Finding fault By Modelling

New modeling and analyses of fault geometry in the Earth’s crust by geoscientist Michele Cooke and colleagues at the University of Massachusetts Amherst are advancing knowledge about fault development in regions where one geologic plate slides past or over another, such as along California’s San Andreas Fault and the Denali Fault in central Alaska.

Findings may help more accurately predict earthquake hazards and allow scientists to better understand how Earth evolved.

Geologists have long been uncertain about the factors that govern how new faults grow, says Cooke, who was recently elected to the board of directors for the Southern California Earthquake Center. This month in an early online issue of the Journal of Geophysical Research, she and colleagues explain fault evolution near fault bends in greater detail than ever before with experiments using kaolin, or china clay, prepared so its strength scales to that of the Earth’s crust when confined in a clay box.

Fault efficiency refers to a dynamic fault system’s effectiveness at transforming input energy from the motions of tectonic plates into movement. For example, a straight fault is more efficient at accommodating strain than a curving fault. An important question is how the efficiency of fault bends evolves with increasing deformation of Earth’s crust.

Master’s student Alex Hatem, who did much of the work in these experiments, with Cooke and postdoctoral scholar Elizabeth Madden, report that fault efficiency increases as new faults grow and link, then reaches a steady state. This implies that bends along crustal faults may persist. The straight fault is the most efficient geometry, Cooke points out. “It’s interesting that bends increase in efficiency through new fault growth but they never become as efficient as straight faults.”

Because earthquakes may stop at restraining bends, it further suggests a new understanding: faults segmented by restraining bends may remain in a sort of stasis rather than developing into systems where earthquakes would rupture the entire length of the fault. Here Cooke explains that comparing a straight fault with a fault at a bend, it is more likely that the fault with the bend will have smaller earthquakes that stop at the bend rather than long earthquake ruptures that pass all the way along the fault.

Her UMass Amherst lab is one of only a handful worldwide to use a state-of-the-art modeling technique based on kaolin clay rather than sand to understand the behavior of the Earth’s crust. Their advanced techniques with the clay include pixel tracking and other quantitative measurements that allow rich details to be obtained from the models and compared with faults around the world.

When scaled properly, data from clay experiments conducted over several hours in a table-top device are useful in modeling restraining bend evolution over thousands of years and at the scale of tens of kilometers. Digital image correlation allows Cooke’s team to measure the details of deformation throughout the experiments.

For this work, they conducted kaolin experiments to model strike-slip rates measured in a restraining bend along a Dead Sea fault in Israel, a fault growth along the Denali Fault in Alaska, and through the San Gorgonio Knot along the San Andreas Fault in southern California.

The UMass Amherst lab is one of only a handful worldwide to use a state-of-the-art modeling technique based on kaolin clay rather than sand to understand the behavior of the Earth's crust. Credit: UMass Amherst

The UMass Amherst lab is one of only a handful worldwide to use a state-of-the-art modeling technique based on kaolin clay rather than sand to understand the behavior of the Earth’s crust.
Credit: UMass Amherst

“We apply the results to the southern San Andreas Fault where a restraining bend has persisted for 25 million years, but during that time its active fault configuration has changed in ways that resemble what we observed in our experiments,” the authors note.

They add, “Results of the clay box experiments provide critical insights into the evolution of restraining bends. Because the experiments scale to crustal lengths and strengths, we can extrapolate from the experiments to kilometer-scale systems. The models show progressive deformation by the successive outboard growth of dipping faults in some cases and persistence of vertical fault in others.”

Understanding the conditions that foster these distinct patterns helps us interpret the geometry and loading of faults within Earth’s crust in order to better constrain earthquake behavior.

Cooke says, “Using new digital image correlation techniques allows us very detailed measurements of the displacement in the experiments to provide insights we didn’t have before. For the fault bends that we tested, the new analysis reveals that efficiency of the faults increases as new faults grow and link and then reaches a steady state. This suggests that restraining bends along crustal faults may persist,” Cooke says.

Video: https://www.youtube.com/watch?v=h6v-TvzwtWM

Source: University of Massachusetts at Amherst. “Finding fault: New information may help understand earthquakes.” ScienceDaily. ScienceDaily, 16 March 2015. <www.sciencedaily.com/releases/2015/03/150316092959.htm>.

Metoposaurus algarvensis was top predator ?

A previously undiscovered species of crocodile-like amphibian that lived during the rise of dinosaurs was among Earth’s top predators more than 200 million years ago, a study shows.

Palaeontologists identified the prehistoric species — which looked like giant salamanders — after excavating bones buried on the site of an ancient lake in southern Portugal.The species was part of a wider group of primitive amphibians that were widespread at low latitudes 220-230 million years ago, the team says.

This is a model of Metoposaurus algarvensis. Credit: Marc Boulay, Cossima Productions

This is a model of Metoposaurus algarvensis.
Credit: Marc Boulay, Cossima Productions

The creatures grew up to 2m in length and lived in lakes and rivers during the Late Triassic Period, living much like crocodiles do today and feeding mainly on fish, researchers say.

The species — Metoposaurus algarvensis — lived at the same time as the first dinosaurs began their dominance, which lasted for over 150 million years, the team says. These primitive amphibians formed part of the ancestral stock from which modern amphibians — such as frogs and newts — evolved, researchers say.

The species were distant relatives of the salamanders of today, the team says. The discovery reveals that this group of amphibians was more geographically diverse than previously thought.The species is the first member of the group to be discovered in the Iberian Peninsula, the team says.

Fossil remains of species belonging to the group have been found in parts of modern day Africa, Europe, India and North America. Differences in the skull and jaw structure of the fossils found in Portugal revealed they belong to a separate species.The new species was discovered in a large bed of bones where up to several hundred of the creatures may have died when the lake they inhabited dried up, researchers say. Only a fraction of the site — around 4 square meters — has been excavated so far, and the team is continuing work there in the hope of unearthing new fossils.

Most members the group of giant salamander-like amphibians was wiped out during a mass extinction 201 million years ago, long before the death of the dinosaurs. This marked the end of the Triassic Period, when the supercontinent of Pangea — which included all the world’s present-day continents — began to break apart. The extinction wiped out many groups of vertebrates, such as big amphibians, paving the way for dinosaurs to become dominant.

The study, published in the Journal of Vertebrate Paleontology, was funded by the German Research Foundation and the National Science Foundation, the Jurassic Foundation, CNRS, Columbia University Climate Center and the Chevron Student Initiative Fund. Additional support was provided by the Municipality of Loulé, Camara Municipal de Silves and Junta de Freguesia de Salir in Portugal.

Dr Steve Brusatte, of the University of Edinburgh’s School of GeoSciences, who led the study, said: “This new amphibian looks like something out of a bad monster movie. It was as long as a small car and had hundreds of sharp teeth in its big flat head, which kind of looks like a toilet seat when the jaws snap shut. It was the type of fierce predator that the very first dinosaurs had to put up with if they strayed too close to the water, long before the glory days of T. rex and Brachiosaurus.”

Dr Richard Butler, of the School of Geography, Earth and Environmental Sciences at the University of Birmingham, said: “Most modern amphibians are pretty tiny and harmless. But back in the Triassic these giant predators would have made lakes and rivers pretty scary places to be.”

Dr Steve Brusatte will discuss his work on recently discovered species and other aspects of palaeontology at a series of events at the Edinburgh International Science Festival, which runs from 4-19 April.

A stiff new layer in Earth’s mantle

By crushing minerals between diamonds, a University of Utah study suggests the existence of an unknown layer inside Earth: part of the lower mantle where the rock gets three times stiffer. The discovery may explain a mystery: why slabs of Earth’s sinking tectonic plates sometimes stall and thicken 930 miles underground.

The findings — published today in the journal Nature Geoscience — also may explain some deep earthquakes, hint that Earth’s interior is hotter than believed, and suggest why partly molten rock or magmas feeding midocean-ridge volcanoes such as Iceland’s differ chemically from magmas supplying island volcanoes like Hawaii’s.

“The Earth has many layers, like an onion,” says Lowell Miyagi, an assistant professor of geology and geophysics at the University of Utah. “Most layers are defined by the minerals that are present. Essentially, we have discovered a new layer in the Earth. This layer isn’t defined by the minerals present, but by the strength of these minerals.”

Earth’s main layers are the thin crust 4 to 50 miles deep (thinner under oceans, thicker under continents), a mantle extending 1,800 miles deep and the iron core. But there are subdivisions. The crust and some of the upper mantle form 60- to 90-mile-thick tectonic or lithospheric plates that are like the top side of conveyor belts carrying continents and seafloors. Oceanic plates collide head-on with continental plates offshore from Chile, Peru, Mexico, the Pacific Northwest, Alaska, Kamchatka, Japan and Indonesia. In those places, the leading edge of the oceanic plate bends into a slab that dives or “subducts” under the continent, triggering earthquakes and volcanism as the slabs descend into the mantle, which is like the bottom part of the conveyor belt. The subduction process is slow, with a slab averaging roughly 300 million years to descend, Miyagi estimates.

Miyagi and fellow mineral physicist Hauke Marquardt, of Germany’s University of Bayreuth, identified the likely presence of a superviscous layer in the lower mantle by squeezing the mineral ferropericlase between gem-quality diamond anvils in presses. They squeezed it to pressures like those in Earth’s lower mantle. Bridgmanite and ferropericlase are the dominant minerals in the lower mantle.

The researchers found that ferropericlase’s strength starts to increase at pressures equivalent to those 410 miles deep — the upper-lower mantle boundary — and the strength increases threefold by the time it peaks at pressure equal to a 930-mile depth.

And when they simulated how ferropericlase behaves mixed with bridgmanite deep underground in the upper part of the lower mantle, they calculated that the viscosity or stiffness of the mantle rock at a depth of 930 miles is some 300 times greater than at the 410-mile-deep upper-lower mantle boundary.

A simplified image of a slab from one of Earth's tectonic plates sinking through the upper mantle above, through the boundary between the upper and lower mantle 410 miles deep, then stalling and pooling at a depth of 930 miles, where University of Utah experiments suggest the existence of an extremely stiff or viscous layer in Earth. Such a layer may explain why tectonic plate slabs seem to pool at 930 miles under Indonesia and South America's Pacific coast. Below the highly viscous zone, slabs can continue to sink to the core-mantle boundary. [show less] Credit: Lowell Miyagi, University of Utah

A simplified image of a slab from one of Earth’s tectonic plates sinking through the upper mantle above, through the boundary between the upper and lower mantle 410 miles deep, then stalling and pooling at a depth of 930 miles, where University of Utah experiments suggest the existence of an extremely stiff or viscous layer in Earth. Such a layer may explain why tectonic plate slabs seem to pool at 930 miles under Indonesia and South America’s Pacific coast. Below the highly viscous zone, slabs can continue to sink to the core-mantle boundary.
Credit: Lowell Miyagi, University of Utah

“The result was exciting,” Miyagi says. “This viscosity increase is likely to cause subducting slabs to get stuck — at least temporarily — at about 930 miles underground. In fact, previous seismic images show that many slabs appear to ‘pool’ around 930 miles, including under Indonesia and South America’s Pacific coast. This observation has puzzled seismologists for quite some time, but in the last year, there is new consensus from seismologists that most slabs pool.”

How stiff or viscous is the viscous layer of the lower mantle? On the pascal-second scale, the viscosity of water is 0.001, peanut butter is 200 and the stiff mantle layer is 1,000 billion billion (or 10 to the 21st power), Miyagi says.

Slab subduction triggers earthquakes and volcanoes

For the new study, Miyagi’s funding came from the U.S. National Science Foundation and Marquardt’s from the German Science Foundation.

“Plate motions at the surface cause earthquakes and volcanic eruptions,” Miyagi says. “The reason plates move on the surface is that slabs are heavy, and they pull the plates along as they subduct into Earth’s interior. So anything that affects the way a slab subducts is, up the line, going to affect earthquakes and volcanism.”

He says the stalling and buckling of sinking slabs at due to a stiff layer in the mantle may explain some deep earthquakes higher up in the mantle; most quakes are much shallower and in the crust. “Anything that would cause resistance to a slab could potentially cause it to buckle or break higher in the slab, causing a deep earthquake.”

Miyagi says the stiff upper part of the lower mantle also may explain different magmas seen at two different kinds of seafloor volcanoes.

Recycled crust and mantle from old slabs eventually emerges as new seafloor during eruptions of volcanic vents along midocean ridges — the rising end of the conveyor belt. The magma in this new plate material has the chemical signature of more recent, shallower, well-mixed magma that had been subducted and erupted through the conveyor belt several times. But in island volcanoes like Hawaii, created by a deep hotspot of partly molten rock, the magma is older, from deeper sources and less well-mixed.

Miyagi says the viscous layer in the lower mantle may be what separates the sources of the two different magmas that supply the two different kinds of volcanoes.

Another implication of the stiff layer is that “if you decrease the ability of the rock in the mantle to mix, it’s also harder for heat to get out of the Earth, which could mean Earth’s interior is hotter than we think,” Miyagi says.

He says scientists believe the average temperature and pressure 410 miles deep at the upper-lower mantle boundary is 2,800 degrees Fahrenheit and 235,000 times the atmospheric pressure on Earth’s surface. He calculates that at the viscous layer’s stiffest area, 930 miles deep, the temperature averages 3,900 degrees Fahrenheit and pressure is 640,000 times the air pressure at Earth’s surface.

Studying Earth’s interior by squeezing crystals

Such conditions prevent geophysicists from visiting Earth’s mantle, so “we know a lot more about the surface of Mars than we do Earth’s interior,” Miyagi says. “We can’t get down there, so we have to do experiments to see how these minerals behave under a wide range of conditions, and use that to simulate the behavior of the Earth.”

To do that, “you take two gem quality diamonds and trap a sample between the tips,” he says. “The sample is about the diameter of a human hair. Because the diamond tips are so small, you generate very high pressure just by turning the screws on the press by hand with Allen wrenches.”

Using diamond anvils, the researchers squeezed thousands of crystals of ferropericlase at pressures up to 960,000 atmospheres. They used ferropericlase with 10 percent and 20 percent iron to duplicate the range found in the mantle.

To observe and measure the spacing of atoms in ferropericlase crystals as they were squeezed in diamond anvils, the geophysicists bombarded the crystals with X-rays from an accelerator at Lawrence Berkeley National Laboratory in California, revealing the strength of the mineral at various pressures and allowing the simulations showing how the rock becomes 300 times more viscous at the 930-mile depth than at 410 miles.

The finding was a surprise because researchers previously believed that viscosity varied only a little bit at temperatures and pressures in the planet’s interior.

The study’s simulations also determined that just below the 930-mile-deep zone of highest viscosity, slabs sink more easily again as the lower mantle becomes less stiff, which happens because atoms can move more easily within ferropericlase crystals.

Descending slabs have been seen as deep as the core-mantle boundary 1,800 miles underground. As the bottom of the conveyor-belt-like mantle slowly moves, the slabs mix with the surrounding rock before the mixture erupts anew millions of years later and thousands of miles away at midocean ridges.

Carnufex carolinensis : predator roles before dinosaurs

A newly discovered crocodilian ancestor may have filled one of North America’s top predator roles before dinosaurs arrived on the continent. Carnufex carolinensis, or the “Carolina Butcher,” was a 9-foot long, land-dwelling crocodylomorph that walked on its hind legs and likely preyed upon smaller inhabitants of North Carolina ecosystems such as armored reptiles and early mammal relatives.

Paleontologists from North Carolina State University and the North Carolina Museum of Natural Sciences recovered parts of Carnufex‘s skull, spine and upper forelimb from the Pekin Formation in Chatham County, North Carolina. Because the skull of Carnufex was preserved in pieces, it was difficult to visualize what the complete skull would have looked like in life. To get a fuller picture of Carnufex‘s skull the researchers scanned the individual bones with the latest imaging technology — a high-resolution surface scanner. Then they created a three-dimensional model of the reconstructed skull, using the more complete skulls of close relatives to fill in the missing pieces.

This is a life reconstruction of Carnufex carolinensis. Credit: Copyright Jorge Gonzales

This is a life reconstruction of Carnufex carolinensis.
Credit: Copyright Jorge Gonzales

The Pekin Formation contains sediments deposited 231 million years ago in the beginning of the Late Triassic (the Carnian), when what is now North Carolina was a wet, warm equatorial region beginning to break apart from the supercontinent Pangea. “Fossils from this time period are extremely important to scientists because they record the earliest appearance of crocodylomorphs and theropod dinosaurs, two groups that first evolved in the Triassic period, yet managed to survive to the present day in the form of crocodiles and birds,” says Lindsay Zanno, assistant research professor at NC State, director of the Paleontology and Geology lab at the museum, and lead author of a paper describing the find. “The discovery of Carnufex, one of the world’s earliest and largest crocodylomorphs, adds new information to the push and pull of top terrestrial predators across Pangea.”

Typical predators roaming Pangea included large-bodied rauisuchids and poposauroids, fearsome cousins of ancient crocodiles that went extinct in the Triassic Period. In the Southern Hemisphere, “these animals hunted alongside the earliest theropod dinosaurs, creating a predator pile-up,” says Zanno. However, the discovery of Carnufex indicates that in the north, large-bodied crocodylomorphs, not dinosaurs, were adding to the diversity of top predator niches. “We knew that there were too many top performers on the proverbial stage in the Late Triassic,” Zanno adds. “Yet, until we deciphered the story behind Carnufex, it wasn’t clear that early crocodile ancestors were among those vying for top predator roles prior to the reign of dinosaurs in North America.”

As the Triassic drew to a close, extinction decimated this panoply of predators and only small-bodied crocodylomorphs and theropods survived. “Theropods were ready understudies for vacant top predator niches when large-bodied crocs and their relatives bowed out,” says Zanno. “Predatory dinosaurs went on to fill these roles exclusively for the next 135 million years.”

Still, ancient crocodiles found success in other places. “As theropod dinosaurs started to make it big, the ancestors of modern crocs initially took on a role similar to foxes or jackals, with small, sleek bodies and long limbs,” says Susan Drymala, graduate student at NC State and co-author of the paper. “If you want to picture these animals, just think of a modern day fox, but with alligator skin instead of fur.”

Beetles beat out extinction ?

Today’s rich variety of beetles may be due to an historically low extinction rate rather than a high rate of new species emerging, according to a new study. These findings were revealed by combing through the fossil record.

“Much of the work to understand why beetles are diverse has really focused on what promotes speciation,” says lead author Dena Smith, Curator of Invertebrate Paleontology and Associate Professor of Geological Sciences at the University of Colorado Museum of Natural History. “By looking at the fossil history of the group, we can see that extinction, or rather lack of extinction may be just as important, if not more important, than origination. Perhaps we should be focusing more on why beetles are so resistant to extinction.” Smith’s study with her coauthor, Jonathan Marcot, Research Assistant Professor of Animal Biology at the University of Illinois, will appear in the Proceedings of the Royal Society B.

To fully explore the evolution of the insect order, Coleoptera, Smith and Marcot used publications that document the fossil record of beetles from international literature as far back as the early 19th century and open access database projects including the EDNA Fossil Insect Database and the Catalogue of Fossil Coleoptera. The team constructed a database of 5,553 beetle species from 221 unique locations. Given the patchy nature of the data at the species level, they performed analyses at the family level and found that the majority of families that are living today also preserved in the fossil record.

The study explores beetles as far back as their origins in the Permian period, 284 million years ago. When compared to the fossil record of other animal groups such as clams, corals, and vertebrates, beetles have among the lowest family-level extinction rates ever calculated. In fact, no known families in the largest beetle subgroup, Polyphaga, go extinct in their evolutionary history. The negligible beetle extinction rate is likely caused by their flexible diets, particularly in the Polyphaga, which include algae, plants, and other animals.

“There are several things about beetles that make them extremely flexible and able to adapt to changing situations,” Smith says. She points to beetles’ ability to metamorphose–a trait shared by many insects–when considering their environmental flexibility. Soft-bodied larvae vary greatly from winged, exoskeleton-ensconced adults. “This means that they can take advantage of very different types of habitats as a larva and then as an adult,” she adds. “Adult beetles can be highly mobile and research that has focused on glacial-interglacial cycles has shown that they can move quickly in response to any climate fluctuations.”

The study explores beetles as far back as their origins in the Permian period, 284 million years ago. Both authors emphasize that illustrating such a history would not have been possible without the fossil record–an often underutilized resource in exploring the evolution of insects.

“I think people have been hesitant to jump into studying insect fossils because there has been the misperception that they are so fragile and rarely fossilize,” Smith says. “I am hoping that this study demonstrates that the fossil record is quite good and can be used in many ways to study the evolution of this diverse and important group.”

Marcot adds, “Not only have these groups gone un-studied, but there are certain things that we can learn from the fossil record that we just can’t learn any place else.”

The rich diversity seen in modern-day beetles could have more to do with extinction resistance than a high rate of new species originations. Credit: Dena Smith

The rich diversity seen in modern-day beetles could have more to do with extinction resistance than a high rate of new species originations.
Credit: Dena Smith

Other insect groups might be similar to Coleoptera in terms of their extinction resistance, and Smith hopes that their work will inspire other entomologists to delve into the fossil record of their favorite insect. For now she is actively working to digitize more fossil specimens, paving the way for future studies to be conducted on a finer scale. The project, known as the Fossil Insect Collaborative and funded by the National Science Foundation, is expected to make available more than half a million fossil insect specimens from the major U.S. collections–many with associated images–in a searchable online database.

“Being a curator of a museum collection, I know that there are many species in our cabinets that have not yet been studied and described,” Smith says. “Once we are able to bring those specimens out of the cabinets and make them more accessible to the broader research community, I think we will be able to look at species level patterns and other really interested questions about the macroevolutionary history of insect groups.”

Rise of East African Plateau dated by whale fossil

A 17-million-year-old whale fossil is helping scientists pinpoint when the East African Plateau started to rise. Determining when the uplift happened has implications for understanding human evolution, scientists say.

Shifts in the Earth’s mantle pushed the East African Plateau upward sometime between 17 million and 13.5 million years ago, researchers report March 16 in the Proceedings of the National Academy of Sciences. Their analysis was based on a Turkana ziphiid fossil first discovered at the edge of the plateau in Kenya in 1964. The beaked whale’s skull was described in a 1975 paper, then misplaced until 2011, when it was rediscovered in a fossil collection kept at Harvard University.

A beaked whale that got stuck in a river 17 million years ago is helping to pinpoint when the East African Plateau began to rise.

A beaked whale that got stuck in a river 17 million years ago is helping to pinpoint when the East African Plateau began to rise.

Studying the fossil and the original field notes describing its discovery, the team, led by Henry Wichura of the University of Potsdam in Germany, determined that the whale must have swum up an ancient river and gotten stuck. Re-creating features of the ancient river suggests that the whale died and was buried in sediments that sat at an elevation only 24 to 37 meters above sea level. Its skull, however, were found at an elevation of 620 meters. That means the skull, and the sediments that held them, were pushed upward at least 590 meters in the last 17 million years.

This map shows the present elevation of the East African Plateau where the whale fossil was found. The region has undergone many geological changes, including massive uplift, an ancient lava flow, as well as rifting during the Jurassic and Cretaceous periods (200 million to 65.5 million years ago) and from the Miocene period (23 million years ago) to today.

This map shows the present elevation of the East African Plateau where the whale fossil was found. The region has undergone many geological changes, including massive uplift, an ancient lava flow, as well as rifting during the Jurassic and Cretaceous periods (200 million to 65.5 million years ago) and from the Miocene period (23 million years ago) to today.

Ancient lava flows show the plateau was already pushed upward by 13.5 million years ago, so the fossil find helps pinpoint the uplift to a 3.5 million year period, the researchers conclude. They note that the plateau’s rise changed the climate in the region from dense rainforest to drier open grassland, which may have driven human evolution.

Source: Article by Ashley Yeager in Science News

A Microrapter fossil from South Korea

A tiny dinosaur about the size of a house cat was recently discovered in South Korea.The dinosaur’s fossilized remains span about 11 inches, but scientists told Korea JoongAng Daily that it was likely about 20 inches long when it was alive.

“Based on the findings so far, we assume that the dinosaur is something close to a microraptor or others in the raptor genera,” Lim Jong-deock, chief curator of the National Research Institute of Cultural Heritage, told the news agency. “However, it’s uncertain at this stage exactly which type of dinosaur it was, and there is a chance that it is a new type that hasn’t been reported to academia as of yet.”

An illustration of a microraptor, which the dinosaur fossil closely resembles.

An illustration of a microraptor, which the dinosaur fossil closely resembles.

The tiny dino is a theropod, a family of carnivorous dinosaurs that includes Tyrannosaurus rex. That means it had sharp teeth and claws–only a whole lot smaller. And if it is indeed a microraptor, it would also have had four wings.

The dinosaur lived during the Cretaceous period, which ended some 66 million years ago with the Cretaceous-Tertiary mass extinction event.

The way this dinosaur has been fossilized is unique in that it was discovered with its vertebrae connected to its ribs,” the institute told the Korea Times.The institute also said there may be another fossilized dinosaur in the rock next to this one. Whatever the dinosaur turns out to be, it’s the first complete dinosaur skeleton found in South Korea, and among the smallest dinosaur fossils ever found in the country.

It is difficult for a small dinosaur to become fossilized and such fossils are very rare across the world,” an unnamed researcher from the National Research Institute of Cultural Heritage told Korea.net. “We need to conduct further research into whether the fossil is related to the Minisauripus, whose footprints were discovered in the southern areas of Gyeongsangnam-do.”

Source:  |  By

 

Aegirocassis benmoulae : A Giant paleo sea creature

Newly discovered fossils of a giant, extinct sea creature show it had modified legs, gills on its back, and a filter system for feeding — providing key evidence about the early evolution of arthropods.

The new animal, named Aegirocassis benmoulae in honor of its discoverer, Mohamed Ben Moula, attained a size of at least seven feet, ranking it among the biggest arthropods that ever lived. It was found in southeastern Morocco and dates back some 480 million years.

Aegirocassis is a truly remarkable looking creature,” said Yale University paleontologist Derek Briggs, co-author of a Nature paper describing the animal. “We were excited to discover that it shows features that have not been observed in older Cambrian anomalocaridids — not one but two sets of swimming flaps along the trunk, representing a stage in the evolution of the two-branched limb, characteristic of modern arthropods such as shrimps.”

Briggs is the G. Evelyn Hutchinson Professor of Geology and Geophysics at Yale and curator of invertebrate paleontology at the Yale Peabody Museum of Natural History. First author Peter Van Roy, an associate research scientist at Yale, led the research; Allison Daley of the University of Oxford is co-author.

Since their first appearance in the fossil record 530 million years ago, arthropods have been the most species-rich and morphologically diverse animal group on Earth. They include such familiar creatures as horseshoe crabs, scorpions, spiders, lobsters, butterflies, ants, and beetles. Their success is due in large part to the way their bodies are constructed: They have a hard exoskeleton that is molted during growth, and their bodies and legs are made up of multiple segments. Each segment can be modified separately for different purposes, allowing arthropods to adapt to every environment and mode of life.

Artist's rendering of Aegirocassis benmoulae. (Screenshot from video available at: https://www.youtube.com/watch?v=6KoqAA-RRnc) Credit: Reconstruction by Marianne Collins, ArtofFact / Video from Yale Peabody Museum of Natural History

Artist’s rendering of Aegirocassis benmoulae. (Screenshot from video available at: https://www.youtube.com/watch?v=6KoqAA-RRnc)
Credit: Reconstruction by Marianne Collins, ArtofFact / Video from Yale Peabody Museum of Natural History

Modern arthropod legs, in their most basic form, have two branches. Each is highly modified to cater to a specific function on that leg, such as locomotion, sensing its surroundings, respiration, or copulation; or it has been lost altogether. Understanding how these double-branched limbs evolved has been a major question for scientists.

A long-extinct group of arthropods, the anomalocaridids, is considered central to the answer. The youngest known anomalocaridids are 480 million years old, and all of them looked quite alien: They had a head with a pair of grasping appendages and a circular mouth surrounded by toothed plates. Their elongate, segmented bodies carried lateral flaps that they used for swimming. Until now, it was believed that anomalocaridids had only one set of flaps per trunk segment, and that they may have lost their walking legs completely.

But the recent discovery of Aegirocassis benmoulae tells another story. The new animal shows that anomalocaridids in fact had two separate sets of flaps per segment. The upper flaps were equivalent to the upper limb branch of modern arthropods, while the lower flaps represent modified walking limbs, adapted for swimming. Furthermore, a re-examination of older anomalocaridids showed that these flaps also were present in other species, but had been overlooked. These findings show that anomalocaridids represent a stage before the fusion of the upper and lower branches into the double-branched limb of modern arthopods.

“It was while cleaning the fossil that I noticed the second, dorsal set of flaps,” said Van Roy, who spent hundreds of hours working on the specimens. “It’s fair to say I was in shock at the discovery, and its implications. It once and for all resolves the debate on where anomalocaridids belong in the arthropod tree, and clears up one of the most problematic aspects of their anatomy.”

Aegirocassis benmoulae is also remarkable from an ecological standpoint, note the researchers. While almost all other anomalocaridids were active predators that grabbed their prey with their spiny head limbs, the Moroccan fossil has head appendages that are modified into an intricate filter-feeding apparatus. This means that the animal could harvest plankton from the oceans.

“Giant filter-feeding sharks and whales arose at the time of a major plankton radiation, and Aegirocassis represents a much, much older example of this — apparently overarching — trend,” Van Roy said.

 Reference:

  1. Peter Van Roy, Allison C. Daley, Derek E. G. Briggs. Anomalocaridid trunk limb homology revealed by a giant filter-feeder with paired flaps. Nature, 2015; DOI: 10.1038/nature14256 & Yale University. “Giant sea creature hints at early arthropod evolution.” ScienceDaily. ScienceDaily, 12 March 2015. <www.sciencedaily.com/releases/2015/03/150312083651.htm>.

Pockmarks :Linking Geology and Microbiology

Linking Geology and Microbiology: Inactive Pockmarks Affect Sediment Microbial Community Structure

Pockmarks are geological features that are found on the bottom of lakes and oceans all over the globe. Some are active, seeping oil or methane, while others are inactive. Active pockmarks are well studied since they harbor specialized microbial communities that proliferate on the seeping compounds. Such communities are not found in inactive pockmarks. Interestingly, inactive pockmarks are known to have different macrofaunal communities compared to the surrounding sediments. It is undetermined what the microbial composition of inactive pockmarks is and if it shows a similar pattern as the macrofauna. The Norwegian Oslofjord contains many inactive pockmarks and they are well suited to study the influence of these geological features on the microbial community in the sediment. Here we present a detailed analysis of the microbial communities found in three inactive pockmarks and two control samples at two core depth intervals. The communities were analyzed using high-throughput amplicon sequencing of the 16S rRNA V3 region. Microbial communities of surface pockmark sediments were indistinguishable from communities found in the surrounding seabed. In contrast, pockmark communities at 40 cm sediment depth had a significantly different community structure from normal sediments at the same depth. Statistical analysis of chemical variables indicated significant differences in the concentrations of total carbon and non-particulate organic carbon between 40 cm pockmarks and reference sample sediments. We discuss these results in comparison with the taxonomic classification of the OTUs identified in our samples. Our results indicate that microbial communities at the sediment surface are affected by the water column, while the deeper (40 cm) sediment communities are affected by local conditions within the sediment.

Bathymetric map of the sampling area in the Oslofjord.  The red crosses indicate the sampling sites and the sampling site designation is given. The map was generated with the www.mareano.no website.  doi:10.1371/journal.pone.0085990.g001

Bathymetric map of the sampling area in the Oslofjord.
The red crosses indicate the sampling sites and the sampling site designation is given. The map was generated with the www.mareano.no website.
doi:10.1371/journal.pone.0085990.g001

Citation: Haverkamp THA, Hammer Ø, Jakobsen KS (2014) Linking Geology and Microbiology: Inactive Pockmarks Affect Sediment Microbial Community Structure. PLoS ONE 9(1): e85990. doi:10.1371/journal.pone.0085990

Editor: Hauke Smidt, Wageningen University, Netherlands

Foraminifera reveal ancient temperatures

New research in Nature Communications showing how tiny creatures drifted across the ocean before falling to the seafloor and being fossilised has the potential to improve our understanding of past climates.

The research published in Nature Communications has identified which planktic foraminifera gathered up in core samples from the ocean floor, drifted thousands of kilometres and which species barely moved at all.The research will help scientists to more accurate distinguish which fossils most accurately reflect ocean and temperature states in the location where they were found.

This is a microscopic photo of the foraminifer Globigerinoides ruber, which is used in this study. Credit: Frank J.C. Peeters, VU University Amsterdam

This is a microscopic photo of the foraminifer Globigerinoides ruber, which is used in this study.
Credit: Frank J.C. Peeters, VU University Amsterdam

“This research will help scientists improve the study of past climates because they will be able to look at a species of foraminifera and the core location to very quickly get a sense of how site-specific that particular proxy measure is,” said Dr Van Sebille, lead-author of the study and a climate scientist at the ARC Centre of Excellence for Climate System Science at UNSW Australia.

“In a way it will give us a good indication of whether the creature we are looking at to get our past-temperature estimates was a bit of a globetrotter or a stay at home type.”

For many decades, deriving past temperatures from the shells of creatures living tens of thousands of years ago has been key to understanding climates of the past.However, interpreting the records has never been easy. This is the reason that many studies have very large margins of error when they use ocean sediments as a way of establishing past temperatures. It also explains why there is a greater focus on the trend of these results over the actual temperature.

“The older the proxy, the wider the margin of error. This is because ocean currents can change, tectonic plates move and there is even variation in which level of the ocean various plankton can be found,” said Dr Scussolini, a contributing author and climate scientist at VU University, Amsterdam.

“This research allows us for the first time to grasp the margins of error caused by drift and also opens an entirely new dimension for the interpretation of the deep-sea climate data.”

The international team used state-of-the-art computer models and analysis on fossil shells to investigate the impact of oceanic drift. In extreme cases the variation in temperature between where the fossilised shell was found and where it came from could be up to 3°C.In other cases for specific plankton and in areas of the ocean where currents were particularly slow, the variation in temperature was negligible.

As a result, the team is now working on creating a tool, so fellow researchers can easily estimate how large the impact of drift for the location is likely to be. This tool will also be extended to other species of plankton.

“Our results highlight the importance of the ocean currents in transporting anything that floats,” said Dr Van Sebille.

“By picking apart this variation we can add another level of certainty to estimates of past temperatures, opening a door that may help us discover what future climate change may bring to our planet.”