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Abruptly Warming Climate Triggered Megabeast Revolutions

Around 34,000 years ago, woolly mammoths went extinct from parts of Europe, only to be replaced by… woolly mammoths. The two groups—the disappearing individuals and their substitutes—belonged to the same species. If you looked at their fossils, you probably couldn’t tell them apart. Their genes, however, reveal them to be part of two genetically distinct lineages, one of which suddenly displaced the other.

Alan Cooper, who specialises in studying the DNA of extinct animals, first noticed this pattern ten years ago, and not just among mammoths. The steppe bison—a huge cow—was quickly replaced by a different bison species. Later, one population of cave bear was swapped out for another genetically distinct population. Later still, the giant short-faced bear disappeared and the modern grizzly took its place. “This all happened very abruptly,” says Cooper. “They’re weren’t all happening at the same time, but the patterns were there, and many of these changes were only detectable through DNA.”

These giant beasts—the woolly mammoth, the cave and short-faced bears, the steppe bison, the Eurasian cave lion, the woolly rhino, and the Irish elk—are now extinct. There have been some two centuries of debate over what killed them. Was it a blitzkrieg of incoming humans, with our insatiable appetites and sharp spears, or was it a change in climate?

The turnovers that Cooper saw were extinctions of a kind, and they certainly didn’t seem to be due to hunting. At least six of them took place tens of thousands of years after humans arrived on the scene. If we hunted these animals to extinction, we sure took our sweet time over it, and in some cases, we seemingly ignored a virtually identical group or species that then took the place of the vanquished. An environmental event seemed more likely. But what kind of event?

To find out, the team used ancient DNA to discover cases of turnover that are hard to observe from fossils alone. They then carbon-dated the bones of the ingoing and outgoing animals to work out when these turnovers happened. Finally, they plotted these dates against an accurate record of North Atlantic climate over the past 60,000 years, gleaned from Greenland ice and Venzeuelan sediments.

Most of the replacement events lined up with sudden bursts of warming called Dansgaard-Oeschger (D-O) events, which happened a lot between 12,000 and 60,000 years ago. In each one, average temperatures abruptly rose by anywhere from 4 to 16 degrees Celsius in just a few decades, before gradually falling again over several millennia. If you plot the temperatures on a graph, you see a distinctive sawtooth pattern—sharp upward spikes of warming and then gentle downward slopes of cooling. “They’re the most abrupt changes in climate that you got in the Pleistocene—those transitions from cold to warm,” says Cooper.

When one group of large beasts cycled into another (and, eventually, into nothing), it usually happened during the warm periods, or interstadials, that followed the D-O events. “Periods of cold are often held up as a key reason for megadeath, but we see that our extinctions and genetic transitions didn’t fall in those periods of time,” says Cooper. During the cold, the animals may have retreated into warmer refuges, and their populations may have contracted, but they didn’t die out entirely. That only happened after sudden warmth.

“In the last two and a half million years, ice ages have been the rule for the earth’s climate system — the warm periods are the exception,” says Jacquelyn Gill from the University of Maine. “Given that, it absolutely makes sense that the authors found evidence for more turnover during warmer climates, rather than cold events.”

“What we don’t know is whether it’s the warming that’s doing the damage or the pace of change,” Cooper adds. It’s probably not as simple as cold-adapted species losing out to warm-adapted ones. The sudden temperature rises would also have caused dramatic changes in rainfall and other weather patterns. They might also have altered the ranges of different animals, bringing separate populations or species into new contact and new conflict. Finally, humans could still have played a role in finishing off these giant beasts, after changing climates had weakened them. Supporting that idea, Cooper’s team found that transition events were less common during earlier parts of the Pleistocene when D-O events were common but humans were not.

“These and previously published data argue convincingly that, sometimes, extinctions happened in the absence of humans—especially local extinctions followed by re-establishment of populations from elsewhere, as more ideal climate conditions returned,” says Beth Shapiro from the University of California, Santa Cruz. But “it’s hard to imagine that humans did not at least contribute somewhat,” she adds. If climate change corralled animals into ever narrower ranges, those “refuges” would have been fantastic hunting grounds—more like slaughterhouses than sanctuaries.

“As animals became stressed due to rapid changes in climate, and consequent reduction in habitat and loss of connectivity between whatever patches of habitat remain, humans are poised to have the biggest potential negative impact on these populations,” says Shapiro. “It’s about timing—poor timing, if you’re a mammoth.”

The synergistic threats of rapidly warming climate and relentlessly destructive humans has lessons for us in the present, says Cooper. “We should really be aware that if you go back 10,000 years, the climate goes apesh*t,” he says. “People generally have no idea about this, but these warm-cold-warm-cold patterns are standard for the Pleistocene. The stability of the Holocene, which human civilisation was built upon, is totally anomalous. That makes me very concerned about prodding the global climate system with a stick”, as we are now doing.

“I think these results are most sobering when applied to the present, where the few remaining megafauna survivors are some of our most threatened,” adds Gill. “When it comes to the conservation of elephants, rhinos, or tigers, it’s clear that we need to be conserving the genetic diversity that may be critical to their survival through the coming centuries of warming.”

Reference: Cooper, Turney, Hughen, Brook, McDonald, Bradshaw. 2015. Abrupt warming events drove Late Pleistocene Holarctic megafaunal turnover. Science http://dx.doi.org/10.1126/science.aac4315

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Darwin’s “Strangest” Beast Finds Place on Tree

Toxodon is perhaps one of the strangest animals ever discovered,” wrote Charles Darwin, a man who was no stranger to strangeness. He first encountered the creature in Uruguay on November 26th, 1834. “Having heard of some giant’s bones at a neighbouring farm-house…, I rode there accompanied by my host, and purchased for the value of eighteen pence the head of the Toxodon,” he later wrote.

The beast’s skeleton, once fully assembled, was a baffling mish-mash of traits. It was huge like a rhino, but it had the chiselling incisors of a rodent—its name means “arched tooth”—and the high-placed eyes and nostrils of a manatee or some other aquatic mammal. “How wonderfully are the different orders, at present time so well separated, blended together in different points of the structure of the toxodon!” Darwin wrote.

Those conflicting traits have continued to confuse scientists. Hundreds of large hoofed mammals have since been found in South America, and they fall into some 280 genera. Scientists still argue about when these mysterious beasts first evolved, whether they belong to one single group or several that evolved separately, and, mainly, which other mammals they were related too. “That’s been difficult to address because they have features that they share with a lot of different groups from across the mammalian tree,” says Ian Barnes from the Natural History Museum in London. “To some degree, people have circled around the same set of evidence for 180 years.”

Now, Barnes’ team, including student Frido Welker from the Max Planck Institute for Evolutionary Anthropology and Ross MacPhee form the American Museum of Natural History, have found a way to break out of the circle. They recovered a hardy protein called collagen from the fossil bones of Toxodon and Macrauchenia, another South American oddity that resembled a humpless camel. By comparing these molecules to those of modern mammals, the team concluded

Toxodon. Illustration by Peter Schouten from the forthcoming book "Biggest, Fiercest, Strangest" W. Norton Publishers (in production)
Toxodon. Illustration by Peter Schouten from the forthcoming book “Biggest, Fiercest, Strangest” W. Norton Publishers (in production)

that the two ancient beasts are most closely related to perissodactyls—odd-toed hoofed mammals like rhinos, tapirs, and horses.

Toxodon looks a bit like a hippo and we now know that the features they share with hippos are probably due to convergence,” says Barnes. “Macrauchenia looks a bit like a camel, but we can now see that it’s not particularly well related to camels.. This has been a longstanding mystery and we have an answer, and that’s satisfying.”

The discovery has bigger implications, though. Many scientists, Barnes included, have recovered DNA from very old fossils. They have sequenced the full genomes of mammoths and Neanderthals, worked out the evolutionary relationships of giant birds, and even discovered entirely new groups of early humans. But ancient DNA has its limits.

To fish it out of fossils, you need molecular bait, and to design that bait, it really helps to know what kind of animal you’re looking for and what they’re related to. If you don’t, and your only clue is “er, some kind of mammal”, then recovering ancient DNA is hard. It becomes harder if the fossils are also very old, since DNA has a half-life of around 521 years. And it becomes absurdly hard if the bones come from warm climates, like most of South America, where DNA degrades even faster than usual.

Collagen, however, is exceptionally durable. This rope-like protein gives strength and elasticity to our skin, ligaments, tendons, and other tissues. “In principle, it should survive ten times longer than DNA in bone,” says Barnes. And while bones contain just a tiny amount of DNA, they carry a huge amount of collagen—this one molecule makes up 25 to 30 percent of the total proteins in our body. (This bounty also means that contamination of ancient samples by collagen from scientists or other creatures isn’t really a problem.)

Macrauchenia. Illustration by Peter Schouten from the forthcoming book "Biggest, Fiercest, Strangest" W. Norton Publishers (in production)
Macrauchenia. Illustration by Peter Schouten from the forthcoming book “Biggest, Fiercest, Strangest” W. Norton Publishers (in production)

To analyse the ancient collagen, Barnes worked with Matthew Collins from the University of York. They assembled near-complete sequences of COL1—the most common form of collagen—from both Toxodon and Macrauchenia. They then compared these sequences to COL1 from 76 mammal species (and one chicken) to build a family tree, with Toxodon and Macrauchenia perched at the base of the perissodactyl branch.

But Maureen O’Leary from the Stony Book School of Medicine, who studies mammal evolution, says that this approach is “not methodologically sound”. Before creating their tree, she says, the team should have combined their data with published information on other molecules and physical features.

Alan Cooper, an ancient DNA specialist from the University of Adelaide, adds that ancient proteins have their problems. Collagen does such an important job that it doesn’t change very easily; when it does, it is severely constrained in how it can change. As such, similarities between two collagen sequences might imply that their owners are genuinely related, or that they were independently forced down the same convergent routes. “The phylogenetic resolution of protein sequences”—that is, their ability to tell you what’s related to what—“is pretty ropey,” says Cooper.

That said, he notes that the team’s family tree makes sense. Toxodon and Macrauchenia are so weird that they could sit anywhere, but the rest of the branches and twigs are (mostly) where they should be. “It’s good to see something come out on Macrauchenia at last,” he adds. “A lot of us having been trying to get ancient DNA out of remains for a while. I suspect that’ll finally happen, at which point it’ll be really interesting to see how the [family trees] compare.”

Toxodon and Macrauchenia belong to two separate orders of South America’s weird hoofed mammals. There are three more, and, “unfortunately, the likelihood is that we won’t get similarly nice results from looking at any of them,” says Barnes. They went extinct too early; their fossils are too old. The only option is to identify the features in Toxodon and Macrauchenia’s bones that hint at their affinities with the horses and rhinos. They might then be able to focus at the same features in their other enigmatic neighbours.

Collins hopes that sequencing ancient proteins will provide researchers with another way of understanding prehistoric life, especially in situations where DNA preserves badly. His team, for example, have looked at proteins in ancient dental plaque to study the history of human milk consumption and our longstanding battles against oral infections. “A lot of people are aware that DNA sequencing is changing, but protein sequencing is undergoing a similar revolution in the sensitivity of the instruments,” adds Barnes. “Who’s to say what we can do?”

Reference: Welker, Collins, Thomas, Wadsley, Brace, Cappellini, Turvey, Reguero, Gelfo, Kramarz, Burger, Thomas-Oates, Ashford, Ashton, Rowsell, Porter, Kessler, Fischer, Baessmann, Kaspar, Olsen, Kiley, Eillott, Kelstrup, Mullin, Hofreiter, Willerslev, Hublin, Orlando, Barnes & MacPhee. 2015. Ancient proteins resolve the evolutionary history of Darwin’s South American ungulates. http://dx.doi.org/10.1038/nature14249

PS: Another team of scientists led by Mary Schweitzer claims to have recovered and sequenced collagen from dinosaurs like Tyrannosaurus and Brachylophosaurus. Those results have always been controversial and still are. Toxodon lived a couple of million years ago; these dinosaurs lived at least 65 million years ago. Even collagen has its limits, although Schweitzer’s team argues that the protein’s rope-like structure protected some parts of it. “We’re working within the accepted limits of collagen survival,” says Barnes. “Schweitzer’s work requires a different mechanism, that I don’t understand, and they’d be the first to admit that the results they get are very, very fragmentary.”


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Deinocheirus Exposed: Meet The Body Behind the Terrible Hand

The original "terrible hands". Credit: Eduard Solà
The original “terrible hands”. Credit: Eduard Solà

For 50 years, the dinosaur was just a pair of arms.

But what arms! Each was eight feet (2.4 metres) long, and ended in three eight-inch (20-centimetre) claws. You can understand why the scientists who discovered this beast called it Deinocheirus mirificus, from the Greek for “terrible hand, which is unusual”.

The arms, hands, and shoulder girdle were discovered in 1965 in Mongolia’s Gobi desert, nestled within a 70-million-year-old sandstone formation. But the rest of the skeleton was missing, save for a few uninformative fragments. Palaeontologists have repeatedly ventured into the Gobi to try and find the rest of the animal, but without success.

These failures have turned Deinocheirus into one of palaeontology’s most enduring mysteries. What kind of dinosaur was it? It was big, but how big? What did it eat? How did it live? No one could say. It was a riddle, wrapped in an enigma, hidden behind two gigantic arms.

Now, a team of palaeontologists led by Yuong-Nam Lee from the Korea Institute of Geoscience & Mineral Resources has finally discovered two well-preserved specimens of Deinocheirus, which reveal the complete body behind those terrible hands.

“These new specimens really solve the mystery once and for all,” says Stephen Brusatte from the University of Edinburgh. “And they tell us Deinocheirus was much weirder than anyone could have imagined—a colossal, slow-moving, horse-headed, hump-backed dinosaur that looks like something out of a bad sci-fi movie.“

The fossils confirm what many scientists had suspected: that Deinocheirus was one of the ostrich-like ornithomimosaurs. These dinosaurs are mostly lithe and fast-running, but Deinocheirus was built for size, not speed. At 11 metres long and 6,000 kilograms in weight, it was huge, almost as big as the infamous Tyrannosaurus rex. It wasn’t a ferocious predator, though. It couldn’t move quickly or bite strongly, and most tellingly of all, its long, duck-like snout had no teeth! In fact, bite marks on the original bones suggest that it was meat for the unfriendly neighbourhood tyrannosaur, Tarbosaurus

Lee suspects that Deinocheirus fed on soft plants, especially those growing on the bottom of streams and lakes. It could have rustled these up with its broad bill, and then sucked them up using the huge tongue that undoubtedly sat inside its cavernous lower jaw. It then ground up its food by swallowing stones and using them as an internal mill, like ostriches and many other birds do today. Lee’s team found more than 1,400 of these gizzard stones, or gastroliths, inside the torsos of their specimens.

But they also found fish remains among the stones. This supports the idea that Deinocheirus frequented freshwater, but it suggests that the giant dinosaur ate pretty much anything. “This alien creature was a monstrous omnivore, a garbage-disposal type of dinosaur that fed on fish, small vertebrates, plants, and probably about anything it could get its hands on,” says Brusatte. And if that’s the case, its terrible hands were probably nothing more than extravagant gathering devices, used to dig for food or pull down high branches.

Lee’s team also showed that the bones at the end of Deinocheirus’s tail were fused into a single structure called a pygostyle—a feature that, in modern birds, supports tail feathers. If Deinocheirus had a pygostyle, it most likely wafted a fan of tail feathers too.

But the most surprising parts of its anatomy were the thick bony spines sticking upwards from its backbone, creating a… sail? Lee cautions that this structure was thicker than a real sail, like those of Spinosaurus or Ouranosaurus. Nor was it like a camel’s thick hump. Instead, Lee thinks that ligaments coming off the spines helped to support the creature’s huge abdomen and legs. The closest analogues are man-made structures—cable-stayed bridges that support a long surface with cables branching off from a few central towers.

Deinocheirus reconstruction. Credit: Yuong-Nam Lee
Deinocheirus reconstruction. Credit: Yuong-Nam Lee

“It is amazing to see what Deinocheirus looked like in its entirety after being known from only two gigantic arms for the past 50 years,” says Darla Zelenitsky from the University of Calgary. “It’s also sad in a way. As a kid, your imagination would run wild about the nature of the beast behind those massive arms. That mystery is now gone.”

Lee’s team made their initial breakthrough in August 16, 2009, in a quarry at Mongolia’s Nemegt Formation. Poachers had already been to work at the site, which was full of isolated bones and several broken fossil-filled blocks. Still, among the remnants, the team found what was clearly the left arm of a Deinocheirus, along with a largely complete skeleton. It was missing parts of the spine, the right arm, and the hands, but the rest of it was there. Jackpot!

After analysing this specimen, the team realised that they already had another Deinocheirus in their collection! It had been collected three years earlier from a different quarry, but since it was missing its front half, no one realised that it belonged to the same animal as terrible hands of 1965. “These specimens remind us of the potential problems with reconstructing a particular dinosaur’s appearance from a few bones or incomplete skeletons,” says Zelenitsky.

Lee now plans to study the bones and brain case of Deinocheirus in more detail, and to really understand the function of the weird back spines. And he wants to find more specimens on his yearly trips to the Gobi Desert. “It will be much easier than before because we know almost all skeletal features of it,” he says.

“Nothing shocks me with dinosaurs anymore,” says Brusatte. “We’ve already seen bizarre new specimens of long-snouted tyrannosaurs, chickens from hell, monstrous dreadnought sauropods, and shark-eating spinosaurs within the last few months, and now this. Who knows what we’ll find next?”

Reference: Lee, Barsbold, Currie, Kobayashi, Lee, Godefroit, Escuillie & Chinzorig. 2014. Resolving the long-standing enigmas of a giant ornithomimosaur Deinocheirus mirificus. Nature http://dx.doi.org/10.1038/nature13874

[Kudos to fellow Phenom Brian Switek for breaking this story a year ago, when the specimens were first described at a conference.]

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Why Dinosaurs Were Like Tuna, Great Whites, and Echidnas

Fifty years ago, dinosaurs lumbered across our screens like the slow-moving, shambling oafs they were thought to be. Now, they stride and sprint. They’re portrayed as active animals, often lithe and agile.

This popular makeover was inspired by a scientific one. Scientists used to believe that dinosaurs, like modern-day reptiles, were cold-blooded ectotherms. That doesn’t mean their blood was literally cold, but that they relied on the environment to heat their bodies. Many lines of evidence challenged this view, suggesting instead that some dinosaurs were warm-blooded endotherms like mammals and birds: they generated body heat by burning energy at a much greater rate than most reptiles.

This debate about dinosaur metabolism—were they ectotherms, endotherms or something in between?—is one of the longest-running in palaeontology. (“It feels like almost everyone working in dino palaeontology has weighed in on it at some point in their career,” says John Hutchinson.) Scientists have tried to address the issue by looking at the structure of their bones, the shape of their legs, the inferred anatomy of their lungs, the presence of insulating feathers, and the ratios of predators to prey. And some have tried to work out how quickly they grew.

Dinosaur bones are like tree trunks—they have rings, and each ring represents a year of growth. By studying specimens of different ages, scientists can work out how quickly these animals grew and how must energy they must have burned to do so. Bone rings give you growth rate, which gives you metabolic rate.

It’s an attractive approach because, unlike bone structure or the presence of feathers, growth can be quantified and clearly compared. “You can put a number on it,” says John Grady from the University of New Mexico. But these numbers come in drips, through piecemeal studies of a few species at most. Grady had grander aspirations.

His team has now amassed data on the growth rates of 381 animal species, both living and extinct, including 21 dinosaurs, 6 extinct crocodiles, and one prehistoric shark. He looked Tyrannosaurus and Apatosaurus, blue whales and deer mice, hammerhead sharks and Komodo dragons. He estimated each animal’s mass, growth rate, and metabolic rates, often refining (or completely reworking) mathematical models from earlier studies.


His analysis revealed that dinosaurs sit somewhere between the endothermic and ecothermic extremes, epitomised by most mammals and reptiles. They couldn’t control their body temperature as precisely as a horse or human; equally, they weren’t as dependent on their environment as a snake or lizard. “The data pointed to dinosaurs not being quite like a reptile or a mammal, but to weird things like great white sharks, leatherback turtles, and tuna.”

Great whites and tuna are mostly cold-blooded but their hard-working muscles naturally heat their blood. In most fish, the warm blood would lose its heat as it travels to the gills for a dose of oxygen. But in these fish, the vessels are arranged so that the warm blood from the muscles travels past cold blood from the gills, and heats it up. They create body heat, and keep that heat in their bodies—a trick that can keep certain body parts up to 14 degrees Celsius hotter than the surrounding water,

The leatherback turtle uses similar heat exchangers, and it’s also very big. Big animals lose heat more slowly than small ones, so the leatherback has a sort of thermal inertia that keeps it warm.

Grady thinks that most dinosaurs used a similar strategy, which he calls mesothermy. They were lukewarm-blooded.

This isn’t just a wishy-washy middle-man term; it has a specific meaning. Endotherms use their metabolism to keep their body temperatures at a fixed point—excepting the occasional chill or fever, you’re almost always at 37 degrees Celsius. Ectotherms have more variable body temperatures and rely on the environment to heat themselves up. Some, like big crocodiles, are homeotherms—they rely on their size to keep a stable body temperature once they bask their way to warmth.

Mesotherms are different. Unlike a basking crocodile, they rely on their own metabolism to raise their body temperature. But unlike you, they don’t keep their temperatures at a fixed point. They turn the heating on, but they have no thermostats. Great whites and leatherbacks are good examples but mammals can be mesotherms too. The echidna—a spiny, egg-laying mammal from Australia—metabolises its way to an average temperature of 31 degrees Celsius, but that can vary by 10 degrees in either direction. It has a thermostat, but a very wobbly one.

Grady’s conclusion isn’t that new. Many, if not most, palaeontologists see the warm-blooded/cold-blooded debate as too simplistic. Instead, they believe there’s a continuum between these extremes, and dinosaurs fell somewhere in the middle.  “There have been many studies arguing for intermediate metabolic rates in dinosaurs,” says Hutchinson, from the Royal Veterinary College, UK. “But this one stands out on its statistical treatment. It is very clear and testable, and it fits with other evidence.”

“To me, a lynchpin would be how this works for polar dinosaurs,” he adds. Grady’s team focused on species that lived in warm climates, and many dinosaurs lived in places with uncomfortable winters. Would a baby dinosaur living in a cold place still be mesothermic, or would it do something different? That’s something for the team to check next.


For now, Gregory Erickson from Florida State University, who has studied dinosaur growth, effusively praised the team’s attention to detail. “This is a remarkably integrative, landmark study [that] sets a new standard for growth research on extinct animals,” he says.  “Now we can more rigorously compare how dinosaurs and the earliest birds grew relative to [living] animals and infer their metabolic status.”

Mieke Köhler from the Catalan Institute of Palaeontology is a bit more reserved. She notes that echidnas, tuna, and leatherbacks are all mesotherms, but control their body temperatures in very different ways. “They rely on completely different metabolic machinery,” she says. “They’re not a discreet group, but a collection of specialists that shifted their physiological state away from the extremes to converge somewhere in the middle.” By bundling the dinosaurs together under the same label, we risk whitewashing important differences in their lifestyles.

They were, after all, a very varied group. They dominated the planet for 185 million years, and there’s more time between Stegosaurus and Tyrannosaurus than between Tyrannosaurus and you. They diversified into forms both titanic and minute. Some had feathers and others didn’t. Some lived in the tropics and others lived in the freezing poles. If modern fish and mammals can vary in their physiology, they would have too. “There was probably variety, but I think many to most were mesotherms,” says Grady. “It makes sense of the conflicting back and forth evidence we’ve had. They’re not like modern birds or like reptiles.”

Even feathered dinosaurs like Archaeopteryx, which was either not quite a bird or just about a bird, came out as mesotherms. That surprised Grady. “This thing that was feathered like a bird wasn’t that much different to these non-feathered dinosaurs in how fast it grew,” he says. And it grew slowly! It took around 2 years for Archaeopteryx to reach adult size. A similarly sized hawk gets there in 6 weeks. “Its energy use was much lower than modern birds, but it was covered in feathers. Maybe it was an endotherm with a low metabolic rate, or something like the echidna. The jury’s still out.”

To Hutchinson, these results hint at a more interesting question than “Were dinosaurs warm-blooded or cold-blooded?” Instead, he would ask: “When did the ancestors of birds evolve a high metabolic rate?”

Grady also wonders if mesothermy could help to explain the long reign and frequent large size of dinosaurs. By raising their body temperatures, they could move their muscles faster and fire their nerves faster, becoming temporarily better at escaping or hunting. That’s why sharks and tuna do it. Swordfish and marlin can even warm up their brains and eyes to process information faster when they hunt.

But fully endothermic animals need to eat a lot to fuel their inner furnaces, which sets a limit to how big they can get. Grady wonders if mesothermy strikes a happy medium, allowing animals to stay competitive while also getting big.

Reference: Grady, Enquist, Dettweiler-Robinson, Wright & Smith. 2014. Evidence for mesothermy in dinosaurs. Science http://dx.doi.org/10.1126/science.1253143

PS: Dinosaur fans might be wondering about a recent controversy in which physicist Nathan Myhrvold challenged many published estimates of dinosaur growth rates, and argued that several papers contained serious flaws and discrepancies in their data. Grady’s paper was mid-way through the peer-review process when Myhrvold’s analysis landed, and he paid serious attention to it. But when he omitted data from the problematic papers (or even for problematic species), his results didn’t change. There are five pages of discussion on this in the supplemental materials for statisticians to pore over.

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A Nervous System From Half A Billion Years Ago

If I tell you that scientists have studied the nervous system of a creature that’s half a billion years old, it’s hard to appreciate what that means. Half a billion years is, to paraphrase Douglas Adams, a vastly, hugely, mind- bogglingly big span of time, when even last week seems like an age ago.

So here’s (a concise history of) what happened since a little creature called Alalcomenaeus died:

Its body sinks to the ocean floor, gets covered in sediment and slowly turns into a stony fossil. Meanwhile, all the world’s land has time to glom together into a mega-continent called Pangaea before breaking up again. Life, was restricted to the oceans, invades the land. Plants and fungi go first, producing thin coverings of mosses and lichens and eventually giant forests. The insects appear, and take to the skies. Other marine animals evolve familiar traits like bones and jaws, and their descendants diversify across the land. Dinosaurs come, see and conquer, before (mostly) dying out. Mammals get their day and one of them, armed with technology and knowledge, unearths Alalcomenaeus from its ancient resting place in what is now China.

As I said: a vastly, hugely, mind-boggling big span of time. Lots happened.

And through all of it, the nervous system of this buried animal remained intact.

A team of scientists have now reconstructed it. There it is in the images above and below —a network of nerves that drove an animal’s behaviour in a time before life on land.

Different images of Alalcomenaeus. (a) is the fossil. (b) is an outline of iron desposits. (c) is a CT scan. (d) is the previous two overlaid on each other. (e) is the nervous system.
Different images of Alalcomenaeus. (a) is the fossil. (b) is an outline of iron desposits. (c) is a CT scan. (d) is the previous two overlaid on each other. (e) is the nervous system.

This is the second such discovery. The first was published last year, when Xiaoya Ma and Nicholas Strausfeld described the brain of a 520-million-year old animal called Fuxianhuia protensa. It consisted of three clusters of nerves (ganglia) that had fused together. Nerves from the second ganglion reached into the creature’s antennae, while nerves from the third one led into a pair of claws. Each of the animal’s eyes was served by three further nerve bundles, known as optic lobes.

“In other words, the specimen had a brain like that of a modern crustacean,” says Strausfeld. Fuxianhuia was clearly an early relative of modern crabs, lobsters and shrimp—a relationship that was unclear from its body alone.

But the team saw the result as just half of a bigger story. Today, the arthropods—successful animals with hard external skeletons and jointed legs—split into two major groups. There’s the mandibulates, which includes all insects, crustaceans, centipedes and millipedes. And there’s the chelicerates, which includes spiders, scorpions and horseshoe crabs. The nervous systems of the two groups look very different. Fuxianhuia exemplified the mandibulate pattern. What about the chelicerate one?

“Last year, we speculated that one day in future, [someone should find] a fossil that would show evidence of a chelicerate brain,” says Strausfeld. “To our surprise, that fossil turned up the very next year.”

The inch-long specimen was found at the fossil-rich Chengjiang site in southwest China. It was clearly an Alalcomenaeus, which one of the most widespread arthropods at the time. The large, claw-like appendages on its head gave it and its relatives their name—the megacherians, meaning “great hand”.

Gengo Tanaka from the Japan Agency for Marine-Earth Science and Technology created a 3-D model of the specimen using a CT-scanner, while using an X-ray microscope to measure the distribution of chemical elements in its body. Iron was especially informative, and revealed the outline of the nervous system but not other tissues like muscles. (“We don’t know why, and I doubt if anyone else does,” says Strausfeld.)

The animal’s brain consists of three fused ganglia, and blends into more ganglia that extend down the length of the animal’s body. It has four eyes, each of which is served by just one optic lobe. That’s a chelicerate layout—in mandibulates, the body ganglia would be more distinct and separated by long nerves, and there would be two to four optic lobes per eye.

The results show that the mandibulate and chelicerate lineages had well and truly split 520 million years ago, and already had the distinctive nervous systems that their modern descendants do. And this means that the ancestors of these groups, and the earliest arthropods, were around well before that. That’s what the team is now looking for.

And another question remains: how could a soft nervous system last for half a billion years? Strausfeld says that the nerves of invertebrates are dense and rich in fats, which makes them water-repellent. This, combined with their hard external skeleton, might have slowed the process of decay long enough for them to fossilise. Indeed, in an earlier study, Strausfeld’s team buried marine worms in mud and put them under high pressure to simulate the start of fossilisation—and their nerves lasted while their muscles decayed.

That’s just a guess, though. “Scientists like to demonstrate how dead animals decay and how they can thus provide misleading information as fossils,” says Strausfeld. “However, fewer scientists try experiments that might imitate conditions leading to extraordinary preservation. And extraordinary preservation that is the hallmark of Chengjiang fossils.”

Reference: Tanaka, Hou, Ma, Edgecombe & Strausfeld. 2013. Chelicerate neural ground pattern in a Cambrian great appendage arthropod. Nature http://dx.doi.org/10.1038/nature12520

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Crouching Bird, Hidden Dinosaur

Great blue heron, by Kozarluha
Great blue heron, by Kozarluha

Here’s a picture of a great blue heron raising its left leg. That joint in the middle, which most people think of as the “knee”, is actually the ankle. The true knee is just about hidden by the feathers on it belly, because the heron is holding its thigh bone horizontally against its body (as shown in pink below). So even though herons look statuesque and upright, they’re actually crouching, as is every other living bird.

Great blue heron, by Kozarluha
Great blue heron, by Kozarluha

Birds evolved from two-legged meat-eating dinosaurs but the earliest of these stood upright, with thigh bones held almost vertically below their hips. At what point did they start to crouch, and why?

Scientists have speculated about this question for decades, but Vivian Allen from the Royal Veterinary College found a clear answer by building virtual dinosaurs. He used medical scanners to reconstruct the skeletons of 17 species, representing offshoots of the lineage that eventually gave rise to birds. These ranged from a crocodile, to dinosaurs like Tyrannosaurus, Allosaurus and Velociraptor, to early birds like Archaeopteryx, to a modern chicken.

By putting virtual flesh on these skeletons, Allen showed that their crouching stance evolved gradually, just as their centre of mass (or centre of gravity) moved forward towards their heads. That seems obvious, but the reason for this weight shift was unexpected. Everyone assumed it was because the dinosaurs’ tails became lighter and shorter. Instead, Allen showed that it was because their arms became bigger.

It’s a slightly ironic result since most people studying the origin of birds already tend to focus on the arms, which slowly evolved from grasping, fuzz-covered limbs to powerful flying wings with flat vane-like feathers. Steve Gatesy from Brown University was the first person to seriously focus on the hind-limbs back in 1990, and his ideas on the evolution of dinosaur leg muscles and running gaits have since become textbook material.

John Hutchinson helped with some of this work but he still saw the origin of the birds’ crouched posture as an open question. Sure, people had compared different dinosaur skeletons by eye, but he wanted some hard numbers for their mass and their centre of mass. Why? Because it’s the key to understanding how dinosaurs moved. “The centre of mass is sort of a shorthand for the whole animal,” says Allen. “You can think of locomotion as using parts of your body to exert forces on your environment to move your centre of mass somewhere.”

Estimating centre of mass is easier said than done. You need to reconstruct a fully-fleshed animal from its bones, so you need exceptionally preserved skeletons and some way of estimating how much flesh surrounded them. Hutchinson started doing this in 1999 and Allen, his PhD student, eventually took up the baton. Fourteen years and 17 species later, their database was ready. “This paper means a lot to me because of that perseverance,” says Hutchinson. “I’m happy Viv stuck with it and believed it could be done, when many colleagues, even in our own lab, would scoff at the audacity!” (You can read Hutchinson’s own post on the study.)

The technique sounds simple: plaster virtual flesh upon virtual bones. “But we knew that these fleshy reconstructions are at least partly subjective, and therefore very difficult, if not impossible, to get right,” says Allen. To get the best estimates, he scanned living animals to see how much their fleshy outline differed from their skeletal one, and used these to build a range of different models. He made each body part—head, arms, tail, and so on—as big and small as they could plausibly be, and combined them to give a range for each animals’ mass and centre of mass.

Some scientists argued that centre of mass gradually moved towards the head over the entire bird line, while others said that it suddenly leapt forward as the earliest proto-birds developed big chests and powerful flapping muscles. Allen’s data supports both ideas to a degree.

He showed that centre of mass did move forward at an accelerated pace after the rise of small maniraptoran dinosaurs like Velociraptor and Deinonychus, roughly coinciding with the origin of flight in this group. But this was just the tail end of a smooth, long-running transition. The group’s posture and centre of mass had already been changing well before any of them took to the skies.

“Once again, this shows that there is no discontinuity between a “dinosaur-style” and a “bird-style” animal,” says Thomas Holtz Jr, a palaeontologist from the University of Maryland. “There is no real morphological moment where you see “Aha! This stopped being a dinosaur and started being a bird right here!” It’s the second decade of the 21st Century, so this shouldn’t be surprise to anyone…”

When Allen analysed the influence of individual body parts, the tail turned out to be unimportant. Instead, the size of the arms (and, to a lesser extent, the head and neck) were strongly correlated with centre of mass.

The result was so surprising that Allen and Hutchinson spent around two years checking the stats and convincing themselves. But the data kept on telling the same story: As the dinosaurs developed beefier arms, first to grasp prey or climb and then eventually to fly, their centre of mass moved forward, and their legs became more crouched. Adding mass to the front of their bodies was more important than taking it away from the back.

Next, Allen wants to use his virtual models to move from studying the evolution of dinosaur stance to understanding the evolution of their movements. That means not just fleshing out a digital skeleton, but simulating muscles, articulating joints, and the physical forces acting upon the moving limb. And the team hopes that others will join in too. They have shared all the images and methods from their study so that other scientists can add to them, or to use the data for their own purposes.

An evolutionary "tree" showing, from top-left going clockwise, Pengornis, Tyrannosaurus, crocodile, Herrerasaurus, Coelophysis, Microraptor. Art by Luis Rey
An evolutionary “tree” showing, from top-left going clockwise, Pengornis, Tyrannosaurus, crocodile, Marasuchus, Coelophysis, Microraptor. Art by Luis Rey

Reference: Allen, Bates, Li & Hutchinson. 2013. Linking the evolution of body shape and locomotor biomechanics in bird-line archosaurs. Nature http://dx.doi.org/10.1038/nature12059

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Is This Dinosaur Painted Correctly?

The animal above, with the fetching punk haircut is Anchiornis huxleyi—a small Chinese feathered dinosaur, about the size of a pigeon. If you look at any image of this creature from the past several years, you’ll probably find the same colour scheme—a body of black and grey, black-and-white stripes on the wings, and a red crest and freckles.

That’s because, in 2010, a group of scientists reconstructed Anchiornis’ colours. It was one of the first of several papers that heralded a renaissance of dinosaur art, assigning actual palettes to creatures whose colour schemes were long thought to be unknowable. Colours, after all, don’t fossilise.

But melanosomes do. These tiny pigment-containing structures are found in feathers and contribute to the colours of living birds. They were also found in the feathers of dinosaurs, and withstood the harsh fossilisation process. Look at the right fossil feathers, and you can still see the melanosomes. Their shape reflects their hues—round meatball-shaped ones are reddish-brown, while long sausage-shaped ones are blackish-grey. By studying the shapes of the fossilised melanosomes, scientists like Jakob Vinther from the University of Bristol have been able to reconstruct dinosaur colours.

But a new study raises some questions about their technique. Melanosomes, it turns out, shrink and distort when they become fossilised, so Anchiornis might have looked very differently to the image above.

Is the melanosomes technique in trouble? Not quite. I cover the new study, and the counterarguments, over at Nature News. Head over there for the rest of the story.

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The Rise and Fall of Four-Winged Birds

Look at the leg of almost any bird and you’ll see feathers covering the thigh but scales covering everything from the ‘knee’ downwards. There are a couple of exceptions—some birds of prey look like they’re wearing baggy trousers and golden eagles have fluffy foot feathers for insulation. But for the most part, living birds have naked lower legs.

It wasn’t always this way. We know that birds evolved from small two-legged, meat-eating dinosaurs that were covered in simple fuzzy feathers. Those on their arms eventually became longer and flatter, evolving from hollow tubes into flat asymmetrical vanes. They transformed from “dino-fuzz” into flight feathers, and their arms transformed into wings.

Meanwhile, it’s tempting to think that the feathers on their hind legs gradually became smaller and gave way to scales. But that’s not how it happened. For a start, we know that some small dinosaurs had long feathers on their legs as well as their arms. And now, 11 newly analysed fossils tell us that some early birds shared the same feature. These specimens suggest that some of our feathered friends had four wings.

It was an ornithologist called William Beebe who first suggested that early birds might have passed through a four-winged gliding stage on their way to evolving true flapping flight. That was in 1915 and though Beebe’s idea was fanciful, there wasn’t much strong evidence behind it.

Then, in 2003, the prolific Chinese dinosaur-hunter Xing Xu found an actual four-winged dinosaur. He called it Microraptor gui. Xu saw the outlines of feathers clearly splaying from the creature’s legs as well as its arms. These were clearly traces of long, flat and asymmetric plumes, much like those that keep today’s flying birds aloft. While it lived, Microraptor probably looked like a starling wearing flares. Xu suggested that it may have used its leg wings to help it glide, while others later suggested that it could have flown like a biplane.

Xu went on to find other dinosaurs with long leg feathers, such as Anchiornis, Pedopenna and Xiaotingia. For a time, it looked like these feathers disappeared before true birds arrived on the scene, but Xu is now back with 11 new fossils that discount that idea.

Confuciusornis. From Zheng et al, 2013. Science/AAAS
Confuciusornis. From Zheng et al, 2013. Science/AAAS

The specimens include species like Sapeornis, Confuciusornis, Cathayornis, and Yanornis. All of them are early birds, perched on primitive branches of the group’s family tree. All of them lived in China during the Cretaceous period. And all of them had four wings, with long feathers on their legs.

You can see them in the images throughout this post—dark shadows protruding from the bones of the lower leg. In some of the specimens, the leg feathers show a stiff, curved central rod (or “rachis”) with symmetrical vanes sticking out from either side. They protrude from the bones at right angles and seem to form a large flat surface.

Xu thinks that these feathers might have helped the owners to fly. They could have produced extra lift or maybe helped the birds to turn more easily. But other scientists who work on the evolution of flight are not convinced. “[Xu] has basically just taken a punt that because the feathers were stiff, they were probably aerodynamic in function,” says Michael Habib from the University of Southern California. “It is a bit of a weak argument.”

Habib thinks that the long asymmetric leg feathers of Microraptor probably did play some role in gliding or flying, but the smaller plumes of other baggy-legged species “might have merely been there because of a developmental quirk”. If some genes are producing large feathers on the front limbs, “it might not take much to tweak a set onto the hind limbs too,” he says.

Kevin Padian from the University of California, Berkeley agrees. He points out that no one has actually done any proper tests to show if the leg feathers were involved in flight. They would certainly have created drag, but they could only have provided lift if they sat in a flat sheet like the wings of modern birds. Xu claims that they were, but Padian says that the feathers could just have been flattened into a plane as they became fossilised.  “It hasn’t been shown that this is really an aerodynamically competent wing,” he says.

Nonetheless, both Habib and Padian praise Xu’s work. “It’s a great study because it establishes that leg feathers were widely distributed,” says Padian. From beginnings as small outgrowths, leg feathers became dramatically bigger in some of the dinosaur groups on the evolutionary line leading to birds. They eventually shrank away again before disappearing entirely and being replaced by scales.

Scenario for the evolution of leg feathers. From Zheng et al, 2013. Science/AAAS
Scenario for the evolution of leg feathers. From Zheng et al, 2013. Science/AAAS

Of course, like any evolutionary story, this one could be falsified or complicated by the next cool discovery. Xu says that if he discovered early birds or feathered dinosaurs with extensive scales on their feet, that would spell trouble for his hypothesis. “But personally, I am quite confident with our scenario,” he says.

Why did the leg feathers, having first become large, eventually disappear? Xu thinks that it was because the birds set their two pairs of limbs towards different ends—the front pair for flying and the hind pair for walking or running. At the same time, they might have moved from life in the trees to life on the ground, or near water. Under all these scenarios, long leg feathers would have just got in the way, and were soon lost.

Something similar may have happened in other flying animals. For example, the earliest flying insects tend to have four wings, while some of the most competent flyers like, well, flies, only have two. The second pair has evolved into a pair of gyroscopes called halteres. “In the early evolution of flight, different animal groups always try to use as much surface as possible,” says Xu. “Once the major flight organ is well developed, the animal just fires the other organs.”

Xu’s 11 specimens all came from private collectors and had been housed at the Shandong Tianyu Museum of Nature for roughly a decade. The museum contains over 2,000 specimens of early birds, many of which preserve beautiful traces of feathers, skin and more. In fact, the museum’s treasure trove of riches is so huge that it has turned into a backlog. There’s simply too much good stuff there to go through. “It took a while for me to realize how important these specimens are,” says Xu. “These days, we are working hard to extract new information from these wonderful specimens and hopefully can produce more interesting results in future.”

Reference: Zheng, Zhou, Wang, Zhang, Zhang, Wang, Wei, Wang & Xu. 2013. Hind Wings in Basal Birds and the Evolution of Leg Feathers. Science http://dx.doi.org/10.1126/science.1228753

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Of Barosaurus and Blood Pressure

This post is for Jose Canseco.

Let me explain.

Earlier this week I wrote about how the largest dinosaurs – 100-foot-plus titans such as the sauropod Supersaurusgot to be so mind-bogglingly huge. The post was a response to baseball player Jose Canseco’s tweets that weaker Jurassic gravity allowed such enormous creatures to exist in the distant past.

As astronomer Matthew Francis elucidated in a piece coordinated with mine, gravity hasn’t significantly changed since the heyday of enormous dinosaurs. And in my own contribution, I outlined how unique aspects of dinosaur biology – such as air sacs and reproducing by laying eggs – explain why immense sauropods were so much larger than any land animals before or since. Here’s the kicker – Canseco actually enjoyed the post, and asked a follow-up question about dinosaur blood pressure!

Here’s Canseco’s question:

On the surface, the idea that long-necked sauropod dinosaurs had pseudo-hearts or blood accelerators seems like a fantastic sci-fi invention. But it’s an idea that paleontologists have actually entertained and addressed in their quest to understand the huge animals. There’s no evidence that dinosaurs of any sort had bizarre accessory hearts, but the idea has still played a small role in the ongoing investigation into how giant dinosaurs actually lived. To start, we have to go back to ancient bones and the ways in which paleontologists put them together.


Pin the Nose on the Dinosaur

Brachiosaurus was not a swampbound dinosaur. The magnificent “arm lizard”, over 80 feet long from snout to tail tip, trod over Late Jurassic, fern-covered floodplains now preserved in the 150 million year old rock of the American west. Still, when my much younger self first saw Zdeněk Burian’s restoration of Brachiosaurus submerged almost up to its head, I couldn’t deny that the illustration just looked right. It wasn’t so much the dinosaur’s bulk, but that the sauropod’s nose was atop its head – why would such an enormous herbivore need a dorsal nose unless the dinosaur hid its girth underwater?


M is for Montanoceratops

Of all the dinosaurs that have ever lived, ceratopsians were some of the most impressive. There was the huge, three-horned Triceratops; Kosmoceratops, the so-called “horniest dinosaur“; and the hook-horned Einiosaurus, to name just a few. Yet ceratopsians were not just prickly giants. (All the big-bodied forms fall into a particular ceratopsian subgroup called ceratopsids.) The wider ceratopsian family included smaller forms with deep tails and skulls that generally lacked the imposing ornaments of their larger cousins. Protoceratops from the Cretaceous of Mongolia’s Gobi Desert is the most familiar of these often-overlooked ceratopsians, but North America sported a variety of genera, too. Among them was Montanoceratops, a comparatively small horned dinosaur that coexisted with its burlier, spikier relatives.


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Fossil Insect Hid By Carrying a Basket of Trash

If you travelled back to Spain, during the Cretaceous period, you might see an insect so bizarre that you’d think you were hallucinating. That’s certainly what Ricardo Pérez-de la Fuente thought when he found the creature entombed in amber in 2008.

The fossilised insect of the larva of a lacewing. Around 1,200 species of lacewings still exist, and their larvae are voracious predators of aphids and other small bugs. They also attach bits of garbage to tangled bristles jutting from their backs, including plant fibres, bits of bark and leaf, algae and moss, snail shells, and even the corpses of their victims. Dressed as walking trash, the larvae camouflage themselves from predators like wasps or cannibalistic lacewings. And even if they are found, the coats of detritus act as physical shields.

We now know that this strategy is an ancient one, because the lacewing in De la Fuente’s amber nugget—which is 110 million years old—also used it. It’s barely a centimetre long, and has the same long legs, sickle-shaped jaws, and trash-carrying structures of modern lacewing larvae. But it took camouflage to even more elaborate extremes. Rather than simple bristles, it had a few dozen extremely long tubes, longer even than the larva’s own body. Each one has smaller trumpet-shaped fibres branching off from it, forming a large basket for carrying trash.

De la Fuente called it Hallucinochrysa diogenesi, a name that is both evocative and cheekily descriptive. The first part comes from the Latin “hallucinatus” and references “the bizarreness of the insect”. The second comes from Diogenes the Greek philosopher, whose name is associated with a disorder where people compulsively hoard trash.


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Fossilised Microbe in 200 Million Year Old Leech Cocoon

If you want to preserve your body so that scientists will dig it up millions of years from now, there are a few standard ways of doing it. You could get buried in sediment, so your bones and other hard tissues turn into stony fossils. You could get trapped in the sap of a tree, which will eventually entomb your body in gorgeous amber. Or if that’s a bit too flashy, try snuggling up in the cocoon of a leech.

Leeches and earthworms secrete cocoons of mucus and lay their eggs inside. After a few days, the mucus hardens into a hard protective capsule that’s remarkably resistant to changes in temperature and chemical attacks. These cocoons fossilise very well, and palaeontologists have found many made by prehistoric leeches, dating right back to the Triassic period when dinosaurs first appeared.

To Benjamin Bomfleur from the University of Kansas, these cocoons are a goldmine of information into the past. In one specimen, 200 million years old, he has found the remains of a microscopic soft-bodied creature that would normally be impossible to fossilise. In the leech’s cocoon, it found a way into the present.


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‘Bird mimic’ dinosaur hints that wings evolved for show not flight

In 1890, the fossil-hunter Othniel Charles Marsh described a new species of dinosaur from Colorado. He only had a foot and part of a hand to go on, but they were so bird-like that Marsh called the beast Ornithomimus – the bird mimic. As the rest of Ornithomimus’ skeleton was later discovered, Marsh’s description seemed more and more apt. It ran on two legs, and had a beaked, toothless mouth. Despite the long tail and grasping arms, it vaguely resembled an ostrich, and it lent its name to an entire family – the ornithomimids—which are colloquially known as “ostrich dinosaurs”.

Now, the bird mimic has become even more bird-like. By analysing two new specimens, and poring over an old famous one, Darla Zelenitsky from the University of Calgary has found evidence that Ornithomimus had feathers. And not just simple filaments, but wings – fans of long feathers splaying from the arms of adults. (More technically, it had “pennibrachia” – a word for wing-like arms that couldn’t be used to glide or fly.)


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At the bottom of a Japanese lake, the key to more accurate carbon-dating

Carbon-dating is a widely used technique that allows us to gauge the age of archaeological samples from up to 60,000 years ago. But it’s not a straightforward method.

It relies on a radioactive version of carbon called carbon-14, which is formed in the atmosphere and is taken up by plants (and whatever eats the plants). Once these die, the carbon-14 in their bodies decays away at a steady, predictable rate. By measuring it, we can calculate how old an ancient sample is.

But there’s a catch. The levels of carbon-14 in the atmosphere vary from year to year, so scientists need some way of assessing these fluctuations to correct their estimates. They need long-running timetables, where each year in the past several millennia can be “read”, but where true levels of atmospheric carbon-14 can be measured.

And now, in the bottom of a Japanese lake, scientists have found the best such timetable yet. As I write in The Scientist:

The sediment of a Japanese lake has preserved a time capsule of radioactive carbon, dating back to 52,800 years ago. By providing a more precise record of this element in the atmosphere, the new data will make the process of carbon-dating more accurate, refining estimates by hundreds of years.

The data will allow archaeologists to better gauge the age of their samples and estimate the timing of important events such as the extinction of Neanderthals or the spread of modern humans through Europe.

“It’s like getting a higher-resolution telescope,” said Christopher Bronk Ramsey from the University of Oxford, who led the study. “We can look [with] more detail at things [such as] the exact relation between human activity and changes in climate.”

Head over there for more.

Image by Christopher Bronk Ramsey