Home Blog Page 230

Research shows how Spanish colonists changed life in the Middle Rio Grande Valley

Study sites in Middle Rio Grande Valley

Spanish settlement of the Middle Rio Grande Valley in New Mexico changed the way people lived, but a new paper in the journal “The Holocene” by UNM Assistant Professor of Anthropology Emily Jones, suggests the change did not come quickly.

“The Columbian Exchange and landscapes of the Middle Rio Grande Valley, AD 1300-1900” is an examination of the impact of Spanish colonization including what people were eating, and an indication of what animals and plants were abundant in the area.

When the Spanish expeditions came to the Middle Rio Grande Valley in 1598 to establish residence, they found inhabited villages and long standing agricultural practices. The Spanish colonists brought seeds, plant cuttings and domestic livestock with them and use of the plants and animals were readily adopted by the Native Americans.

But Jones says animal bones from archeological sites suggest no immediate major impact on the landscape.

Jones’ research focuses on the “Columbian Exchange” or the transformation of landscapes that came with contact between the old and new world. For this paper she examined archeological faunal materials from a number of historic pueblos, missions and villages – essentially the bones left if the trash heaps to determine the animal portion of historic people’s diets.

Jones found significant amounts of wild game (pronghorn, deer and rabbits) alongside domestic animals up through the late 19th century, suggesting hunting was a major part of life through that time.

“I was expecting to see a turnover in the mammals people ate – a change from wild mammals to introduced domesticates, like sheep, goats and cattle – relatively early in the 17th or early 18th century. You would start with wild fauna which would then be mostly replaced by things like sheep, and goats and cattle,” she said. “What I actually found was that this change doesn’t seem to occur until very late in the game in the late 19th and early 20th century.”

The date on mammals have implications about how vegetation may have changed with Spanish colonization. There has been some debate as to when overgrazing became a problem in the Middle Rio Grande Valley – whether it occurred soon after Spanish colonists brought sheet and cattle in 1598 or if livestock populations took some time to make an impact.

Jones’ data may suggest that widespread overgrazing of the landscape did not occur until the time that rail travel brought many more people into the Middle Rio Grande Valley in the late 19th century – a time when other invasive species such as tumbleweeds also became a problem.

“To me the Columbian exchange was an incredible event. It shaped the world we live in now, causing environments in very different parts of the world to look more similar to each other,” Jones said. “This research project is situated in the larger question of when did that change take place and how – was it gradual or quick? To me, this question is really cool.”

Reference:
“The ‘Columbian Exchange’ and landscapes of the Middle Rio Grande Valley, AD 1300–1900.” The Holocene 0959683615588375, first published on June 3, 2015 DOI: 10.1177/0959683615588375

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

NASA explains why June 30 will get extra second

The day will officially be a bit longer than usual on Tuesday, June 30, 2015, because an extra second, or “leap” second, will be added.

“Earth’s rotation is gradually slowing down a bit, so leap seconds are a way to account for that,” said Daniel MacMillan of NASA’s Goddard Space Flight Center in Greenbelt, Md.

Strictly speaking, a day lasts 86,400 seconds. That is the case, according to the time standard that people use in their daily lives — Coordinated Universal Time, or UTC. UTC is “atomic time” — the duration of one second is based on extremely predictable electromagnetic transitions in atoms of cesium. These transitions are so reliable that the cesium clock is accurate to one second in 1,400,000 years.

However, the mean solar day — the average length of a day, based on how long it takes Earth to rotate — is about 86,400.002 seconds long. That’s because Earth’s rotation is gradually slowing down a bit, due to a kind of braking force caused by the gravitational tug of war between Earth, the moon and the sun. Scientists estimate that the mean solar day hasn’t been 86,400 seconds long since the year 1820 or so.

This difference of 2 milliseconds, or two thousandths of a second — far less than the blink of an eye — hardly seems noticeable at first. But if this small discrepancy were repeated every day for an entire year, it would add up to almost a second. In reality, that’s not quite what happens. Although Earth’s rotation is slowing down on average, the length of each individual day varies in an unpredictable way.

The length of day is influenced by many factors, mainly the atmosphere over periods less than a year. Our seasonal and daily weather variations can affect the length of day by a few milliseconds over a year. Other contributors to this variation include dynamics of the Earth’s inner core (over long time periods), variations in the atmosphere and oceans, groundwater, and ice storage (over time periods of months to decades), and oceanic and atmospheric tides. Atmospheric variations due to El Niño can cause Earth’s rotation to slow down, increasing the length of day by as much as 1 millisecond, or a thousandth of a second.

Scientists monitor how long it takes Earth to complete a full rotation using an extremely precise technique called Very Long Baseline Interferometry (VLBI). These measurements are conducted by a worldwide network of stations, with Goddard providing essential coordination of VLBI, as well as analyzing and archiving the data collected.

The time standard called Universal Time 1, or UT1, is based on VLBI measurements of Earth’s rotation. UT1 isn’t as uniform as the cesium clock, so UT1 and UTC tend to drift apart. Leap seconds are added, when needed, to keep the two time standards within 0.9 seconds of each other. The decision to add leap seconds is made by a unit within the International Earth Rotation and Reference Systems Service.

Typically, a leap second is inserted either on June 30 or December 31. Normally, the clock would move from 23:59:59 to 00:00:00 the next day. But with the leap second on June 30, UTC will move from 23:59:59 to 23:59:60, and then to 00:00:00 on July 1. In practice, many systems are instead turned off for one second.

Previous leap seconds have created challenges for some computer systems and generated some calls to abandon them altogether. One reason is that the need to add a leap second cannot be anticipated far in advance.

“In the short term, leap seconds are not as predictable as everyone would like,” said Chopo Ma, a geophysicist at Goddard and a member of the directing board of the International Earth Rotation and Reference Systems Service. “The modeling of the Earth predicts that more and more leap seconds will be called for in the long-term, but we can’t say that one will be needed every year.”

From 1972, when leap seconds were first implemented, through 1999, leap seconds were added at a rate averaging close to one per year. Since then, leap seconds have become less frequent. This June’s leap second will be only the fourth to be added since 2000. (Before 1972, adjustments were made in a different way.)

Scientists don’t know exactly why fewer leap seconds have been needed lately. Sometimes, sudden geological events, such as earthquakes and volcanic eruptions, can affect Earth’s rotation in the short-term, but the big picture is more complex.

VLBI tracks these short- and long-term variations by using global networks of stations to observe astronomical objects called quasars. The quasars serve as reference points that are essentially motionless because they are located billions of light years from Earth. Because the observing stations are spread out across the globe, the signal from a quasar will take longer to reach some stations than others. Scientists can use the small differences in arrival time to determine detailed information about the exact positions of the observing stations, Earth’s rotation rate, and our planet’s orientation in space.

Current VLBI measurements are accurate to at least 3 microseconds, or 3 millionths of a second. A new system is being developed by NASA’s Space Geodesy Project in coordination with international partners. Through advances in hardware, the participation of more stations, and a different distribution of stations around the globe, future VLBI UT1 measurements are expected to have a precision better than 0.5 microseconds, or 0.5 millionths of a second.

“The next-generation system is designed to meet the needs of the most demanding scientific applications now and in the near future,” says Goddard’s Stephen Merkowitz, the Space Geodesy Project manager.

NASA manages many activities of the International VLBI Service for Geodesy and Astrometry including day-to-day and long-term operations, coordination and performance of the global network of VLBI antennas, and coordination of data analysis. NASA also directly supports the operation of six global VLBI stations.

Proposals have been made to abolish the leap second. No decision about this is expected until late 2015 at the earliest, by the International Telecommunication Union, a specialized agency of the United Nations that addresses issues in information and communication technologies.

Note: The above post is reprinted from materials provided by NASA/Goddard Space Flight Center.

Iron: A biological element?

By studying iron extracted from cores drilled in rocks similar to these in Karijini National Park, Western Australia, UW-Madison researchers determined that half of the iron atoms had originated in shallow oceans after being processed by microbes 2.5 billion years ago. Credit: Clark Johnson

Think of an object made of iron: An I-beam, a car frame, a nail. Now imagine that half of the iron in that object owes its existence to bacteria living two and a half billion years ago.

That’s the upshot of a study published this week in the Proceedings of the National Academy of Sciences (PNAS). The findings have meaning for fields as diverse as mining and the search for life in space.

Clark Johnson, a professor of geoscience at the University of Wisconsin-Madison, and former postdoctoral researcher Weiqiang Li examined samples from the banded iron formation in Western Australia. Banded iron is the iron-rich rock found in ore deposits worldwide, from the proposed iron mine in Northern Wisconsin to the enormous mines of Western Australia.

These ancient deposits, up to 150 meters deep, were begging for explanation, says Johnson.

Scientists thought the iron had entered the ocean from hot, mineral-rich water released at mid-ocean vents that then precipitated to the ocean floor. Now Johnson and Li, who is currently at Nanjing University in China, show that half of the iron in banded iron was metabolized by ancient bacteria living along the continental shelves.

The banding was thought to represent some sort of seasonal changes. The UW-Madison researchers found long-term swings in the composition, but not variations on shorter periods like decades or centuries.

The study began with precise measurements of isotopes of iron and neodymium using one of the world’s fastest lasers, housed in the UW-Madison geoscience department. (Isotopes, forms of an atom that differ only by weight, are often used to “fingerprint” the source of various samples.)

Bursts of light less than one-trillionth of a second long vaporized thin sections of the sample without heating the sample itself. “It’s like taking an ice cream scoop and quickly pulling out material before it gets heated,” Johnson explains.

“Heating with traditional lasers gave spurious results.”

It took three years to perfect the working of the laser and associated mass spectrometry instruments, Li says.

Banded iron formations are the primary source of iron ore worldwide. These rocks, at Soudan Underground Mine State Park, Minnesota. Credit: Clark Johnson

Previous probes of the source of banded iron had focused on iron isotopes. “There has been debate about what the iron isotopes were telling us about the source,” Li says. “Adding neodymium changed that picture and gave us an independent measure of the amount coming from shallow continental waters that carried an isotopic signature of life.”

The idea that an organism could metabolize iron may seem strange today, but Earth was very different 2.5 billion years ago. With little oxygen in the atmosphere, many organisms derived energy by metabolizing iron instead of oxygen.

Biologists say this process “is really deep in the tree of life, but we’ve had little evidence from the rock record until now,” Johnson says. “These ancient microbes were respiring iron just like we respire oxygen. It’s a hard thing to wrap your head around, I admit.”

The current study is important in several ways, Johnson says. “If you are an exploration geologist, you want to know the source of the minerals so you know where to explore.”

The research also clarifies the evolution of our planet—and of life itself—during the “iron-rich” era 2.5 billion years ago. “What vestiges of the iron-rich world remain in our metabolism?” Johnson asks. “It’s no accident that iron is an important part of life, that early biological molecules may have been iron-based.”

NASA has made the search for life in space a major focus and sponsors the UW-Madison Astrobiology Institute, which Johnson directs. Recognizing unfamiliar forms of life is a priority for the space agency.

The study reinforces the importance of microbes in geology. “This represents a huge change,” Johnson says. “In my introductory geochemistry textbook from 1980, there is no mention of biology, and so every diagram showing what minerals are stable at what conditions on the surface of the Earth is absolutely wrong.”

Research results like these affect how classes are taught, Johnson says. “If I only taught the same thing, I would be teaching things that are absolutely wrong. If you ever wonder why we combine teaching and research at this university, geomicrobiology gives you the answer. It has completely turned geoscience on its ear.”

Reference:
Biologically recycled continental iron is a major component in banded iron formations, DOI: 10.1073/pnas.1505515112

Note: The above post is reprinted from materials provided by University of Wisconsin-Madison.

Backward-moving glacier helps scientists explain glacial earthquakes

One of the 20 GPS sensors deployed on Helheim Glacier’s chaotic surface. Credit: Alistair Everett, Swansea University; (courtesy of University of Michigan)

The relentless flow of a glacier may seem unstoppable, but a team of researchers from the United Kingdom and the U.S. has shown that during some calving events — when an iceberg breaks off into the ocean — the glacier moves rapidly backward and downward, causing the characteristic glacial earthquakes which until now have been poorly understood.This new insight into glacier behavior, gained by combining field observations in Greenland with laboratory calving experiments, should enable scientists to measure glacier calving remotely and will improve the reliability of models that predict future sea-level rise in a warming climate.

The research is scheduled for publication in Science Express on June 25. The lead author is Tavi Murray of Swansea University. Co-authors include U-M’s L. Mac Cathles, an assistant professor in the Department of Earth and Environmental Sciences and the Department of Atmospheric, Oceanic and Space Sciences and a postdoctoral fellow in the Michigan Society of Fellows.

The Greenland ice sheet is an important contributor to global sea level, and nearly half of the ice sheet’s annual mass loss occurs through the calving of icebergs to the ocean. Glacial earthquakes have increased sevenfold in the last two decades and have been migrating north, suggesting an increase in rates of mass loss from the ice sheet through calving.

“Our new understanding is a crucial step toward developing tools to remotely measure the mass loss that occurs when icebergs break off ice sheets,” Cathles said. “Combining field observations with laboratory measurements from scaled-model calving experiments provided insights into the dynamics of calving and glacial earthquakes that would not have otherwise been possible.”

Helheim Glacier is one of the largest glaciers in southeast Greenland. At 6 kilometers (3.7 miles) wide and more than 200 kilometers (124.3 miles) long, it can flow as fast as 30 meters (98 feet) a day. Icebergs calving from Helheim Glacier have been measured at up to 4 kilometers (2.5 miles) across, with a volume of about 1.25 cubic kilometers (0.3 cubic miles).

During summer 2013, researchers from Swansea, Newcastle and Sheffield universities installed a robust wireless network of Global Positioning System devices on the chaotic surface of Helheim to measure velocity and displacement of the glacier surface.

With U.S. collaborators from U-M, Columbia University and Emory University, earthquake data from the Global Seismographic Network and scaled-down models in water tanks were used to explain the unexpected movements of the glacier in the minutes surrounding the calving events.

“We were really surprised to see the glacier flowing backward in our GPS data. The motion happens every time a large iceberg is calved and a glacial earthquake is produced,” said Swansea’s Murray. “A theoretical model for the earthquakes and the laboratory experiments has allowed us to explain the backward and downward movement.”

U-M’s Cathles helped design and run the laboratory experiments of iceberg calving presented in the paper. The international collaboration grew out of a conversation that Cathles and Murray had at an International Glaciological Society meeting in Chamonix, France, last summer.

“We both presented in the same session and realized that I was measuring in the lab a very similar signal to what Professor Murray was observing in the field,” Cathles said. “That started a year-long collaboration in which the paper’s co-authors talked regularly and collectively developed a model to explain the GPS observations and a deeper understanding of how glacial earthquakes are generated during an iceberg calving event.”

Understanding this glacier behavior and the associated glacial earthquakes is a crucial step toward remote measurement of calving events and their contribution to sea-level change. This tool has the potential to provide unprecedented global, near-real-time estimates of iceberg loss from the ice sheet.

The research was supported by the U.K. Natural Environment Research Council, the U.S. National Science Foundation and the Climate Change Consortium of Wales and Thales U.K.

Video

Reference:
T. Murray, M. Nettles, N. Selmes, L. M. Cathles, J. C. Burton, T. D. James, S. Edwards, I. Martin, T. O’farrell, R. Aspey, I. Rutt, T. Baug. Reverse glacier motion during iceberg calving and the cause of glacial earthquakes. Science, 2015 DOI: 10.1126/science.aab0460

Note: The above post is reprinted from materials provided by University of Michigan. The original item was written by L. Mac Cathles.

Earth’s daily rotation period encoded in an atomic-level protein structure

This image shows Earth and the circadian clock protein KaiC. Credit: IMS/NINS

A collaborative group of Japanese researchers has demonstrated that the Earth’s daily rotation period (24 hours) is encoded in the KaiC protein at the atomic level, a small, 10 nm-diameter biomolecule expressed in cyanobacterial cells.

This research group included: Dr. Jun Abe, Assistant Prof. Atsushi Mukaiyama, and Prof. Shuji Akiyama of the Institute for Molecular Science (IMS) Research Center of Integrative Molecular Systems (CIMoS); Assistant Prof. Toshifumi Mori and Prof. Shinji Saito of the Department of Theoretical and Computational Molecular Science at IMS; Designated Prof. Takao Kondo of Nagoya University; and Assistant Prof. Eiki Yamashita of the Osaka University Institute for Protein Research.

The results of this joint research will help elucidate a longstanding question in chronobiology: How is the circadian period of biological clocks determined? The results will also help understand the basic molecular mechanism of the biological clock. This knowledge might contribute to the development of therapies for disorders associated with abnormal circadian rhythms.

In accordance with diurnal changes in the environment (notably light intensity and temperature) resulting from the Earth’s daily rotation around its axis, many organisms regulate their biological activities to ensure optimal fitness and efficiency. The biological clock refers to the mechanism whereby organisms adjust the timing of their biological activities. The period of this clock is set to approximately 24 hours. A wide range of studies have investigated the biological clock in organisms ranging from bacteria to mammals. Consequently, the relationship between the biological clock and multiple diseases has been clarified. However, it remains unclear how 24-hour circadian rhythms are implemented.

The research group mentioned above addressed this question using cyanobacteria. The cyanobacterial circadian clock can be reconstructed by mixing three clock proteins (KaiA, KaiB, and KaiC) and ATP. A study published in 2007 showed that KaiC ATPase activity, which mediates the ATP hydrolysis reaction, is strongly associated with circadian periodicity. The results of that study indicated that the functional structure of KaiC could be responsible for determining the circadian rhythm.

KaiC ATPase activity exhibits a robust circadian oscillation in the presence of KaiA and KaiB proteins. In the study reported here, the temporal profile of KaiC ATPase activity exhibited an attenuating and oscillating component even in the absence of KaiA and KaiB. A close analysis revealed that this signal had a frequency of 0.91 day-1, which approximately coincided with the 24-hour period. Thus, KaiC is the source of a steady cycle that is in tune with the Earth’s daily rotation.

To identify causal structural factors, the N-terminal domain of KaiC was analyzed using high-resolution crystallography. The resultant atomic structures revealed the underlying cause of KaiC’s slowness relative to other ATPases. “A water molecule is prevented from attacking into the ideal position for the ATP hydrolysis by a steric hindrance near ATP phosphoryl groups. In addition, this hindrance is surely anchored to a spring-like structure derived from polypeptide isomerization,” elaborates Dr. Jun Abe. “The ATP hydrolysis, which involves access of a water molecule to the bound ATP and reverse isomerization of the polypeptide, is expected to require a significantly larger amount of free energy than for typical ATP hydrolysis. Thus, the three-dimensional atomic structure discovered in this study explains why the ATPase activity of KaiC is so much lower (by 100- to 1,000,000-fold) than that of typical ATPase molecules.”

The circadian clock’s period is independent of ambient temperature, a phenomenon known as temperature compensation. One KaiC molecule is composed of six identical subunits, each containing duplicated domains with a series of ATPase motifs. The asymmetric atomic-scale regulation by the aforementioned mechanism dictates a feedback mechanism that maintains the ATPase activity at a constant low level. The authors of this study discovered that the Earth’s daily rotation period (24 hours) is implemented as the time constant of the feedback mechanism mediated in this protein structure.

Technological Implications

KaiC and other protein molecules are capable of moving on short time scales, on the order of 10-12 to 10-1 seconds. This study provides the first atomic-level demonstration that small protein molecules can generate 24-hour rhythms by regulating molecular structure and reactivity. Lab head and CIMoS Director Porf. Shuji Akiyama sees, “The fact that a water molecule, ATP, the polypeptide chain, and other universal biological components are involved in this regulation suggests that humans and other complex organisms may also share a similar molecular machinery. In the crowded intracellular environment that contains a myriad of molecular signals, KaiC demonstrates long-paced oscillations using a small amount of energy generated through ATP consumption. This clever mechanism for timekeeping in a noisy environment may inspire development of highly efficient and sustainable chemical reaction processes and molecular-system-based information processing.”

Glossary

1) Clock protein: A clock protein plays an essential role in the circadian pacemaker. Mutations and deficiencies in clock proteins can alter the intrinsic characteristics of circadian rhythm.

2) ATP: Adenosine triphosphate is a source of energy required for muscle contraction and many other biological activities. ATP, a nucleotide that mediates the storage and consumption of energy, is sometimes referred to as the “currency of biological energy” due to its universality and importance in metabolism. ATP consists of an adenosine molecule bound to three phosphate groups. Upon hydrolysis, the ATPase releases one phosphate molecule plus approximately 8 kcal/mol of energy.

3) Polypeptide isomerization: Protein polypeptide main chains undergo isomerization on a time scale of seconds or longer; therefore, protein isomerization is one of the slowest biological reactions. Most functional protein main chains have a trans conformation, and a few proteins have a functional cis conformation.

Reference:
Jun Abe, Takuya B. Hiyama, Atsushi Mukaiyama, Seyoung Son, Toshifumi Mori, Shinji Saito, Masato Osako, Julie Wolanin, Eiki Yamashita, Takao Kondo, and Shuji Akiyama. Atomic-scale origins of slowness in the cyanobacterial circadian clock. Science, 25 June 2015 DOI: 10.1126/science.1261040

Note: The above post is reprinted from materials provided by National Institutes of Natural Sciences.

Ordovician Carbon Isotope Curve

By Bergstrom, S.M., Xu Chen, Gutierrez-Marco, J.C., and Dronov, A., 2008, Lethaia, DOI: 10.1111/j.1502-3931.2008.00136.x

Click HERE to download a better version (higher resolution)

Copyright © 2013-2014 International Commission on Stratigraphy – ALL RIGHTS RESERVED

Newly found ring of teeth uncovers what common ancestor of molting animals looked like

Left: Hallucigenia sparsa from the Burgess Shale (Royal Ontario Museum 61513) The fossil is 15 mm long. Right: Colour reconstruction of Hallucigenia sparsa. Credit: Left: Jean-Bernard Caron; Right: Danielle Dufault

A new study of an otherworldly creature from half a billion years ago — a worm-like animal with legs, spikes and a head difficult to distinguish from its tail — has definitively identified its head for the first time, and revealed a previously unknown ring of teeth and a pair of simple eyes. The results, published today in the journal Nature, have helped scientists reconstruct what the common ancestor of everything from tiny roundworms to huge lobsters might have looked like.

Researchers from the University of Cambridge, the Royal Ontario Museum and the University of Toronto have found that the creature, known as Hallucigenia due to its strange appearance, had a throat lined with needle-like teeth, a previously unidentified feature which could help connect the dots between it, modern velvet worms and arthropods — the group which contains modern insects, spiders and crustaceans.

Arthropods, velvet worms (onychophorans) and water bears (tardigrades) all belong to the massive group of animals that moult, known as ecdysozoans. Though Hallucigenia is not the common ancestor of all ecdysozoans, it is a precursor to velvet worms. Finding this mouth arrangement in Hallucigenia helped scientists determine that velvet worms originally had the same configuration — but it was eventually lost through evolution.

“The early evolutionary history of this huge group is pretty much uncharted,” said Dr Martin Smith, a postdoctoral researcher in Cambridge’s Department of Earth Sciences, and the paper’s lead author. “While we know that the animals in this group are united by the fact that they moult, we haven’t been able to find many physical characteristics that unite them.”

“It turns out that the ancestors of moulting animals were much more anatomically advanced than we ever could have imagined: ring-like, plate-bearing worms with an armoured throat and a mouth surrounded by spines,” said Dr Jean-Bernard Caron, Curator of Invertebrate Palaeontology at the Royal Ontario Museum and Associate Professor in the Departments of Earth Sciences and Ecology & Evolutionary Biology at the University of Toronto. “We previously thought that neither velvet worms nor their ancestors had teeth. But Hallucigenia tells us that actually, velvet worm ancestors had them, and living forms just lost their teeth over time.”

Hallucigenia was just one of the weird creatures that lived during the Cambrian Explosion, a period of rapid evolutionary development starting about half a billion years ago, when most major animal groups first emerge in the fossil record.

At first, Hallucigenia threw palaeontologists for a bit of a loop. When it was identified in the 1970s, it was reconstructed both backwards and upside down: the spines along its back were originally thought to be legs, its legs were thought to be tentacles along its back, and its head was mistaken for its tail.

Right side up and right way round, Hallucigenia still looks pretty strange: it had pairs of lengthy spines along its back, seven pairs of legs ending in claws, and three pairs of tentacles along its neck. The animals were between 10 and 50 millimetres in length and lived on the floor of the Cambrian oceans.

More significantly, Hallucigenia’s unearthly appearance has made it difficult to link it to modern animal groups and to find its home in the Tree of Life. In 2014, research from Cambridge partially solved this problem by studying the structure of Hallucigenia’s claws, which helped definitively link it to modern velvet worms.

In the new work, researchers used electron microscopy to examine fossils from the collections of the Royal Ontario Museum and the Smithsonian Institution, definitively sorting Hallucigenia’s front from back, and making some surprising observations.

“Prior to our study there was still some uncertainty as to which end of the animal represented the head, and which the tail,” said Smith. “A large balloon-like orb at one end of the specimen was originally thought to be the head, but we can now demonstrate that this actually wasn’t part of the body at all, but a dark stain representing decay fluids or gut contents that oozed out as the animal was flattened during burial.”

Identifying this end as the tail led Caron to revisit the fossils and dig away the sediment that was covering the head: the animals died as they were buried in a mudslide, and their floppy head often ended up pointing down into the mud. “This let us get the new images of the head,” said Caron. “When we put the fossils in the electron microscope, we were initially hoping that we might find eyes, and were astonished when we also found the teeth smiling back at us!”

The new images show an elongated head with a pair of simple eyes, which sat above a mouth with a ring of teeth. In addition, Hallucigenia’s throat was lined with needle-shaped teeth. The fossils originated in the Burgess Shale of Yoho National Park in western Canada, one of the world’s richest sources of fossils from the Cambrian period.

The ring of teeth that surrounded Hallucigenia’s mouth probably helped to generate suction, flexing in and out, like a valve or a plunger, in order to suck its food into its throat. The researchers speculate that the teeth in the throat worked like a ratchet, keeping food from slipping out of the mouth each time it took another ‘suck’ at its food.

“These teeth resemble those we see in many early moulting animals, suggesting that a tooth-lined throat was present in a common ancestor,” said Caron. “So where previously there was little reason to think that arthropod mouths had much in common with the mouths of animals such as penis worms, Hallucigenia tells us that arthropods and velvet worms did ancestrally have round-the-mouth plates and down-the-throat teeth — they just lost or simplified them later.”

The material for this study was collected between 1992 and 2000 and represents more than 165 additional Hallucigenia specimens — including many rare orientations and well-preserved specimens.

Parks Canada, which holds jurisdiction over the Burgess Shale sites located in Yoho and Kootenay national parks, is thrilled by this discovery and eager to share this exciting new piece of the ever-unfolding Burgess Shale story with their visitors.

The research was funded by Clare College, Cambridge, the Natural Sciences and Engineering Research Council of Canada, and the Royal Ontario Museum.

Video

Reference:
Martin R. Smith, Jean-Bernard Caron. Hallucigenia’s head and the pharyngeal armature of early ecdysozoans. Nature, 2015; DOI: 10.1038/nature14573

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

Researchers Reconstruct Dinosaur Tracks

Recent photograph of DFMMh/FV 648, the best preserved footprint, photographed at a low angle. The arrow shows the strongly inclined digit impression IV.

Paleontologists from the University of Bonn use photos to create a digital, three-dimensional model of the discovery site

Twelve years ago, footprints of carnivorous dinosaurs were discovered and excavated in a quarry near Goslar. Paleontologists from the University of Bonn, working with Dinosaur Park Münchehagen and the State Museum of Hanover, have now created a three-dimensional digital model based on photographs of the excavation. The reconstruction of the discovery site suggests that carnivorous dinosaurs hunted herbivorous island-dwelling dinosaurs about 154 million years ago. They believe the predators could have immigrated via a land bridge as sea levels dropped. The findings have now been published in the geoscience journal “Palaeontologia Electronica”.

In 2003, a private fossil collector made a surprising discovery in a limestone quarry near Goslar in Lower Saxony: a total of 20 dinosaur footprints imprinted on a stone slab. Nils Knötschke, from Dinosaur Park Münchehagen, was able to salvage five of the tracks and kept them from being destroyed by the quarry work. Now, about a dozen years later, paleontologists from the University of Bonn, led by Prof. Dr. Martin Sander, have worked with Nils Knötschke and Dr. Oliver Wings from the State Museum of Hanover to reconstruct the tracks in a three-dimensional model, using digital methods. The project was based on photos of the tracks taken at the time when they were excavated.

“Even five years ago, it wouldn’t have been technically possible to do this kind of reconstruction,” says first author Jens N. Lallensack of the Steinmann Institute for Geology, Mineralogy and Paleontology at the University of Bonn. Based on the 3D model, the researchers were able to gain crucial information about the dinosaurs that left the footprints behind, and about their habitat at the time. The tracks, measuring between 36 and 47 centimeters in length, probably represent two different species of predatory dinosaurs from the Theropoda group.

Glimpses of the habitat 154 million years ago

Based on the digital model, we can now see how the individual footprints are positioned in relation to one another. “That allowed us to reconstruct the moving direction, and how fast the animals were traveling. Based on the length of the footprints, we can estimate that the largest animals had a body length of about eight meters. In some places, the carnivorous dinosaurs also left much deeper tracks in the sediment than elsewhere. “Where the ground was soft, the dinosaurs sank in much deeper than where it was dry,” reports Lallensack.

About 154 million years ago, during the Late Jurassic Era, there was a shallow sea throughout this region, with small islands jutting up out of it. Bones found in the Langenberg Quarry confirm that the islands were inhabited by a species of small dinosaurs, Europasaurus holgeri. These herbivores belonged to the group of gigantic, long-necked dinosaurs called sauropods. However, a full-grown Europasaurus only measured six to eight meters – about one-fourth the length of its nearest relative, Camarasaurus. “The dinosaur probably had to shrink down to dwarf size in order to survive, given the limited food available on these small islands in the shallow Central European sea,” says Lallensack.

Theropods probably immigrated via a land bridge

The theropods that originally made the reconstructed dinosaur tracks came on the scene about 35,000 years later. “It’s possible that the sea level dropped during this period – a relatively short time from a geological perspective – and that the mainland carnivorous dinosaurs immigrated at that point,” surmises Dr. Wings, who is heading a research project funded by VolkswagenStiftung at the State Museum of Hanover on the overall Jurassic habitats of the region. The theropod tracks come from a dried-up ocean floor bed very close to one of the islands.

As a result, the researchers suspect that the predatory theropods came from the mainland in order to hunt the herbivorous Europasaurus. All of the limestone in the quarry formed in a shallow sea basin, as evidenced by the large number of marine fossils such as snails, mussels and sea urchins. To date, the tracks are the only indication that the region was temporarily dry, and that large mainland-based carnivorous dinosaurs were present on the former Europasaurus island. “We suspect that is what sealed the fate of these specialized island-dwelling dwarves,” says Lallensack.

Reference:
Jens N. Lallensack, P. Martin Sander, Nils Knötschke, and Oliver Wings. Dinosaur tracks from the Langenberg Quarry (Late Jurassic, Germany) reconstructed with historical photogrammetry: Evidence for large theropods soon after insular dwarfism. Palaeontologia Electronica, 2015: http://palaeo-electronica.org/content/2015/1166-langenberg-tracks

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

Scientists persuade volcanoes to tell their stories

Laser compositional image in 3D of a volcanic crystal. Different crystal zones are shown with different colors. Credit: Courtesy of Teresa Ubide, Trinity College Dublin

Every volcano has a story, but, until now, most of these stories were shrouded in mystery.

However, scientists from Trinity College Dublin have just discovered how to prise volcanic secrets from magma crystals, which means they are better able to piece together the history of global geography and to predict future eruptions of active volcanoes.

Their method will help to understand the reasons for past eruptions, and thus allow more accurate predictions for eruptions yet to occur.

Research fellow in geology in the School of Natural Sciences at Trinity, Dr. Teresa Ubide, was among those who worked out how to persuade volcanoes to tell their stories.

She said: ‘Volcanoes are fascinating, but also dangerous. We need to understand how they work to be better prepared for volcanic eruptions, such as the 2010 Eyjafjallajökull eruption in Iceland, which collapsed air traffic across Europe and caused huge economic, political and cultural problems for huge numbers of people.’

The volcanic cones and lava flows we see on the surface of Earth are fed by magma from great depth. It is thought that the injection of fresh magma into deep reservoirs is the key trigger in volcanic eruptions.

But how is it possible to reconstruct what is going on many kilometres below the surface, at temperatures greater than 1000 degrees Celsius?

Ubide added: ‘Just as investigators reconstruct events to learn the truth, we prise magma injections from the crystals that are transported to the surface by erupted magmas to do the same thing. This method helps us form a detailed picture of the magma history.’

Magmatic crystals typically grow from the center outwards, like tree rings. The microscopic growth rings or zones of crystals record the history of magmatic processes occurring during crystallization, which can be read by expert eyes. The chemical composition of successive growth zones is a particularly valuable source of information about magma history.

The Trinity scientists are funded by SFI to improve the method by which a laser beam, similar to that used for eye surgery, removes a thin film from the surface of the crystals. This produces a group of particles than are analyzed to visualize the precise pattern of growth zones of the crystal.

Importantly, the method works even for chemical elements present at very low concentrations, some of which are particularly useful for unveiling magma history with unprecedented detail.

The article presenting the methodology and its optimization for magmatic crystals has just been published in the journal Chemical Geology.

The paper includes results for crystals from magmas related to the opening of the North Atlantic Ocean, where the separation of tectonic plates made the crust thinner and weaker, allowing the ascent of magmas.

That particular magmatic system developed 79 million years ago in northeast Spain, where the Costa Brava is located today, and where tourists enjoy its warm weather and selected cuisine unaware of the many secrets hidden in the rocks and crystals just next to their beach umbrellas!

Video

Reference:
Teresa Ubide, Cora A. McKenna, David M. Chew, Balz S. Kamber. High-resolution LA-ICP-MS trace element mapping of igneous minerals: In search of magma histories. Chemical Geology, 2015; 409: 157 DOI: 10.1016/j.chemgeo.2015.05.020

Note: The above post is reprinted from materials provided by Trinity College Dublin.

Sefapanosaurus: New Sesotho-named dinosaur from South Africa

South African and Argentinian palaeontologists have discovered a new 200 million year old dinosaur from South Africa, and named it Sefapanosaurus, from the Sesotho word “sefapano”.

The researchers from South Africa’s University of Cape Town (UCT) and the University of the Witwatersrand (Wits University), and from the Argentinian Museo de La Plata and Museo Paleontológico Egidio Feruglio made the announcement in the scientific journal, Zoological Journal of the Linnaean Society. The paper, titled: A new basal sauropodiform from South Africa and the phylogenetic relationships of basal sauropodomorphs, was published online on Tuesday, 23 June 2015.

The specimen was found in the late 1930s in the Zastron area of South Africa’s Free State province, about 30km from the Lesotho border. For many years it remained hidden among the largest fossil collection in South Africa at the Evolutionary Studies Institute (ESI) at Wits University.

A few years ago it was studied and considered to represent the remains of another South African dinosaur, Aardonyx. However, upon further study, close scrutiny of the fossilised bones has revealed that it is a completely new dinosaur.

One of the most distinctive features is that one of its ankle bones, the astragalus, is shaped like a cross. Considering the area where the fossil was discovered, the researchers aptly named the new dinosaur, Sefapanosaurus, after the Sesotho word “sefapano”, meaning “cross”.

Anusuya Chinsamy-Turan, co-author and Professor in the Department of Biological Sciences at UCT, says: “The discovery of Sefapanosaurus shows that there were several of these transitional early sauropodomorph dinosaurs roaming around southern Africa about 200 million years ago.”

Dr Alejandro Otero, Argentinian palaeontologist and lead author, says Sefapanosaurus helps to fill the gap between the earliest sauropodomorphs and the gigantic sauropods. “Sefapanosaurus constitutes a member of the growing list of transitional sauropodomorph dinosaurs from Argentina and South Africa that are increasingly telling us about how they diversified.”

Says Dr Jonah Choiniere, co-author and Senior Researcher in Dinosaur Palaeobiology at the ESI at Wits University: “This new animal shines a spotlight on southern Africa and shows us just how much more we have to learn about the ecosystems of the past, even here in our own ‘backyard’. And it also gives us hope that this is the start of many such collaborative palaeo-research projects between South Africa and Argentina that could yield more such remarkable discoveries.”

Argentinian co-author, Dr Diego Pol, says Sefapanosaurus and other recent dinosaur discoveries in the two countries reveal that the diversity of herbivorous dinosaurs in Africa and South America was remarkably high back in the Jurassic, about 190 million years ago when the southern hemisphere continents were a single supercontinent known as Gondwana.

Finding a new dinosaur among old bones

Otero and Emil Krupandan, PhD-student from UCT, were visiting the ESI collections to look at early sauropodomorph dinosaurs when they noticed bones that were distinctive from the other dinosaurs they were studying.

Krupandan was working on a dinosaur from Lesotho as part of his studies when he realised the material he was looking at was different to Aardonyx. “This find indicates the importance of relooking at old material that has only been cursorily studied in the past, in order to re-evaluate past preconceptions about sauropodomorph diversity in light of new data.”

The remains of the Sefapanosaurus include limb bones, foot bones, and several vertebrae. Sefapanosaurus is represented by the remains of at least four individuals in the ESI collections at Wits University. It is considered to be a medium-sized sauropodomorph dinosaur – among the early members of the group that gave rise to the later long necked giants of the Mesozoic.

Reference:
The researchers are from South Africa’s University of Cape Town (UCT) and the University of the Witwatersrand (Wits University), and from the Argentinian Museo de La Plata and Museo Paleontológico Egidio Feruglio. They made the announcement in a paper, titled: A new basal sauropodiform from South Africa and the phylogenetic relationships of basal sauropodomorphs, published online in the journal, Zoological Journal of the Linnaean Society, on Tuesday, 23 June 2015. DOI: 10.1111/zoj.12247

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

Sudden shift in ‘forcing’ led to demise of Laurentide ice sheet

A study of the demise of the Laurentide Ice Sheet that once covered Canada may help scientists better understand shrinking ice fields today — like this melting ice margin in Greenland. Credit: Courtesy of Oregon State University 

A new study has found that the massive Laurentide ice sheet that covered Canada during the last ice age initially began shrinking through calving of icebergs, and then abruptly shifted into a new regime where melting on the continent took precedence, ultimately leading to the sheet’s demise.

Researchers say a shift in ‘radiative forcing’ began prior to 9,000 years ago and kicked the deglaciation into overdrive. The results are important, scientists say, because they may provide a clue to how ice sheets on Greenland and Antarctica may respond to a warming climate.

Results of the study, which was funded by the National Science Foundation with support from the National Aeronautics and Space Administration (NASA), are being published this week in Nature Geoscience.

David Ullman, a postdoctoral researcher at Oregon State University and lead author on the study, said there are two mechanisms through which ice sheets diminish — dynamically, from the jettisoning of icebergs at the fringes, or by a negative ‘surface mass balance,’ which compares the amount of snow accumulation relative to melting. When more snow accumulates than melts, the surface mass balance is positive.

When melting outpaces snow accumulation, as happened after the last glacial maximum, the surface mass balance is negative.

‘What we found was that during most of the deglaciation, the surface mass balance of the Laurentide Ice Sheet was generally positive,’ Ullman said. ‘We know that the ice sheet was disappearing, so the cause must have been dynamic. But there was a shift before 9,000 years ago and the deck became stacked, as sunlight levels were high because of Earth’s orbit and CO2 increased.

‘There was a switch to a new state, and the ice sheet began to melt away,’ he added. ‘Coincidentally, when melting took off, the ice sheet began pulling back from the coast and the calving of icebergs diminished. The ice sheet got hammered by surface melt, and that’s what drove final deglaciation.’

Ullman said the level of CO2 that helped trigger the melting of the Laurentide ice sheet was near the top of pre-industrial measurements — though much less than it is today. The solar intensity then was higher than today, he added.

‘What is most interesting is that there are big shifts in the surface mass balance that occur from only very small changes in radiative forcing,’ said Ullman, who is in OSU’s College of Earth, Ocean, and Atmospheric Sciences. ‘It shows just how sensitive the system is to forcing, when it might be solar radiation or greenhouse gases.’

Scientists have examined ice cores dating back some 800,000 years and have documented numerous times when increases in summer insolation took place, but not all of them resulted in deglaciation to present-day ice volumes. The reason, they say, is that there likely is a climatic threshold at which severe surface melting is triggered.

‘It just might be that the ice sheet needed an added kick from something like elevated CO2 levels to get things going,’ Ullman said.

Reference:
David J. Ullman, Anders E. Carlson, Faron S. Anslow, Allegra N. LeGrande, Joseph M. Licciardi. Laurentide ice-sheet instability during the last deglaciation. Nature Geoscience, 2015; DOI: 10.1038/ngeo2463

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

Understanding subduction zone earthquakes

Kelsey et al. Figure 1: Location map of Sumatra, Indonesia, depicting rupture areas for the AD 2004 and 2005 subduction zone earthquakes

The 26 December 2004 Mw ~9.2 Indian Ocean earthquake (also known as the Sumatra-Andaman or Aceh-Andaman earthquake), which generated massive, destructive tsunamis, especially along the Aceh coast of northern Sumatra, Indonesia, clearly demonstrated the need for a better understanding of how frequently subduction zone earthquakes and tsunamis occur. Toward that end, Harvey M. Kelsey of Humboldt State University and colleagues present a study of earthquake history in the area.

Using subsidence stratigraphy, the team traced the different modes of coastal sedimentation over the course of time in the eastern Indian Ocean where relative sea-level change evolved from rapidly rising to static from 8,000 years ago to the present day.

Kelsey and colleagues discovered that 3,800 to 7,500 years ago, while sea level was gradually rising, there were seven subduction zone earthquakes recorded in coastal deposits. This was determined in part by the fact that each earthquake caused burial of a mangrove soil by sediment and/or deposition of tsunami sand at the time of the earthquake.

The team also discovered that sea level gradually stopped rising about 3,800 years ago, which meant that buried soils no longer formed. Thus, detecting subduction zone earthquakes required a different approach. They found a record of successive earthquakes in a sequence of stacked tsunami deposits on the coastal plain. Individual tsunami deposits were 0.2 to 0.5 m thick. Based on this information, Kelsey and colleagues determined that in the past 3,800 years there were between four and six tsunamis caused by Andaman-Aceh-type earthquakes.

The authors conclude that knowing the relative sea-level record for a coastal region on a subduction zone margin is the initial step in investigating paleoseismic history. For mid-latitude coasts that border subduction zones, sequences of buried soils may provide a long-duration, subsidence stratigraphic paleoseismic record that spans to the present, but in other settings such as the Aceh coastal plain, joint research approaches, for example targeted foraminiferal analyses and palynology, are required to both exploit the changing form of the relative sea-level curve and characterize coastal evolution in the context of the diminishing importance of accommodation space.

Reference:
“Accommodation space, relative sea level, and the archiving of paleo-earthquakes along subduction zones.” Geology, G36706.1, first published on June 23, 2015, DOI: 10.1130/G36706.1

Note: The above post is reprinted from materials provided by Geological Society of America.

Forgotten fossil indicates earlier origin of teeth

This is a virtual section through the tooth plate of Romundina stellina, with colors gold through purple indicating the first up to the final tooth addition. Credit: Martin Rücklin, Naturalis Biodiversity Center

The tooth plate of just some millimeters in size had been in a box for more than 40 years, without being recognized after the discovery and preparation of the fish it belonged to. Palaeontologists from Naturalis Biodiversity Center, Netherlands and the University of Bristol, United Kingdom, studied the fossil using high energy X-rays at the Swiss Light Source at the Paul Scherrer Institut in Switzerland, revealing the structure and development of teeth and bones. Their findings are published today in Biology Letters.

Teeth are important in our daily life, they are crucial to munch and crunch our food. Jaws and teeth have been important innovations in the evolution of vertebrate animals. More than 98% of vertebrate animals have jaws.

Nevertheless earliest conditions and their origin are disguised in deep time. The search for fossil teeth of the earliest jawed vertebrates can literally be like the search for the needle in a haystack. This includes looking through boxes full of crumb sized bits and pieces of fossils remaining after dissolving rocks in acid.

Lead author, Martin Rücklin of Naturalis Biodiversity Center in Leiden says: “We were able to visualize the finest internal structures and distinguish tissues inside one of the first tooth plates. With powerful computing we combined thousands of X-rays and produced computer models reconstructing the growth of the first teeth.”

Philip Donoghue from the University of Bristol in the UK explains: “We show that the earliest teeth were like our own – but also structured like body scales in primitive fishes. This supports the view that teeth evolved from scales, which arose much earlier in vertebrate evolution.”

Rücklin adds: “Our results suggest that teeth originated deeper in the tree of life than we thought. We will have to look into more basal jawed vertebrates and also jawless fossils. Earliest jaws and teeth seem to be less integrated than we thought and teeth look more complex than expected. I am very happy that my research and our collaboration will be supported by the Vidi-grant of the Netherlands Organization for Scientific Research (NWO) in the next five years, enabling us to investigate these early stages of teeth and how the complex system of our own jaws and teeth evolved.”

Video

Reference:
M. Rucklin, P. C. J. Donoghue. Romundina and the evolutionary origin of teeth. Biology Letters, 2015; 11 (6): 20150326 DOI: 10.1098/rsbl.2015.0326

Note: The above post is reprinted from materials provided by Naturalis Biodiversity Center.

Uplifted island: Isla Santa María island in south of central Chile

Uplift in the Santa María island as a result of the Maule earthquake in 2010. The island experienced a sudden uplift about 2 meters during the earthquake. Credit: Photo: M. Moreno, GFZ

Charles Darwin and his captain Robert Fitzroy witnessed the great earthquake of 1835 in south central Chile. The “Beagle”-Captain’s precise measurements showed an uplift of the island Isla Santa María of 2 to 3 meters after the earthquake. What Darwin and Fitzroy couldn’t know was the fact that 175 years later nearly at the same position such a strong earthquake would recur.

At the South American west coastline the Pacific Ocean floor moves under the South American continent. Resulting that through an in- and decrease of tension the earth’s crust along the whole continent from Tierra del Fuego to Peru broke alongside the entire distance in series of earthquakes within one and a half century. The earthquake of 1835 was the beginning of such a seismic cycle in this area.

After examining the results of the Maule earthquake in 2010 a team of geologists from Germany, Chile and the US for the first time were able to measure and simulate a complete seismic cycle at its vertical movement of the earth’s crust at this place.

In the current online-edition of Nature Geoscience they report about the earthquakes: After the earthquake of 1835 with a magnitude of about 8,5 Isla Santa María was uplifted up to 3 m, subsided again about 1,5 m in the following 175 years, and upliftet anew 1,5-2 m caused by the Maule earthquake with a moment magnitude scale of 8,8.

The Maule earthquake belongs to the great earthquakes, which was fully recorded and therefore well documented by a modern network of space-geodetical and geophysical measuring systems on the ground. More difficult was the reconstruction of the processes in 1835. But nautical charts from 1804 before the earthquake, from 1835 and 1886 as well as the precise documentation of captain Fitzroy allow in combination with present-day methods a sufficient accurate determination of the vertical movement of the earth’s crust along a complete seismic cycle.

At the beginning of such a cycle energy is stored by elastic deformation of the earth’s crust, then released at the time of the earthquake. “But interestingly, our observations hint at a variable subsidence rate during the seismic cycle” explains Marcos Moreno from GFZ German Research Centre for Geosciences, one of the co-authors. “Between great earthquakes the plates beneath Isla Santa María are large locked, dragging the edge of the South American plate, and the island upon it, downward and eastward.” During the earthquakes, motion is suddenly reversed and the edge of the South America Plate and island are thrust upward and to the west.” This complex movement pattern could be perfectly confirmed by a numerical model. In total, over time arises a permanent vertical uplift of 10 to 20% of the complete uplift.

Records of earthquakes show that there are no periodically sequence repetition times or consistent repeating magnitudes of earthquakes. An important instrument for a better estimation of risks caused by earthquakes are the compilation and measurement of earth’s crust deformation through an entire seismic cycle.

Reference:
Robert L. Wesson, Daniel Melnick, Marco Cisternas, Marcos Moreno, Lisa L. Ely. Vertical deformation through a complete seismic cycle at Isla Santa María, Chile. Nature Geoscience, 2015; DOI: 10.1038/NGEO2468

Note: The above post is reprinted from materials provided by GFZ GeoForschungsZentrum Potsdam, Helmholtz Centre.

Expedition Turns up More Fossilized Animal Remains

The elasmosaur piece discovered by Aiden Taylor during the middle school Museum Expedition.

Young Aiden Taylor loves all things dinosaur, so it seemed only natural for him to participate in The University of Alabama’s Museum Expedition this summer.

The 12-year-old Bay Minette native, however, found something that ignited his passion for paleontology even more during his week-long adventure in Greene County.

Taylor recently discovered a baseball-sized neck vertebra from an elasmosaur.

“Half of it was sticking out of the ground,” Taylor said. “It was huge, twice the size of my fist, and I knew I found something good. I yelled to everyone to come over.”

Dana Ehret, Alabama Museum of Natural History paleontologist, said the piece definitely belonged to an elasmosaur.

“The other types of reptile vertebrae that we commonly find in the Mooreville chalk—the geological formation where the vertebrae was found—belong to mosasaurs,” he said. “Mosasaur vertebrae look much different, with a front side that is concave and a back side that is convex. Elasmosaurs, on the other hand, have flattened front and back surfaces.”

A subgroup of the late Cretaceous plesiosaurs, elasmosaurid plesiosaurs are easily recognized by their large body size – some species reach up to 45 feet in length. Although elasmosaurs lived near the end of the dinosaur age – from about 90 million to 65 million years ago – Ehret said the species was not a dinosaur.

Plesiosaurs became extinct by the end of Cretaceous, or about 65.5 million years ago, and they are rare in the fossil record for Alabama. The first elasmosaurid specimen containing more than one or two bones found in the state was discovered in the late 1960s. It consisted of 22 vertebrae, and it is now part of UA Collections. Middle school student Noah Traylor made the second discovery two years ago, also while participating in the middle school Museum Expedition.

“The piece recently discovered definitely belongs to the specimen found two years ago,” Ehret said. “It was found exactly in the same area where the others were found two years ago, and we were specifically looking in that area for more vertebrae.”

The specimen will be prepared and cleaned in the Paleontology Prep Lab, then examined and kept in the collections with the other vertebrae collected two years ago. Ehret said museum staff will continue to check the site periodically to see if more of the specimen erodes out of the chalk. He has also reached out to a professor at Marshall University who specializes in plesiosaurs in an attempt to arrange a visit.

“Finds like this are important because it gives paleontologists a picture into what life was like 80 million years ago in Alabama,” he said. “While we typically find mosasaurs, fish, turtles, sharks, invertebrates and even bird fossils sometimes, elasmosaur fossils tend to be extremely rare.

“When we do find these types of specimens, it helps us to flesh out a more accurate picture of what the Cretaceous sea off the coast of Alabama looked like.

“We can also use these types of specimens to look at how faunas change through time and how reptiles, fish, sharks and invertebrates respond to changes in climate and environment. This is important today because we are undergoing climate changes that are unprecedented in the last 50 plus million years. Fossils can be important for looking at how different groups respond to these large-scale change,” he added.

For Taylor, it’s a great memory that he will carry with him for the rest of his life.

“I love prehistoric animals because they’re just cool,” he said. “They’re unusual, they’ve adapted, evolved and become the creatures that we know today—preserved creatures that amaze people.”

Note: The above post is reprinted from materials provided by University of Alabama in Tuscaloosa.

Exceptional view of deep Arctic Ocean methane seeps

A crinoid is an ocean animal that has long, feathery arms that extend into the water column and use their tiny, sticky tube feet to pick up particles for food. Credit: CAGE

Close to 30,000 high definition images of the deep Arctic Ocean floor were captured on a recent research cruise. This gives researchers insight into the most remote sites of natural methane release in the world.

Over a course of 12 days Dr. Giuliana Panieri and her colleagues from Centre for Arctic Gas Hydrate, Environment and Climate collected images from seven areas of known methane release in the Arctic Ocean. One of them was Vestnesa Ridge, with over 1000 active seep sites at the depth of over 1000 m.

Dr. Panieri collaborated with scientists and engineers at Woods Hole Oceanographic Institution’s MISO Deep-Sea Imaging Facility. The aim was to get a proper view of the deep Arctic Ocean floor.

“We have taken so many samples all over these areas, but we were sampling blind. We needed to see what was going on down there.” sais Panieri who is an awe of the results achieved during the two-week cruise.

The system that was used to get these images is based on the ‘TowCam’ design developed by WHOI scientists and engineers, and funded by the US National Science Foundation. It consists of a color still camera that takes images every 10-15 seconds.

“This is the first time that we have seen these methane seeps in the deep Arctic Ocean areas. The images are amazing.” sais Panieri.

The midnight sun allowed for the tow cam system to be deployed 24/7 providing scientist with data that will be crucial in new discoveries in years to come.

Note: The above post is reprinted from materials provided by University of Tromso (Universitetet i Tromsø – UiT).

An early European had a close Neanderthal ancestor

DNA taken from a 40,000-year-old modern human jawbone reveals that this man had a Neandertal ancestor as recently as four to six generations back. Credit: MPI f. Evolutionary Anthropology/ Paabo

Neanderthals became extinct about 40,000 years ago but contributed on average one to three percent to the genomes of present-day Eurasians. Researchers have now analyzed DNA from a 37,000 to 42,000-year-old human mandible from Oase Cave in Romania and have found that six to nine percent of this person’s genome came from Neanderthals, more than any other human sequenced to date. Because large segments of this individual’s chromosomes are of Neanderthal origin, a Neanderthal was among his ancestors as recently as four to six generations back in his family tree. This shows that some of the first modern humans that came to Europe mixed with the local Neanderthals.

All present-day humans who have their roots outside sub-Saharan Africa carry one to three percent of Neanderthal DNA in their genomes. Until now, researchers have thought it most likely that early humans coming from Africa mixed with Neanderthals in the Middle East around 50,000 to 60,000 years ago, before spreading into Asia, Europe and the rest of the world. However, radiocarbon dating of remains from sites across Europe suggests that modern humans and Neanderthals both lived in Europe for up to 5,000 years and that they may have interbred there, too.

In 2002, a 40,000-year-old jawbone was found by cavers in Oase Cave in south-western Romania and the site was subsequently studied by an international team led by the researchers of the Emil Racovita Institute of Speleology in Romania. Researchers from the Max Planck Institute for Evolutionary Anthropology (Germany), Harvard Medical School (USA), and the Key Laboratory of Vertebrate Evolution and Human Origins in Beijing (China) have now analyzed DNA from this fossil, which is one of the earliest modern-human remains found in Europe. They estimate that five to 11 percent of the genome preserved in the bone derives from a Neanderthal ancestor, including exceptionally large segments of some chromosomes. By estimating how lengths of DNA inherited from an ancestor shorten with each generation, the researchers estimated that the man had a Neanderthal ancestor in the previous four to six generations.

“The data from the jawbone imply that humans mixed with Neanderthals not just in the Middle East but in Europe as well” says Qiaomei Fu, one of the lead researchers of the study. “Interestingly, the Oase individual does not seem to have any direct descendants in Europe today,” says David Reich from Harvard Medical School who coordinated the population genetic analyses of the study. “It may be that he was part of an early migration of modern humans to Europe that interacted closely with Neanderthals but eventually became extinct.”

“It is such a lucky and unexpected thing to get DNA from a person who was so closely related to a Neanderthal” comments Svante Paabo from the Max Planck Institute for Evolutionary Anthropology who led the study. “I could hardly believe it when we first saw the results.” “We hope that DNA from other human fossils that predate the extinction of Neanderthals will help reconstruct the interactions between Neanderthals and modern humans in even more detail,” says Mateja Hajdinjak, another key researcher involved in the study.

“When we started the work on Oase site, everything was already pointing to an exceptional discovery,” remembers Oana Moldovan, the Romanian researcher who initiated the systematic excavation of the cave in 2003. “But such discoveries require painstaking research to be confirmed,” adds Silviu Constantin, her colleague who worked on dating of the site. “We have previously shown that Oase is indeed the oldest modern human in Europe known so far, and now this research confirms that the individual had a Neanderthal ancestor. What more could we wish for?”

Reference:
Qiaomei Fu, Mateja Hajdinjak, Oana Teodora Moldovan, Silviu Constantin, Swapan Mallick, Pontus Skoglund, Nick Patterson, Nadin Rohland, Iosif Lazaridis, Birgit Nickel, Bence Viola, Kay Prüfer, Matthias Meyer, Janet Kelso, David Reich, Svante Pääbo. An early modern human from Romania with a recent Neanderthal ancestor. Nature, 2015; DOI: 10.1038/nature14558

Note: The above post is reprinted from materials provided by Max-Planck-Gesellschaft.

Sixth mass extinction is here: species are disappearing faster since the dinosaurs’ demise

Chart shows the enormous uptick in species loss over the last century. Credit: Image courtesy of Stanford University

There is no longer any doubt: We are entering a mass extinction that threatens humanity’s existence.

That is the bad news at the center of a new study by a group of scientists including Paul Ehrlich, the Bing Professor of Population Studies in biology and a senior fellow at the Stanford Woods Institute for the Environment. Ehrlich and his co-authors call for fast action to conserve threatened species, populations and habitat, but warn that the window of opportunity is rapidly closing.

“[The study] shows without any significant doubt that we are now entering the sixth great mass extinction event,” Ehrlich said.

Although most well known for his positions on human population, Ehrlich has done extensive work on extinctions going back to his 1981 book, Extinction: The Causes and Consequences of the Disappearance of Species. He has long tied his work on coevolution, on racial, gender and economic justice, and on nuclear winter with the issue of wildlife populations and species loss.

There is general agreement among scientists that extinction rates have reached levels unparalleled since the dinosaurs died out 66 million years ago. However, some have challenged the theory, believing earlier estimates rested on assumptions that overestimated the crisis.

The new study, published in the journal Science Advances, shows that even with extremely conservative estimates, species are disappearing up to about 100 times faster than the normal rate between mass extinctions, known as the background rate.

“If it is allowed to continue, life would take many millions of years to recover, and our species itself would likely disappear early on,” said lead author Gerardo Ceballos of the Universidad Autónoma de México.

Conservative approach

Using fossil records and extinction counts from a range of records, the researchers compared a highly conservative estimate of current extinctions with a background rate estimate twice as high as those widely used in previous analyses. This way, they brought the two estimates — current extinction rate and average background or going-on-all-the-time extinction rate — as close to each other as possible.

Focusing on vertebrates, the group for which the most reliable modern and fossil data exist, the researchers asked whether even the lowest estimates of the difference between background and contemporary extinction rates still justify the conclusion that people are precipitating “a global spasm of biodiversity loss.” The answer: a definitive yes.

“We emphasize that our calculations very likely underestimate the severity of the extinction crisis, because our aim was to place a realistic lower bound on humanity’s impact on biodiversity,” the researchers write.

To history’s steady drumbeat, a human population growing in numbers, per capita consumption and economic inequity has altered or destroyed natural habitats. The long list of impacts includes:

  • Land clearing for farming, logging and settlement
  • Introduction of invasive species
  • Carbon emissions that drive climate change and ocean acidification
  • Toxins that alter and poison ecosystems

Now, the specter of extinction hangs over about 41 percent of all amphibian species and 26 percent of all mammals, according to the International Union for Conservation of Nature, which maintains an authoritative list of threatened and extinct species.

“There are examples of species all over the world that are essentially the walking dead,” Ehrlich said.

As species disappear, so do crucial ecosystem services such as honeybees’ crop pollination and wetlands’ water purification. At the current rate of species loss, people will lose many biodiversity benefits within three generations, the study’s authors write. “We are sawing off the limb that we are sitting on,” Ehrlich said.

Hope for the future

Despite the gloomy outlook, there is a meaningful way forward, according to Ehrlich and his colleagues. “Avoiding a true sixth mass extinction will require rapid, greatly intensified efforts to conserve already threatened species, and to alleviate pressures on their populations — notably habitat loss, over-exploitation for economic gain and climate change,” the study’s authors write.

In the meantime, the researchers hope their work will inform conservation efforts, the maintenance of ecosystem services and public policy.

Co-authors on the paper include Anthony D. Barnosky of the University of California at Berkeley, Andrés García of Universidad Autónoma de México, Robert M. Pringle of Princeton University and Todd M. Palmer of the University of Florida.

Video

Reference:
Gerardo Ceballos, Paul R. Ehrlich, Anthony D. Barnosky, Andrés García, Robert M. Pringle and Todd M. Palmer. Accelerated modern human–induced species losses: Entering the sixth mass extinction. Science Advances, 2015 DOI: 10.1126/sciadv.1400253

Note: The above post is reprinted from materials provided by Stanford University. The original item was written by Rob Jordan.

Scientists make new estimates of the deep carbon cycle

Major fluxes of carbon estimated by Craig Manning and Peter Kelemen. Credit: Courtesy of Josh Wood

Over billions of years, the total carbon content of the outer part of the Earth — in its upper mantle, crust, oceans, and atmospheres — has gradually increased, scientists reported this month in the journal Proceedings of the National Academy of Sciences.

Craig Manning, a professor of geology and geochemistry at UCLA, and Peter Kelemen, a geochemistry professor at Columbia University, present new analyses that represent an important advance in refining our understanding of Earth’s deep carbon cycle.

Manning and Kelemen studied how carbon, the chemical basis of all known life, behaves in a variety of tectonic settings. They assessed, among other factors, how much carbon is added to Earth’s crust and how much carbon is released into the atmosphere. The new model combines measurements, predictions and calculations.

Their research includes analysis of existing data on samples taken at sites around the world as well as new data from Oman.

The carbon ‘budget’ near the Earth’s surface exerts important controls on global climate change and our energy resources, and has important implications for the origin and evolution of life, Manning said. Yet much more carbon is stored in the deep Earth. The surface carbon that is so important to us is made available chiefly by volcanic processes originating deep in the planet’s interior.

Today carbon can return to Earth’s deep interior only by subduction — the geologic process by which one tectonic plate moves under another tectonic plate and sinks into the Earth’s mantle. Previous research suggested that roughly half of the carbon stored in subducted oceanic mantle, crust and sediments makes it into the deep mantle. Kelemen and Manning’s new analysis suggests instead that subduction may return almost no carbon to the mantle, and that ‘exchange between the deep interior and surface reservoirs is in balance.’

Some carbon must make it past subduction zones. Diamonds form in the mantle both from carbon that has never traveled to Earth’s surface, known as primordial carbon, and from carbon that has cycled from the mantle to the surface and back again, known as recycled carbon. Manning and Kelemen corroborated their findings with a calculation based on the characteristics of diamonds, which form from carbon in the earth’s mantle.

Deep carbon is important because the carbon at the Earth’s surface, on which we depend, ‘exists only by permission of the deep Earth,’ Manning said, quoting a friend. At times in the Earth’s history, the planet has been warmer (in the Cretaceous period, for example), and shallow seas covered North America. The new research sheds light on the Earth’s climate over geologic time scales.

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

Risk of major sea level rise in Northern Europe

The melting of Greenland contributes to the global sea level, but the loss of mass also means that the ice sheet’s own gravitational field weakens and thus does not attract the surrounding sea as strongly. This means that the sea will fall up to 2,000 km away from the ice sheet, and that the sea level in Northern Europe is not particularly sensitive to the melting of Greenland. Credit: Grinsted, Jevrejeva, Riva, and Dahl-Jensen 

Global warming leads to the ice sheets on land melting and flowing into the sea, which consequently rises. New calculations by researchers from the Niels Bohr Institute show that the sea level in Northern Europe may rise more than previously thought. There is a significant risk that the seas around Scandinavia, England, the Netherlands and northern Germany will rise by up to about 1½ meters in this century. The results are published in a special issue of the scientific journal Climate Research.

Sea level rise is a significant threat to the world’s coastal areas, but the threat is not the same everywhere on Earth – it depends on many regional factors.

“Even though the oceans are rising, they do not rise evenly across the globe. This is partly due to regional changes in the gravitational field and land uplift,” explains Aslak Grinsted, associate professor at the Centre for Ice and Climate at the Niels Bohr Institute, University of Copenhagen.

Sea distributed unevenly

He explains that gravity over the surface of the land and sea varies due to differences in the subsurface and surroundings – the greater the mass, the greater the gravity. The enormous ice sheet on Greenland attracts the sea, which consequently becomes higher around Greenland. When the ice sheet melts and flows out to sea as water, this attraction is reduced and even though more water has entered the sea, the sea level around Greenland would fall.

Another very important effect for Northern Europe is that during the ice age we had a thick ice sheet that weighted down the land. When the weight disappears, then the land rises and even though it has been more than 10,000 years since the ice disappeared, the land is still rising. The calculations show that in the Gulf of Bothnia the land is still rising faster than the expected sea level rise.

The UN Intergovernmental Panel on Climate Change (IPCC) has estimated that the average global warming in this century will rise by 4°C in a business-as-usual scenario. That is to say, if we continue to emit greenhouse gases as we have up to now. The effect will be a rise in sea levels.

“Based on the UN climate panel’s report on sea level rise, supplemented with an expert elicitation about the melting of the ice sheets, for example,how fast the ice on Greenland and Antarctica will melt while considering the regional changes in the gravitational field and land uplift, we have calculated how much the sea will rise in Northern Europe,” explains Aslak Grinsted.

Higher increase than expected

The calculations show that there is a real risk that what have been regarded as high scenarios in the Netherlands and England will be surpassed.

“For London, the calculated best estimate is that sea level will rise by 0.8 meters. In England, a sea level rise of more than 0.9 meters in this century has been considered highly unlikely, but our new calculation shows that there is a 27% chance that this limit is surpassed and we can not exclude a sea level rise of up to 1.75 meters this century,” explains Aslak Grinsted.

For the Netherlands, the best estimate of sea level rise is 0.83 meters, but the calculations show that there is a 26% chance that it will exceed the existing high-end scenario of 1.05 meters and a sea level rise of up to 1.80 meters cannot be excluded.

“Both countries have already established protections for the coasts with barriers, sluice gates, and dikes, but is it enough? I hope that our calculations for worst-case-scenarios will be taken into consideration as the countries prepare for climate change,” says Aslak Grinsted.

Copenhagen is slightly less exposed. Here the best estimate is that sea levels will rise by 0.68 meters, but there is a risk of increases up to 1.6 meters.

But even though the sea level around the world will rise by an average of 80 cm, the sea level in the Gulf of Bothnia in Finland is expected to fall by 10 cm due to land uplift. The land is rising faster than the sea is rising.

The reduced gravitational attraction of the Greenland ice sheet will result in lower sea levels as far away as 2000 km from Greenland in Ireland, Scotland and Norway. This means that the melting from Greenland will contribute 14 cm to the global sea level, but locally in Edinburgh it will result in a fall of 4 cm.

Aslak Grinsted explains that the great uncertainty in relation to future global sea level rise is how quickly the ice on Antarctica will melt and whether it will happen in a large collapse. But even without a collapse of the ice on Antarctica, vulnerable countries should prepare contingency plans in their coastal defence for the ‘worst-case-scenario’.

Note: The above post is reprinted from materials provided by University of Copenhagen – Niels Bohr Institute.

1...229230231...342Page 230 of 342

Related Articles

All