This is seismic reflection data. Credit: Morelia Urlaub and colleagues, and Geology.
The biggest landslides on Earth aren’t on land, but on the seafloor. These mega-slides can move thousands of cubic kilometers of material, and sometimes trigger tsunamis. Yet, remarkably, they occur on nearly flat slopes of less than three degrees.
Morelia Urlaub, a marine geoscientist at the Geomar Helmholtz Center for Ocean Research in Kiel, Germany, voices the obvious question: “How can you fail on a slope that is so flat?” Now, Urlaub and colleagues may have discovered the answer. The smoking — or in this case, oozing — gun is a layer of siliceous microfossils called diatoms.
The study, published online ahead of print for the Geological Society of America’s journal Geology, is the first to identify the weak layer responsible for a submarine mega-slide. Although the nature of these critical weak layers has been highly debated, studying them has been nearly impossible because they are typically destroyed along with the slides.
Urlaub was compiling ocean drilling data from 1980 when she realized that the core sampled the seafloor just outside the Cap Blanc slide, a 149,000 year-old mega-slide off the coast of northwest Africa. She correlated that data with high resolution seismic reflection data recorded in the same area in 2009. Together, these data revealed diatom-rich layers, up to ten meters thick, that traced directly from the core to the base of slide layers within the mega-slide complex.
What’s more, each diatom layer was topped by a layer of clay-rich sediment. That clay is apparently key. “Diatom layers are very compressible and water rich,” Urlaub says. As pressure builds, she explains, water would be squeezed from the diatom layer into the clay. Ultimately the clay or the interface between the clay and diatoms fails, sending the sediments above sliding.
At the Cap Blanc slide, the seafloor slopes at just 2.8 degrees. Yet when it broke loose, the slide transported over 30 cubic kilometers of material, and extended at least 35 kilometers. Another submarine mega-slide 8,500 years ago off Norway moved a staggering 3,000 cubic kilometers, causing a damaging tsunami. And some scientists speculate that the 2011 Tohoku tsunami in Japan may have been amplified by a submarine mega-slide.
Although such slides don’t occur very often, says Urlaub, their size makes them quite significant. “One-fifth of all tsunamis may be caused by undersea mega-slides,” she says. If diatom layers are a major factor, then understanding where paleoclimate conditions may have favored diatom growth might help reveal potential mega-slide sites.
Reference:
Diatom ooze: Crucial for the generation of submarine megaslides?
M. Urlaub, Jacob Geersen, Sebastian Krastel, and Tilmann Schwenk. Geology: DOI: 10.1130/G39892.1
Carbon levels around 3 million years ago were similar to those of today and temperatures were even warmer. If something so significant is mirrored in the past, what else can we learn about extreme climate changes?
Three million years ago the Earth’s climate was warm enough to permit a forested High Arctic inhabited by large mammals. If the idea of melting icebergs, rising sea levels and 400 parts per million of carbon dioxide in the atmosphere sounds all too familiar – welcome to the Pliocene.
For many researchers, the Pliocene, which lasted from 5.3 million to 2.6 million years ago, is our best reference for today’s warming. It was the last time atmospheric CO2 levels were similar to today’s, trapping heat and raising global temperatures to above the levels Earth is experiencing now. A better understanding of the response of the ice sheets to increasing temperature is needed to make more rigorous projections of how much sea level change could be expected in the future.
We live in uncertain times when it comes to the impact of climate change and global warming, so any insights we can gain from the past is an area of scientific interest. EU support under the PLIOTRANS fellowship is helping to further our understanding of the responses of the ice sheets to a warming climate.
When it comes to ice sheets, one size does not fit all
Recent research by a team of scientists, including PLIOTRANS, has been considering how the planet responded to Pliocene warmth. They have published a new paper presenting, for the first time, the transient nature of ice sheets and sea level during the late Pliocene. They show that the Greenland and Antarctic ice sheets might have responded differently to Pliocene heat, melting at different times.
Their transient ice sheet predictions are forced by multiple climate snapshots derived from a climate model set up with late Pliocene boundary conditions with different orbital forcing scenarios appropriate to two Marine Isotope Stages (MISs): KM5c (from 3.226 to 3.184 million years ago), and K1 (from 3.082 to 3.038 million years ago).
Their findings support previous studies, which have shown model results indicate peak MIS KM5c and K1 interglacial temperatures were not globally synchronous: there are leads and lags in temperature in different regions.
When it comes to modeling, this highlights the potential pitfalls of aligning peaks in proxy-derived temperatures across geographically diverse data sites. A single climate model simulation for an interglacial event is inadequate to capture peak temperature change in all regions.
The team explains, ‘We present a first step toward a fully coupled system of ice volume and climate variability across the late Pliocene (…) The model simulations presented here attempt to capture the transient response of climate and ice volume to orbital variations.’
The shape of the Earth’s orbit, the tilt of its axis and the fact that it wobbles, all have a part to play
The episodic nature of the Earth’s glacial and interglacial periods within the present Ice Age (the last couple of million years) have been caused primarily by cyclical changes in the Earth’s circumnavigation of the Sun. The study found that when the cyclical change known as precession variability is large, caution is advised when directly inferring the behaviour of ice sheets from oxygen isotope records in the Pliocene.
Their simulations indicate that the asynchronous response of ice sheets, combined with their transient modelling, is indeed a key factor in predicting orbital timescale sea level for a climate that is warmer than ours is now.
The PLIOTRANS (PLIOcene TRANSient Climate Modelling: Towards a global consensus between ice volume, temperature and relative sea level for the Late Pliocene) fellowship ended last year. Its goal was to reduce the uncertainties associated with future projections of sea-level change.
Note: The above post is reprinted from materials provided by CORDIS.
More than 100 species of cockroaches were used in the new genomic study. Credit: Cameron Richardson and Nathan Lo
Cockroaches are so hardy, a popular joke goes, that they’ve occupied the Earth long before humans first appeared — and will probably even outlast us long after we have annihilated each other by nuclear war.
But now, researchers have used the latest in genomic data to gain the most detailed information yet of their evolutionary history.
Armed with a vast amount of genomic information, a team of researchers led by Dr. Thomas Bourguignon, now professor at the Okinawa Institute of Science and Technology, has performed the first molecular dating to gain the clearest picture yet of the biogeographical history of cockroaches.
They have traced back the key evolutionary time points of the cockroach — all the way back almost 300 million years ago when the Earth’s mass was organized into the Pangaea supercontinent.
This fossil record of cockroaches suggests that most extant families evolved during the breakup of Pangaea (which began ~200 Ma) and prior to the beginning of continental separation within Gondwana (~135 Ma).
“Our results indicate that extant cockroach families have evolved over periods of up to ~180 million years,” said Bourguignon. “Through reconstructions of the ancestral distribution of cockroaches using the known distributions of extant genera sampled in this study, we found evidence that continental breakup has had important impacts on cockroach biogeography.”
To do so, they estimated divergence times of all living cockroach families, based on the complete mitochondrial genomes of 119 cockroach species (and to help their molecular dating, compared with 13 termites, seven mantis and multiple other outgroups).
Their estimates indicate that the last common ancestor for cockroaches appeared much earlier than fossil evidence, around 235 million years ago. This was about 95 million years before the appearance of the first fossils attributed to modern cockroaches during the Cretaceous period around 140 million years ago, and before Pangaea broke up.
Since cockroaches can’t fly very far, and for the most part would be terrestrially bound, one of the more appealing aspects of the study was to compare the cockroach divergence time with the geological history of the Earth.
The authors speculate that, like riding a raft, cockroaches spread to every part of the globe through the seismic continental drifts that occurred during the transition from Pangaea. This is illustrated by many sister cockroach lineages, which diverged prior Gondwana breakup, and diversified on their respective continental plates. But, in addition, within younger cockroach lineages, they did find evidence of transoceanic dispersal in regions near Australia and Indo-Malaysia.
“We believe that our results point to an important role for vicariance (continental drift) in determining the global distributions of cockroaches,” said Bourguignon. “On a global scale, the fossil record also agrees with our hypothesis.”
The study underscores the importance of continental drift in shaping modern insect distribution, and will provide a new framework for future cockroach biogeographical research.
Reference:
Thomas Bourguignon, Tang Qian, Simon Y W Ho, Frantisek Juna, Zongqing Wang, Daej A Arab, Stephen L Cameron, James Walker, David Rentz, Theodore A Evans, Nathan Lo. Transoceanic dispersal and plate tectonics shaped global cockroach distributions: evidence from mitochondrial phylogenomics. Molecular Biology and Evolution, 2018; DOI: 10.1093/molbev/msy013
Fluorite can appear to be almost any colour (Credit: Dirk Wiersma/SPL)
Forget rubies, garnets and sapphires. Fluorite may be the world’s most colourful mineral, because of the enormous range of brilliant and even iridescent colours it displays.
The funny thing is, pure fluorite crystals are transparent.
A crystal’s colour is dictated by the way light interacts with the chemicals in it, and by how these are bonded in an orderly structure, or lattice. Any impurities that work their way into fluorite’s lattice can alter its apparent colour. For example, manganese ions turn it orange.
Structural defects within the lattice, known as colour centres, have a similar effect.
Fluorite’s hallmark deep purple hue is the result of a small number of fluoride ions being permanently forced out of their lattice positions by irradiation or heating. When they move, an electron is left behind in each hole. When light hits the crystal, it is absorbed and re-emitted by these electrons, producing the colour we see.
Some fluorite specimens even have bands of different colours.
Fluorite forms in hydrothermal veins in the Earth’s crust and in cavities in sedimentary rocks. Over the centuries, these fissures are constantly opening and closing, sometimes cutting off the fluids needed for fluorite to form. It’s the subtle changes in the chemistry of these fluids that causes colour zoning in the crystals as they grow.
Selenite
Giant selenite crystals in the Cueva de los Cristales (Credit: Javier Trueba/MSF/NPL)
Buried beneath the Sierra de Naica mountain in Chihuahua, northern Mexico, the Cueva de los Cristales (Cave of Crystals) is home to the largest crystals on planet Earth.
Gargantuan, milky white beams of selenite, some as long as 11m and more than 1m wide, criss-cross the underground chamber. “There is no other place on the planet where the mineral world reveals itself in such beauty,” says Juan Manuel García-Ruiz of the University of Granada in Spain, a geologist who studies the crystals.
The crystals were discovered in 2000 by two brothers excavating new tunnels in the Naica mine, in search of fresh reserves of zinc, silver, and lead.
The cavity, which measures about 10m by 30m, had previously been flooded with heated water. Only when the miners started pumping it out were the monumental structures revealed.
In 2007, García-Ruiz and his team figured out how the crystals were able to grow so big.
Around 26 million years ago, volcanic activity beneath the mine filled the cave with hot water rich in the mineral anhydrite. Anhydrite is stable above 58 °C, but as the underlying magma cooled, it dissolved into the surrounding water.
Very slowly, over hundreds of thousands of years, its chemical components reassembled as gypsum, which can take the form of crystals. Large elongate crystals of gypsum are known as selenite.
Within the Cueva de los Cristales, the temperature has consistently hovered around the magic 58 °C mark ever since.
Another crystal cave, discovered closer to the surface in Naica, also contains selenites. They are still spectacular at about 1m in length, but not as large as those of the Cueva de los Cristales, because this cave cooled faster.
Iceland Spar
Iceland spar is a special form of calcite (Credit: Natural History Museum, London/SPL)
The Icelandic sagas of the 10th century record the details of Viking voyages. They describe a mysterious “sunstone”, which Scandinavian seafarers used to locate the Sun in the sky and navigate on cloudy days.
The identity of the stone stumped scholars for centuries, but in 2011 a convincing candidate was put forward: Iceland spar.
This clear variety of calcite is common in Nordic regions. It bends light by two different amounts, producing a double image (see the picture above).
This property is called birefringence. It’s caused by discrepancies in the binding forces that hold the atoms of the crystal together. The forces are stronger in some directions than others.
When light passes through calcite crystals, it is split into two rays. The asymmetry in the crystal’s structure causes the paths of these two beams to be bent by different amounts, resulting in a double image.
How did that help the Vikings? Researchers studied a piece of Iceland spar discovered aboard an Elizabethan ship that sunk in 1592. They found that moving the stone in and out of a person’s field of vision causes them to see a distinctive double dot pattern that lines up with the direction of the hidden Sun.
Quartz
Quartz is one of the most common crystals on Earth (Credit: Sinclair Stammers/SPL)
Quartz also does interesting things because of its structural asymmetries.
If you squeeze a crystal of quartz, it generates a tiny electric current. The pressure on the crystal’s surface forces ions within it to move out of position, upsetting the overall charge balance and turning the crystal into a tiny battery, with oppositely-charged faces.
The phenomenon is known as the piezoelectric effect, and it also works in reverse. Pass an electric current through a quartz crystal, and it will squeeze itself.
Quartz watches use tiny slivers of cut quartz as oscillators to keep precise time. Electricity from the watch battery causes the crystal to oscillate thousands of times per second, and circuits in the watch convert these oscillations to a once-per-second digital beat.
Quartz was also central to our developing understanding of crystals. In 1669, Danish scientist Nicolas Steno noticed that quartz crystals, irrespective of where on Earth they were found, always showed the same angles between similar crystal faces.
By the turn of the 19th century, French crystallographer René Just Haüy had extended this idea. He realised that the same rules underlie the shapes and angles of all crystals.
We now understand that the shapes of crystals are an expression, on a grand scale, of the orderly lattices in which their constituent atoms are arranged.
Galena
Galena is both a source of lead, and the makings of a radio (Credit: Martin Land/SPL)
Galena is the most common lead-rich mineral, and an important ore of both lead and silver. But that’s just its day job.
It’s the crystal’s ability to extract music and voices from radio waves that makes it truly beguiling. It put galena centre stage in the revolutionary crystal radio sets of the early 1900s.
Galena is a semiconductor, meaning that it will conduct electricity under certain circumstances. In metals, free electrons flow as electricity when a voltage is applied. In galena – a non-metal – small crystal impurities or imbalances in its chemical proportions create a situation where, if electrons can be excited enough, they can be ripped from their atoms and made to flow.
In a crystal radio set, a fine metal wire known as a “cat’s whisker” rests delicately on the surface of a galena crystal. This combination allows current to pass easily in one direction but not the other. This converts the oscillating radio waves picked up by an antenna into an electric signal that can be transformed into sound by speakers.
Not every position on the crystal will perform, so fiddling with the cat’s whisker to find a sweet spot takes patience and skill.
Extra-terrestrial carbon crystals
Diamond is the hardest known natural material on Earth. It is the industry standard for grinding, cutting, drilling and polishing jobs.
But two new kinds of ultra-hard carbon crystals, found embedded in a Finnish meteorite in 2010, put the precious stone to shame.
The Haverö meteorite crashed to Earth in 1971. When researchers used diamond paste to polish a slice, they noticed something extraordinary: small pockets of material emerging in relief from the surface. When they analysed the stubborn crystals, they discovered two completely new forms of carbon.
Diamond is so hard because the carbon atoms inside it are arranged in a tetrahedron-shaped lattice that is immensely strong. In Haverö, the researchers found crystalline carbon arranged in a rhombohedral lattice. This type of diamond was predicted to exist decades ago but had never been seen in nature.
The second substance turned out to be a totally new kind of crystalline carbon, which the researchers call “an intermediate between graphite and diamond”.
Graphite, like diamond, is made up entirely of carbon atoms. However, its atoms are arranged in honeycomb-like sheets. The sheets are only weakly attracted to each other, making it soft and slippery.
When the meteorite entered Earth’s atmosphere, the researchers think pressure shocks and intense heat fused sheets of graphite together, much like the way labs make artificial diamonds.
Unfortunately, the crystals are so small that no one has been able to test the limits of their hardness, nor compare them with the artificial ultra-hard diamonds lonsdaleite and boron nitride.
Autunite
Autunite fluoresces under ultraviolet light (Credit: Joel Arem/SPL)
Autunite is a mineral that the big kid in everyone can get excited about. Its tablet-shaped crystals look like lurid yellow-green scales, its uranium content makes it radioactive, and – the icing on the cake of cool – it fluoresces.
When ultraviolet light shines on an autunite crystal, it imparts energy to electrons within the crystal’s uranium atoms. Each excited electron jumps momentarily away from the nucleus of its atom, then falls back.
When the electrons drop back, they release bursts of visible light. The collective effect makes autunite appear to glow green.
Fluorescent minerals stop glowing when the ultraviolet light source is removed. Other minerals are phosphorescent: the electrons remain in an excited state for longer, so phosphorescent minerals continue to glow for a while even after the light is turned off.
Sugar
Give a sugar crystal a hard whack and it glows blue (Credit: Ted Kinsman/SPL)
Want to see a crystal glow, but don’t have access to a mineral library? No problem.
Get yourself some sugar cubes or polo mints, go to a pitch-black room, and use the bottom of a glass to smash them to pieces. You should see a fleeting faint blue glow emanate from the sugary treats. This is called triboluminescence.
Literally meaning “rub light”, it was first noted by 17th Century polymath Francis Bacon. Later, Robert Boyle observed that: “hard sugar being nimbly scraped with a knife would afford a sparkling light”.
Centuries later, quite how sugar can be triboluminescent is still a mystery.
Current theories postulate that when sugar crystals are scraped, fractured or crushed, their structural asymmetry encourages tiny piezoelectric fields to form. This separates positive and negative charges within the crystal, and when these charges recombine, a spark flies. Then, nitrogen molecules trapped within the crystals absorb this energy and luminesce, much as they do during a lightning storm.
If that’s true, triboluminescence is almost literally a storm in a teacup.
Biophotonic crystal
The spines of this sea mouse (Aphrodita sp.) are photonic (Credit: James King-Holmes/SPL)
Photonic crystals are tiny repeating structures, each about a billionth of a metre across. They can control and manipulate how light flows.
Depending on the angles of its faces, a photonic crystal will only allow certain wavelengths of light through, and blocks all the others. This determines its colour.
The blocked wavelengths are called “photonic band gaps”. Wavelengths near these band gaps tend to scatter and interfere with one another. This is what creates the vivid colours and striking iridescence of some insects, particularly butterflies and beetles, whose colours appear to change depending on the angle they’re viewed from.
Humans can make simple photonic crystals from synthetic polymers. We use them to create things like reflective coatings for sunglasses.
If we could only duplicate the most complex photonic structures – like those seen in beetles, butterflies, bees and spiders – we could use them to improve everything from fibre-optic technologies to solar cells.
So far, engineers have struggled to build precisely-organised three-dimensional structures on usable scales. However, new research into the way biophotonic crystals take shape in insects offers some promising pointers.
Volcanic ice crystals
Snow-like ice crystals in the caves of Mount Erebus (Credit: Chadden Hunter/NPL)
Mount Erebus in Antarctica is the southernmost active volcano in the world. Dotted around its summit is a network of ice caves, which harbour fragile ice formations that occur nowhere else on the planet.
The labyrinth of passages is carved into the snowpack by hot gases from the volcano, which seep out through cracks and fissures in the underlying rock. Within the caves, the warm, steamy air from the volcano hits the frigid walls, whereupon the moisture freezes into intricate, feathery shapes, guided by the air currents.
The resulting crystals look like clusters of snowflakes.
Craig Cary of the University of Waikato in New Zealand has spent time in the caves and was struck by the delicacy of the ice formations. “They hang down maybe half a metre from the ice ceiling, and it only takes the wind generated by a slowly passing body underneath to cause them to fall,” he says.
The crystals are an example of hoarfrost, which is formed when moisture condenses and freezes directly onto objects.
When ice grows slowly, as it does in liquid water, it forms solid hexagonal crystals. But if the water vapour is particularly thick, and there is space to grow, the ice will instead grow into the hexagonally symmetrical branching forms seen at Erebus.
Note: The above post is reprinted from materials provided by BBC Earth. The original article was written by Ceri Perkins.
Colored and black points mark the global distribution of mid-ocean ridges, with ages of 66 million years ago created at spreading rates above and below 35 millimeters a year, respectively. Colors indicate the maximum gravity anomaly within 2 degrees. Credit: Courtesy of Joseph Byrnes
The debate goes on: What killed off the dinosaurs?
New University of Oregon research has identified gravity-related fluctuations dating to 66 million years ago along deep ocean ridges that point to a “one-two punch” from the big meteor that struck off Mexico’s Yucatan peninsula, possibly triggering a worldwide release of volcanic magma that could have helped seal the dinosaurs’ fate.
“We found evidence for a previously unknown period of globally heighted volcanic activity during the mass-extinction event,” said former UO doctoral student Joseph Byrnes.
The study by Byrnes and Leif Karlstrom, a professor in the UO’s Department of Earth Sciences, was published Feb. 7 in Science Advances. It details a record of volcanism preserved along the mid-ocean ridges, which mark the oceanic boundaries of tectonic plates. The evidence comes from changes in the strength of gravity above the seafloor.
The findings of the UO’s National Science Foundation-supported study, Karlstrom said, point to a pulse of accelerated worldwide volcanic activity that includes enhanced eruptions at India’s Deccan Traps after the Chicxulub impact. The Deccan Traps, in west-central India, formed during a period of massive eruptions that poured out layers of molten rock thousands of feet deep, creating one of the largest volcanic features on Earth.
The Deccan Traps region has been in and out of the dinosaur debate. Rare volcanic events at such a scale are known to cause catastrophic disturbances to Earth’s climate, and, when they occur, they are often linked to mass extinctions. Huge volcanic events can eject so much ash and gas into the atmosphere that few plants survive, disrupting the food chain and causing animals to go extinct.
Since evidence of the meteor strike near present-day Chicxulub, Mexico, surfaced in the 1980s, scientists have debated whether the meteor or the Deccan Traps eruptions drove the extinction event that killed off all nonavian dinosaurs.
Progressively improving dating methods indicate that the Deccan Traps volcanoes already were active when the meteor struck. Resulting seismic waves moving through the planet from the meteor strike, Karlstrom said, probably fueled an acceleration of those eruptions.
“Our work suggests a connection between these exceedingly rare and catastrophic events, distributed over the entire planet,” Karlstrom said. “The meteorite’s impact may have influenced volcanic eruptions that were already going on, making for a one-two punch.”
That idea gained strength in 2015 when researchers at the University of California, Berkeley, proposed that the two events might be connected. That team, which included Karlstrom, suggested that the meteorite may have modulated distant volcanism by generating powerful seismic waves that produced shaking worldwide.
Similar to the impacts that normal tectonic earthquakes sometimes have on wells and streams, Karlstrom said, the study proposed that seismic shaking liberated magma stored in the mantle beneath the Deccan Traps and caused the largest eruptions there.
The new findings at the UO extend this eruption-triggering in India to ocean basins worldwide.
Byrnes, now a postdoctoral researcher at the University of Minnesota, analyzed publicly available global data sets on free-air gravity, ocean floor topography and tectonic spreading rates.
In his analyses, he divided the seafloor into 1-million-year-old groupings, constructing a record back to 100 million years ago. At about 66 million years, he found evidence for a “short-lived pulse of marine magmatism” along ancient ocean ridges. This pulse is suggested by a spike in the rate of the occurrence of free-air gravity anomalies seen in the data set.
Free-air gravity anomalies, measured in tiny increments call milligals, account for variations in gravitational acceleration, found from satellite measurements of additional seawater collecting where the Earth’s gravity is stronger. Byrnes found changes in free-air gravity anomalies of between five and 20 milligals associated with seafloor created in the first million years after the meteor.
Reference:
Joseph S. Byrnes, Leif Karlstrom. Anomalous K-Pg–aged seafloor attributed to impact-induced mid-ocean ridge magmatism. Science Advances, 2018; 4 (2): eaao2994 DOI: 10.1126/sciadv.aao2994
Note: The above post is reprinted from materials provided by University of Oregon. Original written by Jim Barlow, University Communications.
Underwater terrain revealed by the survey and points surveyed. Credit: Kobe University
Since the Kobe Ocean Bottom Exploration Center (KOBEC) was established in 2015, it has carried out three survey voyages to the Kikai Caldera, south of Japan’s main islands. Based on these voyages, researchers have confirmed that a giant lava dome was created after the caldera-forming supereruption 7300 years ago. The dome is in the world’s largest class of post-caldera volcano, with a volume of over 32 cubic kilometers. The composition of this lava dome is different from the magma that caused the giant caldera to erupt – it shows the same chemical characteristics as the current post-caldera volcano on the nearby Satsuma Iwo-jima Island. It is possible that currently a giant magma buildup may exist under the Kikai Caldera.
These findings were published in the online edition of Scientific Reports on February 9.
There is roughly a 1 percent chance of a giant caldera-forming eruption occurring within the Japanese archipelago during the next 100 years. An eruption like this would see over 40 cubic kilometers of magma released in one burst, causing enormous damage. The mechanism behind this and how to predict this event are urgent questions.
Researchers equipped training ship Fukae Maru, part of the Kobe University Graduate School of Maritime Sciences, with the latest observation equipment to survey the Kikai Caldera. They chose this volcano for two main reasons. Firstly, for land-based volcanoes it is hard to carry out large-scale observations using artificial earthquakes because of the population density, and it is also difficult to detect giant magma buildups with precise visualization because they are often at relatively low depths (roughly 10km). Secondly, the Kikai Caldera caused the most recent giant caldera-forming eruption in the Japanese archipelago (7300 years ago), and there is a high possibility that a large buildup of magma may exist inside it.
During the three survey voyages, KOBEC carried out detailed underwater geological surveys, seismic reflection, observations by underwater robots, samples and analysis of rocks, and observations using underwater seismographs and electromagnetometers.
In their upcoming March 2018 voyage, researchers plan to use seismic reflection and underwater robots to clarify the formation process of the double caldera revealed in previous surveys and the mechanism that causes a giant caldera eruption.
They will also use seismic and electromagnetic methods to determine the existence of a giant magma buildup, and in collaboration with the Japan Agency for Marine-Earth Science and Technology will carry out a large-scale underground survey, attempting to capture high-resolution visualizations of the magma system within the Earth’s crust (at a depth of approximately 30km). Based on results from these surveys, the team plans to continue monitoring and aims to pioneer a method for predicting giant caldera-forming eruptions.
Formation of metallic ore deposits are predicted to accompany the underwater hydrothermal activity, so the team also plan to evaluate these undersea resources.
Reference:
“Giant rhyolite lava dome formation after 7.3 ka supereruption at Kikai caldera, SW Japan” DOI:10.1038/s41598-018-21066-w
Earthquake simulation. Credit: Lawrence Livermore National Laboratory
In the next 30 years, there is a one-in-three chance that the Hayward fault will rupture with a 6.7 magnitude or higher earthquake, according to the United States Geologic Survey (USGS). Such an earthquake will cause widespread damage to structures, transportation and utilities, as well as economic and social disruption in the East Bay.
Lawrence Livermore and Lawrence Berkeley national laboratory scientists have used some of the world’s most powerful supercomputers to model ground shaking for a magnitude (M) 7.0 earthquake on the Hayward fault and show more realistic motions than ever before. The research appears in Geophysical Research Letters.
Past simulations resolved ground motions from low frequencies up to 0.5-1 Hertz (vibrations per second). The new simulations are resolved up to 4-5 Hertz (Hz), representing a four to eight times increase in the resolved frequencies. Motions with these frequencies can be used to evaluate how buildings respond to shaking
The simulations rely on the LLNL-developed SW4 seismic simulation program and the current best representation of the three-dimensional (3D) earth (geology and surface topography from the USGS) to compute seismic wave ground shaking throughout the San Francisco Bay Area. Importantly, the results are, on average, consistent with models based on actual recorded earthquake motions from around the world.
“This study shows that powerful supercomputing can be used to calculate earthquake shaking on a large, regional scale with more realism than we’ve ever been able to produce before,” said Artie Rodgers, LLNL seismologist and lead author of the paper.
The Hayward fault is a major strike-slip fault on the eastern side of the Bay Area. This fault is capable of M 7 earthquakes and presents significant ground motion hazard to the heavily populated East Bay, including the cities of Oakland, Berkeley, Hayward and Fremont. The last major rupture occured in 1868 with an M 6.8-7.0 event. Instrumental observations of this earthquake were not available at the time, however historical reports from the few thousand people who lived in the East Bay at the time indicate major damage to structures.
The recent study reports ground motions simulated for a so-called scenario earthquake, one of many possibilities.
“We’re not expecting to forecast the specifics of shaking from a future M 7 Hayward fault earthquake, but this study demonstrates that fully deterministic 3D simulations with frequencies up to 4 Hz are now possible. We get good agreement with ground motion models derived from actual recordings and we can investigate the impact of source, path and site effects on ground motions,” Rodgers said.
As these simulations become easier with improvements in SW4 and computing power, the team will sample a range of possible ruptures and investigate how motions vary. The team also is working on improvements to SW4 that will enable simulations to 8-10 Hz for even more realistic motions.
For residents of the East Bay, the simulations specifically show stronger ground motions on the eastern side of the fault (Orinda, Moraga) compared to the western side (Berkeley, Oakland). This results from different geologic materials — deep weaker sedimentary rocks that form the East Bay Hills. Evaluation and improvement of the current 3D earth model is the subject of current research, for example using the Jan. 4, 2018 M 4.4 Berkeley earthquake that was widely felt around the northern Hayward fault.
Ground motion simulations of large earthquakes are gaining acceptance as computational methods improve, computing resources become more powerful and representations 3D earth structure and earthquake sources become more realistic.
Rodgers adds: “It’s essential to demonstrate that high-performance computing simulations can generate realistic results and our team will work with engineers to evaluate the computed motions, so they can be used to understand the resulting distribution of risk to infrastructure and ultimately to design safer energy systems, buildlings and other infrastructure.”
Other Livermore authors include seismologist Arben Pitarka, mathematicians Anders Petersson and Bjorn Sjogreen, along with project leader and structural engineer David McCallen of the University of California Office of the President and LBNL.
This work is part of the DOE’s Exascale Computing Project (ECP). The ECP is focused on accelerating the delivery of a capable exascale computing ecosystem that delivers 50 times more computational science and data analytic application power than possible with DOE HPC systems such as Titan (ORNL) and Sequoia (LLNL), with the goal to launch a U.S. exascale ecosystem by 2021. The ECP is a collaborative effort of two Department of Energy organizations — the DOE Office of Science and the National Nuclear Security Administration.
Simulations were performed using a Computing Grand Challenge allocation on the Quartz supercomputer at LLNL and with an Exascale Computing Project allocation on Cori Phase-2 at the National Energy Research Scientific Computing Center (NERSC) at LBNL.
Reference:
Arthur J. Rodgers, Arben Pitarka, N. Anders Petersson, Björn Sjögreen, David B. McCallen. Broadband (0-4 Hz) Ground Motions for a Magnitude 7.0 Hayward Fault Earthquake With Three-Dimensional Structure and Topography. Geophysical Research Letters, 2018; DOI: 10.1002/2017GL076505
An image of a insect fossilized in amber. Credit: University of Otago
The discovery of fossil insects, nematodes and fungi preserved in amber from sites in Otago is shedding new light on New Zealand’s geological and biological history.
University of Otago paleontologists Associate Professor Daphne Lee and Dr. Uwe Kaulfuss, with Professor Alexander Schmidt of the University of Göttingen, co-led a team of international scientists in collecting and analyzing amber deposits from more than 30 sites throughout New Zealand.
The small and fragile fossils are 25 to 15 million years old and include a number of spiders (including web remains with prey), tiny carnivores such as pseudoscorpions, diverse soil-dwelling mites, detritivores such as springtails, biting and gall midges, fungus gnats and chironomids, scale insects, parasitoid wasps, ants, beetles, and bark lice.
“Some of the arthropods and fungi represent the first fossil records of their groups from the entire Southern Hemisphere,” Associate Professor Lee explains.
Hundreds of kilograms of amber were extracted from lignite deposits, largely near Roxburgh, Hyde and Pomahaka, in Otago. Preparation of the commonly opaque, and often brittle and/or fractured amber to expose inclusions for study is challenging. However, new techniques developed in Professor Schmidt’s laboratory in Germany revealed numerous fossils with 3-D preservation.
The amber derives from the ancestors of the kauri, resin-producing conifers belonging to the Araucariaceae family which still live today in northern New Zealand.
“This means that the source of the resin has remained unchanged for at least the past 25 million years. The amber fossils help in understanding the evolution of these long-lasting forest ecosystems on a geologic time scale,” Associate Professor Lee adds.
Amber, fossilized tree resin, preserves life forms, providing access to delicate organisms that are otherwise rare or absent from the fossil record.
Amber deposits are concentrated in the Northern Hemisphere where their inclusions have been studied intensively. Until now, the scarcity of major deposits from the Southern Hemisphere has severely hampered understanding of the global evolutionary history of terrestrial invertebrate and fungal biotas.
Dr. Kaulfuss says the fossils are significant because of what they tell us about the country’s ecological history, as a long-isolated former Gondwanan landmass.
“These fossils are really important for us because they provide a very rare opportunity to look back on what made up New Zealand’s forest and ecosystem 25 million-years-ago.
“We now know what kind of animals and plants were around at that time and what has gone extinct since then.”
Reference:
Alexander R. Schmidt et al. Amber inclusions from New Zealand, Gondwana Research (2017). DOI: 10.1016/j.gr.2017.12.003
Researchers at the University of Birmingham have discovered that the mass extinction seen in plant species caused by the onset of a drier climate 307 million years ago led to extinctions of some groups of tetrapods, the first vertebrates to live on land, but allowed others to expand across the globe. This research is published today (7th February 2018) in the journal Proceedings of the Royal Society B.
The Carboniferous and Permian periods (358 — 272 million years ago) were critical intervals in the evolution of life on land. During the Carboniferous Period North America and Europe lay in a single land mass at the equator which was covered by dense tropical rainforests. These rainforests flourished because of the warm humid climate, providing an ideal habitat for early tetrapods (vertebrates with four limbs), allowing them to diversify into a variety of species.
But towards the end of this period a major global environment change took place — just as the number of tetrapod species began to increase, the rainforests started to disappear. The climate became much drier causing the mass extinction of many species within the dominant plant groups, such as horsetails and club mosses. Despite this being a catastrophic event for plants, it has been unclear how this affected the early tetrapod community.
Previous attempts to estimate the diversity changes during this period have been hindered by the fossil record, which has not been sampled equally in different time intervals or geographic areas. To fill these gaps in the data, the Birmingham researchers compiled a new dataset from the Paleobiology Database and used advanced statistical methods to estimate diversity and biogeographic changes.
The results of the study show that tetrapod diversity decreased after the rainforest collapse and the onset of drier conditions, largely due to the reduction in suitable habitats for amphibians which needed wet environments to survive.
However they also found that after the rainforest collapse surviving tetrapod species began to disperse more freely across the globe, colonising new habitats further from the equator. Many of these survivors were early amniotes, such as early reptiles, whose generally larger size relative to early amphibians allowed them to travel longer distances, and their ability to lay eggs meant they were not confined to watery habitats.
Emma Dunne, from the University of Birmingham’s School of Geography, Earth and Environmental Sciences, said: ‘This is the most comprehensive survey ever undertaken on early tetrapod evolution, and uses many newly developed techniques for estimating diversity patterns of species from fossil records, allowing us greater insights into how early tetrapods responded to the changes in their environment.’
Dunne continued: ‘We now know that the rainiforest collapse was crucial in paving the way for amniotes, the group which ultimately gave rise to modern mammals, reptiles and birds, to become the dominant group of land vertebrates during the Permian period and beyond.’
Reference:
Dunne E, Close R, Button D, Brocklehurst N, Cashmore D, Lloyd G, Butler R. Diversity change during the rise of tetrapods and the impact of the ‘Carboniferous Rainforest Collapse’. Proceedings of the Royal Society B, January 19, 2018 DOI: 10.5061/dryad.n4k45
It is widely accepted that the Earth’s inner core formed about a billion years ago when a solid, super-hot iron nugget spontaneously began to crystallize inside a 4,200-mile-wide ball of liquid metal at the planet’s center.
One problem: That’s not possible-or, at least, has never been easily explained-according to a new paper published in Earth and Planetary Science Letters from a team of scientists at Case Western Reserve University.
The research team-comprised of post-doctoral student Ludovic Huguet; Earth, Environmental, and Planetary Sciences professors James Van Orman and Steven Hauck II; and Materials Science and Engineering Professor Matthew Willard-refer to this enigma as the “inner-core nucleation paradox.”
That paradox goes like this: Scientists have known for more than 80 years that a crystallized inner core exists. But the Case Western Reserve team asserts that this widely accepted idea neglects one critical point-one that, once added, would suggest the inner core shouldn’t exist.
Here’s why: While it is well known that a material must be at or below its freezing temperature to be solid, it turns out that making the first crystal from a liquid takes extra energy. That extra energy-the nucleation barrier-is the ingredient that models of Earth’s deepest interior have not included until now.
To overcome the nucleation barrier and start to solidify, however, the liquid has to be cooled well below its freezing point-what scientists call “supercooling.”
Alternatively, something different has to be added to the liquid metal of the core-at the center of the planet-that substantially reduces the amount of required supercooling.
But the nucleation barrier for metal-at the extraordinary pressures at the center of the Earth-is enormous.
“Everyone, ourselves included, seemed to be missing this big problem-that metals don’t start crystallizing instantly unless something is there that lowers the energy barrier a lot,” Hauck said.
The Case Western Reserve team contends the most obvious solutions are suspect:
” That the inner core was somehow subjected to a massive supercooling of about 1,800 degrees Fahrenheit (1,000 Kelvin)-well beyond the amount of cooling scientists have concluded. If the Earth’s center had reached this temperature, nearly the entire core should be crystallizing rapidly, but the evidence indicates that it is not.
“That something happened to lower the nucleation barrier, allowing crystallization to occur at a higher temperature. Scientists do this in the lab by adding a piece of solid metal to a slightly supercooled liquid metal, causing the now-heterogeneous material to quickly solidify. But it’s difficult to figure on an earth-sized scale how this could have happened, how a nucleation enhancing solid could have found its way to the center of the planet to allow for the hardening (and expansion) of the inner core, Huguet said.
“So, if the core is a pure (homogenous) liquid, the inner core shouldn’t exist at all because it could not have been supercooled to that extent,” Van Orman said. “And if it’s not homogeneous, how did it become so?
“That’s the inner-core nucleation paradox.”
Possible answers
Then how did the solid inner core form?
At the moment, the team’s favored idea is akin to the second solution above: that large bodies of solid metal slowly dropped from the rocky mantle and into the core to lower the nucleation barrier.
But that would require a massive nugget-maybe the size of a large city-to be heavy enough to drop through the mantle and then large enough to make it the core without entirely dissolving.
If that’s the case, “we need to figure out how that could actually happen,” Van Orman said.
“On the other hand,” he said, “is there some ordinary feature of planetary cores that we have not thought of before-something that allows them to overcome that nucleation barrier?
“It’s time for the whole community to think about this problem and how to test it. The inner core exists, and now we have to figure out how it got there.”
This new map of Earth’s stress field in the Permian Basin of West Texas and southeastern New Mexico could help energy companies avoid causing earthquakes associated with oil extraction. Credit: Jens-Erik Lund Snee
Stanford geophysicists have developed a detailed map of the stresses that act in the Earth throughout the Permian Basin in West Texas and southeastern New Mexico, highlighting areas of the oil-rich region that could be at greater risk for future earthquakes induced by production operations.
The new study, published this month in the journal The Leading Edge, provides a color-coded map of the 75,000-square mile region that identifies those potential oil and gas development sites that would be would be most likely to trigger an earthquake associated with fluid injection.
Previous Stanford research has shown that wastewater injected as a step in hydraulic fracturing (fracking) underlies an increase in seismic activity in parts of the central and eastern U.S., particularly in Oklahoma, starting in 2005. While none of these small-to-moderate earthquakes has yet caused significant property damage or injury, they represent an increased probability of larger earthquakes.
Now, Texas is poised to take center stage as the Permian Basin is becoming the country’s most important oil- and gas-producing region. In the 1920s, energy companies began extracting the basin’s bountiful petroleum deposits during a boom that lasted decades. More recently, the advance of hydraulic fracturing techniques has spurred a new development frenzy. Hundreds of thousands of wells could be drilled in the region in the next few decades.
“We want to get out ahead of the problem in Texas,” said study co-author Mark Zoback, the Benjamin M. Page Professor of Geophysics in Stanford’s School of Earth, Energy & Environmental Sciences (Stanford Earth), who led a number of the Stanford studies in Oklahoma. “We want to stop fluid injection from triggering even small earthquakes in Texas so that the probability of larger earthquakes is significantly reduced.”
To gauge the risk of future quakes, researchers must first understand the direction of the stresses in a region and their approximate magnitude. When the stress field aligns with a pre-existing fault in a certain manner, the fault can slip, potentially producing an earthquake. In regions such as the central and eastern U.S., far from tectonic plate boundaries such as the San Andreas Fault, this slippage occurs as a natural process, but very rarely. But increasing fluid pressure at depth reduces the friction along the fault, sometimes triggering an earthquake.
“Fluid injection can cause a quake on a fault that might not produce a natural earthquake for thousands of years from now,” said study lead author Jens-Erik Lund Snee, a Ph.D. student in the Department of Geophysics at Stanford Earth.
In a previous study, Zoback and postdoctoral scholar Cornelius Langenbruch found that in Oklahoma, fluid injection caused about 6,000 years of natural earthquakes to occur in about five years.
Creating a next-generation stress map
Building on previous efforts to create maps of stress and seismic potential in the Permian Basin, the Stanford researchers added hundreds of new data points from West Texas and southeastern New Mexico, much of the data being provided by the oil and gas industry. Their findings paint a complicated picture of the Permian Basin, which features some relatively consistent horizontal stress areas along with others that show dramatic directional rotations. “We were surprised to see such high variability,” said Lund Snee. “It raises a lot of questions about how you can have rotations like that in the middle of a continental plate, far from a plate boundary.”
“This is the one of the most interesting stress fields I’ve ever seen,” Zoback said. “While the stress field in this region is surprisingly complex, the data is excellent and having documented what it is, we can now take action on this information and try to prevent the Permian Basin from becoming Oklahoma 2.0.”
A tool for safer, more efficient drilling
The Stanford researchers said the new stress map provides oil companies with detailed quantitative data to inform decisions on more effective drilling operations in the Permian Basin. “This is the most complete picture of stress orientation and relative magnitude that they’ve ever had,” Zoback said. “They can use these data every day in deciding the best direction to drill and how to carry out optimal hydraulic fracturing operations.”
Future studies will focus on improving knowledge of fault lines in the region and gaining a better understanding of fluid pressure, specifically how the amount of water injection (both now and in the past) has impacted the geological mechanisms at work in the area.
“There is the potential for a lot of earthquakes in this area,” said Lund Snee. “We want to understand what’s causing them and provide companies with the tools to avoid triggering them.”
Reference:
Jens-Erik Lund Snee et al. State of stress in the Permian Basin, Texas and New Mexico: Implications for induced seismicity, The Leading Edge (2018). DOI: 10.1190/tle37020127.1
A skeleton has been unearthed in Egypt’s Western Desert, whose ancient sands have long helped preserve remains, but unlike most finds this one isn’t a mummy—it’s a dinosaur.
Researchers from Mansoura University in the country’s Nile Delta discovered the new species of long-necked herbivore, which is around the size of a city bus, and it could be just the tip of the sand dune for other desert dinosaur discoveries.
“As in any ecosystem, if we went to the jungle we’ll find a lion and a giraffe. So we found the giraffe, where’s the lion?” said Hesham Sallam, leader of the excavation team and head of the university’s Center for Vertebrate Paleontology.
Sallam, along with four Egyptian and five American researchers, authored an article in the journal Nature Ecology & Evolution published Jan. 29 announcing the discovery.
Experts say the find is a landmark one that could shed light on a particularly obscure period of history for the African continent, roughly the 30 million years before dinosaurs went extinct, between 70 and 80 million years ago.
Named “Mansourasaurus Shahinae” after the team’s university and for one of the paleontology department’s founders, the find is the only dinosaur from that period to have been discovered in Africa, and it may even be an undiscovered genus.
In the article the authors say the team’s findings “counter hypotheses that dinosaur faunas of the African mainland were completely isolated” during the late Mesozoic period. That is, previous theories were that Africa’s dinosaurs during that time existed as if on an island and developed independently from their northern cousins.
But Mansourasaurus’ fossilized skeletal remains suggest an anatomy not very different from those discovered in Europe from the same period, an indication that a land connection between Africa and its northern neighbor may have existed.
While Egypt has a long history of archaeology, paleontology has not enjoyed the same popularity—or had the same success.
In 1911, the German paleontologist Ernst Stromer led an exhibition to the oasis of Bahriya, also in Egypt’s Western Desert. There, he discovered four species of dinosaurs, including a predatory type known as the Spinosaurus, all from the Cretaceous period. But all of his findings were later lost in Allied bombing of the Munich Museum during World War II.
Sallam said researchers don’t know how Mansourasaurus lived and died, except for the fact that it was a plant eater. There’s no indication whether it lived alone or in a herd.
The bones do bear resemblance to another dinosaur discovery in Egypt, that of the Paralititan Stromeri, excavated by an American team from the University of Pennsylvania, whose findings were published in 2001. But only in so much as both were long-necked herbivores grazers. The Paralititan Stromeri is believed to have been among the largest known animals, weighing in at 75 tons and over 30 meters (33 yards) long.
The Mansourasaurus’ smaller size is more typical of the Mesozoic era, when dinosaurs’ time was running out, geologically speaking, according to Sallam. With a long neck and tail, his torso would’ve been similar to that of an African elephant and measuring tip-to-tale over 10 meters (11 yards) and weighing several tons.
Egypt’s Western Desert would have more closely resembled a coastal jungle during the dinosaur’s lifetime, with half of what is the country today under water.
Though finding a dinosaur bone in a vast desert may seem akin to a needle in a haystack, it was also the product of back-breaking work. The team had been scouring the area of the find more than 750 kilometers (466 miles) southwest of the capital for five years before they found the partial skeleton of the Mansourasaurus in 2013.
Sallam said he and a group of doctoral and master’s degree students were heading to give a lecture at a local university when they stumbled on a desert road with the appropriate geological outcroppings that they hadn’t noticed before. The next morning, the team returned to survey it, covering an area of several kilometers. It wasn’t long after they started that one of the students called him on the phone, saying that he should come see the number of bones she’d found.
Sallam said he knew from the first small piece of fossil he was shown that it was a big deal.
“When I first saw it I told them, if this comes out as I expect, your names will go down in history,” he told his students.
There is now some hope the discovery could bring more funding for the paleontology field in Egypt and financing for ongoing studies, Sallam said. But he said he’s most proud of making science real for people who otherwise aren’t exposed to it as much.
“I mean, we’ve made the average Egyptian man, or the Arab man, talk about dinosaurs,” he said.
Reference:
Hesham M. Sallam et al. New Egyptian sauropod reveals Late Cretaceous dinosaur dispersal between Europe and Africa, Nature Ecology & Evolution (2018). DOI: 10.1038/s41559-017-0455-5
Note: The above post is reprinted from materials provided by The Associated Press.
The migration of the dinosaurs across the globe was so rapid that it may have contributed to their demise, new research has found.
A study by University of Reading scientists for the first time reveals the paths taken by the dinosaurs as they expanded out of South America during their rise to world dominance. The research shows that the speed of this expansion meant that the dinosaurs quickly became cosmopolitan and subsequently ran out of land. This lack of space then seriously impeded their ability to produce new species.
The work, published in Nature Ecology and Evolution, links to a previous Reading study that revealed the dinosaurs were in decline as a species 50 million years before the asteroid strike that finally wiped them out.
Ciara O’Donovan, evolutionary biologist at the University of Reading and lead author of the study, said: “Fossil evidence has shown us where the dinosaurs started out and where they died, but there is an important middle period that little was known about. Our research fills this gap in prehistory by revealing how the dinosaurs spread, how fast they moved and what directions they moved in through time.
“The dinosaurs exploded out of South America in a frenzy of movement to cover the planet. It was during this time that diverse forms evolved and eventually led to species such as the fearsome Tyrannosaurus rex, Archaeopteryx (the earliest bird) and the gigantic, long necked Diplodocus. This honeymoon period could not last forever though, and the dinosaurs eventually filled every available habitat on Earth.
“There was nowhere new for species to move to, which may have prevented new species from arising, contributing to the dinosaurs’ pre-asteroid decline. In essence, they were perhaps too successful for their own good.”
‘BLANK CANVAS’
Fossil evidence shows dinosaurs originated in the late Triassic Period (around 230 million years ago) in South America, which was then part of the huge land mass called Pangea. This closely followed the world’s largest extinction event that wiped out almost all of life on Earth.
The scientists developed a novel, statistical method to uncover where every dinosaur species’ ancestors existed, in three dimensional space, on the globe. By doing this they were able to demonstrate that the dinosaurs spread unchecked across the huge available space, at a rate of 1,000km/million years. They dominated every terrestrial habitat, across all the continents as they drifted apart, over the course of 170 million years.
This saturation of the Earth caused the dinosaurs to become increasingly specialised to live in their existing environment, resulting in a fundamental change in the way they evolved and produced new species. This curbed their progress and left them vulnerable to future changes in the environment, such as those caused by the asteroid strike.
Dr. Chris Venditti, evolutionary biologist at the University of Reading and co-author of the paper, said: “Early dinosaurs had a blank canvas and spread quickly across the devastated Earth, taking up every opportunity in their path. Virtually every door was open to them as there was no competition from other species.
“The inability of the dinosaurs to adapt rapidly enough as the Earth became full may explain why they were in decline prior to the asteroid strike, and why they were so susceptible to almost total extinction when it hit.”
Reference:
Ciara O’Donovan et al. Dinosaurs reveal the geographical signature of an evolutionary radiation, Nature Ecology & Evolution (2018). DOI: 10.1038/s41559-017-0454-6
Diverse mineralogy exhumed from the Martian subsurface: A false color image from the HiRISE instrument aboard NASA’s Mars Reconnaissance Orbiter shows amazing diversity of rocks exhumed from the Martian subsurface a meteor impact in the Nili Fossae area. The image is 1 km across. This site and others like it contain rocks that were altered by fluids in the Martian crust billions of years ago, at the time when life first emerged on Earth. These rocks represent exploration targets that could teach us about the origin of life. Credit: NASA/JPL/University of Arizona
The planet Mars has long drawn interest from scientists and non-scientists as a possible place to search for evidence of life beyond Earth because the surface contains numerous familiar features such as dried river channels and dried lake beds that hint at a warmer, wetter, more earthlike climate in the past. However, Dr Joseph Michalski of the Department of Earth Sciences & Laboratory for Space Research at The University of Hong Kong (HKU) and his colleagues have published papers recently that cast increased doubt on the idea of surface life evolving on Mars. These paradigm changing publications have recently been published in Nature Geoscience (December 2017) and Nature Astronomy (February 2018).
For the last 2.5 billion years, surface life on Earth has thrived largely due to the evolution of photosynthesis. Surface life is abundant and very successful because of the availability of sunlight, surface water, generally moderate climate conditions, and the protection of our magnetic field. But the planet Mars would have never experienced such habitable conditions at the surface. Michalski and colleagues published results in Nature Astronomy showing that the climate of Mars has probably been extremely cold and dry most of the time. They argue that the familiar aqueous features on Mars included widespread, weathered soil horizons, could have formed in geologically short climate “excursions.” In other words, Mars was cold and dry throughout its history and only had abundant liquid water at its surface during short episodes of climate change.
However, all hope for life on Mars is not lost. In another paper led by Michalski and published recently, the scientists point out that the prospects for surface life on Mars might be dim, but the possibilities for subsurface life are promising. Life on Earth likely began in hydrothermal systems (environments where hot water reacts with rocks), and there is abundant evidence for many locations where hydrothermal environments exists on Mars at the time when life might have originated in similar environments on Earth. They argue that, in order to understand how life formed on Earth, we should ignore the surface environments on Mars and focus exploration on hydrothermal deposits.
Dr. Michalski and his team in the Department of Earth Sciences and Laboratory for Space Research at HKU explore Mars using remote sensing and infrared spectroscopy. Using infrared data collected at Mars by spacecraft, they can interpret which minerals are there and describe the geology of ancient hydrothermal systems. This type of work is based on laboratory measurements, which provide the required mineralogical background in which to interpret spectroscopic data from Mars. The HKU’ Faculty of Sciences new Infrared Spectroscopy Laboratory is a facility where scientists from around the world can come to measure geological samples in order to compare the measured spectra to data from returned from spacecraft. Michalski and his team use infrared measurements of hydrothermal minerals as a basis to interpret the detection of important minerals on Mars.
“This is an extraordinarily exciting time in Mars exploration” said Michalski. “We are getting very close to being able to detect evidence of ancient life on Mars or, perhaps more importantly, the chemical building blocks on which life forms.”
“This cutting edge and ground-breaking HKU based research is both exciting and thought provoking. It speaks to the very heart of trying to understand how life may have evolved not just on Earth but on other terrestrial bodies both in our own solar system and indeed around other stars that have planets that lie in the so-called “habitable zone” (where liquid water can exist on the surface). The discovery of bacteria two miles down in a Goldmine in South Africa a decade ago chimes perfectly with the thesis Dr. Michalski is proposing here,” said Professor Quentin Parker, Director of Laboratory for Space Research and Associate Dean (Global) of Faculty of Science, The University of Hong Kong.
References:
Joseph R. Michalski, Tullis C. Onstott, Stephen J. Mojzsis, John Mustard, Queenie H. S. Chan, Paul B. Niles, Sarah Stewart Johnson. The Martian subsurface as a potential window into the origin of life. Nature Geoscience, 2017; 11 (1): 21 DOI: 10.1038/s41561-017-0015-2
Janice L. Bishop, Alberto G. Fairén, Joseph R. Michalski, Luis Gago-Duport, Leslie L. Baker, Michael A. Velbel, Christoph Gross, Elizabeth B. Rampe. Surface clay formation during short-term warmer and wetter conditions on a largely cold ancient Mars. Nature Astronomy, 2018; DOI: 10.1038/s41550-017-0377-9
Flowering plants likely originated between 149 and 256 million years ago according to new UCL-led research.
The study, published today in New Phytologist by researchers from the UK and China, shows that flowering plants are neither as old as suggested by previous molecular studies, nor as young as a literal interpretation of their fossil record.
The findings underline the power of using complementary studies based on molecular data and the fossil record, along with different approaches to infer evolutionary timescales to establish a deeper understanding of evolutionary dynamics many millions of years ago.
“The discrepancy between estimates of flowering plant evolution from molecular data and fossil records has caused much debate. Even Darwin described the origin of this group as an ‘abominable mystery’,” explained lead author, Dr Jose Barba-Montoya (UCL Genetics, Evolution & Environment).
“To uncover the key to solving the mystery of when flowers originated, we carefully analysed the genetic make-up of flowering plants, and the rate at which mutations accumulate in their genomes.”
Through the lens of the fossil record, flowering plants appear to have diversified suddenly, precipitating a Cretaceous Terrestrial Revolution in which pollinators, herbivores and predators underwent explosive co-evolution.
Molecular-clock dating studies, however, have suggested a much older origin for flowering plants, implying a cryptic evolution of flowers that is not documented in the fossil record.
“In large part, the discrepancy between these two approaches is an artefact of false precision on both palaeontological and molecular evolutionary timescales,” said Professor Philip Donoghue from the University of Bristol’s School of Earth Science, and a senior author of the study.
Palaeontological timescales calibrate the family tree of plants to geological time based on the oldest fossil evidence for its component branches. Molecular timescales build on this approach, using additional evidence from genomes for the genetic distances between species, aiming to overcome gaps in the fossil record.
“Previous studies into molecular timescales failed to explore the implications of experimental variables and so they inaccurately estimate the probable age of flowering plants with undue precision,” said Professor Ziheng Yang (UCL Genetics, Evolution & Environment) and senior author of the study.
“Similarly, interpretations of the fossil record have not fully recognised its shortcomings as an archive of evolutionary history, that is, that the oldest fossil evidence of flowering plants comes from very advanced, not primitive flowering plant lineages,” Professor Donoghue added.
The researchers compiled a large collection of genetic data for many flowering plant groups including a dataset of 83 genes from 644 taxa, together with a comprehensive set of fossil evidence to address the timescale of flowering plant diversification.
“By using Bayesian statistical methods that borrow tools from physics and mathematics to model how the evolutionary rate changes with time, we showed that there are broad uncertainties in the estimates of flowering plant age, all compatible with early to mid-Cretaceous origin for the group,” said Dr Mario dos Reis (School of Biological and Chemical Sciences at Queen Mary University of London), a co-author of the study.
Reference:
Jose Barba-Montoya, Mario dos Reis, Harald Schneider, Philip C. J. Donoghue, Ziheng Yang. Constraining uncertainty in the timescale of angiosperm evolution and the veracity of a Cretaceous Terrestrial Revolution. New Phytologist, 2018; DOI: 10.1111/nph.15011
One of the most important physical properties of minerals, reflecting the nature of the interaction of the electromagnetic radiation of the visible region with the electrons of the atoms, molecules, and ions of the crystals and with the electron system of the crystal as a whole. In mineralogy, color is one of the primary diagnostic properties of natural compounds, of great importance in geological prospecting for the identification of minerals. The color of gems and semiprecious stones is one of their main qualitative (gem) characteristics. A distinction is made between the color of minerals in individual crystals and lumps of ore, the color of minerals in transparent thin sections (under the microscope), the color of minerals in polished sections (in reflected light), and the color of a mineral’s streak (the color of the fine powder of the mineral).
A comparative evaluation is usually used in describing the color of minerals; the mineral’s color is compared to the color of some commonly known object or substance (indigo blue, apple green, lemon yellow, and blood red) or to mineral “color standards,” such as vermilion red and emerald green. The colors of metals or alloys are used as standards for describing the color of ore minerals: tin white (arsenopyrite), steel gray (molybdenite), brass yellow (chalcopyrite), and copper red (native copper). Methods are being developed for an objective evaluation of the color of minerals, especially of gems, using standard colorimetric characteristics. Many minerals have the property of exhibiting different colors in different crystallographic directions, especially in polarized light, or changing their color with the color temperature of the radiative source illuminating them.
Three main groups of minerals are identified on the basis of the property of color: idiochromatic, allochromatic, and pseudochro-matic. In idiochromatic minerals the color is due to the characteristics of the constituent chemical elements (the species-forming elements or impurities that act as chromophores), the nature of the crystal’s electron structure, more specifically the zonal structure, and the presence of defects in the crystals, for example, vacancies and interstitial atoms. Several subgroups of idiochromatic minerals are distinguished according to the type of optical absorption.
The color of metallic and covalent compounds, such as native metals and sulfides and their analogs, is due to interzonal optical transfers of electrons and the related maximums of reflection (for example, the metallic colors of pyrite and gold) or is due to the fundamental absorption band (cinnabar, orpiment, cuprite).
In another type of idiochromatic mineral, the color is due to electron transfers between different ions, namely, charge transfers. This includes the transfer between a metal ion and ligands and the transfer between differently charged metal ions. Examples are minerals of trivalent iron (the charge transfer O2 → Fe3+); the chromates, vanadates, and molybdates, such as crocoite, vanadinite, and wulfenite (the transfer O2 → Cr6+, V5+, Mo6+); and minerals that at the same time contain the differently charged ions Fe2+ and Fe3+, such as cordierite, vivianite, and aquamarine.
Color associated with ions of the transition metals — Ti, V, Cr, Mn, Fe, Co, Ni, and Cu — is typical of emerald, ruby, rubellite, rhodonite, chrysolite, and malachite. The lanthanides and actinides are chromophores of minerals of the rare-earth elements and uranyl. Their color is due to the transfers of electrons between the d- and f-levels of the chromophore ions.
Color caused by radioactivity is related to the formation of electron-hole color centers by the action of natural ionizing radiation, for example, the dark blue and purple color of halite and fluorite and the yellow and smoky color of quartz and calcite.
In allochromatic minerals the color is due to the presence of impurities, usually inclusions of colored minerals but occasionally bubbles of liquids or gases. For example, the reddish orange color of carnelian is caused by inclusions of iron hydroxides, while the green color of prase, a variety of quartz, is linked to inclusions of spicules of actinolite or chlorite.
In pseudochromatic minerals the color is due to the diffraction and interference of light, as well as to the dispersion, refraction, and total internal reflection of incident white light. These phenomena are related to the structural features of mineral formations (regular alternation of phases of different composition in iridescent labradorites and peristerites and in sunstone [aventurine feldspar] and moonstone; the globular structure of opals) or to the structure of the surface layer of crystals (various types of tarnish, such as the iridiscent film on bornite, chalcopyrite, pyrite, and covellite).
The study of the color of minerals provides information about the crystallochemical and genetic characteristics of minerals and is useful in the synthesis of high-quality analogs of natural gems.
Reference:
Marfunin, A. S. Vvedenie v fiziku mineralov. Moscow, 1974.
Platonov, A. N. Priroda okraski mineralov. Kiev, 1976.
A. N. PLATONOV and T. B. ZDORIK
Fluorite (also called fluorspar) is the mineral form of calcium fluoride, CaF2. It belongs to the halide minerals. It crystallizes in isometric cubic habit, although octahedral and more complex isometric forms are not uncommon.
Mohs scale of mineral hardness, based on scratch Hardness comparison, defines value 4 as Fluorite.
Fluorite is a colorful mineral, both in visible and ultraviolet light, and the stone has ornamental and lapidary uses. Industrially, fluorite is used as a flux for smelting, and in the production of certain glasses and enamels. The purest grades of fluorite are a source of fluoride for hydrofluoric acid manufacture, which is the intermediate source of most fluorine-containing fine chemicals. Optically clear transparent fluorite lenses have low dispersion, so lenses made from it exhibit less chromatic aberration, making them valuable in microscopes and telescopes. Fluorite optics are also usable in the far-ultraviolet and mid-infrared ranges, where conventional glasses are too absorbent for use.
The many colors of fluorite are truly wonderful. The rich purple color is by far fluorite’s most famous and popular color. It easily competes with the beautiful purple of amethyst. Often specimens of fluorite and amethyst with similar shades of purple are used in mineral identification classes to illustrate the folly of using color as the sole means to identify minerals.
The blue, green and yellow varieties of fluorite are also deeply colored, popular and attractive. The colorless variety is not as well received as the colored varieties, but their rarity still makes them sought after by collectors. A brown variety found in Ohio and elsewhere has a distinctive iridescence that improves an otherwise poor color for fluorite. The rarer colors of pink, reddish orange (rose) and even black are usually very attractive and in demand.
Most specimens of fluorite have a single color, but a significant percentage of fluorites have multiple colors and the colors are arranged in bands or zones that correspond to the shapes of fluorite’s crystals. In other words, the typical habit of fluorite is a cube and the color zones are often in cubic arrangement. The effect is similar to phantomed crystals that appear to have crystals within crystals that are of differing colors. A fluorite crystal could have a clear outer zone allowing a cube of purple fluorite to be seen inside. Sometimes the less common habits such as a colored octahedron are seen inside of a colorless cube. One crystal of fluorite could potentially have four or five different color zones or bands.
To top it all off, fluorite is frequently fluorescent and, like its normal light colors, its fluorescent colors are extremely variable. Typically it fluoresces blue but other fluorescent colors include yellow, green, red, white and purple. Some specimens have the added effect of simultaniously having a different color under longwave UV light from its color under shortwave UV light. And some will even demonstrate phosphorescence in a third color! That’s four possible color luminescence in one specimen! If you count the normal light color too. The blue fluorescence has been attributed to the presence of europium ions (Eu +2). Yttrium is the activator for the yellow fluorescence. Green and red fluorescent activation is not exactly pinned down as of yet, but may be due to the elements already mentioned as well as other rare earth metals; also manganese, uranium or a combination of these. Even unbonded fluorine trapped in the structure has been suggested. The word fluorescent was derived from fluorite since specimens of fluorite were some of the first fluorescent specimens ever studied. The naming followed the naming precedence set by opalescence from opal; ergo fluorescence from fluorite.
Another unique luminescent property of fluorite is its thermoluminescence. Thermoluminescence is the ability to glow when heated. Not all fluorites do this, in fact it is quite a rare phenomenon. A variety of fluorite known as “chlorophane” can demonstrate this property very well and will even thermoluminesce while the specimen is held in a person’s hand activated by the person’s own body heat (of course in a dark room, as it is not bright enough to be seen in daylight). The thermoluminescence is green to blue-green and can be produced on the coils of a heater or electric stove top. Once seen, the glow will fade away and can no longer by seen in the same specimen again. It is a one shot deal. Chlorophane (which means to show green) is found in very limited quantities at Amelia Court House, Virginia; Franklin, New Jersey and the Bluebird Mine, Arizona, USA; Gilgit, Pakistan; Mont Saint-Hilaire, Quebec, Canada and at Nerchinsk in the Ural Mountains, Russia.
Fluorite has other qualities besides its great color assortments that make it a popular mineral. It has several different crystal habits that always produce well formed, good, clean crystals. The cube is by far the most recognized habit of fluorite followed by the octahedron which is believed to form at higher temperatures than the cube. Although the cleavage of fluorite can produce an octahedral shape and these cleaved octahedrons are popular in rock shops the world over, the natural (e.g. uncleaved) octahedrons are harder to find.
A rarer habit variety is the twelve sided dodecahedron however it is never seen by itself and usually modifies the cubic crystals by replacing the edges of the cube with one flat face of a dodecahedron. The tetrahexahedron is a twenty four sided habit that is also seen modifying the cubic habit. But instead of one face replacing each cubic edge, two faces modify the cube’s edges. Occasionally combinations of a cube, dodecahedron and tetrahexahedron are seen producing an overall cubic crystal with no less that three minor parallel faces replacing each cubic edge. A fifth form is the hexoctahedron which modifies the cube by placing six very minor faces at each corner of the cube. Twinning is also common in fluorite and symmetrical penetration twins, especially from Cumberland England are much sought after by collectors.
Fluorite, as mention above, has octahedral cleavage. This means that it has four identical directions of cleavage and when cleaved in the right ways can produce a perfect octahedral shape. Many thousands of octahedrons are produced from massive or large undesirable crystals of fluorite (hopefully!) and are sold in rock shops and museum gift shops at a small cost. Fluorite mine workers are reported to sit down at lunch breaks and cleave the octahedrons for the extra cash. The octahedrons are very popular due to their attractive colors, clarity, “diamond-shaped” and low costs, but to a serious collector they are nothing more than “cleavage fragments”.
Fluorite not only is attractive in its own right but is often associated with other attractive minerals. Fluorite crystals will frequently accompany specimens of silver gray galena, brassy yellow pyrite, chalcopyrite or marcasite, golden barite, black sparkling sphalerite, intricately crystallized calcite and crystal clear quartz, even amethyst.
The origin of the word fluorite comes from the use of fluorite as a flux in steel and aluminum processing. It was originally referred to as fluorospar by miners and is still called that today. Fluorite is also used as a source of fluorine for hydrofluoric acid and fluorinated water. The element fluorine also gets its name from fluorite, fluorines only common mineral. Other uses of fluorite include an uncommon use as a gemstone (low hardness and good cleavage reduce its desirability as a gemstone), ornamental carvings (sometimes misleadingly called Green Quartz) and special optical uses.
Fluorite is the most popular mineral for mineral collectors in the world, second only to quartz. Every mineral collection owned by even the newest and youngest of mineral collectors must have a specimen of fluorite. Fluorite is by far one of the most beautiful and interesting minerals available on the mineral markets.
Photos
Why Fluorite Comes in Different Colors?
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Fluorite, Cave-in-Rock, Illinois
Rainbow Fluorite
Fluorite and sphalerite. Origin: Elmwood mine, Smith county, Tennessee, USA. 7,1 x 5,6 x 5,3 cm, picture taken in Belgium. Credit: Jamain
The jaw of the new species Clevosaurus cambrica, here shown as a 3D CT scan model, was adapted for chopping up small prey. Credit: University of Bristol
Fossils found in a quarry near Cardiff in South Wales have been identified by a student and her supervisors at the University of Bristol as a new small species of reptile that lived 205 million years ago.
It is named Clevosaurus cambrica, the second part being Latin and referring to the fact it comes from Wales.
The research was completed by Emily Keeble, an undergraduate in Bristol’s School of Earth Sciences, as part of her final-year project for her palaeontology degree.
The fossils she studied were collected in the 1950s in Pant-y-ffynnon Quarry, and they belong to a new species of the ‘Gloucester lizard’ Clevosaurus (named in 1939 after Clevum, the Latin name for Gloucester).
In the Late Triassic, the hills of South Wales and the South West of England formed an archipelago that was inhabited by small dinosaurs and relatives of the Tuatara, a reptilian living fossil from New Zealand.
The limestone quarries of the region have many caves or fissures containing sediments filled with the bones of abundant small reptile species that give us a unique insight into the animals that scuttled at the feet of the dinosaurs. The fissures are of worldwide importance in yielding such well-preserved small reptiles.
Emily said: “The new species, Clevosaurus cambrica lived side-by-side with a small dinosaur, Pantydraco, and an early crocodile-like animal, Terrestrisuchus. We compared it with other examples of Clevosaurus from locations around Bristol and South Gloucestershire, but our new beast is quite different in the arrangement of its teeth.”
Professor Mike Benton, Emily’s co-supervisor, added: “We were lucky to find quite a lot of the skeleton and Emily was able to scan the blocks and make 3-D reconstructions of the skull, neck, shoulder and arm region.”
Another co-supervisor, Dr. David Whiteside, said: “The teeth of Clevosaurus cambric were likely adapted to dice pieces of flesh, so we interpret this little critter as a predator, feeding on insects and other small animals.”
Pant-y-Fynnon Quarry, near Ogmore and Ewenny, has long been quarried as a source of limestone for building and road surfacing, and the fossils come from cracks or fissures filled with younger, red-coloured sediments.
The animals were living on the high points of the islands, and many of them seem to be quite small, possible evidence for island dwarfing – which has been seen in more recent examples.
Dr. Whiteside added: “The dinosaurs, crocodiles, and lizards were isolated to some extent on their islands, and perhaps smaller ones were better at surviving in the changed ecologies of the islands.”
Reference:
Emily Keeble et al. The terrestrial fauna of the Late Triassic Pant-y-ffynnon Quarry fissures, South Wales, UK and a new species of Clevosaurus (Lepidosauria: Rhynchocephalia), Proceedings of the Geologists’ Association (2018). DOI: 10.1016/j.pgeola.2017.11.001
A study of “Mrs” Ples’ tooth sockets has made scientists think differently about “her” sex. Credit: Ditsong National Museum of Natural History
More than 70 years ago two palaeontologists named Robert Broom and John Robinson discovered a skull at the Sterkfontein Caves near Johannesburg. They nicknamed the skull, which is believed to be about 2.5 million years old, “Mrs Ples”.
Its scientific name is Australopithecus africanus, and it’s extremely significant because scientists believe it to be a distant relative of all humankind. The fossil represents part of the evidence demonstrating that Africa is the continent from which all humanity originated.
In the decades since then the skull’s sex has become the subject of some debate. Not everyone has been convinced by Broom’s insistence that “Mrs Ples” was a female of her species.
Our new research, just published in the South African Journal of Science, offers compelling proof that the naysayers were right. “Mrs” Ples was actually a “Mr”.
We discovered this by making a careful study of her tooth sockets. In many primates, males can be distinguished from females because of differences in the size of their canine teeth. Simply put, adult males have larger canines than females.
Mrs Ples’ teeth were not preserved. Her canine sockets were, and they were about the size one would expect for a female. But our study revealed that the sockets weren’t naturally that small: they’d become smaller because of acid used during work done on the skull about 60 years ago. The acid digested away parts of the skull bone around the tooth sockets.
These findings, which form part of an ongoing debate about the iconic skull’s sex, are further proof that science is a work in progress. Scientists don’t always agree, and they don’t always have the definitive answers. Sometimes it can take decades, or even centuries, to reach a resolution.
Soon after he and Robinson made their landmark discovery, Broom confidently claimed that Mrs Ples was female based on the size of her canine sockets. This was a visual deduction; at that time he did not have a substantial comparative sample for the species, so there was room for doubt.
Measurements of the canine socket were published in 1950 at a time when the fossils found at Sterkfontein were cleaned mechanically.
Initially, Broom used a hammer and chisel to remove the hard calcified sands that surrounded Mrs Ples in the caves. But later, in the 1960s, Robinson used acetic acid to remove further rock – and some fossils, Mrs Ples among them, were damaged in the process.
In 1983, Professor Yoel Rak from Tel Aviv challenged Broom’s opinion. He pointed out that there were prominent ridges on Mrs Ples’s snout, and argued that these were probably associated with the large roots of the canine teeth. Rak became the first to suggest that Mrs Ples ought to be called “Mr” instead.
This view was supported by subsequent research, which one of us – Francis Thackeray – was involved in.
Then opinions changed yet again. In 2012, Professor Fred Grine of the State University of New York re-examined the available evidence. He and his colleagues published an article in the Journal of Human Evolution which insisted Mrs Ples was “an adult female”. The assertion was based in part on the apparently small size of the canine tooth sockets.
A rebuttal and new measurements
The research we’ve just published is a rebuttal to Grine and his colleagues’ arguments. The heart of the issue is that they omitted to present all of the data that Broom had obtained about Mrs Ples before the teeth sockets were damaged by acid.
We compared Broom’s measurements of Mrs Ples against those obtained for about 12 other specimens of Australopithecus africanus from Sterkfontein. These including specimens that have previously been clearly identified as males or females.
Using the measurements of canine sockets from all of these specimens, we were able to show that Mrs – or rather, Mr – Ples should clearly be grouped with small males rather than with large females.
Of course, science being what it is, the debate is probably not over. We are continuing our research on “Mr Ples”, using state of the art CT scans to test our view that the skull is male. For now, and based on our careful comparative study, it seems that the human ancestor who roamed the Sterkfontein Caves so many millions of years ago and whose skull has become a scientific treasure was a male, not a female.
In the final analysis, whether Ples is a Mr or a Mrs doesn’t detract from the significance of what the skull tells us about our human ancestry.
Note: The above post is reprinted from materials provided by Wits University.
Life reconstruction of Wahlisaurus massarae. Credit: of James McKay.
A rare 200 million-year-old ichthyosaur specimen has been discovered in a private collection 22 years after it was originally found.
The fossil is only the second example of Wahlisaurus massarae, a new species of ichthyosaur discovered by The University of Manchester palaeontologist, Dean Lomax. This fossil was originally found in 1996 and has now been donated to a museum.
Ichthyosaurs have recently been in the limelight as the focus of BBC One documentary, ‘Attenborough and the Sea Dragon’. They were a type of sea-going reptile that lived during the time of the dinosaurs. Their fossils are plentiful in the UK and in recent years Lomax has described five different species of the prehistoric reptile.
In 2016, Lomax described an ichthyosaur skeleton that he had examined in the collections of Leicester’s New Walk Museum and Art Gallery. He spotted several unusual features of the bones and determined that the features were unique and represented a new species, which he called Wahlisaurus massarae, in honour of two of his colleagues and mentors: Bill Wahl and Prof. Judy Massare.
He said: “When Wahlisaurus was announced, I was a little nervous about what other palaeontologists would make of it, considering the new species was known only from a single specimen. As a scientist you learn to question almost everything, and be as critical as you can be. My analysis suggested it was something new, but some palaeontologists questioned this and said it was just ‘variation’ of an existing species.”
In this new study, Lomax teamed up with Dr Mark Evans, palaeontologist and curator at the New Walk Museum, Leicester, and fossil collector, Simon Carpenter, of Somerset. The study focuses on a specimen Dean identified in Simon’s collection, which is an almost complete coracoid bone (part of the pectoral girdle) that has exactly the same unique features of the same bone in Wahlisaurus. The specimen was originally collected in 1996, in a quarry in northern Somerset. Once the specimen’s rarity was realised, Simon immediately donated it to Bristol Museum and Art Gallery.
Lomax added: “You can only imagine my sheer excitement to find a specimen of Wahlisaurus in Simon’s collection. It was such a wonderful moment. When you have just one specimen, ‘variation’ can be called upon, but when you double the number of specimens you have it gives even more credibility to your research.”
The new discovery is from a time known as the Triassic-Jurassic boundary, right after a world-wide mass extinction. For these reasons, the team have been unable to determine exactly whether the ichthyosaur was latest Triassic or earliest Jurassic in age, although it is roughly 200 million-year-old.
As part of the study, Dr Evans cleaned the bones and removed additional rock from the first specimen. This assisted in a detailed re-examination of the original skull, which led to the discovery of additional bones. This has provided a better understanding of the skull structure.
“The discovery of the new specimen in a private collection helps to recognise the important contribution of dedicated and responsible fossil collectors. I am especially grateful to Simon for donating the specimen and collecting all of the data available with the specimen when he found it.” Added Lomax.
Reference:
Lomax, D. R., Evans, M. and Carpenter, S. An ichthyosaur from the UK Triassic-Jurassic boundary: A second specimen of the leptonectid ichthyosaur Wahlisaurus massarae Lomax 2016. Geological Journal, 2018 DOI: 10.1002/gj.3155
