Dapple is a global data explorer designed to provide an open and optimal environment for visualizing, presenting and sharing massive quantities of geoscientific data on desktop computers. Dapple lets you browse, discover and display graphically rich data from global and corporate spatial servers – Geosoft DAP servers, NASA servers, USGS servers, and the many, many WMS servers currently available. The Dapple project is an open-source activity derived from the NASA World Wind open source project.
Geosoft started the Dapple open source project in 2004. The Dapple project remains an open source project, however as of June 2012, Geosoft will no longer be playing an active role in the Dapple open source project.
Spatial Data Rights
When you use Dapple, you are browsing and viewing spatial data and information provided by web services on the Internet. Some of that data may be copyrighted or have other terms of use imposed by the supplier of that data. To protect your own liability, you should ensure that your use of that data does not violate any rights or conditions that the supplier of the data may have. The Dapple team shall not be liable in any way for your use of any data.
Explore the earth
Dapple makes it easy to find and visualize massive quantities of geoscientific data available on the Internet.
Search the Web for spatial data
Search internal DAP servers and known Web servers for spatial data
View geoscience data, satellite imagery, remote sensing data, geology maps, geophysical data, and many other earth data sets of interest to geoscientists
Save an earth view and share your view with colleagues
Add new Geosoft DAP, WMS and ArcIMS servers of interest
View GeoTIFF files
View KML files
Software requirements
Dapple can be installed under Windows XP SP3, Windows Vista (32,64) or Windows 7 (32,64). You must be logged in as system administrator or a power-user with rights to install software.
The Dapple installation will look for .Net Framework 2.0, then DirectX, and if either are not present on your system the Dapple install will attempt to install them for you. Should these installations prove a problem, you can choose to install these components yourself from the following reference sites:
Microsoft .Net Framework 2.0
Microsoft DirectX
You can then run the Dapple installation again.
Hardware requirements
Recommended configuration:
Operating System: Windows XP SP3, Windows Vista (32, 64), Windows 7 (32, 64).
CPU: Pentium 4 2.4GHz+ or AMD 2400xp+
System Memory (RAM): 2GB RAM
Hard Disk: Data disk space depends on the volume of project data to be processed and the printer driver you are using, however 100 GB is recommended. This is largely based on your business and data requirements.
Network Speed: 768 Kbits/sec
Graphics Card: 3D-capable with 64MB of VRAM
Screen: 1280×1024, “32-bit True Colour” screen
Screenshots
Adding a WMS server to the list of available WMS services in DappleViewing map and metadata in DappleUsing the metadata legend link to view the legend information
Researchers have discovered a new birth story for mosasaurs. Credit: Illustration by Julius T. Csotonyi
They weren’t in the delivery room, but researchers at Yale University and the University of Toronto have discovered a new birth story for a gigantic marine lizard that once roamed the oceans.
Thanks to recently identified specimens at the Yale Peabody Museum of Natural History, paleontologists now believe that mighty mosasaurs — which could grow to 50 feet long — gave birth to their young in the open ocean, not on or near shore.
The findings answer long-held questions about the initial environment of an iconic predator that lived during the time of the dinosaurs. Mosasaurs populated most waters of the Earth before their extinction 65 million years ago.
“Mosasaurs are among the best-studied groups of Mesozoic vertebrate animals, but evidence regarding how they were born and what baby mosasaur ecology was like has historically been elusive,” said Daniel Field, lead author of a study published online April 10 in the journal Palaeontology. Field is a doctoral candidate in the lab of Jacques Gauthier in Yale’s Department of Geology and Geophysics.
In their study, Field and his colleagues describe the youngest mosasaur specimens ever found. Field had come across the fossils in the Yale Peabody Museum’s extensive collections. “These specimens were collected over 100 years ago,” Field said. “They had previously been thought to belong to ancient marine birds.”
Field and Aaron LeBlanc, a doctoral candidate at the University of Toronto at Mississauga, concluded that the specimens showed a variety of jaw and teeth features that are only found in mosasaurs. Also, the fossils were found in deposits in the open ocean.
“Really, the only bird-like feature of the specimens is their small size,” LeBlanc said. “Contrary to classic theories, these findings suggest that mosasaurs did not lay eggs on beaches and that newborn mosasaurs likely did not live in sheltered nearshore nurseries.”
Reference:
Field, D. J., LeBlanc, A., Gau, A., Behlke, A. D. Pelagic neonatal fossils support viviparity and precocial life history of Cretaceous mosasaurs. Palaeontology, 2015 DOI: 10.1111/pala.12165
Smartphones and other personal electronic devices could, in regions where they are in widespread use, function as early warning systems for large earthquakes according to newly reported research. This technology could serve regions of the world that cannot afford higher quality, but more expensive, conventional earthquake early warning systems, or could contribute to those systems.
The study, led by scientists at the U.S. Geological Survey and published April 10 in the inaugural volume of the new AAAS journal Science Advances, found that the sensors in smartphones and similar devices could be used to build earthquake warning systems. Despite being less accurate than scientific-grade equipment, the GPS (Global Positioning System) receivers in a smartphone can detect the permanent ground movement (displacement) caused by fault motion in a large earthquake.
Using crowd-sourced observations from participating users’ smartphones, earthquakes could be detected and analyzed, and customized earthquake warnings could be transmitted back to users. “Crowd-sourced alerting means that the community will benefit by data generated from the community,” said Sarah Minson, USGS geophysicist and lead author of the study. Minson was a post-doctoral researcher at Caltech while working on this study.
Earthquake early warning systems detect the start of an earthquake and rapidly transmit warnings to people and automated systems before they experience shaking at their location. While much of the world’s population is susceptible to damaging earthquakes, EEW systems are currently operating in only a few regions around the globe, including Japan and Mexico. “Most of the world does not receive earthquake warnings mainly due to the cost of building the necessary scientific monitoring networks,” said USGS geophysicist and project lead Benjamin Brooks.
Researchers tested the feasibility of crowd-sourced EEW with a simulation of a hypothetical magnitude 7 earthquake, and with real data from the 2011 magnitude 9 Tohoku-oki, Japan earthquake. The results show that crowd-sourced EEW could be achieved with only a tiny percentage of people in a given area contributing information from their smartphones. For example, if phones from fewer than 5000 people in a large metropolitan area responded, the earthquake could be detected and analyzed fast enough to issue a warning to areas farther away before the onset of strong shaking. “The speed of an electronic warning travels faster than the earthquake shaking does,” explained Craig Glennie, a report author and professor at the University of Houston.
The authors found that the sensors in smartphones and similar devices could be used to issue earthquake warnings for earthquakes of approximately magnitude 7 or larger, but not for smaller, yet potentially damaging earthquakes. Comprehensive EEW requires a dense network of scientific instruments. Scientific-grade EEW, such as the U.S. Geological Survey’s ShakeAlert system that is currently being implemented on the west coast of the United States, will be able to help minimize the impact of earthquakes over a wide range of magnitudes. However, in many parts of the world where there are insufficient resources to build and maintain scientific networks, but consumer electronics are increasingly common, crowd-sourced EEW has significant potential.
“The U.S. earthquake early warning system is being built on our high-quality scientific earthquake networks, but crowd-sourced approaches can augment our system and have real potential to make warnings possible in places that don’t have high-quality networks,” said Douglas Given, USGS coordinator of the ShakeAlert Earthquake Early Warning System. The U.S. Agency for International Development has already agreed to fund a pilot project, in collaboration with the Chilean Centro Sismologico Nacional, to test a pilot hybrid earthquake warning system comprising stand-alone smartphone sensors and scientific-grade sensors along the Chilean coast.
“The use of mobile phone fleets as a distributed sensor network—and the statistical insight that many imprecise instruments can contribute to the creation of more precise measurements—has broad applicability including great potential to benefit communities where there isn’t an existing network of scientific instruments,” said Bob Iannucci of Carnegie Mellon University, Silicon Valley.
“Thirty years ago it took months to assemble a crude picture of the deformations from an earthquake. This new technology promises to provide a near-instantaneous picture with much greater resolution,” said Thomas Heaton, a coauthor of the study and professor of Engineering Seismology at Caltech.
“Crowd-sourced data are less precise, but for larger earthquakes that cause large shifts in the ground surface, they contain enough information to detect that an earthquake has occurred, information necessary for early warning,” said study co-author Susan Owen of NASA’s Jet Propulsion Laboratory, Pasadena, California.
These are frames from a high-speed video of a metal object slamming into a bed of artificial soil, sand or rock. Shown at slow (top), medium (middle) and high impact speeds (bottom), the changing impact forces illuminated in each frame help explain why soil and sand get stronger when they are struck harder. Credit: Photos courtesy of Abram Clark.
When a missile or meteor strikes the earth, the havoc above ground is obvious, but the details of what happens below ground are harder to see.
Duke University physicists have developed techniques that enable them to simulate high-speed impacts in artificial soil and sand in the lab, and then watch what happens underground close-up, in super slow motion.
In a study scheduled to appear this week in the journal Physical Review Letters, they report that materials like soil and sand actually get stronger when they are struck harder.
The findings help explain why attempts to make ground-penetrating missiles go deeper by simply shooting them harder and faster have had limited success, the researchers say. Projectiles actually experience more resistance and stop sooner as their strike speed increases.
Funded by the Defense Threat Reduction Agency, the research may ultimately lead to better control of earth-penetrating missiles designed to destroy deeply buried targets such as enemy bunkers or stockpiles of underground weapons.
To simulate a missile or meteor slamming into soil or sand, the researchers dropped a metal projectile with a rounded tip from a seven-foot-high ceiling into a pit of beads.
During collision, the kinetic energy of the projectile is transferred to the beads and dissipates as they butt into each other below the surface, absorbing the force of the collision.
To visualize these forces as they move away from the point of impact, the researchers used beads made of a clear plastic that transmits light differently when compressed. When viewed through polarizing filters like those used in sunglasses, the areas of greatest stress show up as branching chains of light called “force chains” that travel from one bead to the next during impact, much like lightning bolts snaking their way across the sky.
The metal projectile fell into the beads at a speed of six meters per second, or nearly 15 miles per hour. But by using beads of varying hardness, the researchers were able to generate pulses that surged through the beads at speeds ranging from 67 to 670 miles per hour.
Each impact was too fast to see with the naked eye, so they recorded it with a high-speed video camera that shoots up to 40,000 frames per second. When they played it back in slow motion, they found that the branching network of force chains buried in the beads varied widely over different strike speeds.
At low speeds, a sparse network of beads carries the brunt of the force, said study co-author Robert Behringer, a professor of physics at Duke.
But at higher speeds, the force chains grow more extensive, which causes the impact energy to move away from the point of impact much faster than predicted by previous models.
New contacts form between the beads at high speeds as they are pressed together, and that strengthens the material.
“Imagine you’re trying to push your way through a crowded room,” said study co-author Abram Clark, currently a postdoctoral researcher in mechanical engineering at Yale University. “If you try to run and push your way through the room faster than the people can rearrange to get out of the way, you’re going to end up applying a lot of pressure and ramming into a lot of angry people.”
Video
Reference:
“Nonlinear Force Propagation During Granular Impact,” A. Clark, A. Petersen, L. Kondic and R. Behringer. Physical Review Letters, April 10. DOI: 10.1103/PhysRevLett.114.144502
Degrading permafrost with frozen permafrost carbon and ice wedges near Noatak, Alaska. Photo by Ted Schuur
As the Earth’s climate continues to warm, researchers are working to understand how human-driven emissions of carbon dioxide will affect the release of naturally occurring greenhouse gases from arctic permafrost. As the perennially frozen soil continues to thaw, the increase of greenhouse gas emissions could significantly accelerate warming conditions changes on Earth.
An estimated 1,330 billion to 1,580 billion tons of organic carbon are stored in permafrost soils of Arctic and subarctic regions with the potential for even higher quantities stored deep in the frozen soil. The carbon is made up of plant and animal remnants stored in soil for thousands of years. Thawing and decomposition by microbes cause the release of carbon dioxide and methane greenhouse gases into the atmosphere.
“Our big question is how much, how fast and in what form will this carbon come out,” said Ted Schuur, NAU biology professor and lead author on a paper published in Nature.
The rate of carbon release can directly affect how fast climate change happens.
Schuur and fellow researchers coalesced new studies to conclude that thawing permafrost in the Artic and sub-Arctic regions will likely produce a gradual and prolonged release of substantial quantities of greenhouse gases spanning decades as opposed to an abrupt release in a decade or less.
Modern climate change is often attributed to human activities as a result of fossil fuel burning and deforestation, but natural ecosystems also play a role in the global carbon cycle. “Human activities might start something in motion by releasing carbon gases but natural systems, even in remote places like the Arctic, may add to this problem of climate change,” Schuur said. During the past 30 years, temperatures in the Arctic have increased twice as fast as other parts of the planet.
Schuur and his team of researchers from around the world also present next steps for improving knowledge of permafrost carbon and how the dynamics will affect the global carbon cycle. Approaches include improving climate change models by integrating newly created databases, changing models to differentiate between carbon and methane emissions and improved observations of carbon release from the landscape as the Arctic continues to warm.
Reference:
Climate change and the permafrost carbon feedback
E. A. G. Schuur, A. D. McGuire, C. Schädel,G. Grosse, J. W. Harden, D. J. Hayes,G. Hugelius, C. D. Koven, P. Kuhry,D. M. Lawrence, S. M. Natali, D. Olefeldt,V. E. Romanovsky, K. Schaefer, M. R. Turetsky, C. C. Treat& J. E. Vonk. DOI:10.1038/nature14338
This is an artist’s reconstruction of combat between two Daspletosaurus. Credit: Copyright Luis Rey
A new study documents injuries inflicted in life and death to a large tyrannosaurine dinosaur. The paper shows that the skull of a genus of tyrannosaur called Daspletosaurus suffered numerous injuries during life, at least some of which were likely inflicted by another Daspletosaurus. It was also bitten after death in an apparent event of scavenging by another tyrannosaur. Thus there’s evidence of combat between two large carnivores as well as one feeding on another after death.
Daspletosaurus was a large carnivore that lived in Canada and was only a little smaller than its more famous cousin Tyrannosaurus. Like other tyrannosaurs it was most likely both an active predator and scavenger. The individual in question, from Alberta Canada, was not fully grown and would be considered a ‘sub-adult’ in dinosaur terms (approximately equivalent to an older teenager in human terms). It would have been just under 6 m long and around 500 kg when it died.
Researchers found numerous injuries on the skull that occurred during life. Although not all of them can be attributed to bites, several are close in shape to the teeth of tyrannosaurs. In particular one bite to the back of the head had broken off part of the skull and left a circular tooth-shaped puncture though the bone. The fact that alterations to the bone’s surface indicate healing means that these injuries were not fatal and the animal lived for some time after they were inflicted.
Lead author Dr David Hone from Queen Mary, University of London said “This animal clearly had a tough life suffering numerous injuries across the head including some that must have been quite nasty. The most likely candidate to have done this is another member of the same species, suggesting some serious fights between these animals during their lives.”
There is no evidence that the animal died at the hands (or mouth) of another tyrannosaur. However, the preservation of the skull and other bones, and damage to the jaw bones show that after the specimen began to decay, a large tyrannosaur (possibly of the same species) bit into the animal and presumably ate at least part of it.
Combat between large carnivorous dinosaurs is already known and there is already evidence for cannibalism in various groups, including tyrannosaurs. This is however an apparently unique record with evidence of both pre- and post-mortem injuries to a single individual.
Reference:
Hone and Tanke. Pre- and postmortem tyrannosaurid bite marks on the remains of Daspletosaurus (Tyrannosaurinae: Theropoda) from Dinosaur Provincial Park, Alberta, Canada. PeerJ, 2015 DOI: 10.7717/peerj.885
Note: The above story is based on materials provided by PeerJ.
This image shows field work in the United Arab Emirates. Credit: D. Astratti
Changes to the Earth’s oceans, caused by extreme volcanic activity, triggered the greatest extinction of all time, a study suggests.
The event, which took place 252 million years ago, wiped out more than 90 per cent of marine species and more than two-thirds of the animals living on land.
It happened when Earth’s oceans absorbed huge amounts of carbon dioxide from volcanic eruptions, researchers say.
This changed the chemical composition of the oceans — making them more acidic — with catastrophic consequences for life on Earth, the team says.
The study, co-ordinated by the University of Edinburgh, is the first to show that highly acidic oceans were to blame.
The findings are helping scientists understand the threat posed to marine life by modern-day ocean acidification. The amount of carbon added to the atmosphere that triggered the mass extinction was probably greater than today’s fossil fuel reserves, the team says.
However, the carbon was released at a rate similar to modern emissions. This fast rate of release was a critical factor driving ocean acidification, researchers say.
The Permian-Triassic Boundary extinction took place over a 60,000 year period, researchers say. Acidification of the oceans lasted for around 10,000 years.
Ocean acidification was the driving force behind the deadliest phase of the extinction, which dealt a final blow to an already unstable ecosystem, researchers say. Increased temperatures and widespread loss of oxygen in the oceans had already put the environment under pressure.
Oceans can absorb some carbon dioxide but the large volume released — at such a fast rate — changed the chemistry of the oceans, the team says.
The mass extinction of both marine and land-based animals demonstrates that extreme change took place in all of Earth’s ecosystems, the team says.
The team analysed rocks unearthed in the United Arab Emirates — which were on the ocean floor at the time — to develop a climate model to work out what drove the extinction. The rocks preserve a detailed record of changing oceanic conditions at the time.
The study, published in the journal Science, was carried out in collaboration with the University of Bremen, Germany, and the University of Exeter, together with the Universities of Graz, Leeds, and Cambridge.
Funding was provided by the International Centre for Carbonate Reservoirs, Natural Environment Research Council, The Leverhulme Trust, German Research Foundation and the Marsden Fund.
Dr Matthew Clarkson, of the University of Edinburgh’s School of GeoSciences, who co-ordinated the study, said: “Scientists have long suspected that an ocean acidification event occurred during the greatest mass extinction of all time, but direct evidence has been lacking until now. This is a worrying finding, considering that we can already see an increase in ocean acidity today that is the result of human carbon emissions.”
Professor Rachel Wood, of the University of Edinburgh’s School of GeoSciences, said: “This work was highly collaborative and the results were only possible because we assembled a unique team of geochemists, geologists and modellers to tackle an important and long-standing problem.”
Reference:
M. O. Clarkson, S. A. Kasemann, R. A. Wood, T. M. Lenton, S. J. Daines, S. Richoz, F. Ohnemueller, A. Meixner, S. W. Poulton, E. T. Tipper. Ocean acidification and the Permo-Triassic mass extinction. Science, 2015 DOI: 10.1126/science.aaa0193
These are ferromanganese crusts with typical band structure. Credit: Source: Buczkowski, USGS.
In the past decades ferromanganese crusts have been the focus of interest due to their resource potential of valuable metals such as cobalt, nickel or rare earth elements, which are highly enriched in these crusts. For the moment, however, the cost of underwater mining outweighs their cost of recovery. Future price development will change this and deep-sea mining may one day become profitable. In their new study, the German marine scientists show that their metal content is not the only value of these crusts but that they are also archives of past climate changes.
Ferromanganese crusts are up to 26 centimeters in thickness showing laminated growth, comparable to tree rings, but on a much longer time scale. Crusts grow at incredibly slow growth rates of only a few millimeters per million years. Forming on the summit and slopes of submarine mountains these chemical sediments thus record changes in ocean chemistry reflecting the evolution of ocean currents and climate on the continents over the course of millions of years.
But how is the information stored in the crusts? The main ultimate sources of chemical substances in seawater are the rocks of the continents. Weathering erodes and dissolves the rocks and transfers the chemical components to the oceans. Some of these substances inherit the “geochemical fingerprints” of their source regions and travel around the globe together with the ocean currents. Changes in climatic conditions, such as the emergence of large-scale glaciations on the continents during the ice ages, have led to a change in the chemical composition of seawater. The huge ice shields grind the rocks more efficiently and release greater amounts of certain chemical compounds to the oceans. “This is how we can track how the conditions on glacial North America changed during the establishment of large past glaciations”, Veit Dausmann, lead author of the study, points out.
Three ferromanganese crusts from water depths between 2200 and 3600 meters were analysed in the study. The specimens are only a few centimeters thick and were recovered from the Canada Basin of the Arctic Ocean during a cruise of U.S. Coast Guard icebreaker Healy in 2005 to explore the US Exclusive Economic Zone in the Arctic Ocean. “Seven million years of the ocean’s past are archived in these crusts”, states James R. Hein, Santa Cruz-based geologist at the USGS and co-author of the study. The ages were determined using the naturally occurring radioactive isotope beryllium-10 at ETH Zurich.
The time series of the geochemical fingerprints show that due to the sluggish mixing of deep waters in the Arctic Ocean, changes in climatic conditions on land have left a particularly distinct record.
The new data show that approximately four million years ago large climatic changes started to emerge that promoted increased glaciation of North America. Since one million years ago this effect has even been amplified in response to the drastic alternations between warm and cold phases of the ice ages. “Deciphering the climatic records preserved in these ferromanganese crusts closes a large gap in our knowledge of the Arctic regions’ past” explains Martin Frank, professor at GEOMAR and co-author of the study. “Due to harsh conditions and inaccessibility of Canada Basin’s long sedimentary records, our commonly used archives of long-term climate change, have not up to now been available.”
Reference:
Dausmann, V. M. Frank, C. Siebert, M. Christl, and J. R. Hein, 2015: The evolution of climatically driven weathering inputs into the western Arctic Ocean since the late Miocene: Radiogenic isotope evidence, Earth and Planetary Science Letters, 419, 111-124, ISSN 0012-821X, DOI: 10.1016/j.epsl.2015.03.007.
After the Isthmus of Panama formed, animals and plants could move back and forth between continents, the Great American Biological Interchange. Smithsonian scientists are debating when this happened. Credit: Smithsonian Tropical Research Institute
New evidence published in Science by Smithsonian geologists dates the closure of an ancient seaway at 13 to 15 million years ago and challenges accepted theories about the rise of the Isthmus of Panama and its impact on world climate and animal migrations.
A team analyzed zircon grains from rocks representing an ancient sea and riverbeds in northwestern South America. The team was led by Camilo Montes, former director of the Panama Geology Project at the Smithsonian Tropical Research Institute. He is now at the Universidad de los Andes.
The team’s new date for closure of the Central American Seaway, from 13 to 15 million years ago, conflicts with the widely accepted 3 million year date for the severing of all connections between the Atlantic and the Pacific, the result of work done by the Panama Paleontology Project, directed by emeritus scientists Jeremy B.C. Jackson and Anthony Coates, also at the Smithsonian Tropical Research Institute
If a land connection was complete by this earlier date, the rise of the Isthmus of Panama from the sea by tectonic and volcanic action predates the movement of animals between continents known as the Great American Biotic Interchange. The rise of the Isthmus is implicated in major shifts in ocean currents, including the creation of the Gulf Stream that led to warmer temperatures in northern Europe and the formation of a great ice sheet across North America.
“Beds younger than about 13 to 15 million years contain abundant zircon grains with a typically Panamanian age,” said Montes. “Older beds do not. We think these zircons were deposited by rivers flowing from the Isthmus of Panama when it docked to South America, nearly 10 million years earlier than the date of 3 million years that is usually given for the connection.”
The new model sends scientists like the University of Colorado at Boulder’s Peter Molnar off to look for other explanations for climate change. Molnar wrote in the journal Paleoceanography, “…let me state that the closing of the Central America Seaway seems to be no more than a bit player in global climate change. Quite likely it is a red herring.”
“What is left now is to rethink what else could have caused such dramatic global processes nearly 3 million years ago,” said Carlos Jaramillo, Smithsonian Tropical Research Institute scientist and member of the research team.
The Smithsonian Tropical Research Institute, headquartered in Panama City, Panama, is a unit of the Smithsonian Institution. The institute furthers the understanding of tropical nature and its importance to human welfare, trains students to conduct research in the tropics and promotes conservation by increasing public awareness of the beauty and importance of tropical ecosystems.
Refernce:
C. Montes, A. Cardona, C. Jaramillo, A. Pardo, J.C. Silva, V. Valencia, C. Ayala, L.C. Pérez-Angel, L.A. Rodriguez-Parra, V. Ramirez, H. Niño. 2015. Middle Miocene closure of the Central American Seaway. Science. April 10. DOI: 10.1126/science.aaa2815
This is a skeleton of Llallawavis scagliai on display at the Museo Municipal de Ciencias Naturales Lorenzo Scaglia, Mar del Plata. Credit: M. Taglioretti and F. Scaglia.
A new species of South American fossil terror bird called Llallawavis scagliai (“Scaglia’s Magnificent Bird”) is shedding light on the diversity of the group and how these giant extinct predators interacted with their environment. The new species, described in the latest issue of the Journal of Vertebrate Paleontology, is the most complete terror bird ever discovered, with more than 90% of the skeleton exquisitely preserved. The new specimen also reveals details of anatomy that rarely preserve in the fossil record, including the auditory region of the skull, voice box, complete trachea, bones for focussing the eye, and the complete palate, allowing an unprecedented understanding of the sensory capabilities of these extinct predatory birds.
“The mean hearing estimated for this terror bird was below the average for living birds,” said Dr. Federico “Dino” Degrange, lead author of the study from the Centro de Investigaciones en Ciencias de la Tierra (CICTERRA), CONICET and the Universidad Nacional de Córdoba, Argentina. “This seems to indicate that Llallawavis may have had a narrow, low vocalization frequency range, presumably used for intraspecific acoustic communication or prey detection.” This is the first time that the structures which indicate hearing sensitivity have been reconstructed for any terror bird, and they may help explain the evolution, behavior, and ecology of this group of fossil birds.
Terror birds, or phorusracids as they are known scientifically, were carnivorous flightless birds up to 3 meters (10 ft) in height with tall hooked beaks. These birds were the predominant predators during the Cenozoic Age in South America and certainly one of the most striking groups that lived during that time. “The discovery of this new species provides new insights for studying the anatomy and phylogeny of phorusrhacids and a better understanding of this group’s diversification,” said Dr. Claudia Tambussi, also of CICTERRA and one of the co-authors of the study. The new species stood 4 feet tall and lived in Argentina approximately 3.5 million years ago in the Pliocene Epoch, towards the end of the reign of the group.
“The discovery of this species reveals that terror birds were more diverse in the Pliocene than previously thought. It will allow us to review the hypothesis about the decline and extinction of this fascinating group of birds” said Degrange.
Reference:
The Journal of Vertebrate Paleontology (JVP) is the leading journal of professional vertebrate paleontology and the flagship publication of the Society. It was founded in 1980 by Dr. Jiri Zidek and publishes contributions on all aspects of vertebrate paleontology.
Citation: Federico J. Degrange, Claudia P. Tambussi, Matías L. Taglioretti, Alejandro Dondas & Fernando Scaglia (2015): A new Mesembriornithinae (Aves, Phorusrhacidae) provides new insights into the phylogeny and sensory capabilities of terror birds, Journal of Vertebrate Paleontology, e912656. DOI: 10.1080/02724634.2014.912656
Shiprock, New Mexico, is in the Four Corners region where an atmospheric methane “hot spot” can be seen from space. Researchers are currently in the area, trying to uncover the reasons for the hot spot. Credit: Wikimedia Commons
Researchers from several institutions are in the Four Corners region of the U.S. Southwest with a suite of airborne and ground-based instruments, aiming to uncover reasons for a mysterious methane “hot spot” detected from space.
“With all the ground-based and airborne resources that the different groups are bringing to the region, we have the unique chance to unequivocally solve the Four Corners mystery,” said Christian Frankenberg, a scientist at NASA’s Jet Propulsion Laboratory, Pasadena, California, who is heading NASA’s part of the effort. Other investigators are from the Cooperative Institute for Research in Environmental Sciences (CIRES) in Boulder, Colorado; the National Oceanic and Atmospheric Administration (NOAA); and the University of Michigan, Ann Arbor.
Last fall, researchers including Frankenberg reported that a small region around the Four Corners intersection of Arizona, Colorado, New Mexico and Utah had the highest concentration of methane over background levels of any part of the United States. An instrument on a European Space Agency satellite measuring greenhouse gases showed a persistent atmospheric hot spot in the area between 2003 and 2009. The amount of methane observed by the satellite was much higher than previously estimated.
The satellite observations were not detailed enough to reveal the actual sources of the methane in the Four Corners. Likely candidates include venting from oil and gas activities, which are primarily coalbed methane exploration and extraction in this region; active coal mines; and natural gas seeps.
Researchers from CIRES, NOAA’s Earth Systems Research Laboratory and Michigan are conducting a field campaign called TOPDOWN (Twin Otter Projects Defining Oil Well and Natural gas emissions) 2015, bringing airborne and ground-based instruments to investigate possible sources of the methane hot spot. The JPL team will join the effort on April 17-24. The groups are coordinating their measurements, but each partner agency will deploy its own suite of instruments.
The JPL participants will fly two complementary remote sensing instruments on two Twin Otter research aircraft. The Next-Generation Airborne Visible/Infrared Imaging Spectrometer (AVIRISng), which observes spectra of reflected sunlight, flies at a higher altitude and will be used to map methane at fine resolution over the entire region. Using this information and ground measurements from the other research teams, the Hyperspectral Thermal Emission Spectrometer (HyTES) will fly over suspected methane sources, making additional, highly sensitive measurements of methane. Depending on its flight altitude, the NASA aircraft can image methane features with a spatial resolution better than three feet (one meter) square. In other words, it can create a mosaic showing how methane levels vary every few feet, enabling the identification of individual sources.
With the combined resources, the investigators hope to quantify the region’s overall methane emissions and pinpoint contributions from different sources. They will track changes over the course of the month-long effort and study how meteorology transports emissions through the region.
“If we can verify the methane detected by the satellite and identify its sources, decision-makers will have critical information for any actions they are considering,” said CIRES scientist Gabrielle Pétron, one of the mission’s investigators. Part of President Obama’s recent Climate Action Plan calls for reductions in methane emissions.
Researchers found an ancient human skull, left, with modern characteristics, and a human jaw, right, with modern and archaic traits, in the same cave in northern Laos. Both artifacts date to 46,000 to 63,000 years ago. Credit: Fabrice Demeter
An ancient human skull and a jawbone found a few meters away in a cave in northern Laos add to the evidence that early modern humans were physically quite diverse, researchers report in PLOS ONE.
The skull, found in 2009 in a cave known as Tam Pa Ling in the Annamite Mountains of present-day Laos, and reported in 2012 in the Proceedings of the National Academy of Sciences, is the oldest modern human fossil found in Southeast Asia. Its discovery pushed back the date of modern human migration through the region by as much as 20,000 years. It revealed that early humans who migrated to the islands and coasts of Southeast Asia after migrating out of Africa also traveled inland much earlier than previously thought, some 46,000 to 63,000 years ago.
The jaw was discovered in late 2010 and is roughly the same age as the skull. Unlike the skull, it has both modern and archaic human traits.
“In addition to being incredibly small in overall size, this jaw has a mixture of traits that combine typical modern human anatomy, such as the presence of a protruding chin, with traits that are more common of our archaic ancestors like Neandertals — for example, very thick bone to hold the molars in place,” said University of Illinois anthropology professor Laura Shackelford, who led the study with anthropologist Fabrice Demeter, of the National Museum of Natural History in Paris.
This combination of archaic and modern human traits is not unusual, Shackelford said. Other ancient human fossils from Africa, Eastern Europe and China also exhibit this amalgam of characteristics, she said.
“Some researchers have used these features as evidence that modern humans migrating into new regions must have interbred with the archaic populations already present in those regions,” Shackelford said. “But a more productive way to look at this variation is to see it as we see people today — showing many traits along a continuum.
“Tam Pa Ling is an exceptional site because it shows that very early modern humans migrating and settling in eastern Asia demonstrated a wide range of anatomy,” Shackelford said.
Reference:
Fabrice Demeter, Laura Shackelford, Kira Westaway, Philippe Duringer, Anne-Marie Bacon, Jean-Luc Ponche, Xiujie Wu, Thongsa Sayavongkhamdy, Jian-Xin Zhao, Lani Barnes, Marc Boyon, Phonephanh Sichanthongtip, Frank Sénégas, Anne-Marie Karpoff, Elise Patole-Edoumba, Yves Coppens, José Braga. Early Modern Humans and Morphological Variation in Southeast Asia: Fossil Evidence from Tam Pa Ling, Laos. PLOS ONE, 2015; 10 (4): e0121193 DOI: 10.1371/journal.pone.0121193
This artist’s rendering shows the collision of two planetary bodies. A collision like this is believed to have formed the moon within the first 150 million years after our solar system formed. Credit: NASA/JPL-Caltech
Within the first 150 million years after our solar system formed, a giant body roughly the size of Mars struck and merged with Earth, blasting a huge cloud of rock and debris into space. This cloud would eventually coalesce and form the moon.
For almost 30 years, planetary scientists have been quite happy with this explanation–with one major exception. Although this scenario makes sense when you look at the size of the moon and the physics of its orbit around Earth, things start to break down a little when you compare their isotopic compositions–the geological equivalent of a DNA “fingerprint.” Specifically, Earth and the moon are too much alike.
The expectation has long been that the moon should carry the isotopic “fingerprint” of the foreign body, which scientists have named Theia. Because Theia came from elsewhere in the solar system, it probably had a much different isotopic fingerprint than early Earth.
Now, a team of scientists at the University of Maryland has generated a new isotopic fingerprint of the moon that could provide the missing piece of the puzzle. By zeroing in on an isotope of Tungsten present in both the moon and Earth, the UMD team is the first to reconcile the accepted model of the moon’s formation with the unexpectedly similar isotopic fingerprints of both bodies. The results suggest that the impact of Theia into early Earth was so violent, the resulting debris cloud mixed thoroughly before settling down and forming the moon. The findings appear in the April 8, 2015 advance online edition of the journal Nature.
“The problem is that Earth and the moon are very similar with respect to their isotopic fingerprints, suggesting that they are both ultimately formed from the same material that gathered early in the solar system’s history,” said Richard Walker, a professor of geology at UMD and co-author of the study. “This is surprising, because the Mars-sized body that created the moon is expected to have been very different. So the conundrum is that Earth and the moon shouldn’t be as similar as they are.”
Several different theories have emerged over the years to explain the similar fingerprints of Earth and the moon. Perhaps the impact created a huge cloud of debris that mixed thoroughly with the Earth and then later condensed to form the moon. Or Theia could have, coincidentally, been isotopically similar to young Earth. A third possibility is that the moon formed from Earthen materials, rather than from Theia, although this would have been a very unusual type of impact.
To tease out an explanation, Walker and his team looked to another well-documented phenomenon in the early history of the solar system. Evidence suggests that both Earth and the moon gathered additional material after the main impact, and that Earth collected more of this debris and dust. This new material contained a lot of Tungsten, but relatively little of this was of a lighter isotope known as Tungsten-182. Taking these two observations together, one would expect that Earth would have less Tungsten-182 than the moon.
Sure enough, when comparing rocks from the moon and Earth, Walker and his team found that the moon has a slightly higher proportion of Tungsten-182. The key, however, is how much.
“The small, but significant, difference in the Tungsten isotopic composition between Earth and the moon perfectly corresponds to the different amounts of material gathered by Earth and the moon post-impact,” Walker said. “This means that, right after the moon formed, it had exactly the same isotopic composition as Earth’s mantle.”
This finding supports the idea that the mass of material created by the impact, which later formed the moon, must have mixed together thoroughly before the moon coalesced and cooled. This would explain both the overall similarities in isotopic fingerprints and the slight differences in Tungsten-182.
It also largely rules out the idea that the Mars-sized body was of similar composition, or that the moon formed from material contained in the pre-impact Earth. In both cases, it would be highly unlikely to see such a perfect correlation between Tungsten-182 and the amounts of material gathered by the moon and Earth post-impact.
“This result brings us one step closer to understanding the close familial relationship between Earth and the moon,” Walker said. “We still need to work out the details, but it’s clear that our early solar system was a very violent place.”
Reference:
Mathieu Touboul, Igor S. Puchtel, Richard J. Walker. Tungsten isotopic evidence for disproportional late accretion to the Earth and Moon. Nature, 2015; DOI: 10.1038/nature14355
Mars distinct polar ice caps, but Mars also has belts of glaciers at its central latitudes — between the blue lines, in both the southern and northern hemispheres. A thick layer of dust covers the glaciers, so they appear as the surface of the ground, but radar measurements show that there are glaciers composed of frozen water underneath the dust. Credit: Mars Digital Image Model, NASA/Nanna Karlsson
Mars has distinct polar ice caps, but Mars also has belts of glaciers at its central latitudes in both the southern and northern hemispheres. A thick layer of dust covers the glaciers, so they appear as surface of the ground, but radar measurements show that underneath the dust there are glaciers composed of frozen water. New studies have now calculated the size of the glaciers and thus the amount of water in the glaciers. It is the equivalent of all of Mars being covered by more than one meter of ice. The results are published in the scientific journal, Geophysical Research Letters.
Several satellites orbit Mars and on satellite images, researchers have been able to observe the shape of glaciers just below the surface. For a long time scientists did not know if the ice was made of frozen water (H2O) or of carbon dioxide (CO2) or whether it was mud.
Using radar measurements from the NASA satellite, Mars Reconnaissance Orbiter, researchers have been able to determine that is water ice. But how thick was the ice and do they resemble glaciers on Earth?
A group of researchers at the Niels Bohr Institute have now calculated this using radar observations combined with ice flow modelling.
Data combined with modelling
“We have looked at radar measurements spanning ten years back in time to see how thick the ice is and how it behaves. A glacier is after all a big chunk of ice and it flows and gets a form that tells us something about how soft it is. We then compared this with how glaciers on Earth behave and from that we have been able to make models for the ice flow,” explains Nanna Bjørnholt Karlsson, a postdoc at the Centre for Ice and Climate at the Niels Bohr Institute at the University of Copenhagen.
Nanna Bjørnholt Karlsson explains that earlier studies have identified thousands of glacier-like formations on the planet. The glaciers are located in belts around Mars between the latitudes 300-500 — equivalent to just south of Denmark’s location on Earth. The glaiciers are found on both the northern and southern hemispheres.
From some locations on Mars they have good detailed high-resolution data, while they only have more sparse data from other areas. But by supplementing the sparse data with information about the flow and form of the glaciers from the very well studied areas, they have been able to calculate how thick and voluminous the ice is across the glacier belts.
Could cover the entire planet
“We have calculated that the ice in the glaciers is equivalent to over 150 billion cubic meters of ice — that much ice could cover the entire surface of Mars with 1.1 meters of ice. The ice at the mid-latitudes is therefore an important part of Mars’ water reservoir,” explains Nanna Bjørnholt Karlsson.
That the ice has not evaporated out into space could actually mean that the thick layer of dust is protecting the ice. The atmospheric pressure on Mars is so low that water ice simply evaporates and becomes water vapour. But the glaciers are well protected under the thick layer of dust.
Reference:
N. B. Karlsson, L. S. Schmidt, C. S. Hvidberg. Volume of Martian mid-latitude glaciers from radar observations and ice-flow modelling. Geophysical Research Letters, 2015; DOI: 10.1002/2015GL063219
Deception wrong-footed scientists three times in ten years, and remains a mystery. Credit: Wikimedia
Only two volcanoes in Antarctica are active. There is Mount Erebus, which is roughly due south of New Zealand, and Deception Island, which lies about 850km south east of Cape Horn.
Mt Erebus has been erupting continuously over the last few decades. Yet the rather smaller Deception Island, in the South Shetland archipelago, is responsible for the largest known eruption in the Antarctic area.
This horseshoe-shaped cauldron-like structure, or caldera, was produced more than 10,000 years ago by an explosive eruption that scattered more than 30km³ of molten rock. The result is an enclosed welcoming bay called Port Foster.
Deception was officially discovered by the British sealing captain William Smith in 1820 and was subsequently used for purposes such as seal hunting and whaling before finding its modern calling as a site for science and tourism. Maybe because you cannot see most of the volcano above the sea, tourists rarely appreciate its hidden destructive potential.
Claimed in the past by the UK, Chile and Argentina, it provides a unique enclosed environment in which to monitor a “volcano under the ice”. All three of those aforementioned countries financed observatories there in the 1960s (Spain added its own in 2000).
Yet two consecutive volcanic eruptions in 1967 and 1969 went unpredicted – remarkable failures in the history of volcano monitoring. Only the Argentinian and the Spanish observatories still exist.
Mud from down below
Deception Island from above. Credit: Wikimedia
The volcanic events at Deception fall into a rare category called subglacial eruptions. The island is situated in a place where there is a glacier on the ocean floor about 100m thick. Scientists would normally expect that if this were hit by lava from below, it would evaporate benignly into steam.
But the lava moving upwards at Deception has several qualities that made things happen differently: it moves slowly and it has high water content. This meant that it turned the glacier into meltwater as well as steam, creating a large overflow of mud to the surface. This was the main cause of the destruction of the UK and Chilean stations.
The reason why this melting was unexpected was because in scientific terms the glacier was “deceptively thin”. The scientists were not expecting it to produce much more than steam. Ironically, the absence of larger glaciers is what made the island the most hospitable location in Antarctica.
We understand these subglacial eruptions much better now than we did in the 1960s. Nowadays there are hazard maps to make visitors aware of the higher-risk spots on the island.
The Deception enigma
Credit: Google Maps
Yet from a volcanic point of view, Deception is a great puzzle. Many volcanoes are caused by subduction, which is where two of the Earth’s tectonic plates crash against one another, sending one plate down and pushing the other upwards. A classic example is the Cascade range in the north-western US, whose most famous volcano is Mt St Helens. The ones that scientists have observed happen on land.
Most volcanoes at sea are like Hawaii and the Azores, which we describe as hot spots. Instead of taking place near the points between tectonic plates, these are holes in the ocean floor where there is a direct line to the Earth’s mantle. The same goes for submerged calderas in the middle of the ocean, of which there are some examples near Japan.
For a time, scientists thought that Deception might be an unusual example of subduction happening in the ocean. But a more recent hypothesis is that the South Shetlands may be what we call a rift zone. This would mean that it is on a point where plates meet, but instead of colliding, there are gaps from them moving away from each other, creating new oceanic crust in the process. A good example of a rift zone is the Iceland, as can be seen in the video eruption below.
The hydrocarbon connection
Detailed geophysical surveys have been carried out across Deception since 2000, mainly financed by Spanish projects. UK geological research on the island has also been extensive.
You may be wondering why governments have spent so much on research there. Don’t be fooled into thinking that this is some kind of place of virtue where different nations fund research just to understand how our Earth works.
Rifts fill up with the remains of volcanic explosions and other sediment eroded from the margins of the valley. This process is critical for the production of oil. Located at the western edge of the arc, Deception is the ideal place to observe rift processes because of the natural harbour, which shelters scientists from the harsh Antarctic weather.
Rifting is the reason for all the oil in the North Sea. The oil is not deposited where the rift is located, but some distance away. In the same way, there is almost no likelihood of an oil discovery on Deception. But understanding the process of rifting there will be a strong indication that there is oil to the north of the South Shetland Islands. It would also confer an exploration advantage worldwide – so Deception without oil is as valuable as Deception with oil.
So Deception could be the key to unveiling how rifts form and where oil is, in places where resources are unexploited. In an era where the political claims to the Antarctic have long since receded, that should ensure that this frozen corner of the world remains important for some time to come.
Video
Note : The above story is based on materials provided by The Conversation. This story is published courtesy of The Conversation (under Creative Commons-Attribution/No derivatives).
Our solar system is far from empty. A rogue asteroid or comet may have been responsible for the largest impact site yet discovered in Warburton in central Australia. Credit: NASA Goddard Space Flight Center, CC BY-SA
Not long ago, asteroid impacts weren’t considered as a significant factor in the evolution of Earth. Following the Late Heavy Bombardment, which pummelled the inner solar system around 3.8 billion to 3.9 billion years ago, asteroid impacts were generally regarded as minor events.
All this changed in the late 1970s, when Walter and Louis Alvarez discovered the 65-million-year-old K-T (Cretaceous-Tertiary boundary) asteroid impact event. This is now known to be linked to the extinction of the dinosaurs, among many other species.
Thus interest in extra-terrestrial impact research – a discipline bridging astronomy and geology – soared when the spectre of dinosaurs escaping asteroid impact-ignited flames was transformed from science fiction to science fact.
Attention has now been drawn to our own shores with the discovery of new impact structures, including two very large asteroid impacts buried more than two kilometres under the surface in northeastern South Australia.
If the preliminary evidence is anything to go by, these could represent the largest impact sites on the planet. One can only imagine the catastrophic event that might have caused them, and the consequences it had for life on Earth at the time.
The impressive Gosses Bluff impact structure in the Northern Territory, which is dates at 142 million years-old. Author provide
To date researchers have identified more than 172 meteorite craters and asteroid impact structures around the world, showing that our planet has never been spared from bombardment by asteroids. Most of the asteroids responsible for these impacts have originated from the asteroid belt between Mars and Jupiter and most of the comets originated from the Oort cloud at the fringe of the solar system.
Here in Australia, we are blessed with a truly ancient landscape, some of which is up to 3.7 billion years old and contains minerals up to 4.4 billion years old. We also have as high degree of geological stability, meaning many of the impact structures have been preserved over the ages.
To date, a total of 33 impact craters and 27 probable-to-likely impact structures have been found in Australia, ranging from small crater clusters such as Henbury, Northern Territory, to large impact structures such as Acraman in South Australia and Woodleigh in Western Australia.
Some of these are well exposed, such as Gosses Bluff, Northern Territory, Spider in the Kimberley and Lawn Hill in Queensland. Others are buried by younger sediments, such as Woodleigh, Western Australia, Yallalie in Western Australia and Tookoonooka and Talundilly in southwest Queensland.
But the largest of them all may have been uncovered under the red expanse of central Australia.
Double impact
Those red splodges show seismic anomalies which coincide with the Warburton structures in north eastern South Australia. These anomalies represent large scars in the Earth crust. Author provided
The first hint at shock metamorphism of the Earth crust in north eastern South Australia was discovered when Tonguc Uysal at the University of Queensland’s Geothermal Energy Centre of Excellence was involved in drilling for geothermal energy in 2009 in the oil and gas rich Cooper Basin, which overlies the Warburton Basin.
While there, he came across telltale evidence of unusual micro-structures within quartz grains from the local granites. He recognised the quartz structures were similar to those that I and my colleagues found in 1999 in the 120 kilometre large impact structure at Woodleigh in Western Australia.
I was intrigued by Tonguc’s findings, and he subsequently offered me the opportunity to analyse the drill core samples myself.
Starting in 2010 I spent many months studying drill core samples from the Warburton Basin, using three-dimensional optical microscopy and scanning electron microscopy. This was followed by detailed transmission electron microscopy undertaken by John Fitzgerald.
We found that the quartz lamella displayed the characteristic deformation pattern which can only be produced by extreme shock pressures above 10 gigapascals (100 kilobars). To put this in perspective, these levels are much greater than the pressures at the base of the continental crust 30km to 50km beneath the Earth’s surface.
Analysis of the Warburton samples suggested shock pressures of between 10 and 20 gigapascals, which can only be produced by an impact by a large asteroid or a comet.
While we were performing our analyses, seismic researchers Brian Kennett and Erdinc Saygin and their colleagues at the Australian National University published a paper reporting very large seismic anomalies in north-eastern South Australia. These anomalies coincide with the region where we found shock features in quartz crystals.
The seismic evidence may be related to deep fracturing of the crust and to an increased geothermal gradient, where the temperature increases more rapidly with depth than in other regions of the Australian continent. This observation was consistent with geophysical modelling of airborne magnetic and gravity data which indicate anomalies under the Cooper Basin, studied by Tony Meixner of Geoscience Australia.
Piecing the evidence together
Using the geophysical anomalies along with the distribution of shocked quartz grains found in drill holes, we estimate the combined size of the twin structures at approximately 400 km. This would make the Warburton twin structures the largest known to date.
However, we are yet to pinpoint the age and the consequences of the Warburton twin impacts. What we do know is the impact must be at least 300 million years old or older. This is based on study of the ages of bodies of granite affected by the impact, which are overlain by younger sediments that show no signs of shock.
Other studies of the cores of zircons in the granite by Tonguc Uysal and Alexander Middleton and their students at the University of Queensland suggest the zircons contain signatures of both a 300 million years old impact and a 420 million years old impact.
If we can resolve the age question, that will allow us to search for fallout ejected from the original crater and related tsunami events, and potentially figure out whether the impacts are related to an extinction event.
The geological record contains a number of extinction events that were associated with impacts by asteroids, such as the 580 million years old Acraman impact event and the 66 million years old Cretaceous–Paleogene event that killed off the dinosaurs.
The most significant mass extinction event, though, is the massive Permian-Triassic extinction which killed off 90% of species alive around 250 million years ago. This was a period of intense volcanic activity and also coincides with the Araguainha impact located in Brazil.
The discovery of the Warburton twin impacts constitutes a milestone in the study of the impact history of Earth, including research of impact events associated with 2.5 billion to 3.5 billion years old formations in the Pilbara Craton in Western Australia. The more we know about these impacts, the better we can understand other phenomena, such as mass extinctions, the formation of certain geological structures over time and related magmatic events.
It also paints a vivid picture of what might have happened on that fateful day a few hundred million years ago, and the catastrophe it must have wrought.
Note : The above story is based on materials provided by The Conversation. This story is published courtesy of The Conversation (under Creative Commons-Attribution/No derivatives).
Using high-resolution x-ray radiation, Bochum-based researchers study extinct marine creatures. Depicted here is a fossil ammonite. Credit: RUBIN, image: René Hoffmann
Using state-of-the-art imaging techniques, palaeontologists at the Ruhr-Universität Bochum (RUB) have been examining extinct marine creatures. Quantitative analyses provide new evidence that ammonites were able to swim using their shell – very much like the recent nautilus. For the purpose of the study, the researchers, together with partners from the industry, developed an evaluation process for high-res CT images. The science magazine “RUBIN” reports about the results.
Method established using the shell of recent nautilus
Ammonites had a visceral mass that was protected by a helical shell with several chambers. One theory postulates that the creatures lived at the bottom of the sea. Another claims that they were able to swim by using their shell with its gas-filled chambers to compensate for the weight of their shell and soft body, rendering them neutrally buoyant. Together with his team, RUB researcher Dr René Hoffmann investigated how much buoyancy an ammonite shell could generate. First, the palaeontologists from Bochum developed a reliable evaluation technique for their CT images, using the nautilus shells as a test object. Their method now enables them to precisely ascertain the volumes of the examined shells and to calculate their weight, as well as the volumes of the gas-filled chambers. The data thus gathered indicate the buoyancy generated by the shell. In order to clarify if the ammonites were able to swim, the researchers need to know if their shell provides sufficient buoyancy to compensate the weight of the visceral mass and the shell. They estimated the latter, basing it on observations of the nautilus animal.
Technique requires special fossils
For the CT analysis, René Hoffmann needed hollow fossilised ammonites. In order to find them, he travelled to Russia and Japan, to name but two. Together with PhD student Robert Lemanis, he analysed a 0.98 millimetres large ammonite hatchling. The result: three to five gas-filled shell chambers would have been sufficient to enable the ammonites to swim freely in the water directly after hatching. The examined shell had eleven chambers. How many of them existed in the moment of hatching, however, cannot be ascertained – the larger the molluscs became, the more chambers they created. Still, the RUB analyses showed that the hatchling would not have been condemned to dwelling at the bottom, even if only one chamber had been filled with gas; using active swimming motions, the young ammonite would have been able to move around freely in water and stop itself from sinking.
Reference:
R. Lemanis, S. Zachow, F. Fusseis, R. Hoffmann (2015): A new approach using high-resolution computed tomography to test the buoyant properties of chambered cephalopod shells, Paleobiology, DOI: 10.1017/pab.2014.17
The image shows a droplet of condensed nano-DNA and within it smaller drops of its liquid crystal phase which show up in polarized light on the left. The liquid crystal droplets act as ‘micro-reactors’. Credit: Noel Clark, University of Colorado
The self-organization properties of DNA-like molecular fragments four billion years ago may have guided their own growth into repeating chemical chains long enough to act as a basis for primitive life, says a new study by the University of Colorado Boulder and the University of University of Milan.
While studies of ancient mineral formations contain evidence for the evolution of bacteria from 3.5 to 3.8 billion years ago — just half a billion years after the stabilization of Earth’s crust — what might have preceded the formation of such unicellular organisms is still a mystery. The new findings suggest a novel scenario for the non-biological origins of nucleic acids, which are the building blocks of living organisms, said CU-Boulder physics Professor Noel Clark, a study co-author.
A paper on the subject led by Tommaso Bellini of the University of Milan was published in a recent issue of Nature Communications. Other CU-Boulder co-authors of the study include Professor David Walba, Research Associate Yougwooo Yi and Research Assistant Gregory P. Smith. The study was funded by the Grant PRIN Program of the Italian Ministries of Education, Universities and Research and by the U.S. National Science Foundation.
The discovery in the 1980’s of the ability of RNA to chemically alter its own structure by CU-Boulder Nobel laureate and Distinguished Professor Tom Cech and his research team led to the development of the concept of an “RNA world” in which primordial life was a pool of RNA chains capable of synthesizing other chains from simpler molecules available in the environment. While there now is consensus among origin-of-life researchers that RNA chains are too specialized to have been created as a product of random chemical reactions, the new findings suggest a viable alternative, said Clark.
The new research demonstrates that the spontaneous self-assembly of DNA fragments just a few nanometers in length into ordered liquid crystal phases has the ability to drive the formation of chemical bonds that connect together short DNA chains to form long ones, without the aid of biological mechanisms. Liquid crystals are a form of matter that has properties between those of conventional liquids and those of a solid crystal — a liquid crystal may flow like a liquid, for example, but its molecules may be oriented more like a crystal.
“Our observations are suggestive of what may have happened on the early Earth when the first DNA-like molecular fragments appeared,” said Clark.
For several years the research group has been exploring the hypothesis that the way in which DNA emerged in the early Earth lies in its structural properties and its ability to self-organize. In the pre-RNA world, the spontaneous self-assembly of fragments of nucleic acids (DNA and RNA) may have acted as a template for their chemical joining into polymers, which are substances composed of a large number of repeating units.
“The new findings show that in the presence of appropriate chemical conditions, the spontaneous self assembly of small DNA fragments into stacks of short duplexes greatly favors their binding into longer polymers, thereby providing a pre-RNA route to the RNA world,” said Clark.
Reference:
Tommaso P. Fraccia, Gregory P. Smith, Giuliano Zanchetta, Elvezia Paraboschi, Yougwooo Yi, David M. Walba, Giorgio Dieci, Noel A. Clark, Tommaso Bellini. Abiotic ligation of DNA oligomers templated by their liquid crystal ordering. Nature Communications, 2015; 6: 6424 DOI: 10.1038/ncomms7424
This is Brontosaurus as researchers see it today — with a Diplodocus-like head. Credit: Davide Bonadonna, Milan, Italy
Although well known as one of the most iconic dinosaurs, Brontosaurus (the ‘thunder lizard’) has long been considered misclassified. Since 1903, the scientific community has believed that the genus Brontosaurus was in fact the Apatosaurus. Now, an exhaustive new study by palaeontologists from Portugal and the UK provides conclusive evidence that Brontosaurus is distinct from Apatosaurus and as such can now be reinstated as its own unique genus.
Brontosaurus is one of the most charismatic dinosaurs of all time, inspiring generations of children thanks to its size and evocative name. However, as every armchair palaeontologist knows, Brontosaurus was in fact a misnomer, and it should be correctly referred to as Apatosaurus. At least, this is what scientists have believed since 1903, when it was decided that the differences between Brontosaurus excelsus and Apatosaurus were so minor that it was better to put them both in the same genus. Because Apatosaurus was named first, it was the one that was used under the rules of scientific naming.
In fact, of course, the Brontosaurus was never really gone – it was simply treated as a species of the genus Apatosaurus: Apatosaurus excelsus. So, while scientists thought the genus Brontosaurus was the same as Apatosaurus, they always agreed that the species excelsus was different from other Apatosaurus species. Now, palaeontologists Emanuel Tschopp, Octávio Mateus, and Roger Benson say that Brontosaurus was a unique genus all along. But let’s start from the beginning.
The history of Brontosaurus is complex, and one of the most intriguing stories in science. In the 1870s, the Western United States formed the location for dozens of new finds of fossil species, most notably of dinosaurs. Field crews excavated numerous new skeletons mostly for the famous and influential palaeontologists Marsh and Cope. During that period, Marsh’s team discovered two enormous, partial skeletons of long-necked dinosaurs and shipped them to the Yale Peabody Museum in New Haven, where Marsh worked. Marsh described the first of these skeletons as Apatosaurus ajax, the “deceptive lizard” after the Greek hero Ajax. Two years later, he named the second skeleton Brontosaurus excelsus, the “noble thunder lizard”. However, because neither of the skeletons were found with a skull, Marsh reconstructed one for Brontosaurus excelsus. Brontosaurus was a massive animal, like Apatosaurus, and like another long-necked dinosaur from the Western United States, Camarasaurus. Because of this similarity, it seemed logical at the time that Brontosaurus had a similarly stout, box-like skull to that of Camarasaurus. However, this reconstruction was later found to be wrong.
Shortly after Marsh’s death, a team from the Field Museum of Chicago found another skeleton similar to both Apatosaurus ajax and Brontosaurus excelsus. In fact, this skeleton was intermediate in shape in many aspects. Therefore, palaeontologists thought that Brontosaurus excelsus was actually so similar to Apatosaurus ajax that it would be more correct to treat them as two different species of the same genus. It was the second extinction of Brontosaurus – a scientific one: from now on, Brontosaurus excelsus became known as Apatosaurus excelsus and the name Brontosaurus was not considered scientifically valid any more.
The final blow to “Brontosaurus” happened in the 1970s, when researchers showed that Apatosaurus was not closely related to Camarasaurus, but to yet another dinosaur from the same area: Diplodocus. Because Diplodocus had a slender, horse-like skull, Apatosaurus and thus also “Brontosaurus” must have had a skull more similar to Diplodocus instead of to Camarasaurus – and so the popular, but untrue myth about “Brontosaurus” being an Apatosaurus with the wrong head was born.
But now, in a new study published in the peer reviewed open access journal PeerJ and consisting of almost 300 pages of evidence, a team of scientists from Portugal and the UK have shown that Brontosaurus was distinct from Apatosaurus after all – the thunder lizard is back!
How can a single study overthrow more than a century of research? “Our research would not have been possible at this level of detail 15 or more years ago”, explains Emanuel Tschopp, a Swiss national who led the study during his PhD at Universidade Nova de Lisboa in Portugal, “in fact, until very recently, the claim that Brontosaurus was the same as Apatosaurus was completely reasonable, based on the knowledge we had.” It is only with numerous new findings of dinosaurs similar to Apatosaurus and Brontosaurus in recent years that it has become possible to undertake a detailed reinvestigation of how different they actually were.
In science, the distinction between species and genera is without clear rules. Does this mean that the decision to resurrect Brontosaurus is just a matter of personal preference? “Not at all”, explains Tschopp, “we tried to be as objective as possible whenever making a decision which would differentiate between species and genus”. The researchers applied statistical approaches to calculate the differences between other species and genera of diplodocid dinosaurs, and were surprised by the result. “The differences we found between Brontosaurus and Apatosaurus were at least as numerous as the ones between other closely related genera, and much more than what you normally find between species,” explained Roger Benson, a co-author from the University of Oxford.
Therefore, Tschopp and colleagues have concluded that it is now possible to resurrect Brontosaurus as a genus distinct from Apatosaurus. “It’s the classic example of how science works”, said Professor Mateus, a collaborator on the research. “Especially when hypotheses are based on fragmentary fossils, it is possible for new finds to overthrow years of research.”
Science is a process, always moving towards a clearer picture of the world around us. Sometimes this also means that we have to step backwards a bit before we continue to advance. That’s what keeps the curiosity going. Hence, it is fitting that the Brontosaurus which sparked the curiosity of millions of people worldwide has now returned to do so again.
Reference:
A specimen-level phylogenetic analysis and taxonomic revision of Diplodocidae (Dinosauria, Sauropoda). Emanuel Tschopp, Octávio Mateus, Roger B.J. Benson. DOI: 10.7717/peerj.857
Note : The above story is based on materials provided by PeerJ.
The Pacific and North America plate boundary off the coast of British Columbia and southeastern Alaska is a complex system of faults capable of producing very large earthquakes. The recent 2012 Mw 7.8 Haida Gwaii and 2013 Mw 7.5 Craig earthquakes released strain built up over years, but did not release strain along the Queen Charlotte Fault, which remains the likely source of a future large earthquake, according to reports published in a special issue of the Bulletin of the Seismological Society of America (BSSA).
“The study of these two quakes revealed rich details about the interaction between the Pacific and North America Plates, advancing our understanding of the seismic hazard for the region,” said Thomas James, research scientist at Geological Survey of Canada and one of the guest editors of the special issue, which includes 19 technical articles on both the Haida Gwaii and Craig events.
The Haida Gwaii and Craig earthquakes offered new information about the tectonic complexity of the region. Prior to the 2012 earthquake, the Queen Charlotte Fault, a strike-slip fault similar to the San Andreas Fault in California, was the dominating tectonic structure in the area.
Nykolaishen et al. used GPS observations of crustal motion to locate the earthquake’s rupture offshore to the west of Haida Gwaii, rather than beneath the islands. A close study of the Haida Gwaii mainshock by Kao et al. revealed the Pacific plate slid at a low angle below the North American plate on a previously suspected thrust fault, confirming the presence of subduction activity in the area.
“This was an event the thrust interface of the plate boundary system, confirming that there is a subduction system in the Haida Gwaii area,” said Honn Kao, seismologist with the Geological Survey of Canada, who, along with his colleagues, examined the source parameters–causative faults, rupture processes and depths–of the mainshock and sequence of strong aftershocks.
“The implication of a confirmed subduction zone is that in addition to the Queen Charlotte Fault, we now have another source which can produce devastating megathrust earthquakes in the area,” said Kao.
The aftershocks clustered around the periphery of the rupture zone, both on the seaward and landward side of the plate boundary and reflected normal faulting behavior–caused by the bending, extending or stretching of rock– rather than the thrust faulting of the mainshock.
“Our observations of normal faulting imply that the mainshock of the Haida Gwaii earthquake dramatically altered the stress field in the rupture zone, especially in a neighboring region,” said Kao.
The distribution of aftershocks occurred to the north of a previously identified seismic gap where large earthquakes have not occurred in historic times. The gap is located to the south of the where 1949 M8.1 Queen Charlotte earthquake ruptured. Though the Haida Gwaii earthquake may have activated some part of the Queen Charlotte Fault, said Kao, it was limited and did not relieve stress along the seismic gap.
The Haida Gwaii rupture shook southeastern Alaska, and the northwest directivity of ground motion may have influenced the timing of the January 2013 Craig earthquake, suggests James et al. in the introduction to the overall special issue.
A report by Stephen Holtkamp and Natalia Ruppert at the University of Alaska Fairbanks examines 1785 aftershocks in the Craig earthquake sequence, identifying a mix of faulting behavior that suggests the region is still in a state of transpression–the plates are both sliding past each other and colliding at an angle.
The articles in this special issue will appear in print in early May and online in April. The special issue features three main themes. The regional tectonic framework and the nature of the interaction between the Pacific and North America plates at the Queen Charlotte Fault zone are presented in five papers. Three papers focus on the Craig earthquake and examine the main shock, aftershocks and crustal motions. Ten papers discuss the Haida Gwaii event.
