среда, 23 января 2019 г.

The Attentive Brain Are you paying attention? Good because…

The Attentive Brain

Are you paying attention? Good because we’re about to dive into how you do that. Two areas in the upper half of the brain, specifically in the parietal and frontal lobes, are established as important for attention. Recent studies in macaques [species of Old World monkey] have implicated a third region, the posterior infero-temporal dorsal area (PITd). However, the PITd is in the lower half of the brain. Researchers now investigate if and how the PITd connects to the other two regions by imaging macaque brains using diffusion tensor imaging (DTI) (pictured). DTI detects nerve tracts in the brain and revealed that the PITd is indeed directly connected to the two other regions involved in attention via three different tracts. As humans have a brain region equivalent to the PITd, the stage is set to find out if it too is involved in attention, expanding our understanding of the brains’ attention network.

Written by Lux Fatimathas

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2019 January 23 Orion over the Austrian Alps Image Credit &…

2019 January 23

Orion over the Austrian Alps
Image Credit & Copyright: Lukáš Veselý

Explanation: Do you recognize this constellation? Through the icicles and past the mountains is Orion, one of the most identifiable star groupings on the sky and an icon familiar to humanity for over 30,000 years. Orion has looked pretty much the same during the past 50,000 years and should continue to look the same for many thousands of years into the future. Orion is quite prominent in the sky this time of year, a recurring sign of (modern) winter in Earth’s northern hemisphere and summer in the south. Pictured, Orion was captured recently above the Austrian Alps in a composite of seven images taken by the same camera in the same location during the same night. Below and slightly to the right of Orion’s three-star belt is the Orion Nebula, while the four bright stars surrounding the belt are, clockwise from the upper left, Betelgeuse, Bellatrix, Rigel, and Saiph.

∞ Source: apod.nasa.gov/apod/ap190123.html

Siderite | #Geology #GeologyPage #Mineral Locality: Tállya,…

Siderite | #Geology #GeologyPage #Mineral

Locality: Tállya, Zemplén Mountains, Borsod-Abaúj-Zemplén County, Hungary

FOV: 3mm

Photo Copyright © Stone Ásványfotós /e-rocks. com

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Serranía de Hornocal, Argentine | #Geology #GeologyPage…

Serranía de Hornocal, Argentine | #Geology #GeologyPage #Argentine

The Serrania del Hornocal is one of the wonders of the province of Jujuy, a limestone formation with different types of minerals being eroded stripped a symphony of colors on the mountainsides.

Read more & More Photos: http://www.geologypage.com/2016/05/serrania-de-hornocal-argentine.html

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Dolomite | #Geology #GeologyPage #Mineral Locality: Cavnic Mine…

Dolomite | #Geology #GeologyPage #Mineral

Locality: Cavnic Mine (Kapnik), Cavnic (Kapnic; Kapnik), Maramures Co., Romania

Size: 13 x 9.8 x 7.7 cm

Photo Copyright © Anton Watzl Minerals

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Astronomers Study Mysterious New Type of Cosmic Blast

ALMA and VLA images of AT2018cow at left; visible-light image of outburst in its host galaxy at right. Images not to same scale. Images of the blast itself do not indicate its size, but are the result of its brightness and the characteristics of the telescopes. Credit: Sophia Dagnello, NRAO/AUI/NSF; R. Margutti, W.M. Keck Observatory; Ho, et al. Hi-res image

Artist’s conception of a cosmic blast with a “central engine,” such as that suggested for AT2018cow. Black hole at center is pulling in material that forms a rapidly-rotating disk that radiates prolific amounts of energy and propels superfast jets of material from its poles. Jet encounters material surrounding the blast. Credit: Bill Saxton, NRAO/AUI/NSF. Hi-res image

Intensely studied event’s characteristics are unprecedented

When astronomers discovered a cosmic explosion in a galaxy nearly 200 million light-years from Earth last June 16, they soon realized it was something different. While still debating the details, scientists now believe they may have gotten their first glimpse of the birth of a powerful phenomenon seen throughout the Universe.

The explosion was discovered by the ATLAS all-sky survey system in Hawaii, and immediately got the attention of astronomers. First, it was unusually bright for a supernova explosion — a common source of such outbursts. In addition, it brightened, then faded, much faster than expected.

Half a year later, “despite being one of the most intensely studied cosmic events in history, watched by astronomers all over the world, we still don’t know what it is,” said Anna Ho, of Caltech, who led a team using the Atacama Large Millimeter/submillimeter Array (ALMA), in Chile, among other telescopes. The object, dubbed AT2018cow, “heralds a new class” of energetic cosmic blasts, Ho added.

The explosion’s unusual characteristics “were enough to get everybody excited,” said Raffaella Margutti, of Northwestern University, who led a team that used telescopes ranging from gamma rays to radio waves, including the National Science Foundation’s Karl G. Jansky Very Large Array (VLA), to study the object. “In addition, AT2018cow’s distance of 200 million light-years, is nearby, by astronomical standards,” making it an excellent target for study, Margutti said.

Astronomers are presenting their findings about the object at the American Astronomical Society’s meeting in Seattle, Washington.

After watching the object and measuring its changing characteristics with a worldwide collection of ground-based and orbiting telescopes, scientists still are not sure exactly what it is, but they have two leading explanations. It may be, they suspect, either a very unusual supernova, or the shredding of a star that passed too close to a massive black hole, called a Tidal Disruption Event (TDE). Researchers are quick to point out, however, that the object’s characteristics don’t match previously-seen examples of either one.

“If it is a supernova, then it is unlike any supernova we have ever seen,” Ho said. The object’s range of colors, or spectrum, she said, “doesn’t look like a supernova at all.” In addition, it was brighter in millimeter waves — those seen by ALMA — than any other supernova.

It also differs from previously-seen Tidal Disruption Events.

“It’s off-center in its host galaxy,” Deanne Coppejans, of Northwestern University, said, meaning it can’t be a star shredded by the supermassive black hole at the galaxy’s center. “If it’s a TDE, then we need an intermediate mass black hole to do the shredding, and those are expected to form in stellar clusters,” Kate Alexander, an Einstein Fellow at Northwestern, added. The problem with that, she pointed out, is that AT2018cow appears to be inside a high-density interstellar medium, which “is difficult to reconcile with the density of gas in stellar clusters.”

Most of the researchers agree that AT2018cow’s behavior requires a central source of ongoing energy unlike those of other supernova explosions. The best candidate, they said, is a black hole that is drawing material from its surroundings. The inflowing material forms a rotating disk around the black hole and that disk radiates prolific amounts of energy. This is the type of “central engine” that powers quasars and radio galaxies throughout the Universe as well as smaller examples such as microquasars.

When a star much more massive than the Sun ceases thermonuclear fusion and collapses of its own gravity, producing a “normal” supernova explosion, no such central engine is produced. However, in the extreme cases called hypernovas, which produce gamma ray bursts, such a central engine produces the superfast jets of material that generate the gamma rays. That engine, however is very short-lived, lasting only a matter of seconds.

If such a central engine powered AT2018cow, it lasted for weeks, making this event distinct from the collapse-induced explosions of supernovas and the more-energetic such explosions that produce gamma ray bursts. In the case of a TDE, the “engine” would come to life as the black hole drew in material from the star shredded by its gravitational pull.

Alternatively, the “engine” resulting from a supernova explosion might be a rapidly-rotating neutron star with an extremely powerful magnetic field — a magnetar.

“We know from theory that black holes and neutron stars form when a star dies, but we’ve never seen them right after they are born. Never,” Margutti said.

“This is very exciting, since it would be the first time that astronomers have witnessed the birth of a central engine,” Ho said.

However, because of AT2018cow’s strange behavior, the verdict still is unclear, the scientists said. The central energy source could be a powerful shock wave hitting a dense shell of material at the object’s core. Either the strange supernova or the TDE explanation still is viable, Ho’s team said.

The astronomers look forward to more work on AT2018cow and to more objects like it.

“During the first few weeks, this object was very bright at millimeter wavelengths, so that means that, with ALMA now available, we may be able to find and study others,” Ho said. “The peak strength of the radio emission starts at ALMA wavelengths, and only moved to VLA wavelengths after a few weeks,” she added.

The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of the European Southern Observatory (ESO), the U.S. National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the Ministry of Science and Technology (MOST) in Taiwan and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI).

ALMA construction and operations are led by ESO on behalf of its Member States; by the National Radio Astronomy Observatory (NRAO), managed by Associated Universities, Inc. (AUI), on behalf of North America; and by the National Astronomical Observatory of Japan (NAOJ) on behalf of East Asia. The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

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Dave Finley, Public Information Officer
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Astronaut Health Study and Spacesuit Work Onboard Station

ISS – Expedition 58 Mission patch.

January 22, 2019

The three Expedition 58 crew members continued studying today the upward flow of fluids inside astronauts’ bodies caused by living in space. The crew also worked on packing a U.S. cargo craft and servicing U.S. spacesuits at the International Space Station.

One easily recognizable symptom of living in space is the “puffy face” astronauts get due to the upward flow of fluids in the body. Underlying impacts of this phenomenon include head and eye pressure changes that occur off Earth which the Fluid Shifts experiment is seeking to better understand.

Image above: Astronaut Anne McClain is inside the Destiny laboratory module surrounded by exercise gear, including laptop computers and sensors that measure physical exertion and aerobic capacity. Image Credit: NASA.

All three crew members gathered in the Zvezda service module throughout the day using a special suit to temporarily reverse these upward fluid shifts. NASA astronaut Anne McClain wore the Lower Body Negative Pressure suit, which pull fluids downward, while Flight Engineer David Saint-Jacques checked her head and eye pressure using a variety of biomedical devices. Commander Oleg Kononenko assisted the duo with guidance from specialists on the ground.

McClain and Saint-Jacques also partnered up before lunchtime to get the Cygnus resupply ship ready for its departure on Feb. 12. The duo reviewed packing procedures and stowed inventory aboard the U.S. space freighter from Northrop Grumman.

Image above: Flyingt over Autral Ocean, seen by EarthCam on ISS, speed: 27’572 Km/h, altitude: 422,60 Km, image captured by Roland Berga (on Earth in Switzerland) from International Space Station (ISS) using ISS-HD Live application with EarthCam’s from ISS on January 22, 2019 at 20:58 UTC. Image Credits: Orbiter.ch Aerospace/Roland Berga.

McClain started the day installing the new Facet Cell crystal growth experiment in the Kibo laboratory module. She spent the rest of the afternoon cleaning cooling loops on U.S. spacesuits in the Quest airlock as NASA prepares for spacewalks at the orbital lab later this year.

Related links:

Expedition 58: https://www.nasa.gov/mission_pages/station/expeditions/expedition58/index.html

Zvezda service module: https://www.nasa.gov/mission_pages/station/structure/elements/zvezda-service-module.html

Cygnus resupply ship: https://orbiterchspacenews.blogspot.com/2018/11/canadian-robotic-arm-installs-us-cygnus.html

Kibo laboratory module: https://www.nasa.gov/mission_pages/station/structure/elements/japan-kibo-laboratory

Quest airlock: https://www.nasa.gov/mission_pages/station/structure/elements/joint-quest-airlock

Fluid Shifts: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=1126

Facet Cell: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=93

Space Station Research and Technology: https://www.nasa.gov/mission_pages/station/research/index.html

International Space Station (ISS): https://www.nasa.gov/mission_pages/station/main/index.html

Images (mentioned), Text, Credits: NASA/Mark Garcia/Orbiter.ch Aerospace/Roland Berga.

Best regards, Orbiter.chArchive link

Archaeologically significant structures unearthed in southern India

Some archaeologically significant structures, including a step pond or Kalyani-like structure, were unearthed during cleaning works at the historical village of Melkote in Pandavapura, Karnataka, in southern India.

Archaeologically significant structures unearthed in southern India
One of the structures unearthed during cleaning work at Melkote in Pandavapura taluk of Mandya district
[Credit: The Hindu]

Infosys Foundation had expressed willingness to clean and maintain the historical monuments in the village, where social reformer and proponent of Sri Vaishnava philosophy Ramanujacharya is believed to have lived. Although the agreement between the foundation and the authorities is yet to be finalised, the foundation recently took up works to clean the area near the ‘Pancha Kalyani’.
According to Revenue Department sources, the foundation of a mantap with beautiful carvings/embossing of idols, the basement of a building suspected to have been demolished or collapsed decades ago, and a small temple pond-like structure, all covered in huge quantities of mud, were unearthed a few days ago.
Infosys Foundation chairperson Sudha Murty had inspected the place on December 2, 2018. She instructed her foundation to take up cleaning works, a revenue officer told The Hindu.
The Archaeological Survey of India or other agencies will be asked to inspect the monuments found and initiate further steps, the officer added. Melkote has over 100 archaeologically significant monuments such as ponds, Kalyanis, temples, and mantaps. The ‘Vairamudi’ utsav at Melkote is one of the famous religious events in the country.

Author: M.T. Shiva Kumar | Source: The Hindu [January 16, 2019]



Greenland ice melting four times faster than in 2003

Greenland is melting faster than scientists previously thought — and will likely lead to faster sea level rise — thanks to the continued, accelerating warming of the Earth’s atmosphere, a new study has found.

Greenland ice melting four times faster than in 2003
Greenland Iceberg [Credit: Ohio State University]

Scientists concerned about sea level rise have long focused on Greenland’s southeast and northwest regions, where large glaciers stream iceberg-sized chunks of ice into the Atlantic Ocean. Those chunks float away, eventually melting. But a new study published in the Proceedings of the National Academy of Sciences found that the largest sustained ice loss from early 2003 to mid-2013 came from Greenland’s southwest region, which is mostly devoid of large glaciers.

“Whatever this was, it couldn’t be explained by glaciers, because there aren’t many there,” said Michael Bevis, lead author of the paper, Ohio Eminent Scholar and a professor of geodynamics at The Ohio State University. “It had to be the surface mass — the ice was melting inland from the coastline.”

That melting, which Bevis and his co-authors believe is largely caused by global warming, means that in the southwestern part of Greenland, growing rivers of water are streaming into the ocean during summer. The key finding from their study: Southwest Greenland, which previously had not been considered a serious threat, will likely become a major future contributor to sea level rise.

“We knew we had one big problem with increasing rates of ice discharge by some large outlet glaciers,” he said. “But now we recognize a second serious problem: Increasingly, large amounts of ice mass are going to leave as meltwater, as rivers that flow into the sea.”

The findings could have serious implications for coastal U.S. cities, including New York and Miami, as well as island nations that are particularly vulnerable to rising sea levels.

And there is no turning back, Bevis said.

“The only thing we can do is adapt and mitigate further global warming — it’s too late for there to be no effect,” he said. “This is going to cause additional sea level rise. We are watching the ice sheet hit a tipping point.”

Climate scientists and glaciologists have been monitoring the Greenland ice sheet as a whole since 2002, when NASA and Germany joined forces to launch GRACE. GRACE stands for Gravity Recovery and Climate Experiment, and involves twin satellites that measure ice loss across Greenland. Data from these satellites showed that between 2002 and 2016, Greenland lost approximately 280 gigatons of ice per year, equivalent to 0.03 inches of sea level rise each year. But the rate of ice loss across the island was far from steady.

Bevis’ team used data from GRACE and from GPS stations scattered around Greenland’s coast to identify changes in ice mass. The patterns they found show an alarming trend — by 2012, ice was being lost at nearly four times the rate that prevailed in 2003. The biggest surprise: This acceleration was focused in southwest Greenland, a part of the island that previously hadn’t been known to be losing ice that rapidly.

Bevis said a natural weather phenomenon — the North Atlantic Oscillation, which brings warmer air to West Greenland, as well as clearer skies and more solar radiation — was building on man-made climate change to cause unprecedented levels of melting and runoff. Global atmospheric warming enhances summertime melting, especially in the southwest. The North Atlantic Oscillation is a natural — if erratic — cycle that causes ice to melt under normal circumstances. When combined with man-made global warming, though, the effects are supercharged.

“These oscillations have been happening forever,” Bevis said. “So why only now are they causing this massive melt? It’s because the atmosphere is, at its baseline, warmer. The transient warming driven by the North Atlantic Oscillation was riding on top of more sustained, global warming.”

Bevis likened the melting of Greenland’s ice to coral bleaching: Once the ocean’s water hits a certain temperature, coral in that region begins to bleach. There have been three global coral bleaching events. The first was caused by the 1997-98 El Niño, and the other two events by the two subsequent El Niños. But El Niño cycles have been happening for thousands of years — so why have they caused global coral bleaching only since 1997?

“What’s happening is sea surface temperature in the tropics is going up; shallow water gets warmer and the air gets warmer,” Bevis said. “The water temperature fluctuations driven by an El Niño are riding this global ocean warming. Because of climate change, the base temperature is already close to the critical temperature at which coral bleaches, so an El Niño pushes the temperature over the critical threshold value. And in the case of Greenland, global warming has brought summertime temperatures in a significant portion of Greenland close to the melting point, and the North Atlantic Oscillation has provided the extra push that caused large areas of ice to melt.”

Before this study, scientists understood Greenland to be one of the Earth’s major contributors to sea-level rise — mostly because of its glaciers. But these new findings, Bevis said, show that scientists need to be watching the island’s snowpack and ice fields more closely, especially in and near southwest Greenland.

GPS systems in place now monitor Greenland’s ice margin sheet around most of its perimeter, but the network is very sparse in the southwest, so it is necessary to densify the network there, given these new findings.

“We’re going to see faster and faster sea level rise for the foreseeable future,” Bevis said. “Once you hit that tipping point, the only question is: How severe does it get?”

Author: Laura Arenschield | Source: Ohio State University [January 21, 2019]



Fossilized slime of 100-million-year-old hagfish shakes up vertebrate family tree

Paleontologists at the University of Chicago have discovered the first detailed fossil of a hagfish, the slimy, eel-like carrion feeders of the ocean. The 100-million-year-old fossil helps answer questions about when these ancient, jawless fish branched off the evolutionary tree from the lineage that gave rise to modern-day jawed vertebrates, including bony fish and humans.

Fossilized slime of 100-million-year-old hagfish shakes up vertebrate family tree
Tethymyxine tapirostrum, is a 100-million-year-old, 12-inch long fish embedded in a slab of Cretaceous
period limestone from Lebanon, believed to be the first detailed fossil of a hagfish
[Credit: Tetsuto Miyashita, University of Chicago]

The fossil, named Tethymyxine tapirostrum,is a 12-inch long fish embedded in a slab of Cretaceous period limestone from Lebanon. It fills a 100-million-year gap in the fossil record and shows that hagfish are more closely related to the blood-sucking lamprey than to other fishes. This means that both hagfish and lampreys evolved their eel-like body shape and strange feeding systems after they branched off from the rest of the vertebrate line of ancestry about 500 million years ago.

“This is a major reorganization of the family tree of all fish and their descendants. This allows us to put an evolutionary date on unique traits that set hagfish apart from all other animals,” said Tetsuto Miyashita, PhD, a Chicago Fellow in the Department of Organismal Biology and Anatomy at UChicago who led the research. The findings are published this week in the Proceedings of the National Academy of Sciences.

The slimy dead giveaway

Modern-day hagfish are known for their bizarre, nightmarish appearance and unique defense mechanism. They don’t have eyes, or jaws or teeth to bite with, but instead use a spiky tongue-like apparatus to rasp flesh off dead fish and whales at the bottom of the ocean. When harassed, they can instantly turn the water around them into a cloud of slime, clogging the gills of would-be predators.

This ability to produce slime is what gave away the Tethymyxine fossil. Miyashita used an imaging technology called synchrotron scanning at Stanford University to identify chemical traces of soft tissue that were left behind in the limestone when the hagfish fossilized. These soft tissues are rarely preserved, which is why there are so few examples of ancient hagfish relatives to study.

Fossilized slime of 100-million-year-old hagfish shakes up vertebrate family tree
Synchrotron scanning of the Tethymyxine tapirostrum hagfish fossil revealed traces of chemical left behind when the
soft tissues fossilized, including signs of keratin that indicate a series of slime-producing glands along the body
[Credit: Tetsuto Miyashita, University of Chicago]

The scanning picked up a signal for keratin, the same material that makes up fingernails in humans. Keratin, as it turns out, is a crucial part of what makes the hagfish slime defense so effective. Hagfish have a series of glands along their bodies that produce tiny packets of tightly-coiled keratin fibers, lubricated by mucus-y goo. When these packets hit seawater, the fibers explode and trap the water within, turning everything into shark-choking slop. The fibers are so strong that when dried out they resemble silk threads; they’re even being studied as possible biosynthetic fibers to make clothes and other materials.
Miyashita and his colleagues found more than a hundred concentrations of keratin along the body of the fossil, meaning that the ancient hagfish probably evolved its slime defense when the seas included fearsome predators such as plesiosaurs and ichthyosaurs that we no longer see today.

“We now have a fossil that can push back the origin of the hagfish-like body plan by hundreds of millions of years,” Miyashita said. “Now, the next question is how this changes our view of the relationships between all these early fish lineages.”

Shaking up the vertebrate family tree

Features of the new fossil help place hagfish and their relatives on the vertebrate family tree. In the past, scientists have disagreed about where they belonged, depending on how they tackled the question. Those who rely on fossil evidence alone tend to conclude that hagfish are so primitive that they are not even vertebrates. This implies that all fishes and their vertebrate descendants had a common ancestor that — more or less — looked like a hagfish.

Fossilized slime of 100-million-year-old hagfish shakes up vertebrate family tree
The Tethymyxine tapirostrum hagfish fossil suggests a new hypothesis for the structure of the vertebrate family tree,
with hagfish and other eel-like creatures branching off early from the lineage that gave rise
 to modern-day jawed vertebrates, including bony fish and humans
[Credit: Tetsuto Miyashita, University of Chicago]

But those who work with genetic data argue that hagfish and lampreys are more closely related to each other. This suggests that modern hagfish and lampreys are the odd ones out in the family tree of vertebrates. In that case, the primitive appearance of hagfish and lampreys is deceptive, and the common ancestor of all vertebrates was probably something more conventionally fish-like.

Miyashita’s work reconciles these two approaches, using physical evidence of the animal’s anatomy from the fossil to come to the same conclusion as the geneticists: that the hagfish and lampreys should be grouped separately from the rest of fishes.

“In a sense, this resets the agenda of how we understand these animals,” said Michael Coates, PhD, professor of organismal biology and anatomy at UChicago and a co-author of the new study. “Now we have this important corroboration that they are a group apart. Although they’re still part of vertebrate biodiversity, we now have to look at hagfish and lampreys more carefully, and recognize their apparent primitiveness as a specialized condition.

Paleontologists have increasingly used sophisticated imaging techniques in the past few years, but Miyashita’s research is one of a handful so far to use synchrotron scanning to identify chemical elements in a fossil. While it was crucial to detect anatomical structures in the hagfish fossil, he believes it can also be a useful tool to help scientists detect paint or glue used to embellish a fossil or even outright forge a specimen. Any attempt to spice up a fossil specimen leaves chemical fingerprints that light up like holiday decorations in a synchrotron scan.

“I’m impressed with what Tetsuto has marshaled here,” Coates said. “He’s maxed out all the different techniques and approaches that can be applied to this fossil to extract information from it, to understand it and to check it thoroughly.”

Author: Matt Wood | Source: University of Chicago Medical Center [January 21, 2019]



Fossil shark teeth discovered in leftover rock that contained SUE the T. rex

SUE the T. rex is the most famous fossil from the Hell Creek Formation of South Dakota–the most complete skeleton ever discovered of the world’s most popular dinosaur. When Field Museum scientists removed the rock surrounding SUE’s bones twenty years ago, they kept the leftover sediment (called matrix). For decades, the leftover matrix sat in underground storage at the museum, until scientists and volunteers began meticulously picking through it in search of tiny fossils. They found the remains of a shark that lived in a river SUE probably drank from.

Fossil shark teeth discovered in leftover rock that contained SUE the T. rex
An illustration showing what Galagadon would have looked like in life, swimming along the river floor
[Credit: (c) Velizar Simeonovski, Field Museum]

“This shark lived at the same time as SUE the T. rex, it was part of the same world,” says Pete Makovicky, the Field Museum’s curator of dinosaurs and one of the authors of the Journal of Paleontology study describing the new species. “Most of its body wasn’t preserved, because sharks’ skeletons are made of cartilage, but we were able to find its tiny fossilized teeth.”

The team, led by North Carolina State University’s Terry Gates, named the shark Galagadon nordquistae, a nod to its teeth, which have a stepped triangle shape like the spaceships in the 1980s video game Galaga, and to Karen Nordquist, the Field Museum volunteer who discovered the fossils.

“It was so tiny, you could miss it if you weren’t looking really carefully,” says Nordquist, a retired chemist who has been microsorting, or sifting through dirt to find tiny fossils, for the Field Museum for fifteen years. “To the naked eye, it just looks like a little bump, you have to have a microscope to get a good view of it.”

The teeth are only a millimeter wide–about the diameter of the head of a pin–and the shark they belonged to was small too. “Galagadon was less than two feet long–it’s not exactly Jaws,” says Makovicky. “It’s comparable to bamboo sharks living today. It probably had a flat face and was very likely camouflage-colored, since its relatives today have a camouflage pattern. It would have eaten small invertebrates and probably spent a fair amount of time lying on the bottom of the riverbed.”

Fossil shark teeth discovered in leftover rock that contained SUE the T. rex
Galagadon teeth [Credit: Terry Gates, NC State University]

But while Galagadon wasn’t breaking any size records, its discovery is making scientists question what they thought they knew about the area where SUE the T. rex was found. “We had always thought of the SUE locality as being by a lake formed from a partially dried-up river–the presence of this shark suggests there must have been at least some connection to marine environments,” says Makovicky. “This wasn’t some Sharknado event–these animals were making their way up rivers from the sea.”

“Today, carpet sharks, which include bamboo sharks and wobbegongs, mostly live in the waters in southeast Asia and Australia, so it’s surprising to find their fossils at the SUE locality. During the Late Cretaceous the continents continued to drift apart, further isolating dinosaurs and other land animals, and at the same time created the Atlantic and Indian oceans. With occasional seaways connecting these young oceans, we have found fossils of marine life flourishing globally, including Galagadon and its relatives. ” says Eric Gorscak, a research associate at the Field Museum and another author on the study.

The study also reflects the importance of learning about fossils beyond big, flashy dinosaurs. “Every species in an ecosystem plays a supporting role, keeping the whole network together,” says Terry Gates, lecturer at North Carolina State University and a research affiliate with the North Carolina Museum of Natural Sciences and lead author of the paper describing the shark. “There is no way for us to understand what changed in the ecosystem during the time of the mass extinction at the end of the Cretaceous without knowing all the wonderful species that existed before.”

“Most people, when they think of fossils, think of big huge dinosaur bones, but in the dirt, there are the bones of tiny animals,” says Nordquist. “When you get those bones and identify them, you get an idea of the whole environment–everything that lived with the big dinosaurs. You learn so much from microsorting.”

Source: Field Museum [January 21, 2019]



Genetic study provides novel insights into the evolution of skin colour

Skin colour is one of the most visible and variable traits among humans and scientists have always been curious about how this variation evolved. Now, a study of diverse Latin American populations led by UCL geneticists has identified new genetic variations associated with skin colour.

Genetic study provides novel insights into the evolution of skin colour
A gallery of busts from the 19th century showing human diversity on display in the Museum of Mankind in Paris
[Credit: Romuald Meigneux/SIPA, via Associated Press]

The study, published in the journal Nature Communications, found that the variation of light skin among Eurasian people evolved independently from different genetic backgrounds.

The genetic study analysed pigmentation in over 6,000 Latin Americans, who have a mix of Native American, European and African ancestry.

It is well established that Native Americans are genetically closely related to East Asians, the initial settlement of the Americas occurring some 15-20,000 years ago, through migration from Eastern Siberia into North America. As a consequence, genetic variations in Native Americans are often shared with East Asians.

This study identifies five new associated regions involving skin, eye and hair colour. Genes affecting skin colour in Europeans have been extensively studied, but here researchers identified an important variation in the gene MFSD12 seen uniquely in East Asians and Native Americans.

They show it was under natural selection in East Asians after they split from Europeans around 40,000 years ago, and was then carried over to America by ancient migrations of Native Americans. It is the first time this gene has been linked to skin colour in Native Americans and East Asians.

Dr Kaustubh Adhikari (UCL Genetics Institute), said: “Our work demonstrates that lighter skin colour evolved independently in Europe and East Asia. We also show that this gene was under strong natural selection in East Asia, possibly as adaptation to changes in sunlight levels and ultraviolet radiation.”

Human physical diversity has fascinated biologists for centuries and despite the discovery of hundreds of genes related to such variation, there is still a lot to be understood in order to gain a fuller picture. Scientists have been calling for more diversity in genetics research to ensure that everyone benefits from the medical outcomes of research.

Only recently scientists published the first major study on the genes linked to skin tone diversity in Africa. Latin Americans are similarly underrepresented in genetics research, in particular in pigmentation research.

“It is commonly thought that variation in pigmentation, such as skin colour, in Latin Americans primarily arises due to people’s varying degree of European or African ancestry. But our new study shows that there is variation inherited from their Native ancestors as well”, said Dr Javier Mendoza-Revilla (UCL Genetics Institute).

Professor Desmond Tobin (Charles Institute of Dermatology, University College Dublin) explained: “The pigment melanin determines our hair, skin and eye colour. This gene MFSD12 influences how melanin is produced and stored in the skin, thus affecting our skin colour. A darker skin produces more melanin, which can help prevent UV light from damaging our DNA and so offers protection against skin cancer.”

“Interestingly, this gene also turned up in the skin colour study in Africans, but the variants were entirely different than those we observe in our study, highlighting the huge genetic diversity in humans and the need to diversify our study populations”, emphasized Professor Andres Ruiz-Linares (UCL Genetics Institute), who led the CANDELA project spanning participants from five countries: Brazil, Colombia, Chile, Mexico and Peru.

In addition to skin tone variation, the scientists also noted a wide variation in eye colour among Latin Americans. “Just like skin colour, early research on eye colour was Europe-centric, and mostly focused on the distinction between blue vs. brown eyes. But we show that eye colour is a broad continuum, and by studying the subtler variation within brown to black, we found two new genes linked to it”, said Dr Anood Sohail (University of Cambridge).

The study’s findings help explain the variation of skin, hair and eye colour of Latin Americans, shed light on human evolution, and inform an understanding of the genetic risk factors for conditions such as skin cancer.

Source: University College London [January 21, 2019]



Ancient climate change triggered warming that lasted thousands of years

A rapid rise in temperature on ancient Earth triggered a climate response that may have prolonged the warming for many thousands of years, according to scientists.

Ancient climate change triggered warming that lasted thousands of years
Fossiliferous core from site in Mayland
[Credit: Rosie Oakes]

Their study, published online in Nature Geoscience, provides new evidence of a climate feedback that could explain the long duration of the Paleocene-Eocene Thermal Maximum (PETM), which is considered the best analogue for modern climate change.

The findings also suggest that climate change today could have long-lasting impacts on global temperature even if humans are able to curb greenhouse gas emissions.

“We found evidence for a feedback that occurs with rapid warming that can release even more carbon dioxide into the atmosphere,” said Shelby Lyons, a doctoral student in geosciences at Penn State. “This feedback may have extended the PETM climate event for tens or hundreds of thousands of years. We hypothesize this is also something that could occur in the future.”

Increased erosion during the PETM, approximately 56 million years ago, freed large amounts of fossil carbon stored in rocks and released enough carbon dioxide, a greenhouse gas, into the atmosphere to impact temperatures long term, researchers said.

Scientists found evidence for the massive carbon release in coastal sediment fossil cores. They analyzed the samples using an innovative molecular technique that enabled them to trace how processes like erosion moved carbon in deep time.

“This technique uses molecules in a really innovative, out-of-the-box way to trace fossil carbon,” said Katherine Freeman, Evan Pugh University Professor of Geosciences at Penn State. “We haven’t really been able to do that before.”

Global temperatures increased by about 9 to 14.4 degrees Fahrenheit during the PETM, radically changing conditions on Earth. Severe storms and flooding became more common, and the warm, wet weather led to increased erosion of rocks.

Ancient climate change triggered warming that lasted thousands of years
A core sample of the Paleocene-Eocene Thermal Maximum taken
from a drilling site in Maryland [Credit: USGS]

As erosion wore down mountains over thousands of years, carbon was released from rocks and transported by rivers to oceans, where some was reburied in coastal sediments. Along the way, some of the carbon entered the atmosphere as greenhouse gas.

“What we found in records were signatures of carbon transport that indicated there were massive erosion regimes occurring on land,” Lyons said. “Carbon was locked on land and during the PETM it was moved and reburied. We were interested in seeing how much carbon dioxide that could release.”

Lyons was studying PETM core samples from Maryland, in a location that was once underwater, when she discovered traces of older carbon that must have once been stored in rocks on land. She initially believed the samples were contaminated, but she found similar evidence in sediments from other Mid-Atlantic sites and Tanzania.

Carbon in these samples did not share common isotope patterns of life from the PETM and appeared oily, as if it been heated over long periods of time in a different location.

“That told us what we were looking at in the records was not just material that was formed during the PETM,” Lyons said. “It was not just carbon that had been formed and deposited at that time, but likely represented something older being transported in.”

The researchers developed a mixing model to distinguish the sources of carbon. Based on the amount of older carbon in the samples, scientists were able to estimate how much carbon dioxide was released during the journey from rock to ocean sediment.

They estimated the climate feedback could have released enough carbon dioxide to explain the roughly 200,000-year duration of the PETM, something that has not been well understood.

The researchers said the findings offer a warning about modern climate change. If warming reaches certain tipping points, feedbacks can be triggered that have the potential to cause even more temperature change.

“One lesson we can learn from this research is that carbon is not stored very well on land when the climate gets wet and hot,” Freeman said. “Today, we’re pushing the system out of equilibrium and it’s not going to snap back, even when we start reducing carbon dioxide emissions.”

Source: Penn State University [January 22, 2019]



Making Muscle A spool of thread can be weaved into almost any…

Making Muscle

A spool of thread can be weaved into almost any piece of clothing but for those without the knack, how that wooly jumper or cardigan came to be can seem impossible to untangle. Researchers studying the heart face a similar challenge as they try to uncover how heart muscle is formed, specifically the units called sarcomeres that allow it to contract. They investigated this process using a variety of microscopy techniques, including structured illumination, to image sarcomeres forming in human heart muscle cells grown in a dish (pictured). The team revealed that sarcomeres within a cell (bottom) are formed from muscle stress fibres (top). They went on to identify several proteins vital for the transition from muscle stress fibres to sarcomeres, adding to a growing picture of how heart muscle is made.

Written by Lux Fatimathas

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