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

New study pinpoints stress factor of mega-earthquake off Japan

New study pinpoints stress-GeologyPage
Graphic of the gravity data off Japan where the 2011 magnitude 9 earthquake occurred. Credit: Scripps Institution of Oceanography, UC San Diego

Scripps Institution of Oceanography, UC San Diego researchers published new findings on the role geological rock formations offshore of Japan played in producing the massive 2011 Tohoku-oki earthquake, one of only two magnitude 9 mega-earthquakes to occur in the last 50 years.

The study, published in the journal Nature, offers new information about the hazard potential of large earthquakes at subduction zones, where tectonic plates converge.

The magnitude 9 quake, which triggered a major tsunami that caused widespread destruction along the coastline of Japan, including the Fukushima nuclear plant disaster, was atypical in that it created an unusually large seismic movement, or slip, of 50 meters (164 feet) within a relatively small rupture area along the earthquake fault.

To better understand what may have caused this large movement, Scripps researchers used gravity and topography data to produce a detailed map of the geological architecture of the seafloor offshore of Japan. The map showed that the median tectonic line, which separates two distinct rock formations, volcanic rocks on one side and metamorphic rocks on the other, extends along the seafloor offshore.

The region over the earthquake-generating portion of the plate boundary off Japan is characterized by variations in water depth and steep topographic gradients of about six kilometers (3.7 miles). These gradients, according to the researchers, can hide smaller variations in the topography and gravity fields that may be associated with geological structure changes of the overriding Japan and subducting Pacific plates.

“The new method we developed has enabled us to consider how changes in the composition of Japan’s seafloor crust along the plate-boundary influences the earthquake cycle,” said Dan Bassett, a postdoctoral researcher at Scripps and lead author of the study.

The researchers suggest that a large amount of stress built up along the north, volcanic rock side of the median tectonic line resulting in the earthquake’s large movement. The plates on the south side of the line do not build up as much stress, and large earthquakes have not occurred there.

“There’s a dramatic change in the geology that parallels the earthquake cycle,” said Scripps geophysicist David Sandwell, a co-author of the study. “By looking at the structures of overriding plates, we can better understand how big the next one will be.”

Reference:
Dan Bassett et al, Upper-plate controls on co-seismic slip in the 2011 magnitude 9.0 Tohoku-oki earthquake, Nature (2016). DOI: 10.1038/nature16945

Note: The above post is reprinted from materials provided by University of California – San Diego.

‘A load of old rot’: Fossil of oldest known land-dweller identified

A load of old rot-GeologyPage
Filaments of Tortotubus. Credit: Martin R. Smith

A fossil dating from 440 million years ago is not only the oldest example of a fossilised fungus, but is also the oldest fossil of any land-dwelling organism yet found. The organism, and others like it, played a key role in laying the groundwork for more complex plants, and later animals, to exist on land by kick-starting the process of rot and soil formation, which is vital to all life on land.

This early pioneer, known as Tortotubus, displays a structure similar to one found in some modern fungi, which likely enabled it to store and transport nutrients through the process of decomposition. Although it cannot be said to be the first organism to have lived on land, it is the oldest fossil of a terrestrial organism yet found. The results are published in the Botanical Journal of the Linnean Society.

“During the period when this organism existed, life was almost entirely restricted to the oceans: nothing more complex than simple mossy and lichen-like plants had yet evolved on the land,” said the paper’s author Dr Martin Smith, who conducted the work while at the University of Cambridge’s Department of Earth Sciences, and is now based at Durham University. “But before there could be flowering plants or trees, or the animals that depend on them, the processes of rot and soil formation needed to be established.”

Working with a range of tiny microfossils from Sweden and Scotland, each shorter than a human hair is wide, Smith attempted to reconstruct the method of growth for two different types of fossils that were first identified in the 1980s. These fossils had once been thought to represent parts of two different organisms, but by identifying other fossils with ‘in-between’ forms, Smith was able to show that the fossils actually represented parts of a single organism at different stages of growth. By reconstructing how the organism grew, he was able to show that the fossils represent mycelium — the root-like filaments that fungi use to extract nutrients from soil.

It’s difficult to pinpoint exactly when life first migrated from the seas to the land, since useful features in the fossil record that could help identify the earliest land colonisers are rare, but it is generally agreed that the transition started early in the Palaeozoic era, between 500 and 450 million years ago. But before any complex forms of life could live on land, there needed to be nutrients there to support them. Fungi played a key role in the move to land, since by kick-starting the rotting process, a layer of fertile soil could eventually be built up, enabling plants with root systems to establish themselves, which in turn could support animal life.

Fungi play a vital role in the nitrogen cycle, in which nitrates in the soil are taken up by plant roots and passed along food chain into animals. Decomposing fungi convert nitrogen-containing compounds in plant and animal waste and remains back into nitrates, which are incorporated into the soil and can again be taken up by plants. These early fungi started the process by getting nitrogen and oxygen into the soil.

Smith found that Tortotubus had a cord-like structure, similar to that of some modern fungi, in which the main filament sends out primary and secondary branches that stick back onto the main filament, eventually enveloping it. This cord-like structure is often seen in land-based organisms, allowing them to spread out and colonise surfaces. In modern fungi, the structure is associated with the decomposition of matter, allowing a fungus colony to move nutrients to where they are needed — a useful adaptation in an environment where nutrients are scarce and unevenly distributed.

In contrast with early plants, which lacked roots and therefore had limited interaction with activity beneath the surface, fungi played an important role in stabilising sediment, encouraging weathering and forming soils.

“What we see in this fossil is complex fungal ‘behaviour’ in some of the earliest terrestrial ecosystems — contributing to soil formation and kick-starting the process of rotting on land,” said Smith. A question, however, is what was there for Tortotubus to decompose. According to Smith, it’s likely that there were bacteria or algae on land during this period, but these organisms are rarely found as fossils.

Additionally, the pattern of growth in Tortotubus echoes that of the mushroom-forming fungi, although unambiguous evidence of mushrooms has yet to be found in the Palaeozoic fossil record. “This fossil provides a hint that mushroom-forming fungi may have colonised the land before the first animals left the oceans,” said Smith. “It fills an important gap in the evolution of life on land.”

The research was supported by Clare College, Cambridge.

Reference:
Martin R. Smith. Cord-forming Palaeozoic fungi in terrestrial assemblages. Botanical Journal of the Linnean Society, 2016; DOI: 10.1111/boj.12389

Note: The above post is reprinted from materials provided by University of Cambridge. The original story is licensed under a Creative Commons Licence.

Extinct Marine Mammal Hunted Clams with a Big Bite

Extinct Marine Mammal-GeologyPage
This image shows lower jaw stress models of Kolponomos newportensis (left) versus Smilodon fatalis during an anchor bite. Credit: AMNH/J. Tseng, C. Grohé, J. Flynn

New research suggests that the feeding strategy of Kolponomos, an enigmatic shell-crushing marine predator that lived about 20 million years ago, was strangely similar to a very different kind of carnivore: the saber-toothed cat Smilodon. Scientists at the American Museum of Natural History used high-resolution x-ray imaging and computerized biting simulations to show that even though the two extinct predators likely contrasted greatly in food preference and environment, they shared similar engineering in jaw structure, suitable for anchoring against prey with the lower jaw and forcefully throwing the skull forward to pry loose its food. The study is published today in the journal Proceedings of the Royal Society B.

The only known specimens of Kolponomos–primarily skulls and teeth of two species–were recovered from ancient marine deposits along the Pacific coast of Oregon, Washington, and possibly Alaska. Because of its peculiar morphology and the small number of fossils, the animal’s place in the evolutionary tree remains a mystery.

“When Kolponomos was first described in the 1960s, it was thought to be a raccoon relative,” said Camille Grohé, a National Science Foundation and Frick Postdoctoral Fellow in the American Museum of Natural History’s Division of Paleontology and a co-author on the new paper. “But later research on the skull base led some to think it might be a seal or a bear relative instead, and studies of its teeth show that they are very similar in both shape and wear to the teeth in sea otters.”

Sea otters pry their prey–hard-shelled marine invertebrates like clams and mussels–off of surfaces using their hands and rock tools, then crush the shells with their teeth or against their chests, again using tools. By studying Kolponomos fossil material from the National Museum of Natural History in Washington, D.C., and comparative specimens from the American Museum of Natural History, the research team originally set out to test if the extinct predator used otter-like shell-crushing to eat. But the scope of the research expanded after Grohé’s collaborator Z. Jack Tseng noticed something curious in parallel to work he was conducting on the saber-toothed cat Smilodon.

“I started seeing a great deal of similarity between the jaws of Kolponomos and Smilodon,” said Tseng, a National Science Foundation and Frick Postdoctoral Fellow in the American Museum of Natural History’s Division of Paleontology and the lead author on the new paper. “Both of them have a distinctive profile with a deep jaw bone that tapers off toward the back, and both have an expansion of the mastoid processes and the skull’s back surface, suggesting large attachment sites for muscles that let the animal move its head powerfully but with control. We definitely didn’t expect to bring Smilodon into this study of feeding in a clam-eating marine carnivore, but that’s what we ended up doing.”

At the Museum’s Microscopy and Imaging Facility, the researchers used computed tomography (CT) to scan the skulls of Kolponomos and six other carnivores: Smilodon, grey wolf, sea otter, river otter, brown bear, and leopard. They then used computerized methods to build sophisticated biomechanical models to look at how efficiently the animals could perform various bites, including the jaw-anchored killing shear-bite that is characteristic of saber-tooth cats.

They found that the jaw mechanics of Kolponomos and Smilodon are more similar to each other than to any of the other animals in the study, pointing to a unique feeding strategy in addition to the previous idea that Kolponomos might have crushed its prey like sea otters do today. Taken together, the researchers suggest that Kolponomos might have pried prey off of rocks with its lower jaw, swung its skull forward to dislodge it, and then crunched it with its chewing teeth.

“Our biomechanical data show that the chewing bites of sea otters and Kolponomos are not very similar,” Tseng said. “They probably still have an overlapping diet based on tooth wear, but their evolutionary solutions for getting to those hard-shelled animals are dramatically different.”

The researchers stress that this finding does not imply shared ancestry between Kolponomos and Smilodon, but rather an intriguing case of convergence–the independent evolution of similar traits.

“This innovative study, showing unexpected feeding similarities between such wildly distinct carnivores, could only happen by applying new technologies to understand specimens from some of the world’s greatest archives of ancient life,” said John J. Flynn, a curator in the Museum’s Division of Paleontology and Dean of the Richard Gilder Graduate School, also an author on this paper.

This work was funded by the U.S. National Science Foundation grant # DEB-1257572 and the American Museum of Natural History’s Frick Postdoctoral Fellowships.

The authors have dedicated this study to the memory of Museum artist Chester Tarka, who illustrated Kolponomos newportensis.

Note: The above post is reprinted from materials provided by American Museum of Natural History.

1...193194195...342Page 194 of 342

Related Articles

All