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Scientists study a 46,000-year-old bird found in Siberia – CNET

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The carcass of a bird that flew the Earth 46,000 years ago has been discovered in Siberia and determined to be an ancient horned lark. The bird, which was exceptionally preserved in the permafrost in the Belaya Gora area of north-eastern Siberia, is helping scientists understand the evolution of larks, which can help determine past climate events. The discovery, reported earlier by CNN, was published in an article in the Communications Biology journal on Friday.

Around 50mg of the bird tissue was used for DNA extraction and genome sequencing, finding a 100% match with the horned lark. The bird hails from the Pleistocene period, which took place between 2.6 million to 11,700 years ago.

“Pleistocene tissue remains recovered from permafrost … have the potential to become instrumental in better understanding processes such as biological regulation and gene expression in relation to past climate change,” the authors said.

The frozen bird was radiocarbon dated to an age of between 44,163 and 48,752 years. Finding an entire frozen carcass provides more opportunities for testing than skeletal remains do.

“For instance, molecular identification of the sex of animal remains … allows for investigations into the behavioural ecology of extinct species,” the journal article said. “[And] sequencing of mitochondrial or nuclear genomes can enable studies of temporal range shifts associated with past climatic fluctuations.”

The authors are from a range of institutions across the world, including the Swedish Museum of Natural History, Stockholm University, Lund University, University of Maine, University of Michigan, The Academy of Science of the Sakha Republic and the Natural History Museum in London.

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NASA astronauts replace faulty space station antenna during spacewalk – Financial Post

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Two NASA astronauts completed a 6-1/2 hour spacewalk on Thursday to replace a faulty antenna on the International Space Station, a mission NASA said carried slightly higher risk posed by orbital debris left from a Russian missile test weeks ago.

Astronauts Thomas Marshburn and Kayla Barron exited an airlock of the orbiting research lab some 250 miles (400 km) above Earth to begin their work at 6:15 a.m. Eastern time (1115 GMT), an hour ahead of schedule.

The “extra-vehicular activity” (EVA) followed a 48-hour delay prompted by a separate orbital debris alert – believed to be the first such postponement in more than two decades of space station history – which NASA later deemed inconsequential.

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The origin of the newly detected debris was left unclear by NASA. A spokesperson said there was no indication it came from fragments of the defunct satellite that Russia blew to pieces https://www.reuters.com/world/us-military-reports-debris-generating-event-outer-space-2021-11-15 with a missile test last month.

Thursday’s outing was the fifth spacewalk for Marshburn, 61, a medical doctor and former flight surgeon with two previous trips to orbit, and a first for Barron, 34, a U.S. Navy submarine officer and nuclear engineer on her debut spaceflight for NASA.

“It was awesome,” Barron told Marshburn afterward.

During the spacewalk, they removed a defective S-band radio communications antenna assembly, now more than 20 years old, and replaced it with a spare stowed outside the space station.

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The space station is equipped with other antennae that can perform the same functions, but installing a replacement system ensures an ideal level of communications redundancy, NASA said.

Marshburn worked with Barron while positioned at the end of a robotic arm maneuvered from inside by German astronaut Matthias Maurer of the European Space Agency, with help from NASA crewmate Raja Chari.

The four arrived at the space station Nov. 11 in a SpaceX Crew Dragon capsule launched from the Kennedy Space Center in Florida, joining two Russian cosmonauts and a NASA astronaut, Mark Vande Hei, already aboard the orbiting outpost.

Four days later, an anti-satellite missile test conducted without warning by Russia generated a debris field in low-Earth orbit, forcing the seven ISS crew members to take shelter in their docked spaceships to allow for a quick getaway until the immediate danger passed, NASA said.

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The residual cloud of debris from the blasted satellite has dispersed since then, according to Dana Weigel, NASA deputy manager of the ISS program.

NASA has calculated that remaining fragments continue to pose a “slightly elevated” background risk to the space station as a whole, and a 7% higher risk of puncturing spacewalkers’ suits, as compared to before Russia’s missile test, Weigel told reporters on Monday.

NASA determined those risk levels fall within an acceptable range and moved ahead with preparations for a spacewalk on Tuesday as originally planned, only for mission control to delay the EVA mission hours before it was to start.

The operation was postponed after NASA received notice from U.S. military space trackers warning of a newly detected debris-collision threat. NASA concluded later there was no risk to spacewalkers or the station after all, and the antenna replacement was rescheduled for Thursday morning.

Thursday’s exercise marked the 245th spacewalk in support of assembly and upkeep of the space station, and the first on record delayed due to a debris alert, NASA spokesperson Gary Jordan said. (Reporting by Steve Gorman in Los Angeles and Brendan O’Brien in Chicago; Editing by Angus MacSwan and Rosalba O’Brien)

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Global extinction event led to evolution of weapon-like teeth in marine reptiles – India Today

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The discovery of a new fossil from central Colombia could shed light on the evolution of marine reptiles. The well preserved metre-long skull discovered by researchers from Canada, Colombia, and Germany is one of the last surviving ichthyosaurs — ancient animals that look like living swordfish.

The marine animal has been named Kyhytysuka, which translates to “the one that cuts with something sharp” in an indigenous language from the region in central Colombia where the fossil was found.

The animal shows the evolution of a unique arsenal of teeth to devour its prey against other ichthyosaurs that had small, equally sized teeth for feeding on small prey. The study of the marine fossil published in the Journal of Systematic Palaeontology states that the discovery has helped in a better understanding of the anatomy of the marine reptile.

Hans Larsson, Director of the Redpath Museum at McGill University and a lead author of the study said that the animal evolved a unique dentition that allowed it to eat large prey. “Whereas other ichthyosaurs had small, equally sized teeth for feeding on small prey, this new species modified its tooth sizes and spacing to build an arsenal of teeth for dispatching large prey, like big fishes and other marine reptiles,” he added.

Skeleton of Kyhytysuka compared to a human for scale. Known bones are shown in white. Credit: (Photo: Dirley Cortés)

Researchers said that they decided to name it Kyhytysuka, to honour the ancient Muisca culture that existed in the region where the fossil was found.

In a bid to clarify the evolution of the unique animal, researchers compared it with other Jurassic and Cretaceous ichthyosaurs and defined a new type of ichthyosaur. They concluded that the species comes from an important transitional time during the Early Cretaceous period when the Earth was coming out of a relatively cool period, had rising sea levels, and the supercontinent Pangea was splitting into northern and southern landmasses.

In a release by McGill University, researchers said that there was also a global extinction event at the end of the Jurassic that changed marine and terrestrial ecosystems.

Dirley Cortés working with the skull of Kyhytysuka. (Photo: Dirley Cortés)

“We are discovering many new species in the rocks this new ichthyosaur comes from. We are testing the idea that this region and time in Colombia was an ancient biodiversity hotspot and are using the fossils to better understand the evolution of marine ecosystems during this transitional time,” Dirley Cortés, a graduate student under the supervision of Hans Larsson and Carlos Jaramillo of the Smithsonian Tropical Research Institute said.

Researchers concluded that the new discovery shakes up the evolutionary tree of ichthyosaurs and “lets us test new ideas of how they evolved.”

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Why increased rainfall in the Arctic is bad news for the whole world? – The Tribune

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Loughborough (UK), Dec 2

Before the end of this century, most of the Arctic will for the first time receive more rain than snow across a whole year. That’s one of the key findings of a new study on precipitation in the Arctic which has major implications – not just for the polar region, but for the whole world.

While a reduction in frozen ocean surface is one of the most widely recognised impacts of Arctic warming, it has also long been anticipated that a warmer Arctic will be a wetter one too, with more intense cycling of water between land, atmosphere and ocean.

The shift from a frozen region towards a warmer, wetter Arctic is driven by the capacity of a warmer atmosphere to hold more moisture, by increased rates of evaporation from ice-free oceans, and by the jet stream relaxing.

The Arctic water cycle is expected to shift from a snow-dominated one towards a rain-dominated one during the 21st century, although the timing of this is uncertain. Now, a team of scientists have published a study in the journal Nature Communications which suggests that this shift will occur earlier than previously projected.

The effect will be particularly strong in autumn, with most of the Arctic Ocean, Siberia and the Canadian Archipelago becoming rain-dominated by the 2070s instead of the 2090s.

Warmer and wetter isn’t necessarily better

Such a profound change to the Arctic water cycle will inevitably affect ecosystems on land and in the ocean. You might intuitively expect that a warmer and wetter Arctic would be very favourable for ecosystems – rainforests have many more species than tundra, after all. But the plants and animals of the Arctic have evolved for cold conditions over millions of years, and their relatively simple food web is vulnerable to disturbance.

For example, warmer temperatures can cause larval insects to emerge earlier, before the fish species that feed upon them have hatched. More rainfall means more nutrients washed into rivers, which should benefit the microscopic plants at the base of the food chain.

However, this also makes rivers and coastal waters more murky, blocking light needed for photosynthesis and potentially clogging filter-feeding animals, including some whales or sharks. Brackish water typically supports fewer species than either freshwater or seawater, so increasing flows of freshwater offshore may well reduce the range of animals and plants along Arctic coasts.

Further into the Arctic Ocean, there are more reasons to doubt the potential benefits of warmer temperatures and greater freshwater circulation. The dissolved constituents of rainfall, river water and melting snow and ice reduce the alkalinity of Arctic surface waters, which makes it harder for marine organisms to build shells and skeletons, and limits chemical neutralisation of the acidifying effects of CO2 absorbed in seawater.

At the same time, rivers flowing through degrading permafrost will wash organic material into the sea that bacteria can convert to CO2, making the ocean more acidic. Fresh water also essentially floats on denser seawater.

This causes the ocean to become stratified, impeding exchanges of nutrients and organisms between the deep sea and the surface, and restricting biological activity. Therefore the likely impacts of a warmer, wetter Arctic on food webs, biodiversity and food security are uncertain, but are unlikely to be uniformly positive.

Arctic change is decades ahead of global averages

Temperature increases in the Arctic have raced ahead of the global average. This will only be reinforced as snowfall is reduced and rainfall increases, since snow reflects the sun’s energy back into space. As the land becomes less snowy and less reflective, bare ground will absorb more solar energy, and thus will warm up.

The Arctic is set to continue warming faster than elsewhere, further diminishing the difference in temperature between the warmest and coldest parts of the planet, with complex implications for the oceans and atmosphere.

The recent COP26 climate summit in Glasgow focused on efforts to “keep 1.5°C alive”. It is worth remembering that the 1.5°C figure is a global average, and that the Arctic will warm by at least twice as much as this, even for modest projections.

The new study underscores the importance of the global 1.5°C target for the Arctic. For instance, at that level of warming Greenland is expected to transition to a rainfall-dominated climate for most of the year. While at 3°C warming, which is close to the current pathway based on existing policies rather than pledges, most regions of the Arctic will transition to a rainfall-dominated climate before the end of the 21st-century.

It’s research that adds further weight to calls for improved monitoring of Arctic hydrological systems and to the growing awareness of the considerable impacts of even small increments of atmospheric warming. (The Conversation) 

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