A new study suggests that all living snakes evolved from a handful of species that survived the giant asteroid impact that wiped out the dinosaurs and most other living things at the end of the Cretaceous. The authors say that this devastating extinction event was a form of ‘creative destruction’ that allowed snakes to diversify into new niches, previously filled by their competitors.
The research, published in Nature Communications, shows that snakes, today including almost 4000 living species, started to diversify around the time that an extra-terrestrial impact wiped out the dinosaurs and most other species on the planet.
The study, led by scientists at the University of Bath and including collaborators from Bristol, Cambridge and Germany, used fossils and analyzed genetic differences between modern snakes to reconstruct snake evolution. The analyses helped to pinpoint the time that modern snakes evolved.
Their results show that all living snakes trace back to just a handful of species that survived the asteroid impact 66 million years ago, the same extinction that wiped out the dinosaurs.
The authors argue that the ability of snakes to shelter underground and go for long periods without food helped them survive the destructive effects of the impact. In the aftermath, the extinction of their competitors—including Cretaceous snakes and the dinosaurs themselves—allowed snakes to move into new niches, new habitats and new continents.
Snakes then began to diversify, producing lineages like vipers, cobras, garter snakes, pythons, and boas, exploiting new habitats, and new prey. Modern snake diversity—including tree snakes, sea snakes, venomous vipers and cobras, and huge constrictors like boas and pythons—emerged only after the dinosaur extinction.
Fossils also show a change in the shape of snake vertebrae in the aftermath, resulting from the extinction of Cretaceous lineages and the appearance of new groups, including giant sea snakes up to 10 meters long.
“It’s remarkable, because not only are they surviving an extinction that wipes out so many other animals, but within a few million years they are innovating, using their habitats in new ways,” said lead author and recent Bath graduate Dr. Catherine Klein, who now works at Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) in Germany.
The study also suggests that snakes began to spread across the globe around this time. Although the ancestor of living snakes probably lived somewhere in the Southern Hemisphere, snakes first appear to have spread to Asia after the extinction.
Dr. Nick Longrich, from the Milner Centre for Evolution at the University of Bath and the corresponding author, said: “Our research suggests that extinction acted as a form of ‘creative destruction’- by wiping out old species, it allowed survivors to exploit the gaps in the ecosystem, experimenting with new lifestyles and habitats.
“This seems to be a general feature of evolution—it’s the periods immediately after major extinctions where we see evolution at its most wildly experimental and innovative.
“The destruction of biodiversity makes room for new things to emerge and colonize new landmasses. Ultimately life becomes even more diverse than before.”
The study also found evidence for a second major diversification event around the time that the world shifted from a warm ‘Greenhouse Earth’ into a cold ‘Icehouse’ climate, which saw the formation of polar icecaps and the start of the Ice Ages.
The patterns seen in snakes hint at a key role for catastrophes—severe, rapid, and global environmental disruptions—in driving evolutionary change.
The new study is published in Nature Communications.
Evolution and dispersal of snakes across the Cretaceous-Paleogene mass extinction, Nature Communications (2021). DOI: 10.1038/s41467-021-25136-y
University of Bath
Modern snakes evolved from a few survivors of dino-killing asteroid (2021, September 14)
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Astronomers Discover an Intermediate-Mass Black Hole as it Destroys a Star – Universe Today
Supermassive black holes (SMBH) reside in the center of galaxies like the Milky Way. They are mind-bogglingly massive, ranging from 1 million to 10 billion solar masses. Their smaller brethren, intermediate-mass black holes (IMBH), ranging between 100 and 100,000 solar masses, are harder to find.
Astronomers have spotted an intermediate-mass black hole destroying a star that got too close. They’ve learned a lot from their observations and hope to find even more of these black holes. Observing more of them may lead to understanding how SMBHs got so massive.
When a star gets too close to a powerful black hole, a tidal disruption event (TDE) occurs. The star is torn apart and its constituent matter is drawn to the black hole, where it gets caught in the hole’s accretion disk. The event releases an enormous amount of energy, outshining all the stars in the galaxy for months, even years.
That’s what happened with TDE 3XMM J215022.4-055108, which is more readily known as TDE J2150. Astronomers were only able to spot the elusive IMBH because of the burst of x-rays emitted by the hot gas from the star as it was torn apart. J2150 is about 740 million light-years from Earth in the direction of the Aquarius constellation. Now a team of researchers has used observations of the distant J2150 and existing scientific models to learn more about the IMBH.
They’ve published their results in a paper titled “Mass, Spin, and Ultralight Boson Constraints from the Intermediate Mass Black Hole in the Tidal Disruption Event 3XMM J215022.4?055108.” The lead author is Sixiang Wen from the University of Arizona. The paper is published in The Astrophysical Journal.
IMBHs are elusive and difficult to study. Astronomers have found several of them in the Milky Way and in nearby galaxies. Mostly they’ve been spotted because of their low-luminosity active galactic nuclei. In 2019 the LIGO and Virgo gravitational wave observatories spotted a gravitational wave from the merger of two IMBHs. As it stands now, there’s a catalogue of only 305 IMBH candidates, even though scientists think they could be common in galactic centers.
One of the problems in seeing them is their low mass itself. While SMBHs can be found by observing how their mass affects the stellar dynamics of nearby stars, IMBHs are typically too small to do the same. Their gravity isn’t powerful enough to change the orbits of nearby stars.
“The fact that we were able to catch this black hole while it was devouring a star offers a remarkable opportunity to observe what otherwise would be invisible,” said Ann Zabludoff, UArizona professor of astronomy and co-author on the paper. “Not only that, by analyzing the flare we were able to better understand this elusive category of black holes, which may well account for the majority of black holes in the centers of galaxies.”
It was the eruption of x-rays that made the event visible. The team compared the observed x-rays with models and was able to confirm the presence of an IMBH. “The X-ray emissions from the inner disk formed by the debris of the dead star made it possible for us to infer the mass and spin of this black hole and classify it as an intermediate black hole,” lead author Wen said.
This is the first time that observations have been detailed enough to be able to use a TDE flare to confirm the presence of an IMBH. It’s a big deal, because though we know that SMBHs lie in the center of galaxies like the Milky Way and larger, our understanding of smaller galaxies and their IMBHs is much more limited. They’re just really hard to see.
“We still know very little about the existence of black holes in the centers of galaxies smaller than the Milky Way,” said co-author Peter Jonker of Radboud University and SRON Netherlands Institute for Space Research, both in the Netherlands. “Due to observational limitations, it is challenging to discover central black holes much smaller than 1 million solar masses.”
The mystery surrounding IMBHs feeds into the mystery surrounding SMBHs. We can see SMBHs at the heart of large galaxies, but we don’t know exactly how they got that massive. Did they go through mergers? Maybe. Through the accretion of matter? Maybe. Astrophysicists mostly agree that both mechanisms may play a role.
Another question surrounds SMBH “seeds.” The seeds could be IMBHs of tens or hundreds of solar masses. The IMBHs themselves could’ve grown from stellar-mass black holes that grew into IMBHs through the accretion of matter. Another possibility is that long before there were actual stars, there were large gas clouds that collapsed into quasi-stars, that then collapsed into black holes. These strange entities would collapse directly from quasi-star to black hole without ever becoming a star, and are known as direct collapse black holes. But these are all hypotheses and models. Astrophysicists need more actual observations, like in the case of TDE J2150, to confirm or rule anything out.
“Therefore, if we get a better handle of how many bona fide intermediate black holes are out there, it can help determine which theories of supermassive black hole formation are correct,” Jonker said.
The team of researchers was also able to measure the black hole’s spin, which has implications for black hole growth, and maybe for particle physics, too. The black hole is spinning quickly, but it’s not spinning as fast as possible. It begs the question, how did the IMBH attain a speed in this range? The spin opens up some possibilities and eliminates others.
“It’s possible that the black hole formed that way and hasn’t changed much since, or that two intermediate-mass black holes merged recently to form this one,” Zabludoff said. “We do know that the spin we measured excludes scenarios where the black hole grows over a long time from steadily eating gas or from many quick gas snacks that arrive from random directions.”
The spin rate may shed some light on potential particle candidates for dark matter, too. One of the hypotheses says that dark matter is made up of particles never seen in a laboratory, called ultralight bosons. These exotic particles, if they exist, would have less than one-billionth the mass of an electron. The IMBHs spin rate may preclude the existence of these candidate particles.
“If those particles exist and have masses in a certain range, they will prevent an intermediate-mass black hole from having a fast spin,” co-author Nicholas Stone said. “Yet J2150’s black hole is spinning fast. So, our spin measurement rules out a broad class of ultralight boson theories, showcasing the value of black holes as extraterrestrial laboratories for particle physics.”
This discovery will build toward a better understanding of dwarf galaxies and their black holes, too. But for that to happen, astrophysicists need to observe more of these IMBH tidal disruption events.
“If it turns out that most dwarf galaxies contain intermediate-mass black holes, then they will dominate the rate of stellar tidal disruption,” Stone said. “By fitting the X-ray emission from these flares to theoretical models, we can conduct a census of the intermediate-mass black hole population in the universe,” Wen added.
As is often the case in astronomy, astrophysics, and cosmology, future telescopes and observatories should advance our knowledge considerably. In this, the Vera C. Rubin Observatory could play a role. The Rubin could discover thousands of TDEs each year.
Then we may finally be able to piece together the story of not only IMBHs but also SMBHs.
NASA splits human spaceflight unit in two, reflecting new orbital economy – CTV News
NASA is splitting its human spaceflight department into two separate bodies – one centred on big, future-oriented missions to the moon and Mars, the other on the International Space Station and other operations closer to Earth.
The reorganization, announced by NASA chief Bill Nelson on Tuesday, reflects an evolving relationship between private companies, such as SpaceX, that have increasingly commercialized rocket travel and the federal agency that had exercised a U.S. monopoly over spaceflight for decades.
Nelson said the shake-up was also spurred by a recent proliferation of flights and commercial investment in low-Earth orbit even as NASA steps up its development of deep-space aspirations.
“Today is more than organizational change,” Nelson said at a press briefing. “It’s setting the stage for the next 20 years, it’s defining NASA’s future in a growing space economy.”
The move breaks up NASA’s Human Exploration and Operations Mission Directorate, currently headed by Kathy Leuders, into two separate branches.
Leuders will keep her associate administrator title as head of the new Exploration Systems Development Mission Directorate, focusing on NASA’s most ambitious, long-term programs, such as plans to return astronauts to the moon under project Artemis, and eventual human exploration of Mars.
A retired deputy associate administrator, James Free, who played key roles in NASA’s space station and commercial crew and cargo programs, will return to the agency as head of the new Space Operations Mission Directorate.
His branch will primarily oversee more routine launch and spaceflight activities, including missions involving the space station and privatization of low-Earth orbit, as well as sustaining lunar operations once those have been established.
“This approach with two areas focused on human spaceflight allows one mission directorate to operate in space while the other builds future space systems,” NASA said in a press release announcing the move.
The announcement came less than a week after SpaceX, which had already flown numerous astronaut missions and cargo payloads to the space station for NASA, launched the first all-civilian crew ever to reach orbit and returned them safely to Earth.
(Reporting by Steve Gorman in Los Angeles; Editing by Leslie Adler)
Elon Musk trolls Biden with Trump line over perceived Inspiration4 snub – CNET
Elon Musk, SpaceX founder and leading orbital travel agent, was feeling a bit slighted by the world’s most powerful man after President Joe Biden failed to acknowledge the company’sthat sent four civilians on a three-day trip in orbit of our planet.
The flight was bankrolled by billionaire Jared Isaacman, who commanded the mission aboard a Crew Dragon capsule, alongside geologist Sian Proctor, data engineer Chris Sembroski and St. Jude Children’s Research Hospital employee Hayley Arceneaux. The quartetoff the coast of Florida on Saturday.
The mission served as a fundraiser for St. Jude, with over $60 million raised from the public so far. Isaacman also pledged $100 million and Musk added $50 million.
When a Twitter user asked why the president hadn’t acknowledged Inspiration4, Musk hopped into the replies.
“He’s still sleeping,” the CEO wrote, in an apparent reference to Donald Trump’s favorite nickname for his former adversary, “sleepy” Joe Biden.
It seems fair to point out, as a number of other Twitter users have, that the president may have a few other things on his plate at the moment, like continuing to manage the response to a global pandemic, climate crisis and various national security threats.
For what it’s worth, NASA administrator Bill Nelson, a Biden appointee, did offer his congratulations to the crew multiple times.
The White House did not immediately respond to a request for comment.
Inspiration4 is the latest in a string ofthis year. Richard Branson flew to the edge of space on the first fully crewed flight of his Virgin Galactic spaceplane in July. Nine days later, Amazon and Blue Origin founder Jeff Bezos cruised a bit higher with three other passengers on his New Shepard spacecraft.
Unlike those flights, which lasted under 15 minutes each, the Inspiration4 mission was a much more complex venture that saw the four passengers performing scientific research during the multiple day flight as they orbited Earth over 40 times.
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