Mars rocks may harbor signs of life from 4 billion years ago

The Jezero Crater delta, a well-preserved ancient river delta on Mars.

Iron-rich rocks near ancient lake sites on Mars could hold vital clues that show life once existed there, research suggests.

These rocks -- which formed in lake beds -- are the best place to seek fossil evidence of life from billions of years ago, researchers say.

A new study that sheds light on where fossils might be preserved could aid the search for traces of tiny creatures -- known as microbes -- on Mars, which it is thought may have supported primitive life forms around four billion years ago.

A team of scientists has determined that sedimentary rocks made of compacted mud or clay are the most likely to contain fossils. These rocks are rich in iron and a mineral called silica, which helps preserve fossils.

They formed during the Noachian and Hesperian Periods of Martian history between three and four billion years ago. At that time, the planet's surface was abundant in water, which could have supported life.

The rocks are much better preserved than those of the same age on Earth, researchers say. This is because Mars is not subject to plate tectonics -- the movement of huge rocky slabs that form the crust of some planets -- which over time can destroy rocks and fossils inside them.

The team reviewed studies of fossils on Earth and assessed the results of lab experiments replicating Martian conditions to identify the most promising sites on the planet to explore for traces of ancient life.

Their findings could help inform NASA's next rover mission to the Red Planet, which will focus on searching for evidence of past life. The US space agency's Mars 2020 rover will collect rock samples to be returned to Earth for analysis by a future mission.

A similar mission led by the European Space Agency is also planned in coming years.

The latest study of Mars rocks -- led by a researcher from the University of Edinburgh -- could aid in the selection of landing sites for both missions. It could also help to identify the best places to gather rock samples.

The study, published in Journal of Geophysical Research, also involved researchers at NASA's Jet Propulsion Laboratory, Brown University, California Institute of Technology, Massachusetts Institute of Technology and Yale University in the US.

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Scientists introduce cosmochemical model for Pluto formation

Ralph Instrument Pluto Maps. New Horizons not only showed humanity what Pluto looks like, but also provided information on the composition of Pluto’s atmosphere and surface. These maps — assembled using data from the Ralph instrument — indicate regions rich in methane (CH4), nitrogen (N2), carbon monoxide (CO) and water (H2O) ices. Sputnik Planitia shows an especially strong signature of nitrogen near the equator. SwRI scientists combined these data with Rosetta’s comet 67P data to develop a proposed “giant comet” model for Pluto formation.

Southwest Research Institute scientists integrated NASA's New Horizons discoveries with data from ESA's Rosetta mission to develop a new theory about how Pluto may have formed at the edge of our solar system.

"We've developed what we call 'the giant comet' cosmochemical model of Pluto formation," said Dr. Christopher Glein of SwRI's Space Science and Engineering Division. The research is described in a paper published online today in Icarus. At the heart of the research is the nitrogen-rich ice in Sputnik Planitia, a large glacier that forms the left lobe of the bright Tombaugh Regio feature on Pluto's surface. "We found an intriguing consistency between the estimated amount of nitrogen inside the glacier and the amount that would be expected if Pluto was formed by the agglomeration of roughly a billion comets or other Kuiper Belt objects similar in chemical composition to 67P, the comet explored by Rosetta."

In addition to the comet model, scientists also investigated a solar model, with Pluto forming from very cold ices that would have had a chemical composition that more closely matches that of the Sun.

Scientists needed to understand not only the nitrogen present at Pluto now -- in its atmosphere and in glaciers -- but also how much of the volatile element potentially could have leaked out of the atmosphere and into space over the eons. They then needed to reconcile the proportion of carbon monoxide to nitrogen to get a more complete picture. Ultimately, the low abundance of carbon monoxide at Pluto points to burial in surface ices or to destruction from liquid water.

"Our research suggests that Pluto's initial chemical makeup, inherited from cometary building blocks, was chemically modified by liquid water, perhaps even in a subsurface ocean," Glein said. However, the solar model also satisfies some constraints. While the research pointed to some interesting possibilities, many questions remain to be answered.

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Cold production of new seafloor

This is the area of investigation at the Cayman Trough in the Caribbean.

A mountain range with a total length of 65,000 kilometers runs through all the oceans. It marks the boundaries of tectonic plates. Through the gap between the plates material from the Earth's interior emerges, forming new seafloor, building up the submarine mountains and spreading the plates apart. Very often, these mid-ocean ridges are described as a huge, elongated volcano. But this image is only partly correct, because the material forming the new seafloor is not always magmatic. At some spreading centres material from the Earth's mantle reaches the surface without being melted. The proportion of seabed formed this has been previously unknown.

Scientists from the Universities of Kiel (Germany), Austin (Texas, USA) and Durham (Great Britain) have now published data in the international journal Nature Geoscience that, for the first time, allow a detailed estimation on how much seafloor is formed by mantle material without magmatic processes. "This phenomenon occurs especially where the seabed spreads at paces of less than two centimeters per year," explains Prof. Dr. Ingo Grevemeyer from the GEOMAR Helmholtz Centre for Ocean Research Kiel, lead author of the study.

One of these zones is located in the Cayman Trough south of the island of Grand Cayman in the Caribbean. In 2015, the researchers used the German research vessel METEOR to investigate the seafloor seismically, i.e. by using sound waves. Sound signals sent through different rocks or sediment layers, are being reflected and refracted in different ways by each layer. Rock, which has been melted and solidified on the seabed, has a different signature in the seismic signal than rock from the Earth's mantle, which has not been melted.

But scientists had a problem so far: The contact with the seawater changes the mantle rocks. "After this process called serpentinisation mantle rocks are barely distinguishable from magmatic rocks in seismic data," says Professor Grevemeyer. Until now, mantle rock on the seabed could only be detected by taking samples directly from the seafloor and analyzing them in the laboratory. "But that way you only get information about a tiny spot. A large-scale or even in-depth information on the composition of the seabed cannot be achieved," says Grevemeyer.

However, during the expedition in 2015, the team not only used the energy of ordinary sound waves -- it also detected so-called shear waves, which occur only in solid materials. They could be recorded very clearly thanks to a clever selection of measuring points.

From the ratio of the speed of both types of waves, the scientists were able to differentiate mantle material from magmatic material. "So we could prove for the first time with seismic methods that up to 25 percent of the young ocean floor is not magmatic at the ultra-slow spreading centre in the Cayman trough," says Ingo Grevemeyer.

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Using the K computer, scientists predict exotic 'di-Omega' particle

Based on complex simulations of quantum chromodynamics performed using the K computer, one of the most powerful computers in the world, the HAL QCD Collaboration, made up of scientists from the RIKEN Nishina Center for Accelerator-based Science and the RIKEN Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS) program, together with colleagues from a number of universities, have predicted a new type of "dibaryon" -- a particle that contains six quarks instead of the usual three. Studying how these elements form could help scientists understand the interactions among elementary particles in extreme environments such as the interiors of neutron stars or the early universe moments after the Big Bang.

Particles known as "baryons" -- principally protons and neutrons -- are composed of three quarks bound tightly together, with their charge depending on the "color" of the quarks that make them up. A dibaryon is essentially a system with two baryons. There is one known dibaryon in nature -- deuteron, a deuterium (or heavy-hydrogen) nucleus that contains a proton and a neutron that are very lightly bound. Scientists have long wondered whether there could be other types of dibaryons. Despite searches, no other dibaryon has been found.

The group, in work published in Physical Review Letters, has now used powerful theoretical and computational tools to predict the existence of a "most strange" dibaryon, made up of two "Omega baryons" that contain three strange quarks each. They named it "di-Omega." The group also suggested a way to look for these strange particles through experiments with heavy ion collisions planned in Europe and Japan.

The finding was made possible by a fortuitous combination of three elements: better methods for making QCD calculations, better simulation algorithms, and more powerful supercomputers.

The first essential element was a new theoretical framework called the "time-dependent HAL QCD method": It allows researchers to extract the force acting between baryons from the large volume of numerical data obtained using the K computer.

The second element was a new computational method, the unified contraction algorithm, which allows much more efficient calculation of a system with a large number of quarks.

The third element was the advent of powerful supercomputers. According to Shinya Gongyo from the RIKEN Nishina Center, "We were very lucky to have been able to use the K computer to perform the calculations. It allowed fast calculations with a huge number of variables. Still, it took almost three years for us to reach our conclusion on the di-Omega."

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Hot cars can hit deadly temperatures fast

How hot is a car after one hour in the sun or shade?

A lot can happen at 160 degrees Fahrenheit: Eggs fry, salmonella bacteria dies, and human skin will suffer third-degree burns. If a car is parked in the sun on a hot summer day, its dashboard can hit 160 degrees in about an hour. One hour is also about how long it can take for a young child trapped in a car to suffer heat injury or even die from hyperthermia.

Researchers from Arizona State University and the University of California at San Diego School of Medicine have completed a study to compare how different types of cars warm up on hot days when exposed to different amounts of shade and sunlight for different periods of time. The research team also took into account how these differences would affect the body temperature of a hypothetical 2-year-old child left in a vehicle on a hot day. Their study was published May 24 in the journal Temperature.

"Our study not only quantifies temperature differences inside vehicles parked in the shade and the sun, but it also makes clear that even parking a vehicle in the shade can be lethal to a small child," said Nancy Selover, an Arizona State climatologist and research professor in ASU's School of Geographical Sciences and Urban Planning.

From January through May 2018, six children have died after being left in hot cars in the United States. That number will go up. Annually in the U.S., an average of 37 children left in hot cars die from complications of hyperthermia -- when the body warms to above 104 degrees and cannot cool down. More than 50 percent of cases of a child dying in a hot car involve a parent or caregiver who forgot the child in the car.

The findings

Researchers used six vehicles for the study: Two identical silver mid-size sedans, two identical silver economy cars, and two identical silver minivans. During three hot summer days with temperatures in the 100s in Tempe, Arizona, researchers moved the cars from sunlight to shade for different periods of time throughout the day. Researchers measured interior air temperature and surface temperatures throughout different parts of the day.

"These tests replicated what might happen during a shopping trip," Selover said. "We wanted to know what the interior of each vehicle would be like after one hour, about the amount of time it would take to get groceries. I knew the temperatures would be hot, but I was surprised by the surface temperatures."

For vehicles parked in the sun during the simulated shopping trip, the average cabin temperature hit 116 degrees in one hour. Dash boards averaged 157 degrees, steering wheels 127 degrees, and seats 123 degrees in one hour.

For vehicles parked in the shade, interior temperatures were closer to 100 degrees after one hour. Dash boards averaged 118 degrees, steering wheels 107 degrees and seats 105 degrees after one hour.

The different types of vehicles tested warmed up at different rates, with the economy car warming faster than the mid-size sedan and minivan.

"We've all gone back to our cars on hot days and have been barely able to touch the steering wheel," Selover said. "But, imagine what that would be like to a child trapped in a car seat. And once you introduce a person into these hot cars, they are exhaling humidity into the air. When there is more humidity in the air, a person can't cool down by sweating because sweat won't evaporate as quickly."

Hyperthermia

A person's age, weight, existing health problems and other factors, including clothing, will affect how and when heat becomes deadly. Scientists can't predict exactly when a child will suffer a heatstroke, but most cases involve a child's core body temperature rising above 104 degrees for an extended period.

In the study, the researchers used data to model a hypothetical 2-year old boy's body temperature. The team found that a child trapped in a car in the study's conditions could reach that temperature in about an hour if a car is parked in the sun, and just under two hours if the car is parked in the shade.

"We hope these findings can be leveraged for the awareness and prevention of pediatric vehicular heatstroke and the creation and adoption of in-vehicle technology to alert parents of forgotten children," said Jennifer Vanos, lead study author and assistant professor of climate and human health at U.C. San Diego.

Hyperthermia and heatstroke effects happen along a continuum, Vanos said. Internal injuries can begin at temperatures below 104 degrees, and some heatstroke survivors live with brain and organ damage.

Why memories fail

Forgetting a child in the car can happen to anyone, said Gene Brewer, an ASU associate professor of psychology. Brewer, who was not involved in the heat study, researches memory processes, and has testified as an expert witness in a court case involving a parent whose child died in a hot car.

"Often these stories involve a distracted parent," he said. "Memory failures are remarkably powerful, and they happen to everyone. There is no difference between gender, class, personality, race or other traits. Functionally, there isn't much of a difference between forgetting your keys and forgetting your child in the car."

Most people spend a lot of time on routine behaviors, doing the same activities over and over without thinking about them. For example, driving the same route to work, taking the children to daycare on Tuesdays and Thursdays, or leaving car keys in the same spot every day. When new information comes into those routines, such as a parent's daycare drop-off day suddenly changing or an emergency phone call from a boss on the way to work, that's when memory failures can occur.

"These cognitive failures have nothing to do with the child," Brewer said. "The cognitive failure happens because someone's mind has gone to a new place, and their routine has been disrupted. They are suddenly thinking about new things, and that leads to forgetfulness. Nobody in this world has an infallible memory."

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Land rising above the sea 2.4 billion years ago changed planet Earth

A conceptual rendering suggests how Earth's land elevations and oceans may have appeared during the assembly of Kenorland, left, and later, right, after the Great Oxygenation Event. A University of Oregon-led study has potentially narrowed the window on when significant amounts of land emerged from under the ocean's surface.

Chemical signatures in shale, the Earth's most common sedimentary rock, point to a rapid rise of land above the ocean 2.4 billion years ago that possibly triggered dramatic changes in climate and life.

In a study published in the May 24 issue of the journal Nature, researchers report that shale sampled from around the world contains archival quality evidence of almost imperceptible traces of rainwater that caused weathering of land from as old as 3.5 billion years ago.

Notable changes in the ratios of oxygen 17 and 18 with more common oxygen 16, said lead author Ilya Bindeman, a geologist at the University of Oregon, allowed researchers to read the chemical history in the rocks.

In doing so, they established when newly surfaced crust was exposed to weathering by chemical and physical processes, and, more broadly, when the modern hydrologic process of moisture distillation during transport over large continents started.

The evidence is from analyses of three oxygen isotopes, particularly the rare but stable oxygen 17, in 278 shale samples drawn from outcrops and drill holes from every continent and spanning 3.7 billion years of Earth's history. The analyses were done in Bindeman's Stable Isotope Laboratory.

Based on his own previous modeling and other studies, Bindeman said, total landmass on the planet 2.4 billion years ago may have reached about two-thirds of what is observed today. However, the emergence of the new land happened abruptly, in parallel with large-scale changes in mantle dynamics.

Isotopic changes recorded in the shale samples at that time also coincides with the hypothesized timing of land collisions that formed Earth's first supercontinent, Kenorland, and high-mountain ranges and plateaus.

"Crust needs to be thick to stick out of water," Bindeman said. "The thickness depends on its amount and also on thermal regulation and the viscosity of the mantle. When the Earth was hot and the mantle was soft, large, tall mountains could not be supported. Our data indicate that this changed exponentially 2.4 billion years ago. The cooler mantle was able to support large swaths of land above sea level."

Temperatures on the surface when the new land emerged from the sea would have likely been hotter than today by several tens of degrees, he said.

The study found a stepwise change in triple-isotopes of oxygen around that time frame. That, the scientists said, resolves previous arguments for a gradual or stepwise emergence of land between 1.1 and 3.5 billion years ago. At 2.4 billion years ago, Bindeman said, the newly emerged land began to consume carbon dioxide from the atmosphere amid chemical weathering.

The timing also coincides with the transition from the Archean Eon, when simple prokaryotic life forms, archaea and bacteria, thrived in water, to the Proterozoic Eon, when eukaryotes, such as algae, plants and fungi, emerged.

"In this study, we looked at how weathering proceeded over 3.5 billion years," Bindeman said. "Land rising from water changes the albedo of the planet. Initially, Earth would have been dark blue with some white clouds when viewed from space. Early continents added to reflection. Today we have dark continents because of lots of vegetation."

Exposure of the new land to weathering, he said, may have set off a sink of greenhouse gases such carbon dioxide, disrupting the radiative balance of the Earth that generated a series of glacial episodes between 2.4 billion and 2.2 billion years ago. That, he said, may have spawned the Great Oxygenation Event in which atmospheric changes brought significant amounts of free oxygen into the air. Rocks were oxidized and became red. Archean rocks are gray.

In the absence of much land, he said, photons from the sun interacted with water and heated it. A bright surface, provided by emerging land, would reflect sunlight back into space, creating additional torque on radiative-greenhouse balance and a change in climate.

"What we speculate is that once large continents emerged, light would be reflected back into space and initiate runaway glaciation," Bindeman said. "Earth would have seen its first snowfall."

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People with family history of alcoholism release more dopamine in expectation of alcohol

People with a family history of alcohol use disorder (AUD) release more dopamine in the brain's main reward center in response to the expectation of alcohol than people diagnosed with the disorder, or healthy people without any family history of AUD, reports a new study in Biological Psychiatry: Cognitive Neuroscience and Neuroimaging.

"This exaggerated reward center stimulation by expectation of alcohol may put the [individuals with family history] at greater risk of alcohol use disorder, and could be a risk factor in itself," said first author Lawrence Kegeles, MD, PhD, of Columbia University.

The study examined a range of risk for AUD, including 34 healthy participants with no family history of AUD, 16 healthy participants with a family history of the disorder (referred to as the family-history positive, or FHP, group), and 15 participants diagnosed with AUD. Dr. Kegeles and colleagues used PET brain scanning to measure the amount of dopamine release in areas of the brain important for reward and addiction. The participants underwent the brain scans after receiving either an alcohol drink -- a cocktail of vodka, tonic, and cranberry -- or a placebo drink without the vodka. Although the participants didn't know the order in which they would receive the drinks, if they received the placebo drink first they were cued into expecting the alcohol drink next.

All three groups had similar dopamine release-levels in response to the alcohol, suggesting that alcohol-induced dopamine release is normal in AUD. However, "we found that the FHP participants had a much more pronounced response to the placebo drink than the other groups, indicating that expectation of alcohol caused the FHP group to release more reward center dopamine," said Dr. Kegeles. The release of dopamine into the reward center is thought to reinforce alcohol consumption and possibly contribute to risk of AUD.

"This research finding exemplifies how advances in imaging brain chemistry using PET scanning can provide new insights into how differences in brain function in people with a family history of alcoholism can explain their own potential for addiction," said Cameron Carter, MD, Editor of Biological Psychiatry: Cognitive Neuroscience and Neuroimaging.

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When the dinosaurs died, so did forests -- and tree-dwelling birds

The asteroid impact that eliminated non-avian dinosaurs destroyed global forests. Here, a hyopothetical surviving bird lineage -- small-bodied and specialized for a ground-dwelling lifestyle--flees a burning forest in the aftermath of the asteroid strike.

Sixty-six million years ago, the world burned. An asteroid crashed to Earth with a force one million times larger than the largest atomic bomb, causing the extinction of the dinosaurs. But dinosaurs weren't the only ones that got hit hard -- in a new study, scientists learned that the planet's forests were decimated, leading to the extinction of tree-dwelling birds.

"Looking at the fossil record, at plants and birds, there are multiple lines of evidence suggesting that the forest canopies collapsed," says Regan Dunn, a paleontologist at the Field Museum in Chicago and a co-author on the study in Current Biology. "Perching birds went extinct because there were no more perches."

"We drew on a variety of approaches to stitch this story together," said Daniel Field, the paper's lead author, of the Milner Centre for Evolution at the University of Bath. "We concluded that the temporary elimination of forests in the aftermath of the asteroid impact explains why arboreal birds failed to survive across this extinction event. The ancestors of modern arboreal birds did not move into the trees until forests had recovered from the extinction-causing asteroid."

The project's pollen expert, Antoine Bercovici of the Smithsonian Institution and the Denver Museum of Nature and Science, helped determine that the world's forests were destroyed by looking at microscopic fossils of pollen and spores. Dunn explains, "After a disaster like a forest fire or a volcanic eruption, the first plants to come back are the fastest colonizers -- especially ferns." That's because ferns don't sprout from seeds, but from spores, which are much smaller -- just a single cell. "Spores are minuscule, the size of a grain of pollen, so they're easily dispersed. They get picked up by the wind and go further than seeds can, and all they need to grow is a wet spot."

"The spores are tiny -- you could fit four across a single strand of your hair," says Dunn. "To see them, we take a sample of rock from the time frame just after the collision and dissolve it in acid. Then we purify it so that all that remains is the organic debris, like pollen, spores and little leaf bits, then we look at them under a microscope."

Immediately after the asteroid hit, the fossil record shows the charcoal remains of burnt trees, and then, tons of fern spores. An abundance of fern spores in the fossil record often comes on the heels of a natural disaster that destroyed larger plants like trees.

"Our study examined the fossil record from New Zealand, Japan, Europe and North America, which showed there was a mass deforestation across the globe at the end of the Cretaceous period," says co-author Bercovici.

And with no more trees, the scientists found, tree-dwelling birds went extinct. The birds that did survive were ground-dwellers -- birds whose fossilized remains show longer, sturdier legs like we see in modern ground birds like kiwis and emus. The Cretaceous equivalent of robins and sparrows, with delicate little legs made for perching on tree branches, had no place to live.

"Today, birds are the most diverse and globally widespread group of terrestrial vertebrate animals -- there are nearly 11,000 living species," says Field. "Only a handful of ancestral bird lineages succeeded in surviving the mass extinction event 66 million years ago, and all of today's amazing living bird diversity can be traced to these ancient survivors."

And while fossil animals like dinosaurs and birds often get more love than fossil plants, Dunn says that plants are critical to understanding life on earth. "Plants are everything, plants are the context in which all terrestrial life evolves and survives. They're primary producers, they make energy available to all life forms by capturing it from the sun -- we can't do that."

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Unprecedented detail in pulsar 6,500 light-years from Earth

The pulsar PSR B1957+20 is seen in the background through the cloud of gas enveloping its brown dwarf star companion.

A team of astronomers has performed one of the highest resolution observations in astronomical history by observing two intense regions of radiation, 20 kilometres apart, around a star 6500 light-years away.

The observation is equivalent to using a telescope on Earth to see a flea on the surface of Pluto.

The extraordinary observation was made possible by the rare geometry and characteristics of a pair of stars orbiting each other. One is a cool, lightweight star called a brown dwarf, which features a "wake" or comet-like tail of gas. The other is an exotic, rapidly spinning star called a pulsar.

"The gas is acting as like a magnifying glass right in front of the pulsar," says Robert Main, lead author of the paper describing the observation being published May 24 in the journal Nature. "We are essentially looking at the pulsar through a naturally occurring magnifier which periodically allows us to see the two regions separately."

Main is a PhD astronomy student in the Department of Astronomy & Astrophysics at the University of Toronto, working with colleagues at the University of Toronto's Dunlap Institute for Astronomy & Astrophysics and Canadian Institute for Theoretical Astrophysics, and the Perimeter Institute.

The pulsar is a neutron star that rotates rapidly -- over 600 times a second. As the pulsar spins, it emits beams of radiation from the two hotspots on its surface. The intense regions of radiation being observed are associated with the beams.

The brown dwarf star is about a third the diameter of the Sun. It is roughly two million kilometres from the pulsar -- or five times the distance between the Earth and the moon -- and orbits around it in just over 9 hours. The dwarf companion star is tidally locked to the pulsar so that one side always faces its pulsating companion, the way the moon is tidally locked to the Earth.

Because it is so close to the pulsar, the brown dwarf star is blasted by the strong radiation coming from its smaller companion. The intense radiation from the pulsar heats one side of the relatively cool dwarf star to the temperature of our Sun, or some 6000°C.

The blast from the pulsar could ultimately spell its companion's demise. Pulsars in these types of binary systems are called "black widow" pulsars. Just as a black widow spider eats its mate, it is thought that the pulsar, given the right conditions, could gradually erode gas from the dwarf star until the latter is consumed.

In addition to being an observation of incredibly high resolution, the result could be a clue to the nature of mysterious phenomena known as Fast Radio Bursts, or FRBs.

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Utah fossil reveals global exodus of mammals' near relatives to major continents

The new species Cifelliodon wahkarmoosuch is estimated to have weighed 2.5 pounds and probably grew to be about the size of a small hare.

A nearly 130-million-year-old fossilized skull found in Utah is an Earth-shattering discovery in one respect.

The small fossil is evidence that the super-continental split likely occurred more recently than scientists previously thought and that a group of reptile-like mammals that bridge the reptile and mammal transition experienced an unsuspected burst of evolution across several continents.

"Based on the unlikely discovery of this near-complete fossil cranium, we now recognize a new, cosmopolitan group of early mammal relatives," said Adam Huttenlocker, lead author of the study and assistant professor of clinical integrative anatomical sciences at the Keck School of Medicine of USC.

The study, published in the journal Nature on May 16, updates the understanding of how mammals evolved and dispersed across major continents during the age of dinosaurs. It suggests that the divide of the ancient landmass Pangea continued for about 15 million years later than previously thought and that mammal migration and that of their close relatives continued during the Early Cretaceous (145 to 101 million years ago).

"For a long time, we thought early mammals from the Cretaceous (145 to 66 million years ago) were anatomically similar and not ecologically diverse," Huttenlocker said. "This finding by our team and others reinforce that, even before the rise of modern mammals, ancient relatives of mammals were exploring specialty niches: insectivores, herbivores, carnivores, swimmers, gliders. Basically, they were occupying a variety of niches that we see them occupy today."

The study reveals that the early mammal precursors migrated from Asia to Europe, into North America and further onto major Southern continents, said Zhe-Xi Luo, senior author of the study and a paleontologist at the University of Chicago.

Fossil find: a new species

Huttenlocker and his collaborators at the Utah Geological Survey and The University of Chicago named the new species Cifelliodon wahkarmoosuch.

Found in the Cretaceous beds in eastern Utah, the fossil is named in honor of famed paleontologist Richard Cifelli. The species name, "wahkarmoosuch" means "yellow cat" in the Ute tribe's language in respect of the area where it was found.

Scientists used high-resolution computed tomography (CT) scanners to analyze the skull.

"The skull of Cifelliodon is an extremely rare find in a vast fossil-bearing region of the Western Interior, where the more than 150 species of mammals and reptile-like mammal precursors are represented mostly by isolated teeth and jaws," said James Kirkland, study co-author in charge of the excavation and a Utah State paleontologist.

With an estimated body weight of up to 2.5 pounds, Cifelliodon would seem small compared to many living mammals, but it was a giant among its Cretaceous contemporaries. A full-grown Cifelliodon was probably about the size of a small hare or pika (small mammal with rounded ears, short limbs and a very small tail).

It had teeth similar to fruit-eating bats and could nip, shear and crush. It might have incorporated plants into its diet.

The newly named species had a relatively small brain and giant "olfactory bulbs" to process sense of smell. The skull had tiny eye sockets, so the animal probably did not have good eyesight or color vision. It possibly was nocturnal and depended on sense of smell to root out food, Huttenlocker said.

Supercontinent existed longer than previously thought

Huttenlocker and his colleagues placed Cifelliodon within a group called Haramiyida, an extinct branch of mammal ancestors related to true mammals. The fossil was the first of its particular subgroup -- Hahnodontidae -- found in North America.

The fossil discovery emphasizes that haramiyidans and some other vertebrate groups existed globally during the Jurassic-Cretaceous transition, meaning the corridors for migration via Pangean landmasses remained intact into the Early Cretaceous.

Most of the Jurassic and Cretaceous fossils of haramiyidans are from the Triassic and Jurassic of Europe, Greenland and Asia. Hahnodontidae was previously known only from the Cretaceous of Northern Africa. It is to this group that Huttenlocker argues Cifelliodon belongs, providing evidence of migration routes between the continents that are now separated in northern and southern hemispheres.

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Lightening up dark galaxies

One of the new dark-galaxy candidates, identified through a combination of spectral information (left) and images reflecting the emission of gas (middle) and stars (right). The position of the dark-galaxy candidate is marked by the red circle.

Despite substantial progress over the past half a century in understanding of how galaxies form, important open questions remain regarding how precisely the diffuse gas known as the 'intergalactic medium' is converted into stars. One possibility, suggested in recent theoretical models, is that the early phase of galaxy formation involves an epoch when galaxies contain a great amount of gas but are still inefficient at forming stars. Direct proof of such a 'Dark Phase' has been so far elusive, however -- after all, dark galaxies do not emit much visible light. The observational discovery of such galaxies would therefore fill an important gap in our understanding of galaxy evolution.

There are ways to bring dark galaxies to lighten up though. An international team led by Dr. Raffaella Anna Marino and Prof. Sebastiano Cantalupo from the Department of Physics at ETH Zurich has now done just that and thus was able to search the sky for potential dark galaxies with unprecedented efficiency. And successfully so, as they report in a paper published today in The Astrophysical Journal: they have identified at least six strong candidates for dark galaxies.

To overcome the obstacle that their target objects are dark, the team used a flashlight of sorts, which came in the form of quasars. These emit intense ultraviolet light, which in turn induces fluorescent emission in hydrogen atoms known as the Lyman-alpha line. As a result, the signal from any dark galaxies in the vicinity of the quasar gets a boost, making them visible. Such 'fluorescent illumination' has been used before in searches for dark galaxies, but Marino et al. now looked at the neighbourhood of quasars at greater distances than has been possible in earlier observations.

Also, they acquired the full spectral information for each of the dark-galaxy candidates. Deep observations -- 10 hours for each of the six quasar fields they studied -- enabled Marino and her colleagues to efficiently tell dark-galaxy candidates apart from other sources. From initially 200 Lyman-alpha emitters, half a dozen regions remained that are unlikely to be normal star-forming stellar populations, making them robust candidates for dark galaxies.

The advances in observational capability have become possible thanks to the Multi Unit Spectroscopic Explorer (MUSE) instrument at the Very Large Telescope (VLT) of the European Southern Observatory (ESO) in Chile. In essence, previous studies were limited to imaging a relative narrow band of frequencies, for which specific filters had to be designed. The MUSE instrument instead allowed hunting 'blindly' -- without filters -- for dark galaxies around quasars at larger distances from Earth than had been possible so far.

From Science Daily

Birds from different species recognize each other and cooperate

This is a splendid fairy-wren.

Cooperation among different species of birds is common. Some birds build their nests near those of larger, more aggressive species to deter predators, and flocks of mixed species forage for food and defend territories together in alliances that can last for years. In most cases, though, these partnerships are not between specific individuals of the other species -- any bird from the other species will do.

But in a new study published in the journal Behavioral Ecology, scientists from the University of Chicago and University of Nebraska show how two different species of Australian fairy-wrens not only recognize individual birds from other species, but also form long-term partnerships that help them forage and defend their shared space as a group.

"Finding that these two species associate was not surprising, as mixed species flocks of birds are observed all over the world," said Allison Johnson, PhD, a postdoctoral scholar at the University of Nebraska who conducted the study as part of her dissertation research at UChicago. "But when we realized they were sharing territories with specific individuals and responding aggressively only to unknown individuals, we knew this was really unique. It completely changed our research and we knew we had to investigate it."

Variegated fairy-wrens and splendid fairy-wrens are two small songbirds that live in Australia. The males of each species have striking, bright blue feathers that make them popular with bird watchers. Their behavior also makes them an appealing subject for biologists. Both species feed on insects, live in large family groups, and breed during the same time of year. They are also non-migratory, meaning they live in one area for their entire lives, occupying the same eucalyptus scrublands that provide plenty of bushes and trees for cover.

When these territories overlap, the two species interact with each other. They forage together, travel together, and seem to be aware of what the other species is doing. They also help each other defend their territory from rivals. Variegated fairy-wrens will defend their shared territory from both variegated and splendid outsiders; splendid fairy-wrens will do the same, while fending off unfamiliar birds from both species.

"Splendid and variegated fairy-wrens are so similar in their habitat preferences and behavior, we would expect them to act as competitors. Instead, we've found stable, positive relationships between individuals of the two species," said Christina Masco, PhD, a graduate student at UChicago and a co-author on the new paper.

Many songbirds can recognize familiar members of their own species on the basis of the unique songs each bird sings. However, in this research the investigators believed this recognition occurred across species. How could they be so certain?

From 2012-2015, Johnson, Masco, and their former advisor, Stephen Pruett-Jones, PhD, associate professor of ecology and evolution at UChicago, studied these species at Brookfield Conservation Park in South Australia. The first unusual observation Johnson made was that when playing a recorded vocalization of one species, the other species would respond and fly in to investigate what was going on.

To follow up on this observation, the researchers monitored both fairy-wren species in the darkness before dawn and captured clear recordings of their signature songs. After sunrise, they broadcast the recorded songs from a speaker to simulate an intrusion by a particular bird into a group's territory. The objective was to see how territory owners reacted to the songs of familiar and unfamiliar members of the other species.

The researchers placed a speaker about 30 meters away from a subject fairy-wren and played the songs of four different individuals: a fairy-wren that occupied the same territory (a co-resident or "friendly" bird), a fairy-wren from an adjacent territory (a neighbor), a fairy-wren from an area five or more territories away (an unknown bird), and a red-capped robin, a common species in the park that doesn't pose a threat to the fairy-wrens (as a control group).

Both splendid and variegated fairy-wrens demonstrated the ability to recognize their co-residents' songs despite the species difference. Socially dominant males of both species responded more aggressively to songs of neighbors and unknown birds of the other fairy-wren species than they did to friendly birds sharing their territory, or to the red-capped robin. When they heard songs from friendly birds, they didn't respond, suggesting they didn't see them as a threat.

By forming and keeping these associations with another species, fairy-wrens can better defend their nests from predators and their territories from rivals. There is also evidence that interacting with the other species has additional benefits besides territorial defense. While the splendid fairy-wrens didn't change their behavior when associating with the other species, the variegated fairy-wrens spent more time foraging, were less vigilant, and had more success raising their young.

Johnson, Masco, and Pruett-Jones believe the fairy-wrens associate with the other species as a form of cooperation. By interacting with other species that share the same territory instead of working against them, these already social species create a larger group to help defend their territory and ward off intruders. In other words, if you can't beat 'em, join 'em.

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Study casts doubt on traditional view of pterosaur flight

This is an image of a reliable reconstruction. Soft tissues like ligaments play a big role in determining a joint's range of motion. But soft tissues rarely fossilize, causing problems for paleontologists trying to reconstruct who extinct creatures may have lived. Now researchers have shown a new method for inferring the extent to which ligaments inhibit joint movement, which could be helpful in reconstructing ancient species.

Most renderings and reconstructions of pterodactyls and other extinct flying reptiles show a flight pose much like that of bats, which fly with their hind limbs splayed wide apart. But a new method for inferring how ancient animals might have moved their joints suggests that pterosaurs probably couldn't strike that pose.

"Most of the work that's being done right now to understand pterosaur flight relies on the assumption that their hips could get into a bat-like pose," said Armita Manafzadeh, a Ph.D. student at Brown University who led the research with Kevin Padian of the University of California, Berkeley. "We think future studies should take into account that this pose was likely impossible, which might change our perspective when we consider the evolution of flight in pterosaurs and dinosaurs."

The research, published in Proceedings of the Royal Society B, is an effort to help paleontologists infer the range of motion of joints in a way that takes into account the soft tissues -- particularly ligaments -- that play key roles in how joints work. Generally, soft tissues don't fossilize, leaving paleontologists to infer joint motion from bones alone. And there aren't many constraints on how that's done, Manafzadeh says. So she wanted to find a way to use present-day animals to test the extent to which ligaments limit joint motion.

It's an idea that started with grocery store chickens, Manafzadeh says.

"If you pick up a raw chicken at the grocery store and move its joints, you'll reach a point where you'll hear a pop," she said. "That's the ligaments snapping. But if I handed you a chicken skeleton without the ligaments, you might think that its joints could do all kinds of crazy things. So the question is, if you were to dig up a fossil chicken, how would you think its joints could move, and how wrong would you be?"

For this latest study, she used not a grocery store chicken, but dead quail. Birds are the closest living relative of extinct pterosaurs and four-winged dinosaurs. After carefully cutting away the muscles surrounding the birds' hip joints, she manipulated the joints while taking x-ray videos. That way, she could determine the exact 3-D positions of the bones in poses where the ligaments prevented further movement.

This technique enabled Manafzadeh to map out the range of motion of the quail hip with ligaments attached, which she could then compare to the range of motion that might have been inferred from bones alone. For the bones-only poses, Manafzadeh used traditional criteria that paleontologists often use -- stopping where the two bones hit each other and when the movement pulled the thigh bone out of its socket.

She found that over 95 percent of the joint positions that seemed plausible with bones alone were actually impossible when ligaments were attached.

The next step was to work out how the range of motion of present-day quail hips might compare to the range of motion for extinct pterosaurs and four-winged dinosaurs.

The assumption has long been that these creatures flew a lot like bats do. That's partly because the wings of pterosaurs were made of skin and supported by an elongated fourth finger, which is somewhat similar to the wings of bats. Bat wings are also connected to their hind limbs, which they splay out widely during flight. Many paleontologists, Manafzadeh says, assume pterosaurs and four-winged dinosaurs did the same. But her study suggests that wasn't possible.

In quail, a bat-like hip pose seemed possible based on bones alone, but outward motion of the thigh bone was inhibited by one particular ligament -- a ligament that's present in a wide variety of birds and other reptiles related to pterosaurs. No evidence, Manafzadeh says, suggests that extinct dinosaurs and pterosaurs wouldn't have had this ligament, too.

And with that ligament attached, this new study suggests that the bat-like pose would be impossible. According to Manafzadeh's work, this pose would require the ligament to stretch 63 percent more than the quail ligament can. That's quite a stretch, she says.

"That's a huge difference that would need to be accounted for before it can be argued that a pterosaur or 'four-winged' dinosaur's hip would be able to get into this bat-like pose," Manafzadeh said. And that, she says, may require a rethinking of the evolution of flight in these animals.

In addition to calling into question traditional ideas about flight in pterosaurs and early birds, the research also provides new ways of assessing joint mobility for any joint of any extinct species by looking at its living relatives.

Read more at Science Daily

Danish Bone Trove Yields Earliest Evidence of Barbarian Battle

A femur, tibia, and fibula are among thousand of bones found on the Jutland peninsula in Denmark, where archaeologists believe an epic battle occurred 2,000 years ago.

Thousands of bones from boys and men likely killed in a ferocious battle 2,000 years ago have been unearthed from a bog in Denmark, researchers said Monday.

Without local written records to explain, or a battlefield to scour for evidence, experts are nevertheless piecing together a story of the Germanic people, often described by the Romans as "barbarians" for their violent nature.

Four pelvic bones strung on a stick were among the remains of at least 82 people found during archaeological excavations at Alken Enge, on Denmark's Jutland peninsula, indicating an organized and ritual clearing of a battlefield, said the report in the Proceedings of the National Academy of Sciences.

The site, which has been studied since 2009, has yielded the earliest discovery of "a large contingent of fighters from a defeated army from the early first century AD," said the PNAS report.

Well preserved

"The bones are extremely well preserved," co-author Mette Løvschal, of the department of archaeology and heritage studies at Aarhus University, told AFP.

"And you can see stuff that you can normally not see in them, like the gnaw marks of animals and you can see the cut marks from sharp weapons. That is highly unusual," she said.

The more than 2,300 human bones were contained in peat and lake sediments over 185 acres (75 hectares) of wetland meadows. Radiocarbon dating put them between 2 BC and 54 AD.

In this era, Roman soldiers were pressing an expansion northward, and around 7 AD, the Romans suffered a massive loss in which tens of thousands of warriors were killed by the Germanic people.

"What they do in the succeeding decades is have these military raids in Germania, basically to punish the barbarians for this huge defeat," said Løvschal. "What we actually think we are seeing here could be the remains of one of those punitive campaigns."

Young and old males

Løvschal said the bones appear to be from a "fairly heterogeneous population," with some as young as 13 to 14, and others as old as 40-60.

The bog is estimated to hold the remains of around 380 men who died from combat injuries.

"They do not seem to have a lot of healed trauma, from experience with previous battles," she said. "They could have had previously very little experience with battle."

Four pelvic bones threaded onto a stick, which are among thousands of bones found at the site of an ancient battle 2,000 years ago.

 The bones show weapon strikes predominantly on the right side, with few injuries around the midsection where the fighters may have been holding shields with their left arms.

Experts think the bodies may have been lying on the battlefield for quite some time, possibly six months to a year, because many bones show signs of being gnawed by dogs or wolves.

They were stripped of their personal belongings before being deposited into the bog.

Questions remain

Many questions remain. Who was involved in the battle? Was it tribe-against-tribe, or Germanic fighters against Roman warriors?

And what is the meaning of stringing pelvic bones on a stick?

"Those four pelvises on a stick could almost point to having connotations to sexual humiliation," said Løvschal. "It seems to have aggressive undertones to it as well. So it has been difficult to say who did it."

Archaeologists could also see another telling change in the landscape after the battle.

Read more at Seeker

Sweet potatoes didn't originate in the Americas as previously thought

A) Modern distribution of the sweet potato family (yellow line) and genus (white line). B) Fossil leaf of Ipomoea meghalayensis. C) Modern leaf of Ipomoea eriocarpa, showing similar size, shape and vein pattern.

Sweet potatoes may seem as American as Thanksgiving, but scientists have long debated whether their plant family originated in the Old or New World. New research by an Indiana University paleobotanist suggests it originated in Asia, and much earlier than previously known.

IU Bloomington emeritus professor David Dilcher and colleagues in India identified 57-milion-year-old leaf fossils from eastern India as being from the morning glory family, which includes sweet potatoes and many other plants. The research suggests the family originated in the late Paleocene epoch in the East Gondwana land mass that became part of Asia.

"I think this will change people's ideas," Dilcher said. "It will be a data point that is picked up and used in other work where researchers are trying to find the time of the evolution of major groups of flowering plants."

Previous fossil evidence had suggested the morning glory family may have originated in North America about 35 million years ago. But molecular analyses had supported the idea that it originated earlier and in the Old World. The new research provides evidence for that conclusion.

The discovery also suggests the morning glory family and the nightshade family, which includes potatoes and tomatoes, diverged earlier than previously thought. Together with the recent, separate discovery of 52-million-year-old nightshade fossils in Argentina, it suggests that morning glories developed in the East and nightshades in the West.

The 17 fossils analyzed in the study are the earliest recorded fossils for both the morning glory family, known as Convolvulaceae, and the order Solanales, which includes morning glories and nightshades. Morning glory fossils are rare because the plants' soft structure was not easily preserved in rocks.

Dilcher's collaborators, Gaurav Srivastava and Rakesh C. Mehrotra of India's Birbal Sahni Institute of Palaeosciences, discovered the fossils in Meghalaya, a state in northeastern India.

The researchers used microscopic analysis of the shape and structure of the leaves, comparing details of the leaf veins and cells with plants in the genus Ipomoea. Using such analysis to examine evolutionary relationships has been a hallmark of Dilcher's paleobotany research career.

The leaves the researchers studied are in the genus Ipomoea, which includes sweet potato but also hundreds of other plants, most of which don't produce food for humans.

"We don't know that these were sweet potatoes," said Dilcher, emeritus professor in the Department of Earth and Atmospheric Sciences and the Department of Biology in the IU Bloomington College of Arts and Sciences. "We can't say there were delicious sweet potatoes there. There may have been, or there may not."

Read more at Science Daily

Michael Jackson's antigravity tilt -- Talent, magic, or a bit of both?

When was the last time you watched a Michael Jackson music video? If your answer is "never" or "not for quite a while," you are really missing a treat. According to Rolling Stone, "No single artist ... shaped, innovated or defined the medium of 'music video' more than Michael Jackson."

Back in the 1980s and early 1990s, MTV had only one format -- music videos -- and that genre really took off when Jackson burst on the scene in 1983 with his musical hit "Billie Jean." Prior to his arrival on MTV, most videos were merely visual promos for artists' songs, and in some cases the visual side of the promos detracted from the music. Michael Jackson, on the other hand, took his incredible music and added story lines, special effects, cinematography, and amazing choreography. He created high-budget brief movies highlighting both music and dance.

And about that dance. . . . Jackson executed dance moves we thought impossible, at the time and even now. Almost every fan tried to dance like him, but very few could pull it off. Some of Jackson's dance moves appear to defy the laws of gravity. In one move featured in his 1987 music video "Smooth Criminal," he pitches forward 45 degrees, with his body straight as a rod and his shoes resting on the stage, and holds the position. That is not how the human body works! How did Michael Jackson do it? Was it talent, magic, or both?

Three neurosurgeons from the Postgraduate Institute of Medical Education and Research in Chandigarh, India -- Nishant S. Yagnick, Manjul Tripathi, and Sandeep Mohindra -- set out to examine the antigravity tilt introduced in "Smooth Criminal" from a neurosurgeon's point of view.

First, Yagnick et al. walk us through some basics of spinal biomechanics to show just how impressive is the feat. Even the strongest of dancers can only maintain a 25- to 30-degree forward tilt from the ankle.

Admitted fans of Jackson, the neurosurgeons document how the antigravity tilt was accomplished, taking into account the talent and core strength of the artist, as well as his inventiveness and use of a patented aid, that together seem to move his body past human limits. They also warn other neurosurgeons of new forms of spinal injuries, as dancers follow Jackson's example and attempt "to jump higher, stretch further, and turn faster than ever before."

The full story on the antigravity tilt is published today in a new article in the Journal of Neurosurgery entitled "How did Michael Jackson challenge our understanding of spine biomechanics?."

Read the article soon. This is one of those mysteries where the solution is as fascinating as the performance. After you've read the article, you may want to go to YouTube and check out "Smooth Criminal" and other Michael Jackson music videos.

Read more at Science Daily

Hotter bodies fight infections and tumors better -- researchers show how

Slight rise in temperature and inflammation - such as a fever - speeds up cellular 'clock' in which proteins switch genes on and off to respond to infection.

The hotter our body temperature, the more our bodies speed up a key defence system that fights against tumours, wounds or infections, new research by a multidisciplinary team of mathematicians and biologists from the Universities of Warwick and Manchester has found.

The researchers have demonstrated that small rises in temperature (such as during a fever) speed up the speed of a cellular 'clock' that controls the response to infections -- and this new understanding could lead to more effective and fast-working drugs which target a key protein involved in this process.

Biologists found that inflammatory signals activate 'Nuclear Factor kappa B' (NF-κB) proteins to start a 'clock' ticking, in which NF-κB proteins move backwards and forwards into and out of the cell nucleus, where they switch genes on and off.

This allows cells to respond to a tumour, wound or infection. When NF-κB is uncontrolled, it is associated with inflammatory diseases, such as Crohn's disease, psoriasis and rheumatoid arthritis.

At a body temperature of 34 degrees, the NF-κB clock slows down. At higher temperatures than the normal 37 degree body temperature (such as in fever, 40 degrees), the NF-κB clock speeds up.

Mathematicians at the University of Warwick's Systems Biology Centre calculated how temperature increases make the cycle speed up.

They predicted that a protein called A20 -- which is essential to avoid inflammatory disease -- might be critically involved in this process. The experimentalists then removed A20 from cells and found that the NF-kB clock lost its sensitivity to increases in temperature.

Lead mathematician Professor David Rand, Professor of Mathematics and a member of the University of Warwick's Zeeman Institute for Systems Biology and Infectious Disease Epidemiology (SBIDER), explained that in normal life the 24 hour body clock controls small (1.5 degree) changes in body temperature.

He commented: "the lower body temperature during sleep might provide a fascinating explanation into how shift work, jet lag or sleep disorders cause increased inflammatory disease"

Mathematician Dan Woodcock from the University of Warwick said: "this is a good example of how mathematical modelling of cells can lead to useful new biological understanding."

While the activities of many NF-kB controlled genes were not affected by temperature, a key group of genes showed altered profiles at the different temperatures. These temperature sensitive genes included key inflammatory regulators and controllers of cell communication that can alter cell responses.

This study shows that temperature changes inflammation in cells and tissues in a biologically organised way and suggests that new drugs might more precisely change the inflammatory response by targeting the A20 protein.

Read more at Science Daily

Major fossil study sheds new light on emergence of early animal life 540 million years ago

These are exceptionally preserved soft-bodied fossils of the Cambrian predator and stem-lineage euarthropod Anomalocaris canadensis from the Burgess Shale, Canada. Top left: Frontal appendage showing segmentation similar to modern-day euarthropods. Bottom right: Full body specimen showing one pair of frontal appendages (white arrows) and mouthparts consisting of plates with teeth (black arrow) on the head.

All the major groups of animals appear in the fossil record for the first time around 540-500 million years ago -- an event known as the Cambrian Explosion -- but new research from the University of Oxford in collaboration with the University of Lausanne suggests that for most animals this 'explosion' was in fact a more gradual process.

The Cambrian Explosion produced the largest and most diverse grouping of animals the Earth has ever seen: the euarthropods. Euarthropoda contains the insects, crustaceans, spiders, trilobites, and a huge diversity of other animal forms alive and extinct. They comprise over 80 percent of all animal species on the planet and are key components of all of Earth's ecosystems, making them the most important group since the dawn of animals over 500 million years ago.

A team based at Oxford University Museum of Natural History and the University of Lausanne carried out the most comprehensive analysis ever made of early fossil euarthropods from every different possible type of fossil preservation. In an article published today in the Proceedings of the National Academy of Sciences they show that, taken together, the total fossil record shows a gradual radiation of euarthropods during the early Cambrian, 540-500 million years ago.

The new analysis presents a challenge to the two major competing hypotheses about early animal evolution. The first of these suggests a slow, gradual evolution of euarthropods starting 650-600 million years ago, which had been consistent with earlier molecular dating estimates of their origin. The other hypothesis claims the nearly instantaneous appearance of euarthropods 540 million years ago because of highly elevated rates of evolution.

The new research suggests a middle-ground between these two hypotheses, with the origin of euarthropods no earlier than 550 million years ago, corresponding with more recent molecular dating estimates, and with the subsequent diversification taking place over the next 40 million years.

"Each of the major types of fossil evidence has its limitation and they are incomplete in different ways, but when taken together they are mutually illuminating and allow a coherent picture to emerge of the origin and radiation of the euarthropods during the lower to middle Cambrian," explains Professor Allison Daley, who carried out the work at Oxford University Museum of Natural History and at the University of Lausanne. "This indicates that the Cambrian Explosion, rather than being a sudden event, unfolded gradually over the ~40 million years of the lower to middle Cambrian."

The timing of the origin of Euarthropoda is very important as it affects how we view and interpret the evolution of the group. By working out which groups developed first we can trace the evolution of physical characteristics, such as limbs.

It has been argued that the absence of euarthropods from the Precambrian Period, earlier than around 540 million years ago, is the result of a lack of fossil preservation. But the new comprehensive fossil study suggests that this isn't the case.

"The idea that arthropods are missing from the Precambrian fossil record because of biases in how fossils are preserved can now be rejected," says Dr Greg Edgecombe FRS from the Natural History Museum, London, who was not involved in the study. "The authors make a very compelling case that the late Precambrian and Cambrian are in fact very similar in terms of how fossils preserve. There is really just one plausible explanation -- arthropods hadn't yet evolved."

Read more at Science Daily

Lightning in the eyewall of a hurricane beamed antimatter toward the ground

Hurricane Patricia was the most intense tropical cyclone ever recorded in the Western Hemisphere as it approached the west coast of Mexico in 2015. Researchers detected a reverse positron beam from a terrestrial gamma-ray flash associated with lightning in the eyewall of the hurricane.

Hurricane Patricia, which battered the west coast of Mexico in 2015, was the most intense tropical cyclone ever recorded in the Western Hemisphere. Amid the extreme violence of the storm, scientists observed something new: a downward beam of positrons, the antimatter counterpart of electrons, creating a burst of powerful gamma-rays and x-rays.

Detected by an instrument aboard NOAA's Hurricane Hunter aircraft, which flew through the eyewall of the storm at its peak intensity, the positron beam was not a surprise to the UC Santa Cruz scientists who built the instrument. But it was the first time anyone has observed this phenomenon.

According to David Smith, a professor of physics at UC Santa Cruz, the positron beam was the downward component of an upward terrestrial gamma-ray flash that sent a short blast of radiation into space above the storm. Terrestrial gamma-ray flashes (TGFs) were first seen in 1994 by space-based gamma-ray detectors. They occur in conjunction with lightning and have now been observed thousands of times by orbiting satellites. A reverse positron beam was predicted by theoretical models of TGFs, but had never been detected.

"This is the first confirmation of that theoretical prediction, and it shows that TGFs are piercing the atmosphere from top to bottom with high-energy radiation," Smith said. "This event could have been detected from space, like almost all the other reported TGFs, as an upward beam caused by an avalanche of electrons. We saw it from below because of a beam of antimatter (positrons) sent in the opposite direction."

One unexpected implication of the study, published May 17 in the Journal of Geophysical Research: Atmospheres, is that many TGFs could be detected via the reverse positron beam using ground-based instruments at high altitudes. It's not necessary to fly into the eye of a hurricane.

"We detected it at an altitude of 2.5 kilometers, and I estimated our detectors could have seen it down to 1.5 kilometers. That's the altitude of Denver, so there are a lot of places where you could in theory see them if you had an instrument in the right place at the right time during a thunderstorm," Smith said.

Despite the confirmation of the reverse positron beam, many questions remain unresolved about the mechanisms that drive TGFs. Strong electric fields in thunderstorms can accelerate electrons to near the speed of light, and these "relativistic" electrons emit gamma-rays when they scatter off of atoms in the atmosphere. The electrons can also knock other electrons off of atoms and accelerate them to high energies, creating an avalanche of relativistic electrons. A TGF, which is an extremely bright flash of gamma-rays, requires a large number of avalanches of relativistic electrons.

"It's an extraordinary event, and we still don't understand how it gets so bright," Smith said.

The source of the positrons, however, is a well known phenomenon in physics called pair production, in which a gamma ray interacts with the nucleus of an atom to create an electron and a positron. Since they have opposite charges, they are accelerated in opposite directions by the electric field of the thunderstorm. The downward moving positrons produce x-rays and gamma-rays in their direction of travel when they collide with atomic nuclei, just like the upward moving electrons.

"What we saw in the aircraft are the gamma-rays produced by the downward positron beam," Smith said.

First author Gregory Bowers, now at Los Alamos National Laboratory, and coauthor Nicole Kelley, now at Swift Navigation, were both graduate students at UC Santa Cruz when they worked together on the instrument that made the detection. The Airborne Detector for Energetic Lightning Emissions (ADELE) mark II was designed to observe TGFs up close by measuring x-rays and gamma-rays from aircraft flown into or above thunderstorms.

Getting too close to a TGF could be hazardous, although the risk drops off rapidly with distance from the source. The gamma-ray dose at a distance of one kilometer would be negligible, Smith said. "It's hypothetically a risk, but the odds are quite small," he said. "I don't ask pilots to fly into thunderstorms, but if they're going anyway I'll put an instrument on board."

Read more at Science Daily

Giant Chinese salamander is at least five distinct species, all heading toward extinction

This photograph shows one living Chinese giant salamander from Guangxi Province.

With individuals weighing in at more than 140 pounds, the critically endangered Chinese giant salamander is well known as the world's largest amphibian. But researchers reporting in the journal Current Biology on May 21 now find that those giant salamanders aren't one species, but five, and possibly as many as eight. The bad news as highlighted by another report appearing in the same issue is that all of the salamanders -- once thought to occur widely across China -- now face the imminent threat of extinction in the wild, due in no small part to demand for the amphibians as luxury food.

The discoveries highlight the importance of genetic assessments to properly identify the salamanders, the researchers say. It also suggests that the farming and release of giant salamanders back into the wild without any regard for their genetic differences is putting the salamanders' already dire future at even greater risk. In fact, some of the five newly identified species may already be extinct in the wild.

"We were not surprised to discover more than one species, as an earlier study suggested, but the extent of diversity -- perhaps up to eight species -- uncovered by the analyses sat us back in our chairs," says Jing Che from the Kunming Institute of Zoology, Chinese Academy of Sciences. "This was not expected."

"The overexploitation of these incredible animals for human consumption has had a catastrophic effect on their numbers in the wild over an amazingly short time span," adds Samuel Turvey, from ZSL (Zoological Society of London. "Unless coordinated conservation measures are put in place as a matter of urgency, the future of the world's largest amphibian is in serious jeopardy."

The researchers were surprised to learn just how much movement of salamanders has already occurred due to human intervention. Salamander farms have sought to "maximize variation" by exchanging salamanders from distant areas, without realizing they are in fact distinct species, Che explains. As a result, she says, wild populations may now be at risk of becoming locally maladapted due to hybridization across species boundaries.

The researchers including Ya-Ping Zhang and Robert Murphy suspected Chinese giant salamanders might represent distinct species despite their similar appearances. That's because the salamanders inhabit three primary rivers in China, and several smaller ones, they explain. Each runs independently to sea.

Given that giant salamanders can't move across the land, they suspected that salamanders living in different river systems might have had opportunity to diverge over time into what should now be recognized as distinct species. And, indeed, that's exactly what the genetic evidence now suggests.

In the second study, Turvey and colleagues conducted field surveys and interviews from 2013 and 2016, in an effort that was possibly the largest wildlife survey ever conducted in China. The data revealed that populations of this once-widespread species are now critically depleted or extirpated across all surveyed areas of their range, and illegal poaching is widespread. The researchers were unable to confirm survival of wild salamanders at any survey site.

While the harvesting of wild salamanders is already prohibited, the findings show that farming practices and existing conservation activities that treat all salamander populations as a single species are potentially doing great damage, the researchers say.

"Conservation strategies for the Chinese giant salamander require urgent updating," Che says. She says it is especially critical to reconsider the design of reserves to protect the salamanders and an effort that has already released thousands of farm-started baby salamanders back into the wild.

Read more at Science Daily

First interstellar immigrant discovered in the solar system

This is an image of stellar nursery NGC 604 (NASA/HST), where star systems are closely packed and asteroid exchange is thought to be possible. Asteroid (514107) 2015 BZ 509 emigrated from its parent star and settled around the Sun in a similar environment.

A new study has discovered the first known permanent immigrant to our Solar System. The asteroid, currently nestling in Jupiter's orbit, is the first known asteroid to have been captured from another star system. The work is published in Monthly Notices of the Royal Astronomical Society: Letters.

The object known as 'Oumuamua was the last interstellar interloper to hit the headlines in 2017. However it was just a tourist passing through, whereas this former exo-asteroid - given the catchy name (514107) 2015 BZ509 - is a long-term resident.

All of the planets in our Solar System, and the vast majority of other objects as well, travel around the Sun in the same direction. However 2015 BZ509 is different - it moves in the opposite direction in what is known as a 'retrograde' orbit.

"How the asteroid came to move in this way while sharing Jupiter's orbit has until now been a mystery," explains Dr Fathi Namouni, lead author of the study. "If 2015 BZ509 were a native of our system, it should have had the same original direction as all of the other planets and asteroids, inherited from the cloud of gas and dust that formed them."

However the team ran simulations to trace the location of 2015 BZ509 right back to the birth of our Solar System, 4.5 billion years ago when the era of planet formation ended. These show that 2015 BZ509 has always moved in this way, and so could not have been there originally and must have been captured from another system.

"Asteroid immigration from other star systems occurs because the Sun initially formed in a tightly-packed star cluster, where every star had its own system of planets and asteroids," comments Dr Helena Morais, the other member of the team.

"The close proximity of the stars, aided by the gravitational forces of the planets, help these systems attract, remove and capture asteroids from one another."

The discovery of the first permanent asteroid immigrant in the Solar System has important implications for the open problems of planet formation, solar system evolution, and possibly the origin of life itself.

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Genome structure of dinosaurs discovered by bird-turtle comparisons

This is an Apalone spinifera spiny softshell turtle hatchling.

A discovery by scientists at the University of Kent has provided significant insight into the overall genome structure of dinosaurs.

By comparing the genomes of different species, chiefly birds and turtles, the Kent team were able to determine how the overall genome structure (i.e. the chromosomes) of many people's favourite dinosaur species -- like Velociraptor or Tyrannosaurus -- might have looked through a microscope.

The research was carried out in the laboratory of Professor Darren Griffin, of the University's School of Biosciences, and is now published in the journal Nature Communications. It involved extrapolating the likely genome structure of a shared common ancestor of birds and turtles that lived around 260 million years ago -- 20 million years before the dinosaurs first emerged.

Dr Becky O'Connor, senior postdoctoral researcher and co-author of the Nature Communications paper, then traced how chromosomes changed over evolutionary time from a reptile ancestor to the present day.

The team found that, although the individual chromosomes rearranged their genes internally, this did not occur much at all between the chromosomes -- what the scientists describe as 'a significant discovery'.

Birds (which are themselves living dinosaurs) have a lot of chromosomes compared to most other species and that is possibly one of the reasons why they are so diverse. This research suggests that the pattern of chromosomes (karyotype) seen in early emerging dinosaurs and later theropods is similar to that of most birds and, again, may help explain their great diversity.

The new discovery suggests that, had scientists had the opportunity to make a chromosome preparation from a theropod dinosaur, it might have looked very similar to that of a modern-day ostrich, duck or chicken.

One of the key pieces of biotechnology that made it possible was the development of a set of fluorescent probes derived from birds that worked well on the chromosomes of turtles.

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Annotation tool provides step toward understanding links between disease, mutant RNA

bpRNA.

Researchers at Oregon State University have developed a computer program that represents a key step toward better understanding the connections between mutant genetic material and disease.

Known as bpRNA, the software is a big-data annotation tool for secondary structures in ribonucleic acids.

"It's capable of parsing RNA structures, including complex pseudoknot-containing RNAs, so you end up with an objective, precise, easily-interpretable description of all loops, stems and pseudoknots," said corresponding author David Hendrix. "You also get the positions, sequence and flanking base pairs of each structural feature, which enables us to study RNA structure en masse at a large scale."

RNA works with DNA, the other nucleic acid -- so named because they were first discovered in the cell nuclei of living things -- to produce the proteins needed throughout the body. DNA contains a person's hereditary information, and RNA delivers the information's coded instructions to the protein-manufacturing sites within the cells. Many RNA molecules do not encode a protein, and these are known as noncoding RNAs.

"There are plenty of examples of disease-associated mutations in noncoding RNAs that probably affect their structure, and in order to statistically analyze why those mutations are linked to disease we have to automate the analysis of RNA structure," said Hendrix, assistant professor of biochemistry and biophysics in the College of Science. "RNA is one of the fundamental, essential molecules for life, and we need to understand RNAs' structure to understand how they function."

Secondary structures are the base-pairing interactions within a single nucleic acid polymer or between two polymers. DNA has mainly fully base-paired double helices, but RNA is single stranded and can form complicated interactions.

Hendrix says bpRNA, presented this month in a paper in Nucleic Acids Research, features the largest and most detailed database to date of secondary RNA structures.

"To be fair it's a meta-database, but our special sauce is the tool to annotate everything," said Hendrix, who is also an assistant professor in the OSU College of Engineering. "Before there was no way of saying where all the structural features were in an automated way. We provide a color-coded map of where everything is. These annotations will enable us to identify statistical trends that may shed light on RNA structure formation and may open the door for machine learning algorithms to predict secondary RNA structure in ways that haven't been possible."

Researchers have successfully tested the tool on more than 100,000 structures, "many of which are very complex, with lots of complex pseudoknots."

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A new map for a birthplace of stars

Gas in the Orion A cloud star-forming region. Each of the three colors (red, green and blue) represents a different velocity range.

A Yale-led research group has created the most detailed maps yet of a vast seedbed of stars similar to Earth's Sun.

The maps provide unprecedented detail of the structure of the Orion A molecular cloud, the closest star-forming region of high-mass stars. Orion A hosts a variety of star-forming environments, including dense star clusters similar to the one where Earth's Sun is believed to have formed.

"Our maps probe a wide range of physical scales needed to study how stars form in molecular clouds, and how young stars impact their parent cloud," said Yale postdoctoral associate Shuo Kong, first author of a study about the group's research that appears in the Astrophysical Journal Supplement.

The research team includes astronomers from institutions in the U.S., Chile, Japan, France, Germany, Spain, and the U.K. The team's principal investigators are Yale astronomy professor Héctor G. Arce, ALMA Observatory scientist John Carpenter, and Caltech astronomy professor Anneila Sargent.

Kong said the team constructed its maps of the Orion A cloud by combining data from a single-dish telescope and an interferometer. The Yale Center for Research Computing assisted in handling the large dataset and producing the images.

The dataset and maps are collectively known as the CARMA-NRO Orion Survey. The name refers to the Combined Array for Research in Millimeter Astronomy (CARMA), an interferometer that was located in California, and the Nobeyama Radio Observatory (NRO) telescope, in Japan.

"Our survey is a unique combination of data from two very different telescopes," said Yale graduate student Jesse Feddersen, a co-author of the study. "We have combined the zoom of CARMA with the wide-angle of NRO to simultaneously capture the details of individual forming stars and the overall shape and motions of the giant molecular cloud."

In addition, the maps will help researchers calibrate star formation models for extragalactic studies. "The data we provide here will benefit research on a broad range of evolutionary stages of the star formation process and on the environment stars form," Arce said.

Yale graduate student María José Maureira is also a co-author of the study.

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