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Fossil clues paint vivid picture of dinosaurs' doomsday – CBC News

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An artistic construction shows a seiche wave surging into the Tanis river, bringing in fishes and everything in its path while impact spherules rain down from the sky on the day of the deadly asteroid impact in modern-day Mexico. (Joschua Knüppe)

On a spring day 66 million years ago, paddlefish and sturgeon swam in a river that meandered through a flourishing landscape populated by mighty dinosaurs and small mammals in North Dakota’s southwestern corner.

Death came from above that day.

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Scientists said on Wednesday that well-preserved fish fossils unearthed at the site are providing a deeper understanding of one of the worst days in the history of life on Earth and shedding light on the global calamity triggered by an asteroid 12 kilometres wide striking Mexico’s Yucatan Peninsula.

The ensuing mass extinction erased about three-quarters of Earth’s species, including the dinosaurs at the end of the Cretaceous Period, paving the way for mammals — eventually including humans — to become dominant.

What happened right after impact

The researchers determined that it was springtime at the fossil site called the Tanis deposit — and throughout the northern hemisphere — based on sophisticated examinations of bones from three paddlefishes and three sturgeons that died within about 30 minutes of the impact that occurred 3,500 kilometres (2,200 miles) away.

Melanie During excavates a paddlefish in the Tanis deposit. Scientists found evidence that a hail of glass pelted the site. Small spherules — molten material blasted by the impact into space that crystallized before falling back to Earth — were embedded in fish gills. (Jackson Leibach)

They found evidence that a hail of glass pelted the site, after finding small spherules — molten material blasted by the impact into space that crystallized before falling back to Earth — embedded in fish gills.

The Tanis fossils also indicated that a huge standing wave of water swept through after the impact, burying the local denizens alive. Among the dinosaurs living in the Tanis area was apex predator Tyrannosaurus rex.

“Every living thing in Tanis on that day saw nothing coming and was killed almost instantaneously,” said Melanie During, a paleontology doctoral student at Uppsala University in Sweden, and lead author of the research published in the journal Nature.

During compared the fossils deposited at Tanis to “a car crash frozen in place.”

How scientists know it was a spring day

Multiple lines of evidence pointed to a springtime impact.

Annual growth rings in certain fish bones — resembling those in tree trunks — showed increased growth levels associated with springtime after reduced growth in leaner winter months. Chemical evidence from one of the paddlefishes indicated that food availability was increasing as it does in springtime, but not at peak summer levels.

Cut sections of bone are embedded in epoxy resin, on glass balls for X-ray fluorescence analysis at the Vrije Universiteit Brussel (VUB) in Belgium. Growth patterns in the bone showed that the asteroid impact occurred in springtime. (Vrije Universiteit Brussel)

Springtime marks a time of growth and reproduction for many organisms.

“This season is crucial for the survival of species,” said study co-author Sophie Sanchez, an Uppsala University senior lecturer in paleohistology.

In the southern hemisphere, it was autumn at the time, Sanchez noted, a season when many creatures prepare for the deprivations of winter.

Dinosaurs — aside from their bird descendants — went extinct, as did major marine groups, including the carnivorous reptiles that dominated the seas. Among the survivors were paddlefishes and sturgeons, which survive to this day.

The Tanis fossils helped the researchers better understand the events following the impact, which left a crater about 180 kilometres (110 miles) wide at a Yucatan site called Chicxulub.

Most extinction caused by climate catastrophe that followed

The asteroid rocked the continental plate, generated earthquakes, sparked extensive wildfires, unleashed a massive shockwave in the air and seismic waves on the ground, and spawned massive standing waves called seiche waves — perhaps hundreds of yards tall — in water bodies.

These waves, carrying immense amounts of sediment and debris, inundated the Tanis site within approximately 15 to 30 minutes after the impact, burying alive all the inhabitants, including the fish whose fossils were studied.

The peril did not end that day. A cloud of dust enrobed Earth, precipitating a climate catastrophe akin to a “nuclear winter” that blocked sunlight for perhaps years, condemning countless species to oblivion.

“Although most of the extinction unfolded during the aftermath of the impact, which lasted much longer, zero hour — the exact timing of the impact — determined the course of the mass extinction,” said study co-author Jeroen van der Lubbe, a geochemist and paleoclimatologist at Vrije Universiteit Amsterdam in the Netherlands.

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Marine plankton could act as alert in mass extinction event: UVic researcher – Langley Advance Times

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A University of Victoria micropaleontologist found that marine plankton may act as an early alert system before a mass extinction occurs.

With help from collaborators at the University of Bristol and Harvard, Andy Fraass’ newest paper in the Nature journal shows that after an analysis of fossil records showed that plankton community structures change before a mass extinction event.

“One of the major findings of the paper was how communities respond to climate events in the past depends on the previous climate,” Fraass said in a news release. “That means that we need to spend a lot more effort understanding recent communities, prior to industrialization. We need to work out what community structure looked like before human-caused climate change, and what has happened since, to do a better job at predicting what will happen in the future.”

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According to the release, the fossil record is the most complete and extensive archive of biological changes available to science and by applying advanced computational analyses to the archive, researchers were able to detail the global community structure of the oceans dating back millions of years.

A key finding of the study was that during the “early eocene climatic optimum,” a geological era with sustained high global temperatures equivalent to today’s worst case global warming scenarios, marine plankton communities moved to higher latitudes and only the most specialized plankton remained near the equator, suggesting that the tropical temperatures prevented higher amounts of biodiversity.

“Considering that three billion people live in the tropics, the lack of biodiversity at higher temperatures is not great news,” paper co-leader Adam Woodhouse said in the release.

Next, the team plans to apply similar research methods to other marine plankton groups.

Read More: Global study, UVic researcher analyze how mammals responded during pandemic

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Scientists Say They Have Found New Evidence Of An Unknown Planet… – 2oceansvibe News

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In the new work, scientists looked at a set of trans-Neptunian objects, or TNOs, which is the technical term for those objects that sit out at the edge of the solar system, beyond Neptune

The new work looked at those objects that have their movement made unstable because they interact with the orbit of Neptune. That instability meant they were harder to understand, so typically astronomers looking at a possible Planet Nine have avoided using them in their analysis.

Researchers instead looked towards those objects and tried to understand their movements. And, Dr Bogytin claimed, the best explanation is that they result from another, undiscovered planet.

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The team carried out a host of simulations to understand how those objects’ orbits were affected by a variety of things, including the giant planets around them such as Neptune, the “Galactic tide” that comes from the Milky Way, and passing stars.

The best explanation was from the model that included Planet 9, however, Dr Bogytin said. They noted that there were other explanations for the behaviour of those objects – including the suggestion that other planets once influenced their orbit, but have since been removed – but claim that the theory of Planet 9 remains the best explanation.

A better understanding of the existence or not of Planet 9 will come when the Vera C Rubin Observatory is turned on, the authors note. The observatory is currently being built in Chile, and when it is turned on it will be able to scan the sky to understand the behaviour of those distant objects.

Planet Nine is theorised to have a mass about 10 times that of Earth and orbit about 20 times farther from the Sun on average than Neptune. It may take between 10,000 and 20,000 Earth years to make one full orbit around the Sun.

You may be tempted to ask how an entire planet could ‘hide’ in our solar system when we have zooming capabilities such as the new iPhone 15 has, but consider this: If Earth was the size of a marble, the edge of our solar system would be 11 kilometres away. That’s a lot of space to hide a planet.

[source:independent]

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Dragonfly: NASA Just Confirmed The Most Exciting Space Mission Of Your Lifetime – Forbes

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NASA has confirmed that its exciting Dragonfly mission, which will fly a drone-like craft around Saturn’s largest moon, Titan, will cost $3.35 billion and launch in July 2028.

Titan is the only other world in the solar system other than Earth that has weather and liquid on the surface. It has an atmosphere, rain, lakes, oceans, shorelines, valleys, mountain ridges, mesas and dunes—and possibly the building blocks of life itself. It’s been described as both a utopia and as deranged because of its weird chemistry.

Set to reach Titan in 2034, the Dragonfly mission will last for two years once its lander arrives on the surface. During the mission, a rotorcraft will fly to a new location every Titan day (16 Earth days) to take samples of the giant moon’s prebiotic chemistry. Here’s what else it will do:

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  • Search for chemical biosignatures, past or present, from water-based life to that which might use liquid hydrocarbons.
  • Investigate the moon’s active methane cycle.
  • Explore the prebiotic chemistry in the atmosphere and on the surface.

Spectacular Mission

“Dragonfly is a spectacular science mission with broad community interest, and we are excited to take the next steps on this mission,” said Nicky Fox, associate administrator of the Science Mission Directorate at NASA Headquarters in Washington. “Exploring Titan will push the boundaries of what we can do with rotorcraft outside of Earth.”

It comes in the wake of the Mars Helicopter, nicknamed Ingenuity, which flew 72 times between April 2021 and its final flight in January 2023 despite only being expected to make up to five experimental test flights over 30 days. It just made its final downlink of data this week.

Dense Atmosphere

However, Titan is a completely different environment to Mars. Titan has a dense atmosphere on Titan, which will make buoyancy simple. Gravity on Titan is just 14% of the Earth’s. It sees just 1% of the sunlight received by Earth.

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The atmosphere is 98% nitrogen and 2% methane. Its seas and lakes are not water but liquid ethane and methane. The latter is gas in Titan’s atmosphere, but on its surface, it exists as a liquid in rain, snow, lakes, and ice on its surface.

COVID-Affected

Dragonfly was a victim of the pandemic. Slated to cost $1 billion when it was selected in 2019, it was meant to launch in 2026 and arrive in 2034 after an eight-year cruise phase. However, after delays due to COVID, NASA decided to compensate for the inevitable delayed launch by funding a heavy-lift launch vehicle to massively shorten the mission’s cruise phase.

The end result is that Dragonfly will take off two years later but arrive on schedule.

Previous Visit

Dragonfly won’t be the first time a robotic probe has visited Titan. As part of NASA’s landmark Cassini mission to Saturn between 2004 and 2017, a small probe called Huygens was despatched into Titan’s clouds on January 14, 2005. The resulting timelapse movie of its 2.5 hours descent—which heralded humanity’s first-ever (and only) views of Titan’s surface—is a must-see for space fans. It landed in an area of rounded blocks of ice, but on the way down, it saw ancient dry shorelines reminiscent of Earth as well as rivers of methane.

The announcement by NASA makes July 2028 a month worth circling for space fans, with a long-duration total solar eclipse set for July 22, 2028, in Australia and New Zealand.

Wishing you clear skies and wide eyes.

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