“There’s a very faint dimple here,” Sterling Nesbitt says, holding up a palm-sized fossil to the light. The fossil, a pelvic bone, belonged to a creature called Teleocrater rhadinus. The slender, 2-meter-long reptile ran on all fours and lived 245 million years ago, about 10 million to 15 million years before scientists think dinosaurs first appeared.

Nesbitt, a paleontologist at Virginia Tech in Blacksburg, tilts the bone toward the overhead light, illuminating a small depression in the fossil. The dent, about the size of a thumbprint, marks the place where the leg bone fit into the pelvis. In a true dinosaur, there would be a complete hole there in the hip socket, not just a depression. The dimple is like a waving red flag: Nope, not a dinosaur.

The hole in the hip socket probably helped dinosaurs position their legs underneath their bodies, rather than splayed to the sides like a crocodile’s legs. Until recently, that hole was among a handful of telltale features paleontologists used to identify whether they had their hands on an actual dinosaur specimen.

Another no-fail sign was a particular depression at the top of the skull. Until Teleocrater mucked things up. The creature predated the dinosaurs, yet it had the dinosaur skull depression.
The once-lengthy list of “definitely a dinosaur” features had already been dwindling over the past few decades thanks to new discoveries of close dino relatives such as Teleocrater. With an April 2017 report of Teleocrater’s skull depression (SN Online: 4/17/17), yet another feature was knocked off the list.

Today, just one feature is unique to Dinosauria, the great and diverse group of animals that inhabited Earth for about 165 million years, until some combination of cataclysmic asteroid and volcanic eruptions wiped out all dinosaurs except the birds.
“I often get asked ‘what defines a dinosaur,’ ” says Randall Irmis, a paleontologist at the Natural History Museum of Utah in Salt Lake City. Ten to 15 years ago, scientists would list perhaps half a dozen features, he says. “The only one to still talk about is having a complete hole in the hip socket.”

The abundance of recent discoveries of dinosauromorphs, a group that includes the
dinosaur-like creatures that lived right before and alongside early dinosaurs, does more than call diagnostic features into question. It is shaking up long-standing ideas about the dinosaur family tree.

To Nesbitt, all this upheaval has placed an even more sacred cow on the chopping block: the uniqueness of the dinosaur.

“What is a dinosaur?” Nesbitt says. “It’s essentially arbitrary.”
Shared traits
In 1841, British paleontologist Sir Richard Owen coined the term “dinosaur.” Owen was contemplating the fossil remains of three giant creatures — a carnivore named Megalosaurus, the plant-eating Iguanodon and the heavily armored Hylaeosaurus. These animals shared several important features with one another but not other animals, he determined. (In particular, he noted, the creatures’ giant legs were upright and tucked beneath their bodies, and each of the animals had five vertebrae fused together and welded to the pelvis.)

Owen decided the animals should be biologically classified together as their own group, or taxon. He named the group “Dinosauria” for “fearfully great lizards.”

In Owen’s day, it was a bit easier to spot similarities between fossils, says paleontologist Stephen Brusatte of the University of Edinburgh. “Back then, there were so few dinosaurs. But the more fossils you find, the patterns become more complicated,” he says. “With every new discovery, you get a different view of what features define a dinosaur. It’s nowhere near as clear-cut as it used to be.”

Dino survivors
The largest extinction of species on Earth, the “Great Dying,” happened about 252 million years ago at the end of the Permian Period (SN: 9/19/15, p. 10). About 96 percent of marine species and 70 percent of land species succumbed.

In the period that followed, the Triassic, spanning 252 million to 201 million years ago, new reptilian species arose and flourished. This was the time of the dinosauromorphs, crocodylians (the ancestors of crocodiles) and, of course, the dinosaurs themselves. No one knows exactly when dinosaurs arose, although it was probably around 230 million years ago.
For tens of millions of years, the dinosaurs lived alongside numerous other reptile lineages. But at the end of the Triassic, dramatic climate change played a role in another mass extinction. Dinosaurs somehow survived and went on to dominate the planet during the Jurassic Period.
Paleontologists once assumed the dinosaurs were somehow superior, with physical features that helped them outcompete the other reptiles. “But that’s not borne out by new dinosaur relatives,” Nesbitt says. Dinosaurs and dinosauromorphs, researchers found, were very similar. The new bonanza of dinosauromorph fossils reveals a repeating pattern of parallel evolution, such as lengthening legs or having legs oriented directly under the body. In short, Nesbitt says, dinosaurs “are not doing anything different than their closest relatives.”

On the heels of those discoveries, many paleontologists suspect that the reason for dinosaurs’ rapid expansion in the Jurassic is simply that the creatures took advantage of the sudden availability of ecological niches left behind by their long-dead cousins from the Triassic.

But that doesn’t explain why dinosaurs survived the extinction at the end of the Triassic, while their dinosauromorph cousins (and most of the crocodylians) died out. That’s a question no one yet has answered.

Maybe dinosaurs had some anatomical characteristics that helped them survive, suggests Max Langer, a paleontologist at the University of São Paulo. “But we don’t know what those features were.”
Uprooting the family tree
To identify the animal that left behind a fossil, paleontologists pore over the bone, noting each bump, groove and hole, measuring the length of a tibia bone or counting the digits on a forelimb. Before powerful computers were available, scientists constructed evolutionary trees by noting which species share different bumps and grooves, and assessing whether those features (also called characters) were inherited from a common ancestor, or passed along to descendants.

Langer calls that approach to phylogenetic analyses “old-fashioned.” Today, scientists use computer algorithms to help construct elaborate phylogenetic, or evolutionary, trees. But the fossil characters are still the raw data required to create those trees, and the analyses are only as good as those data. Different researchers may choose different features to consider, and may interpret the fossils differently, too. Those concerns hit home among dinosaur researchers last year, when a team proposed a fundamental reorganization of the dinosaur evolutionary tree.

For about 130 years, the basic structure of the dinosaur family tree was considered relatively stable. Dinosaurs were split into two main lines based on the shape of the hips. Both lines had the hole in the hip socket, still considered unique to all dinosaurs. One line known as the ornithischians, also had a pubis bone that pointed down toward the tail. That group includes giant herbivores such as the three-horned Triceratops and plate-armored Stegosaurus. The other line’s pubis bone pointed down toward the front, a hip shape shared by long-necked sauropods such as Brachiosaurus and by carnivorous theropods such as Tyrannosaurus rex. With those hip similarities, sauropods and theropods have long been considered closer “sister” groups, while ornithischians were seen as more distant relations.

But in March 2017, Ph.D. student Matthew Baron and vertebrate paleontologist David Norman of the University of Cambridge, along with paleobiologist Paul Barrett of the Natural History Museum in London, proposed upending that long-standing arrangement.

At the heart of their paper, published in Nature, was the observation that ornithischians have been somewhat overlooked in previous phylogenetic analyses. The herbivorous ornithischians were a really diverse bunch, with a spectacular array of frills and armors and horns and crests.

So the researchers decided to see how different the family tree would look if an analysis included many more ornithischian species. The team incorporated some 457 different fossil characters from 74 species of all kinds of dinosaurs and dinosaur relatives (SN: 4/15/17, p. 7).

The newly constructed tree might as well have been from a whole different forest. It shuffled the three big groups around, putting ornithischians and theropods together into a new group and suggesting that sauropods had split off earlier.

Baron and his coauthors found that the ornithischians had more than 20 features in common with predatory theropods.

The paper made a splash, but many paleontologists were skeptical. The bar to revise a tree that had stood decades of previous phylogenetic analyses ought to be pretty high, Brusatte says.

Indeed, one point arising from the study was just how subjective phylogenetic analyses can be, Irmis says. Which species a study includes clearly affects how the tree turns out, he says. Plus, he adds, “a slight difference in how one person interprets the anatomy of a fossil or a particular character can make a cumulatively huge difference.”

Langer, Brusatte and several paleontologist colleagues decided to tackle the character interpretation part of the problem head on. “When the paper came out, there was this flurry of excitement,” Brusatte says. “But a lot of us noticed right away that there wasn’t a huge amount of description about the characters.” The concern was that, if the fossils weren’t carefully examined and the characters properly assessed, those errors could dramatically skew the results.

So the researchers divvied up the task of traveling around the world to visit the fossils included in the original paper and to reassess all 457 characters described — in person. “It was essentially a replication study,” Brusatte says.

The team went in expecting to cast doubt on the tree created by Baron, Norman and Barrett — or possibly to completely debunk it. But that didn’t exactly happen.

Langer, Brusatte and their coauthors reported last November in Nature that their analyses showed that the original, 130-year-old evolutionary tree was still the best fit to the dinosaur dataset used by Baron’s team.

But, they found, the original tree wasn’t that much more likely to be correct than the newly described tree. “This is the thing that really blew us away: It wasn’t actually a statistically significant result,” Brusatte says. In fact, the often-accepted tree wasn’t even that much more likely than an older, third arrangement of the tree that grouped ornithischians closer to the other herbivores in the family, the long-necked sauropods, and left the fierce theropods as the outliers.

“There is currently great uncertainty about early dinosaur relationships and the basic
structure of the dinosaur family tree,” the researchers concluded. “It seems that the flood of new
discoveries over the past decades has revealed unexpected complexity.”

Brusatte adds: “We shouldn’t rewrite the textbooks just yet. But we’ve taken what we thought was a certainty and turned it into a mystery — and a big mystery, at that.”
Catch-22
How the different dinosaur groups are related to one another may seem like insider baseball, Nesbitt says. But the evolutionary tree is the common ground, the framework within which researchers can discuss dinosaur evolution, dinosaur origins and what binds all dinosaurs together. “It makes it difficult to ask questions about how features are evolving if we can’t have some agreed-upon taxonomy,” he adds.

Similarly, without an agreed-upon evolutionary tree, it’s hard to know which anatomical features to follow through the tree — such as any that might have helped dinosaurs survive the end-Triassic extinction. Each arrangement of the evolutionary tree seems to highlight different features as being particularly important, Langer says. “If you don’t know how the tree is arranged, you can’t say which feature characterizes [dinosaurs].”

The thorny problem revolves around which to tackle first: How to define a dinosaur or how to redraw the dinosaur family tree?

But Langer suggests the answer, as always, is to return to the fossils. In the paper by Langer and his coauthors, they make a plea for researchers to do the mundane work. “We proposed that we need more … anatomical descriptions and definition of characters,” Langer says. “It’s boring to do, but people have to do more of this.”

Finding Teleocrater
As Nesbitt cradles the Teleocrater pelvic bone, he turns to a tall cabinet of wide, shallow drawers. He slides open a drawer filled with dozens of carefully labeled boxes, each holding one or more bones from Teleocrater, collected during a 2015 expedition to Tanzania’s Ruhuhu Basin.

The first known fossils of Teleocrater rhadinus, to date the only species of the genus Teleocrater, were actually discovered in the 1930s. But those fossils — a few bits of vertebrae, pelvis and limb — languished unidentified in London’s Natural History Museum for several decades.
The Ruhuhu Basin, an area dating to between 247 million and 242 million years ago, was a popular place in the Triassic. The site contains abundant fossils, diverse assemblages of Triassic animals including relatives of crocodylians, giant-headed amphibians and ancient relatives of modern mammals called cynodonts.

In 2010, Nesbitt described a species of dinosauromorph from the Ruhuhu Basin dubbed Asilisaurus kongwe. But on his 2015 expedition, he was hoping to find more evidence that would help identify the mysterious Teleocrater — perhaps even a skull.

He hit pay dirt: His team found a bone bed containing at least three Teleocrater individuals, including a braincase and jawbone. The skull was a particularly exciting find, because it showed the team that Teleocrater, clearly a nondinosaur from other features, had the skull depression, just like a true dinosaur.

Paleontologists tend to say that finding more fossils from early dinosaurs and their close relatives is the surest way to fill in the gaps on how the creatures evolved and to tidy up the family tree.

Nesbitt laughs. “Now we have way more fossils,” he says, “and it’s way messier.”

Early plants made Earth muddier. Ancient riverbed deposits of mud rock — rocks containing bits of clay and silt smaller than grains of sand — began increasing around 458 million years ago, around the time that rootless plants became common across Earth, researchers say.

Anecdotally, geologists have long noted that early sediment deposits became muddier at some point, and suggested a connection with plants (SN: 6/22/74, p. 398). But no one had ever pinpointed when that muddening happened.
So geologists William McMahon and Neil Davies, both of the University of Cambridge, decided to look for when amounts of mud rock began increasing in 704 ancient river deposits from 3.5 billion to 300 million years ago. The researchers searched through nearly 1,200 published papers for data on mud rock in river deposits, and collected new field data at 125 ancient river outcrops. At those outcrops, the researchers calculated the percent of mud rock in the overall deposit by measuring the thickness of the muddy layers compared with the thickness of layers containing larger grains such as sand.

The resulting fractions showed the median mud content was about 1 percent before around 458 million years ago. At that point, the mud content steadily increased over about the next 100 million years or so to reach a median of about 26 percent in outcrops dated 359 million to 299 million years old, McMahon and Davies report in the March 2 Science.

That steady upsurge suggests that neither cyclical nor episodic forces — such as glacial-interglacial changes or tectonic events — could have driven the increase in muddiness. Instead, plants are the likeliest culprit. A primitive group of rootless plants called bryophytes, which includes modern mosses and liverworts, had likely become common by about 458 million years ago. Rooted plants further increased the mud content when they arose and began to spread around 430 million years ago, eventually forming great forests about 382 million years ago.
That plants like bryophytes influenced the formation of mud deposits long before roots appeared is a surprise, says geobiologist Woodward Fischer of Caltech who wrote a commentary about the study for the same issue of Science. “The plants of that time were tiny little scrappy things,” Fischer says. “They’re closer to green mats.”
Exactly how ancient plants, rooted or not, helped increase Earth’s muddiness is still uncertain. Earth had mud before it had plants: Weathering of rocks can create silt and clay, and microbes and fungi also erode rock material into ever tinier bits. But plants can speed up the production of clays, for example, by secreting organic acids that change soil chemistry.

Plants also likely play a major role in shaping landscapes by altering the distribution of clay and silt. “There’s something the plants are doing that has to do with the construction of floodplain deposits,” Fischer says. Even scrappy little bryophytes can increase how much mud remains on land by inhibiting wind and water from carrying sediment away. As plants evolved, their influence on the landscape became stronger. Some studies have suggested that the appearance of rooted plants altered the flow of rivers by stabilizing riverbanks, he says.

The new research could also help scientists better interpret sediment formations on Mars, where there are no plants. Earth before the rise of bryophytes is more similar to the Red Planet than modern Earth, Davies says. “If you want an analog for Mars, you need to look at a time when Earth was like Mars.”

In the fraught days following a mass shooting, people often ask if an assault weapons ban or allowing concealed carry permits would reduce the likelihood of further violence. But reliable evidence on the effects of those policies can be hard to find.

Now the largest comprehensive analysis of research on U.S. gun policy in years offers some answers, but also troublingly little guidance. A glaring finding of the study, published by the RAND Corporation March 2, is how little work has been done to know which policies work.
“The research literature on gun policies is really very thin,” says Andrew Morral, a behavioral scientist at RAND, a nonpartisan institute based in Santa Monica, Calif.

Ideally, solid research leads to effective public health policies, which then reduce deaths, be it from guns, car accidents or fires. But when it comes to gun research, good science is lacking, says Morral, who led the study. So legislators typically turn to experts and advocates who can disagree vehemently about the effects of laws.

The goal of the report is to help people understand “what is reasonably well-known and what isn’t,” says Morral. “Hopefully we can work from there and identify where research can be most helpful.”
Morral and his colleagues reviewed existing research on 13 types of gun policies, including concealed carry laws and waiting periods, and their impact on health, and safety, including mass shootings, suicides and accidental deaths. Next the researchers looked to see if those studies were any good. Out of thousands of studies considered for the analysis, a mere 63 met the research team’s strict criteria: Studies had to use rigorous methods and establish cause and effect.

The team ranked the strength of the evidence of a given policy’s effectiveness as limited (at least one study showed an effect, which wasn’t contradicted by other studies), moderate (two or more studies showed the same effect, no contradictory studies) or supported (three or more studies with at least two independent datasets found an effect with no contradictory studies). Here are the biggest takeaways:

1. There’s not enough data to show what would prevent mass shootings. There is no universal definition of a mass shooting, which, along with their relative rarity, makes it hard it hard to spot trends, such as whether mass shootings are on the rise. Studies looking at seven of the investigated policies, including concealed carry laws and background checks, were inconclusive about whether those policies lowered the likelihood of a mass shooting. For nearly half the gun policies, including gun-free zones, prohibitions associated with mental illness and stand-your-ground laws, no studies met the researchers’ criteria.
2. Keeping guns out of the hands of kids is good policy. There’s solid evidence that these laws reduce unintentional firearm injuries and deaths among children. There’s some evidence these laws also reduce adult unintentional firearm injuries and deaths.
3. Gun policies can decrease the number of suicides. This is no small thing: Of the more than 36,000 U.S. gun deaths each year, two-thirds are suicides. Laws that prevent kids from getting access to guns reduce the number of suicides by young people. And there’s some limited evidence that keeping guns away from people with certain mental illnesses, minimum-age requirements and background checks all prevent suicides.
4. Background checks can work. Designed to prevent certain people, such as convicted felons or those subject to a restraining order, from buying guns, background checks do reduce some gun violence. There’s moderate evidence that these laws can reduce the number of firearm homicides and suicides and limited evidence that background checks reduce violent crime and homicides in general.
5. Keeping guns out of the hands of the mentally ill has mixed effects. While there’s limited evidence that these laws can reduce the number of suicides, there’s slightly stronger proof that these laws reduce the amount of violent crime in general.
6. Allowing people to carry concealed guns ups gun violence. There’s limited evidence that laws that guarantee a right to carry increase unintentional firearm injuries among adults and increase violent crime.
7. Saying it’s OK to “stand your ground” can also lead to gun violence. Rather than curtailing gun deaths, there’s moderate evidence that laws that let people claim self-defense even if they don’t ty to retreat from a perceived threat lead to an uptick in homicide rates. There were no studies that met the researchers’ strict criteria demonstrating that stand-your-ground laws lower the likelihood of any gun-related violence.
   The analysts found little or no research on the impact of other policies, including gun-free zones, firearm sales reporting requirements and bans on assault weapons.

Many scientists, including the authors of the RAND report, blame federal directives that, for the past two decades, have forbidden the Centers for Disease Control and Prevention from “advocating or promoting gun control” and slashed its funding.

“That sent a very loud signal that firearms research was dangerous to your budget,” Morral says.

Similar language was added to the funding bill for the National Institutes of Health in 2012 and the end result is today the U.S. government invests very little in research on firearms and public health (SN: 5/14/16, p. 16). A recent JAMA study comparing spending on leading causes of mortality, such as cancer, malnutrition and hypertension, found that gun violence research funding was only 1.6 percent of what would be expected, given the number of people that die from guns each year. The same analysis looked at the volume of scientific papers published for each cause of death and, relative to mortality rates, guns were the least researched.

Good data are needed for good policy, says David Hemenway, an expert on injury and violence prevention at Harvard T.H. Chan School of Public Health. To understand, for example, whether collapsible steering columns in cars prevent driver deaths, it takes data on head-on collisions, says Hemenway, not just motor vehicle deaths in general. Such fine-grained data are lacking for much of gun-related violence.

Those data likely will reveal that there’s no one-size-fits-all policy to reduce gun-related violence, says Hemenway. Interventions that reduce gun violence in at-risk communities might be very different than, say, policies for reducing mass shootings. But without the research, it’s hard to know. Hemenway is confident that over time, data and science will win out. “Every success in public health meets with opposition,” he says. “You have to fight and fight and it takes much longer than you hope.”

There’s so much water on some of TRAPPIST-1’s seven Earth-sized planets that any life lurking there might be difficult to detect.

New estimates of the makeup of these potentially habitable worlds suggests that two of them are more than half water, by mass, researchers report March 19 in Nature Astronomy. Earth, by comparison, is less than 0.1 percent water.

TRAPPIST-1’s planets are so wet that most of the water probably isn’t even liquid, but ice formed under high pressure, says Cayman Unterborn, an exogeologist at Arizona State University in Tempe. That would change the chemistry happening on the planet in a way that could make any signs of life tricky to distinguish from geochemical processes.
TRAPPIST-1 is a cool, dim star about 39 light-years from Earth. Since the star system’s discovery in 2017, it’s been a prime focus for scientists seeking life outside of our solar system because some of the seven planets might have the right conditions to host life (SN: 12/23/17, p. 25). They’re rocky rather than gaseous, and at least three are at a distance from the star that could let them host liquid water.

Unterborn and his colleagues used previous estimates of the mass and diameter of TRAPPIST-1’s planets to calculate the worlds’ densities. Then, the team used a computer program to test different compositions of basic planetary building blocks to determine which makeups would yield planets with those densities.
Frozen or liquid water is less dense than rock, but more dense than a gas. So a less dense planet might have a higher proportion of water or gases compared with a denser, rockier world. But Unterborn doesn’t think the TRAPPIST-1 planets are massive enough to hold onto much of an atmosphere — it would probably escape into space. So the team concluded the lower densities in this system probably come from the presence of water.
The researchers focused on four of the seven planets for which they had the best data. The first and second planets from the dwarf star are probably less than 15 percent water by mass, still far wetter than Earth, the researchers found.

The fifth and sixth planets, both in the habitable zone, are more than half water — a volume so large that the water pressure alone could force much of it into a form of ice, Unterborn says. He estimates that on the fifth planet, TRAPPIST-1f, liquid water extends down about 200 kilometers — about 20 times deeper than the Mariana Trench on Earth. Below that, a nearly 2,300-kilometer layer of ice stretches almost halfway to the center of the planet.

These water estimates might throw a wet blanket on the chances of finding life on any of TRAPPIST-1’s planets, if it exists at all. The thick covering of ice and water might mess up some of the geological processes that, at least on Earth, help regulate the planet’s temperature over long periods of time. If so, that might be an impediment to life getting a foothold. Having so much water might also slow or halt the movement of building blocks of life, such as carbon and phosphorus (the backbone of DNA), into oceans. That could make it harder for us to detect whether certain molecules in the water are hints of the presence of living organisms, or just the by-products of geological processes.

It doesn’t rule out life, Unterborn says, but it does make it harder to find. When it comes to understanding the way a planet’s geologic composition affects chemical processes, “the vast majority of data that’s out there is for one planet, and it’s ours,” he says. The TRAPPIST-1 system is “such an extreme of rocky planet chemistry.”

Updated estimates of the TRAPPIST-1 planets’ masses were published in February (SN Online: 2/5/18), and this study doesn’t use those numbers, says Billy Quarles, a physicist at the University of Oklahoma in Norman who wasn’t part of the study. Based on the newer estimates, TRAPPIST-1’s planets aren’t quite as wet as this study predicts. But the big-picture conclusion — that some of the planets contain far more water than Earth — still holds up, he says.

People call Lucy Jones the “earthquake lady.” For nearly 40 years, Jones, a seismologist, has been a leading voice in California on earthquake science and safety. A few months after retiring from the U.S. Geological Survey in 2016, she founded the Dr. Lucy Jones Center for Science and Society to bring policy makers and scientists together to discuss disaster resilience.

Now Jones is bringing that discussion to the public in her new book, The Big Ones. She offers a fascinating history of how catastrophic natural events — including the Lisbon earthquake of 1755, Iceland’s Laki volcanic eruption in 1783 (SN: 2/17/15, p. 29) and Hurricane Katrina in 2005 — have shaped politics, culture and society. Science News talked with Jones about the book, which she hopes will be a wake-up call, encouraging people to be ready for when, not if, the next disaster strikes. The discussion that follows has been edited for length and clarity.
Why is now the time to write about the science behind natural disasters and the stories of people affected?
We need stories to believe that these disasters can really happen to us. I’m a scientist. I know that research isn’t based on stories, but the stories help communicate the science. And disasters all have such cool stories, don’t they?

How did you choose which disasters to include?
I wrote about disasters that were big enough to imperil the nature of society. Look at the Laki eruption. The country of Iceland completely changed. They lost a quarter of their population. Most of their records, like the church records of baptisms and deaths, disappeared. People can’t trace their families back before that time because the country fell apart. That’s one of the things that I wanted to do: discuss that level of catastrophe.

You write that you were surprised that presenting data, like earthquake probabilities, doesn’t move people to act. Why do you think hard numbers don’t motivate people?
The numbers are often about the things we don’t understand, the uncertainty. Scientists and engineers actually like uncertainty; that’s why we spend our lives studying it. When we talk about the probabilities of an earthquake, we’re talking about the part we don’t understand, which is: When will it happen? That gives people a reason to say, I won’t deal with it now. If we have a 50 percent chance of rain today, and the storm veers off and doesn’t happen, then the rain never gets to us. So if it doesn’t happen today, it’s just not going to happen at all.
We use exactly the same words to say we’ve got a 50 percent chance of an earthquake in the next 50 years. And that allows people to think, well, maybe if it doesn’t happen in this time, then it’s not going to happen. I want people to realize it’s going to happen; we just don’t know when. When people ask me what’s the probability of an earthquake, I say, it’s 100 percent, just give me enough time.
One of the themes in The Big Ones is disaster preparedness. How can people be ready for a disaster?
What matters is community. And when you have a disruption that imperils society itself, people will leave unless they’ve got a good reason to stay. The reason you stay is the people you care about. That whole “prepper” movement, I think, is a counterproductive approach because it tends to be, “I’m sure society is falling apart, so I’m getting my guns. I’m getting my stuff. I’m going to protect my family.” And that’s an implicit message that your neighbor is going to be your enemy. It becomes self-fulfilling. That type of prepper is one of the contributions to the world falling apart.

Bootlace worms with spooky-stretchy bodies secrete a family of toxins new to scientists. These compounds might inspire novel ways to attack pests such as cockroaches.

Tests first identified the toxins in mucus coating a bootlace species that holds the record as the world’s longest animal, says pharmacognosist Ulf Göransson of Uppsala University in Sweden. This champion marine worm (Lineus longissimus) can stretch up to 55 meters, longer than an Olympic-sized pool, and coats itself in mucus smelling a bit like iron or sewage. That goo holds small toxic proteins, now dubbed nemertides, that are also found in 16 other bootlace worm species, Göransson and colleagues write March 22 in Scientific Reports.
The newly described nemertides attack tiny channels in cell walls that control the amount of sodium flowing in and out of the cell. Much vital cell business, such as communications between nerves, depends on the right flux through these voltage-gated sodium channels, as they’re called. Injections of small amounts of one of these nemertides permanently paralyzed or killed invasive green crabs (Carcinus maenas) and young cockroaches (Blattella germanica).

“This study certainly has a lot of novelty to it, since marine worms are a tremendously neglected area of venom research,” says Bryan Grieg Fry at the University of Queensland in Australia, where he explores the evolution of animal poisons.

Unlike earthworms, the 1,300 or so species of bootlace, or ribbon, worms have no segments. Some scientists give these animals their own phylum, Nemertea. Bootlace worms have a brain but no lungs. Like many other slender marine creatures, bootlace worms breathe directly through the skin. The worms are carnivorous, supping on crustaceans, mollusks and other worms.

They’re marvels of body expansion and contraction. An L. longissimus “of about 10 meters can be held in your hand as a slimy heap,” says study coauthor Malin Strand, a marine biologist and molecular systematist at the Swedish University of Agricultural Sciences in Uppsala. She estimates the worms could live for around 10 years “or maybe much longer.”
How L. longissimus or the other species in the study use their toxins isn’t clear, she says. The stringy creatures aren’t easy to keep in captivity, Strand says. She has some worms that have deigned to eat in her lab only once in three to four years.

Göransson proposes that toxic mucus may be useful for defense. He has seen video with Nemertean worms stretched out on the seafloor. “If you’re a crab or a fish, it must be tempting to take a nip,” he says, but there’s little sign of anything bothering them.

He once tried some bare-handed contact with a small lab specimen and didn’t feel much of anything, although he’s been warned about “tingling” or even hands going temporarily numb. One of the nemertide toxins tested in the new paper was 100 times as effective on sodium channels in insect cells as in mammal ones, the researchers found.

Still, Göransson prefers to wear gloves.

For the first time, researchers have played matchmaker between two specific atoms, joining them together to form a molecule.

Typically, chemists make molecules by mixing up many constituent atoms, some of which stick to each other to form the desired compounds. In the new, supercontrolled chemical reaction, researchers trapped a single sodium atom in one optical tweezer — a device that snares small particles in a laser beam — and a cesium atom in another tweezer. Both atoms were cooled to less than one ten-thousandth of a degree above absolute zero.

The researchers moved these tweezers closer together until the laser beams overlapped, allowing the sodium and cesium atoms to collide. A third laser shot a pulse of light at the atoms to provide a boost of energy that helped the atoms bond into a sodium cesium molecule, researchers report online April 12 in Science.

Fashioning individual molecules atom by atom could allow researchers to study atomic collisions in the most controlled environment possible, as well as to observe how molecules behave in isolation. Researchers could also use optical tweezers to construct molecules with specific quantum properties, says study coauthor Kang-Kuen Ni, a chemist at Harvard University. These designer molecules could store qubits of data in future quantum computers, she says (SN: 3/10/12, p. 26).

An ultraprecise new measurement has given some weird particle physics theories a black eye.

By measuring one of nature’s most fundamental constants more precisely than before, scientists have tested proposed tweaks to the standard model, the theory governing fundamental particles. The result, reported April 13 in Science, casts doubt on hypothetical particles called dark photons and other potential oddities.

The quantity in question is the fine-structure constant, a number that governs the strength of electromagnetic interactions (SN: 11/12/16, p. 24), such as those that confine electrons within atoms. Previously, the most precise measurement of the constant was indirect, relying on a measurement of the electron’s magnetic properties and using complex theoretical calculations to infer the constant’s value.
Now, physicist Holger Müller of the University of California, Berkeley and colleagues have measured the constant more directly. The team fired lasers at cesium atoms to create a quantum superposition — a bizarre state in which each atom is in two places at once — and watched how the atoms interfered with themselves as they recombined. This interference reveals how fast the atom moved when hit by the laser, which scientists then used to calculate the fine-structure constant.

The answer: The fine-structure constant is approximately 1/137.035999046.

If the new measurement disagreed with the earlier one, that might be an indication of new particles. But the two agree reasonably well, which confirms that the electron is probably not composed of smaller particles and disfavors the possibility of dark photons. These hypothetical particles are similar to run-of-the-mill photons, or particles of light, but unlike normal photons would have mass and interact very weakly with known particles.
But while close, the two measurements didn’t match perfectly, a result which leaves some wiggle room for physicists to think up other types of strange new particles.

Clouds of linked-up atoms are doing the splits.

Scientists forged quantum connections between separate regions within clouds of ultracold atoms, demonstrating entanglement between thousands of particles in two different locations. Previous similar experiments had entangled several thousand atoms, but only within one entire cloud (SN Online: 3/25/15).

Now researchers have split up a cloud of entangled atoms into separate regions, either by considering two areas in a single cloud to be distinct or by actually forming two separate clouds, according to a trio of papers (found here, here and here) published in the April 27 Science. The new technique is a step toward quantum devices that make precise measurements, for example of electric fields.

Entanglement is a bizarre quantum phenomenon where separate objects, whether individual particles or groups of particles, behave as a conjoined entity. Measuring one object immediately reveals information about the other, even when the two are in different locations, such as distinct atomic clouds.

Nicholas Blackwell and his father went to a hardware store about three years ago seeking parts for a mystery device from the past. They carefully selected wood and other materials to assemble a stonecutting pendulum that, if Blackwell is right, resembles contraptions once used to build majestic Bronze Age palaces.

With no ancient drawings or blueprints of the tool for guidance, the two men relied on their combined knowledge of archaeology and construction.

Blackwell, an archaeologist at Indiana University Bloomington, had the necessary Bronze Age background. His father, George, brought construction cred to the project. Blackwell grew up watching George, a plumber who owned his own business, fix and build stuff around the house. By high school, the younger Blackwell worked summers helping his dad install heating systems and plumbing at construction sites. The menial tasks Nicholas took on, such as measuring and cutting pipes, were not his idea of fun.
But that earlier work paid off as the two put together their version of a Bronze Age pendulum saw — a stonecutting tool from around 3,300 years ago that has long intrigued researchers. Power drills, ratchets and other tools that George regularly used around the house made the project, built in George’s Virginia backyard, possible.

“My father enjoyed working on the pendulum saw, although he and my mother were a bit concerned about what the neighbors would think when they saw this big wooden thing in their backyard,” Blackwell says. Anyone walking by the fenceless yard had a prime view of a 2.5-meter-tall, blade-swinging apparatus reminiscent of Edgar Allan Poe’s literary torture device.
No one alive today has seen an actual Bronze Age pendulum saw. No frameworks or blades have been excavated. Yet archaeologists have suspected for nearly 30 years that a contraption capable of swinging a sharp piece of metal back and forth with human guidance must have created curved incisions on large pieces of stonework from Greece’s Mycenaean civilization. These distinctive cuts appeared during a century of palace construction, from nearly 3,300 years ago until the ancient Greek society collapsed along with a handful of other Bronze Age civilizations. Mycenaeans built palaces for kings and administrative centers for a centralized government. These ancient people spoke a precursor language to that of Classical Greek civilization, which emerged around 2,600 years ago.

In Blackwell’s view, only one tool — a pendulum saw — could have harnessed enough speed and power to slice through the especially tough type of rock that Mycenaeans used for pillars, gateways and thresholds in palaces and some large tombs.

Kings at the time valued this especially hard rock, known as conglomerate, for the look of its mineral and rock fragments, which form colorful circular and angled shapes.

In the early 20th century, archaeologists excavating a Mycenaean hill fort called Tiryns first noticed curved cut marks on the sides of pillar bases and other parts of a royal palace. The researchers assumed that ancient workers sliced through conglomerate blocks with curved, handheld saws and a lot of elbow grease.
Some investigators still suspect that handheld saws make more sense than a swinging pendulum blade. But scholarly opinions began to change as similar marks were found on stonework at other Mycenaean sites, including the fortified town and citadel of Mycenae. Separate reports in the 1990s by German archaeologists proposed that a pendulum device produced curved Mycenaean masonry marks. One of the researchers estimated that a pendulum saw would have needed to swing from a massive arm, between 3 meters and 8 meters high, to create the observed curved cuts. His calculations rested on an assumption that the curved saw marks represented segments of perfect, geometric circles, which in some cases would have required the wide arc of an especially tall pendulum.
Blackwell doubted that Mycenaeans used pendulum saws as tall as 8 meters, the equivalent of about 2½ stories. But there was only one way to find out. His experiments, described in the February Antiquity, indicate that a wooden contraption supporting a blade-tipped swinging arm had to reach only about 2½ meters high to create stone marks like those at Tiryns and Mycenae.

The Indiana researcher’s homemade pendulum saw “is the most persuasive reconstruction of a Mycenaean sawing machine that was used to cut hard stones, especially conglomerate,” says archaeologist Joseph Maran of the University of Heidelberg in Germany. Only one other life-size model of a pendulum saw exists.

Swing time
Blackwell’s experimental cutting device swung into action in December 2015 right where it was built, in his parents’ Virginia backyard.

Positioned on opposite sides of the apparatus, Blackwell and his brother-in-law, Brandon Synan, pulled the sawing arm back and forth with a rope. A metal blade bolted to the bottom of the arm sliced into a limestone block. Unlike the type of conglomerate used in the Mediterranean region, limestone was readily available. The two tested four types of saw blades in the initial trials and again in February 2017.

Blackwell reviewed seven previously published designs and the one actual model of a pendulum saw that may have been used by a nearby Bronze Age society; they offered little encouragement. No consensus existed on the best shape for the blade or the most effective framework option. Designers were most notably stumped by how to build a pendulum that adjusted downward as the blade cut deeper into the stone.

Blackwell decided to build a device with two side posts, each studded with five holes drilled along its upper half, supported by a base and diagonal struts. A removable steel bar ran through opposite holes on the posts and could be set at different heights. In between the posts, the bar passed through an oval notch in the upper half of a long piece of wood — the pendulum. The notch is slightly longer than a dollar bill, giving the steel bar some leeway so the pendulum could move up and down freely while sawing.

Finally, the apparatus needed a tough, sharp business end. A Greek archaeologist that Blackwell met while working at the American School of Classical Studies at Athens from 2012 to 2015 put him in touch with a metalsmith from Crete. The craftsman fashioned four bronze blades with different shapes for testing on the pendulum saw: a long, curved blade; a triangular blade with a rounded tip; a short, straight-edged saw and a long, straight-edged saw with rounded corners. During tests with each blade, Blackwell added water and sand to the limestone surface every two minutes for lubrication and to enhance the saw’s grinding power.
Blackwell suspected the triangular blade would penetrate the limestone enough to produce the best replicas of Mycenaeans’ arced cuts. He was wrong. Putting that blade through its paces, he found that only the tip creased the stone as the pendulum swung. The triangular blade yielded a shallow, wobbly groove that would have sorely disappointed status-conscious Mycenaean elites.

The short, straight blade did even worse. It repeatedly got stuck in the stone block during trials.

But in a dramatic showing, the long, curved blade left three concave incisions that looked much like saw marks at Tiryns. It took 45 minutes of sawing to reach a depth of 25.5 millimeters, a partial cut by Mycenaean standards. Blackwell and his brother-in-law took short breaks after every 12 minutes of pendulum pulling. “It takes a lot of physical effort to use a pendulum saw,” Blackwell says.

The elongated, straight blade with rounded corners proved easiest to use. It made one Mycenaean-like cut after only 24 minutes of sawing. Either the straight or the curved blade could have fit the bill for Mycenaean stoneworkers.

Close inspection of successful experimental cuts showed that Blackwell’s pendulum saw created curved incisions that were not segments of perfect circles. So an actual Mycenaean pendulum saw need not have been as tall as those earlier calculations had called for.
Blackwell suspects that Mycenaean masons tied or glued blades to one side of a pendulum’s arm. After sawing deep enough so that the pendulum’s wooden end hit rock, a worker chiseled and hammered off stone on one side of the incision so that the blade could be lowered for deeper sawing. Repeating those steps several times eventually left a flat face at the incision.

A half-finished pillar base from Mycenae preserves evidence of this procedure, Blackwell says. The stone displays a long, curved cut on a flat, vertical surface near one of its sides. The cut abruptly stops partway down. At that level, stone abutting the incision shows signs of having been pounded off.

Ghost saw
Even after Blackwell’s hands-on experiments, the Mycenaean pendulum saw remains an archaeological apparition. Some researchers believe it existed. Others don’t.

“Pendulum saws could have been a solution to Mycenaeans’ specific problem of having to work with conglomerate,” says archaeologist James Wright of Bryn Mawr College in Pennsylvania. Mycenaean conglomerate is considerably harder and more resistant to cutting than other types of rock that were available to the Mycenaeans and neighboring societies. Blackwell’s successful experimental incisions in limestone “conform with cut marks on Mycenaean stones,” Wright adds. The next step is to see how Blackwell’s pendulum saw performs on the tougher challenge of slicing through conglomerate.
While Blackwell’s experimental device produces Mycenaean-style curved cuts, that doesn’t mean Mycenaeans invented and used pendulum saws, contends archaeologist Jürgen Seeher of the German Archaeological Institute’s branch in Istanbul. Seeher built and tested the only other reconstruction of a pendulum saw.

In a 2007 paper published in German, Seeher concluded that there was a better option than his pendulum saw: a long, curved saw attached to a wooden bar and pulled back and forth by two people, like a loggers’ saw. A loggers’ saw could have produced curved marks on palace stones of ancient Hittite society, which existed at the same time as the Mycenaeans in what is now Turkey.

Unlike their Greek neighbors, Hittites did not construct pillars and gateways out of conglomerate. But a handheld, two-man saw would have enabled something a pendulum saw could not: precise cutting of conglomerate blocks from different angles, Seeher says.

“A handheld saw moved by two men is much more under control than a free-hanging pendulum,” he says.

Seeher has archaeological evidence on his side. Double-handled loggers’ saws have been excavated at sites from the Late Bronze Age Minoan society on Crete. Hittites and Mycenaeans, contemporaries of the Minoans, could easily have modified that design to cut stone instead of wood, Seeher proposes. They would have had to substitute rock-grinding straight edges for wood-cutting serrated edges.

Blackwell disagrees. He is convinced that Mycenaean craft workers trained for years to operate pendulum saws, just as skilled artisans like his dad go through a long apprenticeship to learn their trade. Mycenaeans may have worked in teams that took turns using pendulum saws to cut conglomerate into palace structures, he speculates. Those workers probably used highly abrasive emery sand from the Greek island of Naxos to amplify the grinding power of their swinging saws, Wright adds.

Blackwell worked with his own family team to create a rough approximation of what a Mycenaean pendulum saw may have looked like and how it was handled. His father’s construction expertise was crucial to the project. But those teenage summers doing scut work at building sites probably didn’t hurt, either.