A newly discovered species of ankylosaur protected itself from predators with a tail weapon that is unlike anything in the paleontological record. Indeed, in an effort to describe it, the best comparison dinosaur describers could find was the Mesoamerican war club, the macuahuitl. The advantages and disadvantages of this slashing blade compared to the spikes and maces developed by other armored dinosaurs remain a mystery, but the discovery proves Gondwanan Cretaceous species were in need of as much protection as their northern hemisphere counterparts.
Faced with the fearsome predators of the era, many herbivorous dinosaurs found armor insufficient developing tails that could do serious damage to the shins, and possibly soft underbellies, of anything that tried to eat them. Some may have also found these useful in mating conflicts with their own species.
Having failed to develop a more scientific term, paleontologists adopted the name “the thagomizer” after a Gary Larson cartoon. A paper in Nature describes a newly identified late Cretaceous ankylosaur from Chile, whose defining feature is its thagomizer, which even the paper’s headline calls “bizarre”.
The discovery is different enough from anything known it needs a new genus, and the authors have called it Stegouros, which confusingly has nothing to do with the famous Stegosauruses. The name comes from the Greek words for “roof” and “tail”; Stegouros lived 80 million years later and on the other side of the world from its near namesake. The species name is elengassen.
Only one Stegouros fossil has been found – another major contrast to the common Stegosaurus – but that one is almost complete. At 180-200 centimeters (6-7 foot) long, tail included, it is believed to have been fully grown.
The tail was relatively short by the standards of armored dinosaurs and ended in seven pairs of flat bony deposits that form a shape somewhat like a fern frond, for those unfamiliar with ancient Aztec weaponry. It could probably slice deep into any perceived threats.
S. elengassen had a skull and teeth similar to other ankylosaurs, including the much more common representatives in the northern hemisphere. The rest of its body, however, looks like a throwback to earlier times, including some features that do indeed resemble stegosauruses.
S. elengassen was found in a layer dated between 74.9-71.7 million years old from Magellanes as the southern tip of Chile. The site was a delta at the time in which many dinosaurs and other animals were trapped. At the time South America was still connected to Antarctica and Australia as part of the supercontinent Gondwana. It’s nearest known relatives appear to be the larger Antarctopelta and Australia’s Kunbarrasaurus, but Stegouros had several noticeable differences from each. The authors propose a new clade called Parankylosauria (“next to the ankylosaurs”) to combine these. ““The Parankylosauria lack many features of the ‘true’ ankylosaurs that were already present in the middle Jurassic, about 165 million years ago. Therefore, the roots of Parankylosauria must be very old , before that date ” said Dr Alexander Vargas of the University of Chile said in a statement.
The authors still believe ankylosaurs were genuinely less common in the southern hemisphere than in the north, but our limited knowledge of the Gondwana species also partially reflects the amount of exploration done there. No dinosaurs from Chile were described before 2011, Stegouros is the fourth in ten years.
Although they may not have been common, the fact the southern hemisphere ankylosaurs represented a line that stretched back almost 100 million years suggests tanks of the animal kingdom might still be around today, were it not for a meddling asteroid.
Scientists study trajectory of meteorite that landed in B.C. in October – Red Deer Advocate
VANCOUVER — Scientistsstudying a meteorite that landed next to a British Columbia woman’s head last year say it was diverted to that path about 470 million years ago.
The small meteorite broke through a woman’s ceiling in Golden, B.C., in October, landing on her pillow, next to where she had been sleeping moments earlier.
Philip McCausland,a lead researcher mapping the meteorite’s journey, said Monday they know the 4.5-billion-year-old rock collided with something about 470 million years ago, breaking into fragments and changing the trajectory of some of the pieces.
McCausland, who’s an adjunct professor at Western University in London, Ont., said the meteorite is of scientific significance because it will allow scientists to study how material from the asteroid belt arrives on Earth.
“There’s 50,000 to 60,000 identified meteorites now in the world, but most have no context. We don’t know really where they came from,” he said.
“In cases where we have known orbits, where they were observed coming in well enough that we can reconstruct what the orbit was before it hit the Earth’s atmosphere, we can actually (determine) where they came from in the asteroid belt. Golden is one of those,” he said, referring to the location of where the meteorite landed.
Researchers determined the meteorite is an L chondrite, one of the most commonly found types of meteorites to fall to Earth. Despite this, he said only about five L chondrites have known orbits.
He said the Canadian team is now working with scientists in Switzerland, the U.K., U.S. and Italy to learn more about the meteorite and its path to Golden.
“We know we’re still going to get something interesting out of this,” McCausland said. “We actually do want to get a good handle on how things get delivered from the asteroid belt, and this is a useful part of putting that together.”
Most of the meteorite has been returned to Ruth Hamilton, the woman who had the close call, and McCausland said it’s up to her to decide what to do with it.
Whether she decides to keep, sell or donate the rock, he said there is cultural significance of the rock to Canada. If she sells it to an international buyer, she would be required to go through the exportation process, he said.
Hamilton said she hasn’t yet made up her mind on what to do with the meteor. It’s currently sitting in a safety deposit box.
“I don’t have any plans for it right now, but once they’re done analyzing it, I’ll get all the documentation that proves it’s a meteorite,” she said. “It’s going to be officially named the Golden Meteorite.”
Before her roof is permanently repaired this spring, Hamilton said she intends to remove the section where the meteorite crashed through to keep it preserved alongside the rock.
McCausland said the research will likely conclude in May, and the scientists will then publish their work in an academic journal.
“Whenever something like this happens, I like to tell people it could happen to any of us; anyone can find a meteorite. It’s unlikely one will crash through your roof, but it can happen,” McCausland said. “It’s nature and, if anything, it’s a reminder that we’re part of something bigger.”
Elon Musk’s Starlink Is Causing More Streaks to Appear in Space Images – Gizmodo
Researchers at the Zwicky Transient Facility in California have analyzed the degree to which SpaceX’s Starlink satellite constellation is affecting ground-based astronomical observations. The results are mixed.
The new paper, published in The Astrophysical Journal Letters and led by former Caltech postdoctoral scholar Przemek Mróz, offers some good news and some bad news. The good news is that Starlink is not currently causing problems for scientists at the Zwicky Transient Facility (ZTF), which operates out of Caltech’s Palomar Observatory near San Diego. ZTF, using both optical and infrared wavelengths, scans the entire night sky once every two days in an effort to detect sudden changes in space, such as previously unseen asteroids and comets, stars that suddenly go dim, or colliding neutron stars.
But that doesn’t mean Starlink satellites, which provide broadband internet from low Earth orbit, aren’t having an impact. The newly completed study, which reviewed archival data from November 2019 to September 2021, found 5,301 satellite streaks directly attributable to Starlink. Not surprisingly, “the number of affected images is increasing with time as SpaceX deploys more satellites,” but, so far, science operations at ZTF “have not yet been severely affected by satellite streaks, despite the increase in their number observed during the analyzed period,” the astronomers write in their study.
The bad news has to do with the future situation and how satellite megaconstellations, whether Starlink or some other fleet, will affect astronomical observations in the years to come, particularly observations made during the twilight hours. Indeed, images most affected by Starlink were those taken at dawn or dusk. In 2019, this meant satellite streaks in less than 0.5% of all twilight images, but by August 2019 this had escalated to 18%. Starlink satellites orbit at a low altitude of around 324 miles (550 km), causing them to reflect more sunlight during sunset and sunrise, which creates a problem for observatories at twilight.
Astronomers perform observations at dawn and dusk when searching for near-Earth asteroids that might appear next to the Sun from our perspective. Two years ago, ZTF astronomers used this technique to detect 2020 AV2—the first asteroid entirely within the orbit of Venus. A concern expressed in the new paper is that, when Starlink gets to 10,000 satellites—which SpaceX expects to achieve by 2027—all ZTF images taken during twilight will contain at least one satellite streak. Following yesterday’s launch of a Falcon 9 rocket, the Starlink megaconstellation consists of over 2,000 satellites.
In a Caltech press release, Mróz, now at the University of Warsaw in Poland, said he doesn’t “expect Starlink satellites to affect non-twilight images, but if the satellite constellation of other companies goes into higher orbits, this could cause problems for non-twilight observations.” A pending satellite constellation managed by OneWeb, a UK-based telecommunications firm, will orbit at an operational altitude of 745 miles (1,200 km), for example.
The researchers also estimated the fraction of pixels that are lost as a result of a single satellite streak, finding it to be “not large.” By “not large” they mean 0.1% of all pixels in a single ZTF image.
That said, “simply counting pixels affected by satellite streaks does not capture the entirety of the problem, for example resources that are required to identify satellite streaks and mask them out or the chance of missing a first detection of an object,” the scientists write. Indeed, as Thomas Prince, an astronomer at Caltech and a co-author of the study pointed out in the press release, a “small chance” exists that “we would miss an asteroid or another event hidden behind a satellite streak, but compared to the impact of weather, such as a cloudy sky, these are rather small effects for ZTF.”
SpaceX has not responded to our request for comment.
The scientists also looked into the measures taken by SpaceX to reduce the brightness of Starlink satellites. Implemented in 2020, these measures include visors that prevent sunlight from illuminating too much of the satellite’s surface. These measures have served to reduce the brightness of Starlink satellites by a factor of 4.6, which means they’re now at a 6.8 magnitude (for reference, the brightest stars shine at a magnitude 1, and human eyes can’t see objects much dimmer than 6.0). This marks a major improvement, but it’s still not great, as members of the 2020 Satellite Constellations 1 workshop asked that satellites in LEO have magnitudes above 7.
The current study only considered the impacts of Starlink on the Zwicky Transient Facility. Every observatory will be affected differently by Starlink and other satellites, including the upcoming Vera C. Rubin Observatory, which is expected to be badly affected by megaconstellations. Observatories are also expected to experience problems as a result of radio interference, the appearance of ghost-like artifacts, among other potential issues.
Earth's core is rapidly cooling, study reveals. Is our planet becoming 'inactive'? – USA TODAY
Planet Earth hits 6th warmest year on record
Earth simmered to the sixth hottest year on record in 2021, according to several newly released temperature measurements. (Jan. 13)
Earth’s interior is cooling faster than we previously estimated, according to a recent study, prompting questions about how long people can live on the planet.
There’s no exact timetable on the cooling process, which could eventually turn Earth solid, similar to Mars. But results from a new study, published in the peer-reviewed journal Earth and Planetary Science Letters, focuses on how quickly the core may cool by studying bridgmanite, a heat-conducting mineral commonly found at the boundary between the Earth’s core and mantle.
“Our results could give us a new perspective on the evolution of the Earth’s dynamics,” ETH Zurich professor Motohiko Murakami, the lead author of the study, said in a press release. “They suggest that Earth, like the other rocky planets Mercury and Mars, is cooling and becoming inactive much faster than expected.”
While the process may be moving quicker than previously thought, it’s a timeline that “should be hundreds of millions or even billions of years,” Murakami told USA TODAY.
The boundary between the Earth’s outer core and mantle is where the planet’s internal heat interaction exists. The scientific team studied how much bridgmanite conducts from the Earth’s core and found higher heat flow is coming from the core into the mantle, dissipating the overall heat and cooling much faster than initially thought.
“This measurement system let us show that the thermal conductivity of bridgmanite is about 1.5 times higher than assumed,” Murakami said in the press release. “We still don’t know enough about these kinds of events to pin down their timing.”
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