Dr Mikael Siversson examining the jaws of a modern long fin mako shark (Isurus paucus). Credit: H.Ryan/WA Museum
As an undergraduate student of geology I had become fascinated by palaeontology—in particular the study of marine vertebrate fossils from the Cretaceous period (145-66 million years ago).
Together with a fellow student I saved up enough money to travel to the USA in search of fossils.
One day we were prospecting a 75 million-year-old floodplain and shallow marine sediments, exposed in spectacularly scenic badland areas of north central Montana.
I was busy dry sieving a lens of marginal marine sand full of perfectly preserved shark teeth when my friend stumbled across an articulated but headless skeleton of a long-necked plesiosaur lying on its back in estuarine mud.
As we began marking the vertebrae I noticed deep bite marks on one of the leg bones.
Further excavation revealed a few teeth of a large individual of the apex predatory shark Archaeolamna kopingensis.
Sharks may lose teeth as they bite into tough prey and a plesiosaur’s torso was built like a tank.
The discovery and excavation of the plesiosaur skeleton and the dramatic story it reveals, with a shark probably weighing several hundred kilograms tearing at its limbs, cemented my desire as a young student to pursue a career in palaeontology.
Cretaceous plesiosaur skeleton. Credit: M. Siversson/WA Museum
In August 2011 a field party from the WA Museum came across another Cretaceous ‘crime scene’: this time in the Giralia Range, southeast of Exmouth where marine rocks of Early Cretaceous age are well-exposed.
One of the volunteers discovered a few bones lying near the top of a small hill of the Gearle Siltstone, which is approximately 108-107 million years old in this particular area.
The bones looked so well-preserved he initially thought they must have belonged to a modern animal like a sheep or a goat.
I was, however, able to determine that they were in fact of Cretaceous age and belonged to an extinct, dolphin-like marine reptile called an ichthyosaur.
The most complete bone discovered is a surangular bone that, together with several additional bones, makes up the lower jaw in these reptiles.
Upon closer examination I noticed that the incomplete front part of the bone had been nearly completely sheared off at an angle.
Another jaw fragment of the same ichthyosaur has multiple, parallel bite marks probably produced by smaller sharks.
Front tooth of the early Cretaceous shark Dwardius, Giralia Range. Credit: M.Siversson/WA Museum
All but one of the shark species co-occurring with ichthyosaurs in the Giralia Range were either small or very rare.
A distant relative of the white shark, belonging in the extinct genus Dwardius, was however both common and large enough to potentially prey on ichthyosaurs.
Its fossilised teeth have been found in England, France and now also in Western Australia.
The ‘detective’ aspect of vertebrate palaeontology, looking for clues on the bones, is an incredibly exciting field of research.
In some cases palaeontologists have found direct evidence of predatory behaviour with tooth-fragments of the predator imbedded in healed bone tissue.
Blake Weissling researching in the Antarctic in 2007.
In October, UTSA College of Sciences faculty members Stephen Ackley and Blake Weissling wlll travel to the Arctic as a part of a project funded by the Office of Naval Research (ONR) to study the diminishing ice cover. The pair will join a team of nearly 20 scientists from around the world for the 42-day trip from Nome, Alaska into the Arctic Ocean.
Ackley has conducted research in the polar regions for more than 30 years and has a specific geographic location, “Ackley Point,” named after him. Ackley Point is located on Ross Island, an island formed by four volcanoes in the Ross Sea, near Antarctica. This will be his 12th trip to study polar sea ice, conducted from either drifting ice camps or aboard a vessel.
An assistant research professor in the UTSA Department of Geological Sciences, Weissling has led UTSA students conducting ice research in the Arctic, the Antarctic and at Pico de Orizaba, a volcano east of Mexico City. Ackley and Weissling will travel on the “Sikuliak,” an icebreaking ship making its maiden voyage into the ice.
Project leaders hope to develop methods to quantify how the ice is changing. Satellite remote sensing has captured how the ice surface area has been changing, but accurately measuring the region’s ice thickness from above has been a challenge.
“The Navy is particularly concerned with improving its models for atmospheric sensing and for waves,” said Ackley. “When the ice cover is taken away, then the potential for ocean waves builds up. The waves can be a major factor in any kind of economic development involving oil rigs, shipping, search and rescue efforts, and Navy operations. Large waves can also affect the native residents going out to hunt.”
Weissling added, “We are going to be looking for storm events so we can measure the oceanographic, meteorological, and ice parameters associated with waves. We will be looking at how the waves are interacting with the ice edge, because the ice edge dampens wave fields dramatically.”
The UTSA researchers are supported by an ONR research grant as well as a $500,000 Department of Defense instrumentation grant. They have used the instrumentation grant to purchase sophisticated equipment including radars, a light detection and ranging (LIDAR) system and two electromagnetic induction meters. LIDAR systems incorporate a remote sensing method that uses light in the form of a pulsed laser to measure variable distances to the Earth. The electromagnetic induction instruments will enable researchers to measure sea ice thickness within a few centimeters of accuracy, either on the surface or from the vessel.
Once the researchers return, they envision another two years of data analysis.
After the exploratory trip is complete, UTSA faculty members representing various colleges will benefit. Much of the equipment purchased has additional applications and can be used in the geosciences, civil engineering, architecture and archaeology.
The May 12, 2015 M 7.3 Nepal earthquake (SE of Zham, China) occurred as the result of thrust faulting on or near the decollément associated with the Main Himalayan Thrust, which defines the interface between the underthrusting India plate and the overriding Eurasia plate to the north. At the location of this earthquake, approximately 80 km to the east-northeast of the Nepalese capital of Kathmandu, the India plate is converging with Eurasia at a rate of 45 mm/yr towards the north-northeast – a fraction of which (~18 mm/yr) is driving the uplift of the Himalayan mountain range. The May 12, 2015 event is the largest aftershock to date of the M 7.8 April 25, 2015 Nepal earthquake – known as the Gorkha earthquake – which was located 150 km to the west, and which ruptured much of the decollément between these two earthquakes.
While commonly plotted as points on maps, earthquakes of this size are more appropriately described as slip over a larger fault area. Events of the size of the May 12, 2015 earthquake are typically about 55×30 km in size (length x width). The April 25, 2015 M 7.8 mainshock had approximate dimensions of ~120×80 km, directed from its hypocenter eastwards, and towards Kathmandu. The May 12, 2015 earthquake is located just beyond the eastern end of that rupture.
The boundary region of the India and Eurasia plates has a history of large and great earthquakes. Prior to April 25, four events of M6 or larger had occurred within 250 km of this area over the past century. One, a M 6.9 earthquake in August 1988, 140 km to the south-southeast of the May 12 event, caused close to 1500 fatalities. The largest, an M 8.0 event known as the 1934 Nepal-Bihar earthquake, ruptured a large section of the fault to the south of this May 2015 event, and east of the April 2015 mainshock, in a similar location to the 1988 earthquake. It severely damaged Kathmandu, and is thought to have caused around 10,600 fatalities. Prior to the 20th century, a large earthquake in 1833 is thought to have ruptured a similar area as the April 25, 2015 event. To date, there have been close to 100 M3+ aftershocks of the Gorkha earthquake. In the first two hours after the May 12 event, six further aftershocks have occurred, to the southwest-to-southeast of that earthquake.
Seismotectonics of the Himalaya and Vicinity
Seismicity in the Himalaya dominantly results from the continental collision of the India and Eurasia plates, which are converging at a relative rate of 40-50 mm/yr. Northward underthrusting of India beneath Eurasia generates numerous earthquakes and consequently makes this area one of the most seismically hazardous regions on Earth. The surface expression of the plate boundary is marked by the foothills of the north-south trending Sulaiman Range in the west, the Indo-Burmese Arc in the east and the east-west trending Himalaya Front in the north of India.
The India-Eurasia plate boundary is a diffuse boundary, which in the region near the north of India, lies within the limits of the Indus-Tsangpo (also called the Yarlung-Zangbo) Suture to the north and the Main Frontal Thrust to the south. The Indus-Tsangpo Suture Zone is located roughly 200 km north of the Himalaya Front and is defined by an exposed ophiolite chain along its southern margin. The narrow (<200km) Himalaya Front includes numerous east-west trending, parallel structures. This region has the highest rates of seismicity and largest earthquakes in the Himalaya region, caused mainly by movement on thrust faults. Examples of significant earthquakes, in this densely populated region, caused by reverse slip movement include the 1934 M8.1 Bihar, the 1905 M7.5 Kangra and the 2005 M7.6 Kashmir earthquakes. The latter two resulted in the highest death tolls for Himalaya earthquakes seen to date, together killing over 100,000 people and leaving millions homeless. The largest instrumentally recorded Himalaya earthquake occurred on 15th August 1950 in Assam, eastern India. This M8.6 right-lateral, strike-slip, earthquake was widely felt over a broad area of central Asia, causing extensive damage to villages in the epicentral region.
The Tibetan Plateau is situated north of the Himalaya, stretching approximately 1000km north-south and 2500km east-west, and is geologically and tectonically complex with several sutures which are hundreds of kilometer-long and generally trend east-west. The Tibetan Plateau is cut by a number of large (>1000km) east-west trending, left-lateral, strike-slip faults, including the long Kunlun, Haiyuan, and the Altyn Tagh. Right-lateral, strike-slip faults (comparable in size to the left-lateral faults), in this region include the Karakorum, Red River, and Sagaing. Secondary north-south trending normal faults also cut the Tibetan Plateau. Thrust faults are found towards the north and south of the Tibetan Plateau. Collectively, these faults accommodate crustal shortening associated with the ongoing collision of the India and Eurasia plates, with thrust faults accommodating north south compression, and normal and strike-slip accommodating east-west extension.
Along the western margin of the Tibetan Plateau, in the vicinity of south-eastern Afghanistan and western Pakistan, the India plate translates obliquely relative to the Eurasia plate, resulting in a complex fold-and-thrust belt known as the Sulaiman Range. Faulting in this region includes strike-slip, reverse-slip and oblique-slip motion and often results in shallow, destructive earthquakes. The active, left-lateral, strike-slip Chaman fault is the fastest moving fault in the region. In 1505, a segment of the Chaman fault near Kabul, Afghanistan, ruptured causing widespread destruction. In the same region the more recent 30 May 1935, M7.6 Quetta earthquake, which occurred in the Sulaiman Range in Pakistan, killed between 30,000 and 60,000 people.
On the north-western side of the Tibetan Plateau, beneath the Pamir-Hindu Kush Mountains of northern Afghanistan, earthquakes occur at depths as great as 200 km as a result of remnant lithospheric subduction. The curved arc of deep earthquakes found in the Hindu Kush Pamir region indicates the presence of a lithospheric body at depth, thought to be remnants of a subducting slab. Cross-sections through the Hindu Kush region suggest a near vertical northerly-dipping subducting slab, whereas cross-sections through the nearby Pamir region to the east indicate a much shallower dipping, southerly subducting slab. Some models suggest the presence of two subduction zones; with the Indian plate being subducted beneath the Hindu Kush region and the Eurasian plate being subducted beneath the Pamir region. However, other models suggest that just one of the two plates is being subducted and that the slab has become contorted and overturned in places.
Shallow crustal earthquakes also occur in this region near the Main Pamir Thrust and other active Quaternary faults. The Main Pamir Thrust, north of the Pamir Mountains, is an active shortening structure. The northern portion of the Main Pamir Thrust produces many shallow earthquakes, whereas its western and eastern borders display a combination of thrust and strike-slip mechanisms. On the 18 February 1911, the M7.4 Sarez earthquake ruptured in the Central Pamir Mountains, killing numerous people and triggering a landside, which blocked the Murghab River.
Further north, the Tian Shan is a seismically active intra-continental mountain belt, which extends 2500 km in an ENE-WNW orientation north of the Tarim Basin. This belt is defined by numerous east-west trending thrust faults, creating a compressional basin and range landscape. It is generally thought that regional stresses associated with the collision of the India and Eurasia plates are responsible for faulting in the region. The region has had three major earthquakes (>M7.6) at the start of the 20th Century, including the 1902 Atushi earthquake, which killed an estimated 5,000 people. The range is cut through in the west by the 700-km-long, northwest-southeast striking, Talas-Ferghana active right-lateral, strike-slip fault system. Though the system has produced no major earthquakes in the last 250 years, paleo-seismic studies indicate that it has the potential to produce M7.0+ earthquakes and it is thought to represent a significant hazard.
The northern portion of the Tibetan Plateau itself is largely dominated by the motion on three large left-lateral, strike-slip fault systems; the Altyn Tagh, Kunlun and Haiyuan. The Altyn Tagh fault is the longest of these strike slip faults and it is thought to accommodate a significant portion of plate convergence. However, this system has not experienced significant historical earthquakes, though paleoseismic studies show evidence of prehistoric M7.0-8.0 events. Thrust faults link with the Altyn Tagh at its eastern and western termini. The Kunlun Fault, south of the Altyn Tagh, is seismically active, producing large earthquakes such as the 8th November 1997, M7.6 Manyi earthquake and the 14th November 2001, M7.8 Kokoxili earthquake. The Haiyuan Fault, in the far north-east, generated the 16 December 1920, M7.8 earthquake that killed approximately 200,000 people and the 22 May 1927 M7.6 earthquake that killed 40,912.
The Longmen Shan thrust belt, along the eastern margin of the Tibetan Plateau, is an important structural feature and forms a transitional zone between the complexly deformed Songpan-Garze Fold Belt and the relatively undeformed Sichuan Basin. On 12 May 2008, the thrust belt produced the reverse slip, M7.9 Wenchuan earthquake, killing over 87,000 people and causing billions of US dollars in damages and landslides which dammed several rivers and lakes.
Southeast of the Tibetan Plateau are the right-lateral, strike-slip Red River and the left-lateral, strike-slip Xiangshuihe-Xiaojiang fault systems. The Red River Fault experienced large scale, left-lateral ductile shear during the Tertiary period before changing to its present day right-lateral slip rate of approximately 5 mm/yr. This fault has produced several earthquakes >M6.0 including the 4 January 1970, M7.5 earthquake in Tonghai which killed over 10,000 people. Since the start of the 20th century, the Xiangshuihe-Xiaojiang Fault system has generated several M7.0+ earthquakes including the M7.5 Luhuo earthquake which ruptured on the 22 April 1973. Some studies suggest that due to the high slip rate on this fault, future large earthquakes are highly possible along the 65km stretch between Daofu and Qianning and the 135km stretch that runs through Kangding.
Shallow earthquakes within the Indo-Burmese Arc, predominantly occur on a combination of strike-slip and reverse faults, including the Sagaing, Kabaw and Dauki faults. Between 1930 and 1956, six M7.0+ earthquakes occurred near the right-lateral Sagaing Fault, resulting in severe damage in Myanmar including the generation of landslides, liquefaction and the loss of 610 lives. Deep earthquakes (200km) have also been known to occur in this region, these are thought to be due to the subduction of the eastwards dipping, India plate, though whether subduction is currently active is debated. Within the pre-instrumental period, the large Shillong earthquake occurred on the 12 June 1897, causing widespread destruction.
This image of ash and gases exploding from Volcan de Colima was taken by the research team during the study. Credit: Paul Cole/Plymouth University
The varying scale and force of certain volcanic eruptions are directly influenced by the distribution of gases within magma inside a volcano’s conduit, according to a new study.
Using state of the art equipment including UV cameras and electron microscopes, researchers from Plymouth University led a project to analyse the eruptive plumes and ash generated by Volcán de Colima, the most active volcano in the Americas.
Working alongside academics from the University of Cambridge and the Universidad de Colima in Mexico, they documented for the first time marked differences in the vesicularity, crystal characteristics and glass composition in juvenile material from the volcanic explosions.
The results led them to suggest that degassing which occurs during magma ascent leads to a build-up of both fast-ascending gas-rich magma pulses together with slow-ascending gas poor pulses within the volcano’s conduit, which in turn determine the explosivity of any resulting eruption.
This particular type of volcanic activity is known as a Vulcanian explosion, and while they are explosive and short-lived, they often see large amounts of ash and magma fired more than 10km into the Earth’s atmosphere.
Dr Paul Cole, Lecturer in Geohazards at Plymouth University, said: “Vulcanian explosions can be hazardous, and the purpose of this study is to try and get some understanding of what controls the explosions themselves. Volcan de Colima became active again in 2013, and our concern is that this may be the forerunner to something more serious as it has previously erupted every 100 years or so, with the last major eruption in 1913. With tens of thousands of people living in communities regularly evacuated because of the volcano, any increased knowledge of its activity could obviously have a marked effect.”
Vulcanian explosions are among the most common types of volcanic activity observed at silicic volcanoes, and have also recently been in evidence at the Calbuco volcano in Chile.
Magma ascent rates have often been invoked as being the fundamental control on their explosivity, yet until now this factor is poorly constrained, partly due to the rarity of ash samples and low gas fluxes.
For this study, researchers employed a multi-disciplinary approach to address this, measuring sulphur dioxide fluxes emanating from the summit, as well as collecting ash for subsequent quantitative crystal and micro-geochemical analysis.
Dr Cole added: “This research has enhanced our knowledge, but we now need to explore whether the phenomena we have identified here are mirrored elsewhere. The current eruptions at Calbuco in Chile can also further our understanding of this type of activity and assist in our efforts to build a picture of how this gaseous interaction takes place, and the effects it has. Ultimately, it could help in our ongoing efforts to improve safety for communities living in the shadow of volcanoes.”
Aerial view of porphyry copper deposit at Butte, Montana. Credit: Stephen Kesler
Climate helps drive the erosion process that exposes economically valuable copper deposits and shapes the pattern of their global distribution, according to a new study from researchers at the University of Idaho and the University of Michigan.
Nearly three-quarters of the world’s copper production comes from large deposits that form about 2 kilometers (1.2 miles) beneath the Earth’s surface, known as porphyry copper deposits. Over the course of millions to tens of millions of years, they are exposed by erosion and can then be mined.
Brian Yanites of the University of Idaho and Stephen Kesler of the University of Michigan examined data on the age and number of exposed porphyry copper deposits worldwide. When they compared those data to the climate in each region, they noticed a pattern: The youngest deposits are in areas of high rainfall, such as the tropics, where erosion was rapid. Deposits are older in dry areas that have low rates of erosion.
Then they counted the number of deposits in the different regions and found something striking. Where erosion is rapid, there were relatively few deposits, but locations with low erosion rates contain lots of deposits. Such regions include the Atacama Desert in the Andes Mountains and the American Southwest–both places where porphyry copper mining is important to the economy.
By using porphyry copper deposits as a marker of a specific depth (2 kilometers) beneath the Earth’s surface, Yanites and Kesler were able to determine how rapidly the overlying crust had been eroded. The results showed that climate-driven erosion influenced the age and abundance of exposed copper porphyry deposits around the world.
Their findings are scheduled for online publication May 11 in Nature Geoscience.
“An important conclusion of this paper is that climate has a strong impact on the rate at which mountains are eroded and on the distribution of global copper resources. This effect persists over very long periods of Earth’s history,” said Kesler, an emeritus professor in the U-M Department of Earth and Environmental Sciences.
“The length of time is surprising. Most people would say that rainfall and climate are important to erosion, but usually only over short periods–perhaps up to a million years. This study shows that the effects have extended for tens of millions of years.”
Yanites is an assistant professor in UI’s Department of Geological Sciences and a former postdoctoral researcher at U-M. He is a geomorphologist, studying Earth’s topography. Kesler is an economic geologist, studying the formation of deposits that can be mined for raw materials.
“This is the first time that we’ve found a connection between geomorphology and economic geology,” Yanites said. “It’s exciting to think that erosion and the building of our mountain landscapes influences where society gets its resources from, and it’s another line of evidence showing the importance of climate in shaping the landscape.”
The study shows that the number of porphyry copper deposits in a region reflects the cumulative history of erosion experienced by the rocks there. As erosion removes overlying material, underlying rock rises toward the surface. So the amount of time a rock unit spends at a specific crustal depth depends on the history of erosion above that zone.
Rocks that are rapidly exhumed spend less time at depths of around 2 kilometers that are most favorable for the processes that form porphyry copper deposits. Therefore, fewer deposits will be observed when this level is exposed at the surface.
Yanites compared the relationship between erosion rate and the number of copper deposits in a region to a game on the TV show “American Gladiators,” where competitors had to run past tennis-ball-launching cannons to reach their goal.
“The faster the competitors run, the lower the chance that they will get hit because they spend less time in the ‘danger zone,'” Yanites said. “Similarly, rock layers that spend less time in the porphyry production zone–due to rapidly eroding landscapes above–have less of a chance of getting injected with one of these valuable deposits.”
Kesler said the new paper is the result of a fortuitous collaboration that developed several years ago after Yanites attended a talk by Kesler about a mathematical model describing how copper deposits move through the Earth’s crust after forming at a depth of 2 kilometers. Yanites was a U-M postdoc at the time.
“Because we know how many deposits are at the surface, and we know the ages of those deposits, the model calculation told us how many deposits were in the subsurface,” Kesler said. “And because we know the rate at which we mine copper, we could show that there are enough deposits to supply the mining industry for only a few thousand years. This puts a limit on what you might essentially call the sustainability of our lifestyle on the planet, even with good recycling.”
Yanites borrowed data from the study by Kesler and retired U-M professor Bruce Wilkinson and used it to reach novel conclusions about the climate signal in exhumation patterns revealed by porphyry copper deposits. The work by Yanites and Kesler was supported in part by the National Science Foundation.
Two university research teams are employing satellite imagery and supercomputers to produce high-resolution images to aid the Nepali earthquake relief effort. This image is a hillshade-rendered Digital Terrain Model image of the Kathmandu Valley, Nepal, created by SETSM software. The Ohio Supercomputer Center is providing the computing power for these data-intensive calculations. Credit: Ian Howat/The Ohio State University
Researchers who normally use high-resolution satellite imagery to study glaciers are using their technology this week to help with disaster relief and longer-term stabilization planning efforts related to the recent earthquake in Nepal.
On April 25, a violent earthquake struck central Nepal, killing more than 7,000 people and destroying hundreds of thousands of homes. The deadliest earthquake in Nepal since 1934, the tremor killed at least 19 climbers and crew on Mount Everest and reportedly produced casualties in the adjoining countries of Bangladesh, China and India.
Two research teams – one at The Ohio State University and another at the University of Minnesota – are working quickly to employ Surface Extraction for TIN-based Searchspace Minimization (SETSM) software to produce high-resolution, 3-D digital surface maps for use in the Nepali relief effort. The Ohio Supercomputer Center is providing the computing power for these data-intensive calculations.
“These data are critical for a range of uses, including mapping infrastructure, planning rescues and assessing slope stability,” explained Ian Howat, Ph.D., an associate professor of Earth Sciences at Ohio State and a principal investigator in the Glacier Dynamics Research Group at the university’s Byrd Polar and Climate Research Center. “Thus far, we have produced a mosaic that models the Kathmandu area with measurements at eight-meter intervals.”
“To support this effort, we have granted the SETSM team priority queuing and an emergency allocation of up to 60,000 core hours for use of our flagship supercomputer system, the Oakley Cluster,” said Brian Guilfoos, HPC Client Services Manager at the Ohio Supercomputer Center.
The SETSM software is a fully automatic algorithm for deriving the surface maps, called Digital Terrain Models, or DTMs. The maps are created from applying the algorithm to sets of overlapping pairs of high-resolution satellite images acquired by colleagues at the Polar Geospatial Center at the University of Minnesota. The satellite images are acquired from the Worldview-1 and Worldview-2 satellites, owned by DigitalGlobe Inc., and are licensed through the National Geospatial-Intelligence Agency’s NextView program. The Polar Geospatial Center will distribute the final products on the organization’s website.
“Besides improving on this DTM, we will be processing the entirely useable archive of Worldview stereo imagery over Nepal, starting this week, in order to expand coverage,” said Myoung-Jong Noh, a member of the Glacier Dynamics Research Group at the Byrd Center and the lead author of a scientific paper on SETSM in the journal GIScience & Remote Sensing.
The DTMs are built using photogrammetric techniques in which common features are identified in each image and are used to model the relative three-dimensional position of the terrain. These DTMs are constructed without ground control and rely on the satellite-positioning model to locate the surface in space. The accuracy of the DTM is expected to be within several meters in the vertical dimension. The initial version of the Nepal mosaic was produced automatically and, therefore, has some small errors and edge artifacts that will be improved in the days ahead.
In partnership with the Polar Geospatial Center, the Ohio State group has embarked on a massive implementation of SETSM to derive high-resolution DTM mosaics of large areas, such as the Greenland Ice Sheet. SETSM is currently installed and running on high performance computing systems at the Ohio Supercomputer Center, the National Science Foundation’s Extreme Science and Engineering Discovery Environment and the National Aeronautics and Space Administration. SETSM was developed as part of grant NNX10AN61G from the National Aeronautics and Space Administration.
Two Saurornitholestes sullivani raptors attacks a subadult hadrosaur Parasaurolophus tubicen. Credit: Illustration by Mary P. Wiliams
A researcher from the University of Pennsylvania has identified a species of dinosaur closely related to Velociraptor, the group of creatures made infamous by the movie “Jurassic Park.” The newly named species likely possessed a keen sense of smell that would have made it a formidable predator.
Steven Jasinski, a doctoral student in the School of Arts & Sciences’ Department of Earth and Environmental Science at Penn and acting curator of paleontology and geology at the State Museum of Pennsylvania, discovered the new species while investigating a specimen originally assigned to a previously known species. His analysis suggests the fossil — part of the dinosaur’s skull — actually represents a brand new species, which Jasinski has named Saurornitholestes sullivani.
Jasinski reported his findings this month in the New Mexico Museum of Natural History and Science Bulletin.
The specimen, roughly 75 million years old, was discovered by paleontologist Robert Sullivan in the Bisti/De-Na-Zin Wilderness Area of New Mexico in 1999. When first described, scientists believed it was a member of Saurornitholestes langstoni, a species of theropod dinosaurs in the Dromaeosauridae family that had been found in present-day Alberta, Canada.
But when Jasinski began a comparative analysis of the specimen to other S. langstoni specimens, he found subtle differences. Notably, he observed that the surface of the skull corresponding with the brain’s olfactory bulb was unusually large. This finding implies a powerful sense of smell.
“This feature means that Saurornitholestes sullivani had a relatively better sense of smell than other dromaeosaurid dinosaurs, including Velociraptor, Dromaeosaurus, and Bambiraptor,” Jasinski said. “This keen olfaction may have made S. sullivani an intimidating predator as well.”
S. sullivani comes from the end of the time of dinosaurs, or the Late Cretaceous, and represents the only named dromaeosaur from this period in North America south of Montana.
At the time S. sullivani lived, North America was split into two continents separated by an inland sea. This dinosaur lived on the western shores in an area called Laramidia.
Numerous dromaeosaurs, which are commonly called raptors, are known from more northern areas in Laramidia, including Alberta and Montana. However, S. sullivani represents the only named dromaeosaur from the Late Cretaceous of southern Laramidia.
S. sullivani shared its world with numerous other dinosaurs. Plant-eating contemporary dinosaurs included the duck-billed hadrosaurs Parasaurolophus walkeri and Kritosaurus navajovius, the horned dinosaur Pentaceratops sternbergii, the pachycephalsaurs Stegoceras novomexicanum and Sphaerotholus goodwini and the ankylosaurs Nodocephalosaurus kirtlandensis and recently named Ziapelta sanjuanensis. Other contemporary meat-eating theropods included the tyrannosaurs Bistahieversor sealeyi and Daspletosaurus, along with ostrich-like ornithomimids.
Though a distinct species, S. sullivani appears to be closely related to S. langstoni. Finding the two as distinct species further shows that differences existed between dinosaurs between the northern and southern parts of North America.
At less than 3 feet at its hip and roughly 6 feet in length, S. sullivani was not a large dinosaur. However, previous findings of related species suggest the animal would have been agile and fast, perhaps hunting in packs and using its acute sense of smell to track down prey.
“Although it was not large, this was not a dinosaur you would want to mess with,” Jasinski said
New research, led by the University of Southampton, has questioned the role played by ocean acidification, produced by the asteroid impact that killed the dinosaurs, in the extinction of ammonites and other planktonic calcifiers 66 million years ago.
Ammonites, which were free-swimming molluscs of the ancient oceans and are common fossils, went extinct at the time of the end-Cretaceous asteroid impact, as did more than 90 per cent of species of calcium carbonate-shelled plankton (coccolithophores and foraminifera).
Comparable groups not possessing calcium carbonate shells were less severely affected, raising the possibility that ocean acidification, as a side-effect of the collision, might have been responsible for the apparent selectivity of the extinctions.
Previous CO2 rises on Earth happened so slowly that the accompanying ocean acidification was relatively minor, and ammonites and other planktonic calcifiers were able to cope with the changing ocean chemistry. The asteroid impact, in contrast, caused very sudden changes.
In the first modelling study of ocean acidification which followed the asteroid impact, the researchers simulated several acidifying mechanisms, including wildfires emitting CO2 into the atmosphere (as carbon dioxide emissions dissolve in seawater they lower the pH of the oceans making them more acidic and more corrosive to shells) and vaporisation of gypsum rocks leading to sulphuric acid or ‘acid rain’ being deposited on the ocean surface.
The researchers concluded that the acidification levels produced were too weak to have caused the disappearance of the calcifying organisms.
Professor Toby Tyrrell, from Ocean and Earth Science at the University of Southampton and co-author of the study, says: “While the consequences of the various impact mechanisms could have made the surface ocean more acidic, our results do not point to enough ocean acidification to cause global extinctions. Out of several factors we considered in our model simulation, only one (sulphuric acid) could have made the surface ocean severely corrosive to calcite, but even then the amounts of sulphur required are unfeasibly large.
“It throws up the question, if it wasn’t ocean acidification what was it?”
Possible alternative extinction mechanisms, such as intense and prolonged darkness from soot and aerosols injected into the atmosphere, should continue to be investigated.
The study, which is published in the Proceedings of the National Academy of Sciences (PNAS), involved researchers from the University of Southampton and the Leibniz Center for Tropical Marine Ecology. The project received funding from the European Project on Ocean Acidification and funding support from NERC, Defra and DECC to the UK Ocean Acidification programme (grant no. NE/H017348/1).
Reference:
Toby Tyrrell, Agostino Merico, and David Ian Armstrong McKay. Severity of ocean acidification following the end-Cretaceous asteroid impact. PNAS, May 11, 2015 DOI: 10.1073/pnas.1418604112
Scientists have successfully replicated the molecular processes that led from dinosaur snouts to the first bird beaks. Credit: Image courtesy of Yale University
Using the fossil record as a guide, a research team led by Yale paleontologist and developmental biologist Bhart-Anjan S. Bhullar and Harvard developmental biologist Arhat Abzhanov conducted the first successful reversion of a bird’s skull features. The scientists replicated ancestral molecular development to transform chicken embryos in a laboratory into specimens with a snout and palate configuration similar to that of small dinosaurs such as Velociraptor and Archaeopteryx.
Just don’t call them dino-chickens.
“Our goal here was to understand the molecular underpinnings of an important evolutionary transition, not to create a ‘dino-chicken’ simply for the sake of it,” said Bhullar, lead author of the study, published online May 12 in the journal Evolution.
Finding the mechanism to recreate elements of dinosaur physiology has been a topic of popular interest for some time. It has been featured in everything from molecular biologist Jack Horner’s 2009 book, “How to Build a Dinosaur,” to the upcoming Hollywood movie “Jurassic World.”
In this case, the fascination derives from the importance of the beak to avian anatomy. “The beak is a crucial part of the avian feeding apparatus, and is the component of the avian skeleton that has perhaps diversified most extensively and most radically — consider flamingos, parrots, hawks, pelicans, and hummingbirds, among others,” Bhullar explained. “Yet little work has been done on what exactly a beak is, anatomically, and how it got that way either evolutionarily or developmentally.”
In the new study, Bhullar and his colleagues detail a novel approach to finding the molecular mechanism involved in creating the skeleton of the beak. First, they did a quantitative analysis of the anatomy of related fossils and extant animals to generate a hypothesis about the transition; next, they searched for possible shifts in gene expression that correlated with the transition.
The team looked at gene expression in the embryos of emus, alligators, lizards, and turtles. The researchers discovered that both major living lineages of birds (the common neognaths and the rarer paleognaths) differ from the major lineages of non-bird reptiles (crocodiles, turtles, and lizards) and from mammals in having a unique, median gene expression zone of two different facial development genes early in embryonic development. This median gene expression had previously only been observed in chickens.
Using small-molecule inhibitors to eliminate the activity of the proteins produced by the bird-specific, median signaling zone in chicken embryos, the researchers were able to induce the ancestral molecular activity and the ancestral anatomy. Not only did the beak structure revert, but the process also caused the palatine bone on the roof of the mouth to go back to its ancestral state. “This was unexpected and demonstrates the way in which a single, simple developmental mechanism can have wide-ranging and unexpected effects,” Bhullar said.
The work took Bhullar from the alligator nests at Rockefeller Wildlife Refuge in southern Louisiana to an emu farm in Massachusetts. He extracted DNA from various species in order to clone fragments of genetic material to look for specific gene expression.
Bhullar said the research has several implications. For example, he said, if a single molecular mechanism was responsible for this transformation, there should be a corresponding, linked transformation in the fossil record. “This is borne out by the fact that Hesperonis — discovered by Othniel Charles Marsh of the Yale Peabody Museum of Natural History — which is a near relative of modern birds that still retains teeth and the most primitive stem avian with a modernized beak in the form of fused, elongate premaxillae, also possesses a modern bird palatine bone,” he said.
Premaxillae are the small bones at the tip of the upper jaw of most animals, but are enlarged and fused to form the beak of birds.
Bhullar noted that this same approach could be used to investigate the underlying developmental mechanisms of a host of great evolutionary transformations.
The other corresponding authors are Zachary Morris, Elizabeth Sefton, Bumjin Namkoong, and Jasmin Camacho, all of Harvard; Atalay Tok, of Uppsala University; Masayoshi Tokita, of Toho University; and David Burnham, of the University of Kansas.
Reference:
Bhart-Anjan S. Bhullar, Zachary S. Morris, Elizabeth M. Sefton, Atalay Tok, Masayoshi Tokita, Bumjin Namkoong, Jasmin Camacho, David A. Burnham, Arhat Abzhanov. A molecular mechanism for the origin of a key evolutionary innovation, the bird beak and palate, revealed by an integrative approach to major transitions in vertebrate history. Evolution, 2015; DOI: 10.1111/evo.12684
Note: The above story is based on materials provided by Yale University. The original article was written by Jim Shelton
Huge bolts of pryoclastic lightning flash as the Calbuco volcano in southern Chile erupts Credit: Martin Bernetti/AFP
A new study shows that relatively small external disturbances play a crucial role in chaotic phenomena like the recent Calbuco volcanic eruption in Chile, leading to drum-beat-like seismicity.
Volcanoes are considered chaotic systems. They are difficult to model because the geophysical and chemical parameters in volcanic eruptions exhibit high levels of uncertainty. Now, Dmitri V. Alexandrov and colleagues from the Ural Federal University in Ekaterinburg, in the Russian Federation, have further extended an eruption model — previously developed by other scientists — to the friction force at work between the volcanic plug and volcanic conduit surface. The results, published in EPJB, provide evidence that volcanic activity can be induced by external noises that would not otherwise have been predicted by the model.
Predicting when, where and how volcanic eruptions will happen is likely to remain empirical. That is, until it is possible to improve the modelling of their dynamics. The challenge of such models is that the volcanic eruption dynamics are very complex, involving simultaneous unrelated processes and offering a variety of possible scenarios.
The authors built on a previous study demonstrating the influence of noise in triggering eruptions. Namely, they assumed that, under complex friction forces, the volcano plug and conduit exhibit a previously identified mechanism, called stick-slip behaviour, which causes the volcanic plug to rise and fall in an attenuated manner. They then studied the influence of random disturbances on these dynamics. They also tested the resulting model with experimental data from the Mount St. Helen’s eruption, dating back to 2004 and 2005.
Alexandrov and colleagues show that the external noise is also linked to the appearance of large-amplitude oscillations in the volcanic plug and high seismicity. An increase in noise intensity leads to drumbeat-type plug movement, exhibiting irregular periodicity dependent on noise. Such beat-type behaviour is a building block for understanding the physical mechanisms of volcanic drumbeat seismicity.
Reference:
Dmitri V. Alexandrov, Irina A. Bashkirtseva, Lev B. Ryashko. How a small noise generates large-amplitude oscillations of volcanic plug and provides high seismicity. The European Physical Journal B, 2015; 88 (4) DOI: 10.1140/epjb/e2015-60130-6
This graphic illustrates separating rare earth metals with UV light. Credit: KU Leuven – Department of Chemical Engineering
Researchers from the KU Leuven Department of Chemical Engineering have discovered a method to separate two rare earth elements — europium and yttrium — with UV light instead of with traditional solvents. Their findings, which were published in Green Chemistry, offer new opportunities for the recycling of fluorescent lamps and low-energy light bulbs.
Europium and yttrium are two rare earth metals that are commonly used in sustainable technology and high-tech applications. As these rare earth metals are difficult to mine, there is a great interest in recycling them. Europium and yttrium can be recovered from red lamp phosphor, a powder that is used in fluorescent lamps such as neon tubes.
In early 2015, KU Leuven chemists developed ionic liquid technology to recycle europium and yttrium from collected fluorescent lamps and low-energy light bulbs. Their method recycles the red lamp phosphor as a whole to reuse the powder in lamps. For other applications, however, it is necessary to separate europium and yttrium from the rare-earth mixture.
Separating the two rare earth elements is a complicated process. Professor Tom Van Gerven from the Department of Chemical Engineering explains: “The traditional method dissolves europium and yttrium in aqueous acid. An extractant and a solvent are then added to the aqueous liquid, leading to two separate layers known as ‘phases’: an aqueous layer containing the rare earth metals and a solvent layer with the extractant. When the two layers come into contact, one of the two rare earth metals is extracted to the solvent, while the other rare earth metal remains in the aqueous layer.”
But this process leaves much to be desired in terms of efficiency and purity: it needs to be repeated dozens of times to recover a high percentage of a particular rare earth metal, and there will still be traces of yttrium in the europium-containing liquid and vice versa.”
In collaboration with KU Leuven chemists the researchers have now managed to recover europium from the liquid mixture with UV light instead of a solvent. “The UV light influences the electrically charged particles known as ions. Both europium and yttrium have three positive charges per ion. When we shine UV light upon the solution of europium and yttrium, we add energy to the system. As a result, one positive charge per europium ion is neutralized. When we add sulphate, only the europium reacts with it. The result is a precipitate that can easily be filtered, while the yttrium remains in the solution,” says Bart Van den Bogaert, who is preparing a PhD on the subject.
The advantages of UV light are that it does not leave behind any harmful chemicals in the liquid and that the separation efficiency and purity in synthetic mixtures is very high: more than 95% of the europium is recovered from the solution. The precipitate itself is 98,5% pure, so it contains hardly any traces of yttrium. A similar purity was obtained with industrial mixtures, but the efficiency of the separation still needs to be improved. That will be one of the next projects tackled by the KU Leuven researchers.
Reference:
Bart Van den Bogaert, Daphné Havaux, Koen Binnemans, Tom Van Gerven. Photochemical recycling of europium from Eu/Y mixtures in red lamp phosphor waste streams. Green Chem., 2015; 17 (4): 2180 DOI: 10.1039/C4GC02140A
An international group of scientists has proposed that fallout from hundreds of nuclear weapons tests in the late 1940s to early 1960s could be used to mark the dawn of a new geological age in Earth history — the Anthropocene.
The study, led by Dr Colin Waters of the British Geological Survey, published new research in the Bulletin of the Atomic Scientists. The research involved 10 members of the Anthropocene Working Group that is chaired by Professor Jan Zalasiewicz of the Department of Geology at the University of Leicester and Gary Hancock, a world expert on plutonium in the environment.
The researchers state that the mid-twentieth century coincides with the ‘Great Acceleration’ of human population growth, economic development and industrialization. The emergence of megacities, facilitated by the production of huge quantities of concrete, is coincident with earth movement on a vast scale. Mineral exploitation has resulted in the generation of marked geochemical signatures across the globe and this age of hydrocarbon burning has resulted in greatly increased carbon emissions. Humanity’s modification of the planet has caused an increase in species extinctions and invasions. All these features are being expressed in the sediments accumulating across the planet and will be recognizable to the geoscientists of the far future.
They pose the question: “If the sum of these changes is a recognition that we now live in a new epoch, the Anthropocene, how can we define when it started?”
The standard practice for defining geological time units is to identify a single reference point (or “golden spike”) that fixes the lower boundary of the time unit within a succession of rock or sediment layers. The boundary should be characterized by a signature that is both rapidly developed and wide-spread. The proposal led by Dr Waters is that the programme of atmospheric nuclear weapons testing may have generated such a signature.
Dr Waters said: “It is sobering to think that the actions of humanity over a few short years in the mid-20th century created such large amounts of artificial radionuclides that scattered across the Earth as fallout, producing a signal in modern strata that, in the case of plutonium, will be a detectable for about 100,000 years into the future.”
Starting with the 1945 detonation of the Trinity device in New Mexico, the extent of such fallout was initially quite localized. But with the introduction in 1952 of the much larger “thermonuclear” or “hydrogen” weapons tests, the fallout dispersed over the entire Earth surface. The amount of fallout peaked in 1962, the year before the Partial Nuclear Test-Ban Treaty largely drove the nuclear detonations underground. The 1952 rise in abundance of the isotope plutonium-239 is preferred as it is rare in nature, is a significant component of fallout, is relatively immobile in sediments, has a long half-life so will persist long into the future and the rise is broadly coincident with the onset of the “Great Acceleration.”
Professor Zalasiewicz said: “The Anthropocene has struck a chord in the wider world that none of the other geological time units have done — not even the dinosaur-haunted Jurassic. Human beings don’t merely inhabit the world. They alter it, on an increasingly epic scale.”
In 2016, the Anthropocene Working Group hopes to make recommendations on whether this new time unit should be formalized and, if so, how it might be defined and characterized.
Reference:
C. N. Waters, J. P. M. Syvitski, A. Gauszka, G. J. Hancock, J. Zalasiewicz, A. Cearreta, J. Grinevald, C. Jeandel, J. R. McNeill, C. Summerhayes, A. Barnosky. Can nuclear weapons fallout mark the beginning of the Anthropocene Epoch? Bulletin of the Atomic Scientists, 2015; 71 (3): 46 DOI: 10.1177/0096340215581357
Calcit crystals in the Alum Shale as indicators of methane formation Credit: GFZ
Considering geological time scales, the occurrence of biogenic shale gas in Sweden´s crust is relatively young. An international team of geoscientists (led by Hans-Martin Schulz, German Research Centre for Geosciences GFZ) found that biogenic methane in the Alum Shale in South Sweden formed due to deglaciation around 12.000 years ago. Moreover, the formation processes were due to complex interactions between neotectonic activity and the occurrence of a deep biosphere. Applying a new hydrogeochemical modelling approach, the specific methane generation process was unravelled and quantified for the first time in Europe.
Around 300 million years ago the Variscan Mountain belt was formed in Central Europe. Its orogeny and uplift was coupled to extensional movements in today´s Northern Europe. As a result, mafic magmas intruded the early Palaeozoic rock sequence and led to oil formation in the Alum Shale followed by its expulsion. Migrating bitumens impregnated the Alum Shale outside the area of thermal influence.
The melting of the up to three kilometers thick glaciers at the end of the last glaciation led to a beginning uplift of the formerly glaciated Baltic Sea region which still today rises by up to 10 mm per year. A consequence of this uplift tendency is the formation of fractures along which melting water migrated into the subsurface. It is important to note that low contents of dissolved solids in formation water is a prerequisite for methanogenic microbes to convert soluble oil components into methane. Accordingly, methane is stored in black shale today and can be found up to approximately 100 meters depth.
Up to now, similar biogenic methane resources were exclusively known from North America which was glaciated as Northern Europe. The most prominent example is the Antrim Shale of Devonian age in Michigan.
Reference:
Hans-Martin Schulz, Steffen Biermann, Wolfgang van Berk, Martin Krüger, Nontje Straaten, Achim Bechtel, Richard Wirth, Volker Lüders, Niels Hemmingsen Schovsbo, and Stephen Crabtree. From shale oil to biogenic shale gas: Retracing organic–inorganic interactions in the Alum Shale (Furongian–Lower Ordovician) in southern Sweden. AAPG Bulletin, May 2015 DOI: 10.1306/10221414014
A wild-type Chironomus larva with normal head (left) and abdomen (right) development is shown. Credit: Urs Schmidt-Ott/University of Chicago
Newly evolved genes can rapidly assume control over fundamental functions during early embryonic development, report scientists from the University of Chicago. They identified a gene, found only in one specific group of midge flies, which determines the patterning of the head and tail in developing embryos. This newly discovered gene has the same developmental role as an unrelated, previously-known gene which appears to have been lost or altered in certain fly families during evolution. The findings, published in Science on May 7, suggest that evolutionary changes to the genetics of fundamental biological processes occur more frequently than previously thought.
“The genes that drive embryonic polarity are not conserved across flies and their evolutionary replacement does not seem to be rare at all,” said study senior author Urs Schmidt-Ott, PhD, associate professor of organismal biology and anatomy at the University of Chicago. “The hijacking of this early developmental pathway by novel or newly evolved genes happens at a much higher frequency than previously thought.”
In the common fruit fly Drosophila and related flies, the gene bicoid determines which end of an embryo will develop into the head and which will become the tail. However, most flies and other insects lack bicoid, and how they establish this head-to-tail polarity has been poorly understood. Early studies of chironomids, a group of mosquito-like midges, found that ultraviolet light or RNAse targeted toward the front portion of embryos led to double-abdomen formation (two tail ends and no head), which suggested that localized RNA in the anterior egg might function as head determinant.
To identify which gene products were being disrupted, Schmidt-Ott’s team profiled and compared gene expression levels between the front and rear halves of Chironomus embryos. Out of thousands of candidates, the team identified a specific gene, which appeared to be necessary for the formation of head-to-tail polarity. Double-abdomen formation occurred when this gene, called panish, was silenced in early Chironomus embryos. These embryos could be returned to normal with the addition of an independent source of panish gene product.
Although panish and bicoid perform essentially the same function, they are structurally unrelated and found in completely separate families of flies. Both genes act by regulating other genes involved in genetic patterning, but panish represses them while bicoid activates them.
The team found no evidence of panish in flies other than Chironomus, suggesting that panish is a newly evolved gene that appropriated the function of regulating head-to-tail polarity. They also reexamined the occurrence of bicoid and discovered that the gene has been repeatedly lost or substantially altered in certain fruit flies and tsetse flies during evolution.
Despite the importance of head-to-tail patterning in early embryonic development, it appears that genes that regulate the process are poorly conserved in flies, and that new genes took over the role far more often than previously thought.
The discovery of this phenomenon now opens a multitude of new research avenues. Schmidt-Ott and his colleagues are now investigating questions such as how do genes appropriate new roles, why it happens so frequently and whether such instances share common features.
“It’s astonishing how a newly evolved gene can, in a very short amount of time, take over control of such a fundamental process,” Schmidt-Ott said. “Given that a small sample of examined genomes already suggests four independent fundamental substitutions, we probably are looking at the ‘tip of the iceberg’ for these events.”
Reference:
Jeff Klomp, Derek Athy, Chun Wai Kwan, Natasha I. Bloch, Thomas Sandmann, Steffen Lemke, Urs Schmidt-Ott. A cysteine-clamp gene drives embryo polarity in the midge Chironomus. DOI: 10.1126/science.aaa7105
Mimulus peregrinus — the foreigner, is a new flower species native to Scotland. Credit: University of Stirling
A Stirling scientist who discovered a new Scottish flower has made an unexpected second finding which provides unique insight into our understanding of evolution.
Dr Mario Vallejo-Marin, a Plant Evolutionary Biologist at the University of Stirling, first unearthed a new species of monkeyflower on the bank of a stream in South Lanarkshire, Southern Scotland in 2012.
A subsequent expedition two years later led Dr Vallejo-Marin to locate the impressive yellow flower some 350 miles north, near Stromness on the Orkney Islands off the north coast of Scotland.
“Orkney was a missing region which hadn’t been sampled,” explained Dr Vallejo-Marin, Senior Lecturer in the School of Natural Sciences. “There were different varieties of monkey flower on the island, but when we spotted this population I knew it was unusual as after looking at hundreds of plants, you get to recognise the subtle differences.
“Usually a species forms once in a particular location then spreads to other regions. In this case, the opposite has occurred as the same species has evolved multiple times in different places. It shows that when the conditions are right, the origin of species is a repeatable phenomenon.”
After the initial discovery, Dr Vallejo-Marin named the species Mimulus peregrinus – which translates as ‘the foreigner’ – given its origins from two invasive species first brought to the UK from the USA and South America in the 1800s.
It was a particularly rare find given hybrid plants of its kind are normally infertile. Instead, it doubled the amount of DNA in its cells and evolved to form a new species in a process known as polyploidisation, the same mechanism by which Wheat, Cotton and Tobacco originated.
Dr Vallejo-Marin added: “It is impossible to say whether Mimulus peregrinus evolved first in the south or in the north of Scotland, but our discovery of a very young species of this kind has allowed us to study evolution as it happens. We only know of a handful of other plant species as young as Mimulus peregrinus and so in this respect it is like looking at the big bang in the first milliseconds of its occurrence.
“The process of evolution it has followed is particularly interesting and adds complexity to our conception of the tree of life. Instead of branching out as it grows, Mimulus peregrinus is an example of how some branches can come back together again and spawn new species that are in part the combination of their ancestors.”
Dr Vallejo-Marin’s research is published in the Journal Evolution. The research was completed with UK colleagues from Queen Mary University of London and with Whitman College and the College of William and Mary in the USA.
Reference:
Mario Vallejo-Marín, Richard J. A. Buggs, Arielle M. Cooley andJoshua R. Puzey. Speciation by genome duplication: Repeated origins and genomic composition of the recently formed allopolyploid species Mimulus peregrinus. DOI: 10.1111/evo.12678
This is the Agham fluvial terrace, located roughly 400 m above the current river level of the upper Shyok valley, NW Himalayas, India. See related article by J.H. Blöthe and colleagues. Credit: J.H. Blöthe and colleagues and Geology
Large landslides are an important process of erosion in the Himalaya-Karakoram ranges (HKR). These high-relief landscapes are characterized by steep slopes that are prone to frequent landsliding. By mapping nearly 500 large (greater than 0.1 km2) landslides in the HKR, Jan Henrik Blöthe and colleagues find that the vast majority of these mass movements lie in the lower portions of the landscape, whereas glaciers and rock glaciers occupy the higher elevations almost exclusively.
These findings suggest that different processes dominate the gross erosion in the HKR at different elevations: Large landslides appear to preferentially undermine the topography in response to incision along major rivers, whereas glacial erosion and/or more frequent and smaller slope failures, associated with intense frost action, compensate for this role at higher elevations.
In this study published in Geology, Blöthe and colleagues introduce a new method that they term excess topography (ZE) to identify the location of potentially unstable rock-mass volumes. They find that locations with high values of ZE are concentrated near or below the median elevation, which is also where the majority of the mapped landslides occur, and conclude that the HKR are characterized by two vertical domains of landslide and (peri-)glacial erosion that may respond to different time scales of perturbation
Reference:
Large landslides lie low: Excess topography in the Himalaya-Karakoram ranges
Jan Henrik Blöthe et al., University of Potsdam, Potsdam, Germany; and University of Bonn, Bonn, Germany. Published online ahead of print on 27 Apr. 2015; DOI: 10.1130/G36527.1.
Odaraia alata, an arthropod resembling a submarine from the middle Cambrian Burgess Shale. Credit: Jean Bernard Caron (Royal Ontario Museum)
A new study from the University of Cambridge has identified one of the oldest fossil brains ever discovered – more than 500 million years old – and used it to help determine how heads first evolved in early animals. The results, published today (7 May) in the journal Current Biology, identify a key point in the evolutionary transition from soft to hard bodies in early ancestors of arthropods, the group that contains modern insects, crustaceans and spiders.
The study looked at two types of arthropod ancestors – a soft-bodied trilobite and a bizarre creature resembling a submarine. It found that a hard plate, called the anterior sclerite, and eye-like features at the front of their bodies were connected through nerve traces originating from the front part of the brain, which corresponds with how vision is controlled in modern arthropods.
The new results also allowed new comparisons with anomalocaridids, a group of large swimming predators of the period, and found key similarities between the anterior sclerite and a plate on the top of the anomalocaridid head, suggesting that they had a common origin. Although it is widely agreed that anomalocaridids are early arthropod ancestors, their bodies are actually quite different. Thanks to the preserved brains in these fossils, it is now possible to recognise the anterior sclerite as a bridge between the head of anomalocaridids and that of more familiar jointed arthropods.
“The anterior sclerite has been lost in modern arthropods, as it most likely fused with other parts of the head during the evolutionary history of the group,” said Dr Javier Ortega-Hernández, a postdoctoral researcher from Cambridge’s Department of Earth Sciences, who authored the study. “What we’re seeing in these fossils is one of the major transitional steps between soft-bodied worm-like creatures and arthropods with hard exoskeletons and jointed limbs – this is a period of crucial transformation.”
Ortega-Hernández observed that bright spots at the front of the bodies, which are in fact simple photoreceptors, are embedded into the anterior sclerite. The photoreceptors are connected to the front part of the fossilised brain, very much like the arrangement in modern arthropods. In all likelihood these ancient brains processed information like in today’s arthropods, and were crucial for interacting with the environment, detecting food, and escaping from predators.
During the Cambrian Explosion, a period of rapid evolutionary innovation about 500 million years ago when most major animal groups emerge in the fossil record, arthropods with hard exoskeletons and jointed limbs first started to appear. Prior to this period, most animal life on Earth consisted of enigmatic soft-bodied creatures that resembled algae or jellyfish.
These fossils, from the collections of the Royal Ontario Museum in Toronto and the Smithsonian Institution in Washington DC, originated from the Burgess Shale in Western Canada, one of the world’s richest source of fossils from the period.
Since brains and other soft tissues are essentially made of fatty-like substances, finding them as fossils is extremely rare, which makes understanding their evolutionary history difficult. Even in the Burgess Shale, one of the rare places on Earth where conditions are just right to enable exceptionally good preservation of Cambrian fossils, finding fossilised brain tissue is very uncommon. In fact, this is the most complete brain found in a fossil from the Burgess Shale, as earlier results have been less conclusive.
“Heads have become more complex over time,” said Ortega-Hernández, who is a Fellow of Emmanuel College. “But what we’re seeing here is an answer to the question of how arthropods changed their bodies from soft to hard. It gives us an improved understanding of the origins and complex evolutionary history of this highly successful group.”
UC Berkeley seismologists were surprised last August to see a dramatic increase in faint tremors occurring under the San Andreas Fault near Parkfield, in Central California, about 10 hours after a magnitude 6.0 earthquake struck Napa. Somehow, that quake triggered tiny rumblings 250 miles away that lasted for about 100 days before dropping off.
These same researchers have recently found two other places in California where tremors are happening below the zone where earthquakes normally occur, and have now embarked on a comprehensive search for tremors throughout the state.
Key to discovering the connection between tremors and earthquakes is TremorScope, a set of four seismic stations to be placed about 900 feet underground near Parkfield to listen for these faint whispers. They will be added to four new surface stations already deployed as a part of the project.
“It’s a big job, but we hope to develop a near-real-time tremor monitoring capability in the TremorScope area and elsewhere,” said UC Berkeley seismologist Robert Nadeau, who will be working on the project with help from the Berkeley Institute for Data Science.
TremorScope is funded by a $1.2 million grant from the Gordon and Betty Moore Foundation.
“Tremors are associated with big, very slow movements on the fault, and there is speculation that they might cause big earthquakes,” said research seismologist Peggy Hellweg, UC Berkeley project lead for TremorScope and operations manager at the Berkeley Seismological Laboratory. “But we see tremor activity with earthquakes and earthquakes without tremor, so the connection is still unclear.”
Tremors originate beneath the zone where earthquakes occur and appear to be associated with slipping rocks deep in the earth. UC Berkeley seismologists discovered tremors just south of the Parkfield area of the San Andreas Fault in 2004, and subsequent studies suggest that changes in tremor activity may precede earthquakes. Tremors also have been detected in active earthquake zones in Japan, Washington state and other subduction zones around the world.
TremorScope is designed to measure these tremors more precisely than ever before, using geophones sensitive to high-frequency ground movement and broadband seismometers able to record low-frequency rumblings. Geophones and broadband seismometers are to be installed in four deep boreholes drilled around an area of the San Andreas Fault near Parkfield that seems to be the center of tremor activity where the northern and southern segments of the fault meet. The borehole instruments, which can detect quieter tremors because of less noise underground, complement instruments already in place at four surface stations in the area.
A surface accelerometer was installed in January at a site on the property of Cass Vineyard and Winery, located 12 miles east of Highway 101 near Paso Robles. The borehole instruments will be installed at the winery site May 6 and 7, with installation of the three other borehole seismometers scheduled in the coming months.
“With the four surface seismometers now installed, TremorScope is already helping us to locate tremor,” Nadeau said. “The deeper borehole seismometers will be able to give us a range of frequencies at higher resolution to figure out what is going on underground.”
Video
Seismologist Peggy Hellweg explains the TremorScope project, which involves four subsurface borehole seismometers and four surface seismometers to monitor faint tremors under the San Andreas Fault near Parkfield. Video by Roxanne Makasdjian and Phil Ebiner.
Geophysicist Horst Rademacher explains how a simple seismograph records the Earth’s shaking. Video by Roxanne Makasdjian and Phil Ebiner.
Artist’s impression of a rocky and water-rich asteroid being torn apart by the strong gravity of the white dwarf star. Similar objects in the Solar System likely delivered the bulk of water on Earth and represent the building blocks of the terrestrial planets. Credit: Image copyright Mark A. Garlick, space-art.co.uk, University of Warwick
Water delivery via asteroids or comets is likely taking place in many other planetary systems, just as it happened on Earth, new research strongly suggests.
Published by the Royal Astronomical Society and led by the University of Warwick, the research finds evidence for numerous planetary bodies, including asteroids and comets, containing large amounts of water.
The research findings add further support to the possibility water can be delivered to Earth-like planets via such bodies to create a suitable environment for the formation of life.
Commenting on the findings lead researcher Dr Roberto Raddi, of the University of Warwick’s Astronomy and Astrophysics Group, said: “Our research has found that, rather than being unique, water-rich asteroids similar to those found in our Solar System appear to be frequent. Accordingly, many planets may have contained a volume of water, comparable to that contained in the Earth.
“It is believed that the Earth was initially dry, but our research strongly supports the view that the oceans we have today were created as a result of impacts by water-rich comets or asteroids.”
In observations obtained at the William Herschel Telescope in the Canary Islands, the University of Warwick astronomers detected a large quantity of hydrogen and oxygen in the atmosphere of a white dwarf (known as SDSS J1242+5226). The quantities found provide the evidence that a water-rich exo-asteroid was disrupted and eventually delivered the water it contained onto the star.
The asteroid, the researchers discovered, was comparable in size to Ceres — at 900km across, the largest asteroid in the Solar System.
“The amount of water found SDSS J1242+5226 is equivalent to 30-35% of the oceans on Earth,” explained Dr Raddi.
The impact of water-rich asteroids or comets onto a planet or white dwarf results in the mixing of hydrogen and oxygen into the atmosphere. Both elements were detected in large amounts in SDSS J1242+5226.
Research co-author Professor Boris Gänsicke, also of University of Warwick, explained: “Oxygen, which is a relatively heavy element, will sink deep down over time, and hence a while after the disruption event is over, it will no longer be visible.
“In contrast, hydrogen is the lightest element; it will always remain floating near the surface of the white dwarf where it can easily be detected. There are many white dwarfs that hold large amounts of hydrogen in their atmospheres, and this new study suggests that this is evidence that water-rich asteroids or comets are common around other stars than the Sun.”
Reference:
R. Raddi, B. T. Gänsicke, D. Koester, J. Farihi, J. J. Hermes, S. Scaringi, E. Breedt and J. Girven. Likely detection of water-rich asteroid debris in a metal-polluted white dwarf,. Monthly Notices of the Royal Astronomical Society, 2015 (in press) DOI: 10.1093/mnras/stv701
UCLA’s William Newman, trained as an applied mathematician and theoretical physicist, has spent much of his career developing equations that explore the likelihood of earthquakes in certain regions. Credit: William Newman
In 2012, six Italian seismologists were sent to prison because they failed to predict the 2009 L’Aquila 6.3 magnitude earthquake.
To some that may seem absurd but it points to the faith so many have come to place in science’s ability to predict and prevent tragedies. Experts had for decades predicted that Nepal would experience a massive earthquake, but were unable to provide a more precise warning about the recent 7.8-magnitude quake that devastated the country. The Italian seismologists had similarly predicted earthquake probabilities but could not give an exact date.
Science and mathematics have not reached a point where they can forecast with certainty the exact time and specific severity of these cataclysmic events—and may never do so.
“The best we can do is make an assessment of there being a heightened risk in a certain geographic area over a certain window of time,” said William Newman, a theoretical physicist at the University of California, Los Angeles, who has received funding from the National Sceince Foundation (NSF) for his work aimed at improving natural hazard predictions. “We can determine a sense of what is likely to occur, but we will never know exactly.”
Newman has spent much of his 35-year career working in computational and applied mathematics but also has employed mathematics in applications to probe natural disaster issues such as earthquakes and climate change.
These days, mathematicians seem to be able to model almost anything, but, as Newman points out, the devil is not only in the details but in creating models that can be used for accurate prediction. In the case of tectonic plates, the randomness of their interaction limits the certainty of predictions, and those predictions become less certain as time passes. In much the same way that a weather forecaster can be more certain about predicting tomorrow’s weather than next month’s, Newman believes earthquake prediction accuracy has the potential to fall off.
“For mathematicians, three aspects come to mind,” Newman said. “We like to think of the equations being well posed, well defined, and that we can run with them. In [Edward] Lorenz’s case (whose model of turbulence celebrated its 50th anniversary recently), his equations about atmospheric behavior were, by and large, eminently reasonable. He supersimplified and saw that if he perturbed the initial conditions, after a certain amount of time, he could predict nothing.”
Yes, you read that right: nothing.
The problem for mathematicians is that forecasting accuracy can only weaken as more variables cloud the equations and models they build. In the case of earthquakes, Newman says the prospects for good predictions are even more dismal than for atmospheric ones. Chaotic dynamics and complexity prevail.
In Los Angeles, where Newman lives, mathematicians and geophysicists have worked together and determined that sometime in the next 30 years, the area is likely to see a substantial earthquake due to its proximity to the San Andreas Fault. And as each year passes, the risk increases in this window of time. The mathematicians can only put so many pre-determined variables into their equations, including the patterns of tectonic plate changes and the environmental conditions that coincide with earthquake occurrences.
“We have to go into this realizing there are bounds,” Newman said. “We are looking at complex systems that can produce patterns we just don’t understand.”
Additionally, while the news focuses on an earthquake and its aftershocks, there are also “foreshocks.” But recognizing a a foreshock is impossible without seeing the seismic event that follows. So trying to formulate day-to-day seismologic predictions after any earthquake event can also be confounding.
One could easily draw the conclusion at this point that we walk away from the issue, shaking our heads. But mathematicians, computer scientists, physicists, geologists, engineers, and social scientists working together on this issue do provide value, each adding something that could improve the scientific community’s understanding of this obviously complex issue.
As instruments become increasingly refined and data proliferate around the world, scientists also gain a better understanding of the consequences of earthquakes.
“It is true that scientists know very little about earthquake predictions,” said Junping Wang, program director in NSF’s mathematics division. “But this is exactly why we need to support earthquake research. Researching is the only way we can ever hope to build models that help to improve earthquake prediction and build a resilient society.”
As they conduct more research in seismology, scientists are able to gain more and better knowledge that can benefit local policymakers looking to enhance preparedness and emergency response to earthquakes and cascading disasters.
“There are still plenty of opportunities where scientific and mathematical research can improve our knowledge,” Wang said. “Understanding why an earthquake happened and how it happened helps us build better models, even if they can’t tell us a specific date and time. With increased knowledge comes better preparedness.”
Earthquake advice from a mathematician
“We can only tell people that there is a certain risk in a certain window of time,” Newman said. “Then it’s a matter of preparedness.”
He cites the example of the Northridge earthquake that rocked the UCLA Mathematical Sciences Building in 1994. Architects designed expansion joints in different sections of the building because they knew that, at some point, it would have to cope with the trauma of earthquakes. In that case, some of the offices went through an “unexpected expansion,” but Newman notes that ultimately the repairs were “essentially cosmetic.”
Newman, who carries the distinction of being a member of UCLA’s mathematics, physics and geology departments, routinely takes students to the San Andreas Fault—and specifically Vazquez Rocks, a set of formations exposed by seismic activity—for their research. He emphasizes that to prevent the fallout of earthquakes like the recent one in Nepal, policymaking that establishes building codes and individual preparedness are essential.
“If you live here, you have to earthquake-proof your home and your business. You need to be able to take care of yourself,” he said. “And then when an earthquake does occur, hopefully, it will just be an inconvenience.”
