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10 Pterosaur Facts from AMNH's New Exhibit

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AMNH

For a long time, scientists didn't know much about pterosaurs; it was tough to even find fossils of the creatures, since only a tiny fraction died in places where their bones could be preserved. But now, the time is ripe for an exhibition of pterosaurs, says Mark Norell, chair of the American Museum of Natural History's Paleontology Division. "We've learned a lot recently about pterosaurs," he tells mental_floss, "and nobody's ever done an exhibition before."

Norell is one of the curators of the museum's new exhibition, Pterosaurs: Flight in the Age of the Dinosaurs, which opens on Saturday. He prepped by creating a wish list of pterosaur fossils and casts, which he got by exchanging some of the museum's fossil casts and things he'd excavated with museum curators around the world. There were items Norell knew he needed to have for this exhibition: "There's the unique pterosaur embryo. We had to have the eudimorphodon, which is the pterosaur from Italy. We had to have dimorphodon from The National History Museum of London. I really wanted to get Dark Wing," top, a fossil discovered in Germany in 2001 that's so well-preserved scientists were able to see details of the wing structure.

The exhibition doesn't just have fossils; scientists also built full-sized models of different pterosaurs and created interactive programs that allow visitors to fly like the creatures. Here's what we learned from an early tour.

1. Pterosaurs weren’t dinosaurs. In fact, that’s the main myth that Norell wants to dispel. Pterosaurs were cousins of the dinosaurs that evolved from a land-dwelling reptile. They were the first animals after insects to evolve powered flight, and the largest creatures ever to fly.

2. The animals varied widely in size, according to Norell: “They range from Nemicolopterus cryptus, which is about the size of a finch, to Quetzalcoatlus northropi,” above, which had a wingspan of more than 33 feet. So far, more than 150 species of pterosaurs have been discovered, and scientists believe there were probably thousands more.

3. Scientists once imagined many ways that pterosaurs might move on land—including upside down in trees, like sloths, or hopping and running on two feet, like birds—but recently discovered fossil tracks suggest that pterosaurs walked on all fours, folding up their wings like umbrellas.

4. Listen up, producers of Jurassic World: If you're going to put pterosaurs in your movie, make sure they've got a little fuzz. New research has revealed that pterosaurs were actually fluffy, which means they were probably warm-blooded, like bats and birds.

5. Scientists aren’t really sure what pterosaurs used their crests for, but they do have some theories: species recognition, sexual selection, cooling, and steering. But Michael Habib, Assistant Professor of Cell and Neurobiology at the University of Southern California and an expert on pterosaur flight who participated in the exhibition, thinks that last one is unlikely, based on tests scientists have performed on model pterosaur heads in wind tunnels. “In order to get [the crests] into a position where they really help at all—for the few crests that could produce useful force in that regard—you had to put the head and neck into really awkward positions that were potentially damaging to the animal,” Habib says. “That also matches what we see in terms of the anatomy, if that is true. If they were used for some other functions—say, a display function—you'd expect the crest would sometimes be very large, and they would be highly variable in the shape. Sure enough, they’re all over the place. They don't seem to particularly correlate with wing shape and structure at all. And that speaks strongly against any kind of aerodynamic function.” That doesn’t mean the crests wouldn’t have an aerodynamic effect; in fact, they’d increase drag. “They would be costly,” Habib says. “But a lot of display structure is costly.”

6. Their eggs were soft-shelled, and only a few have been found so far. (Dinosaurs, by comparison, laid hard-shelled eggs.) By the time a pterosaur hatched, its wings were fully formed; it probably could have taken off shortly after it hatched. Though scientists once imagined pterosaurs caring for their young in nests, they now believe the young hatchlings were on their own from the start.

7. Pterosaur bones were hollow, with walls as thin as playing cards. Like bird's bones, they were strengthened by internal struts. By comparing pterosaur and bird brain casts, scientists have determined that the creatures' brains were similar in certain ways—both had well developed regions for vision and balance, which are important in flying. 

8. Pterosaurs lived from 220 million years ago to 66 million years ago, when they were wiped out with the non-avian dinosaurs.


Photo by Erin McCarthy

9. The first pterosaur discovered and described was Pterodactylus Antiquus (above). It was acquired by a German ruler in the late 1700s and kept in a Wunderkammer, or Curiosity Cabinet; the specimen was eventually named by French naturalist Georges Cuvier, who correctly identified it as a flying reptile, in 1809. (Ptero-dactyle means “wing finger.”) And the discoveries keep coming today: Norell and some colleagues have discovered parts of a new pterosaur that they think is around 15 percent bigger than Quetzalcoatlus 

10. Pterosaurs' closest living relatives are two vastly different animals: Crocodiles and birds. 

All photos courtesy of AMNH unless otherwise noted.

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Man Buys Two Metric Tons of LEGO Bricks; Sorts Them Via Machine Learning
May 21, 2017
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iStock // Ekaterina Minaeva

Jacques Mattheij made a small, but awesome, mistake. He went on eBay one evening and bid on a bunch of bulk LEGO brick auctions, then went to sleep. Upon waking, he discovered that he was the high bidder on many, and was now the proud owner of two tons of LEGO bricks. (This is about 4400 pounds.) He wrote, "[L]esson 1: if you win almost all bids you are bidding too high."

Mattheij had noticed that bulk, unsorted bricks sell for something like €10/kilogram, whereas sets are roughly €40/kg and rare parts go for up to €100/kg. Much of the value of the bricks is in their sorting. If he could reduce the entropy of these bins of unsorted bricks, he could make a tidy profit. While many people do this work by hand, the problem is enormous—just the kind of challenge for a computer. Mattheij writes:

There are 38000+ shapes and there are 100+ possible shades of color (you can roughly tell how old someone is by asking them what lego colors they remember from their youth).

In the following months, Mattheij built a proof-of-concept sorting system using, of course, LEGO. He broke the problem down into a series of sub-problems (including "feeding LEGO reliably from a hopper is surprisingly hard," one of those facts of nature that will stymie even the best system design). After tinkering with the prototype at length, he expanded the system to a surprisingly complex system of conveyer belts (powered by a home treadmill), various pieces of cabinetry, and "copious quantities of crazy glue."

Here's a video showing the current system running at low speed:

The key part of the system was running the bricks past a camera paired with a computer running a neural net-based image classifier. That allows the computer (when sufficiently trained on brick images) to recognize bricks and thus categorize them by color, shape, or other parameters. Remember that as bricks pass by, they can be in any orientation, can be dirty, can even be stuck to other pieces. So having a flexible software system is key to recognizing—in a fraction of a second—what a given brick is, in order to sort it out. When a match is found, a jet of compressed air pops the piece off the conveyer belt and into a waiting bin.

After much experimentation, Mattheij rewrote the software (several times in fact) to accomplish a variety of basic tasks. At its core, the system takes images from a webcam and feeds them to a neural network to do the classification. Of course, the neural net needs to be "trained" by showing it lots of images, and telling it what those images represent. Mattheij's breakthrough was allowing the machine to effectively train itself, with guidance: Running pieces through allows the system to take its own photos, make a guess, and build on that guess. As long as Mattheij corrects the incorrect guesses, he ends up with a decent (and self-reinforcing) corpus of training data. As the machine continues running, it can rack up more training, allowing it to recognize a broad variety of pieces on the fly.

Here's another video, focusing on how the pieces move on conveyer belts (running at slow speed so puny humans can follow). You can also see the air jets in action:

In an email interview, Mattheij told Mental Floss that the system currently sorts LEGO bricks into more than 50 categories. It can also be run in a color-sorting mode to bin the parts across 12 color groups. (Thus at present you'd likely do a two-pass sort on the bricks: once for shape, then a separate pass for color.) He continues to refine the system, with a focus on making its recognition abilities faster. At some point down the line, he plans to make the software portion open source. You're on your own as far as building conveyer belts, bins, and so forth.

Check out Mattheij's writeup in two parts for more information. It starts with an overview of the story, followed up with a deep dive on the software. He's also tweeting about the project (among other things). And if you look around a bit, you'll find bulk LEGO brick auctions online—it's definitely a thing!

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8 Common Dog Behaviors, Decoded
May 25, 2017
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Dogs are a lot more complicated than we give them credit for. As a result, sometimes things get lost in translation. We’ve yet to invent a dog-to-English translator, but there are certain behaviors you can learn to read in order to better understand what your dog is trying to tell you. The more tuned-in you are to your dog’s emotions, the better you’ll be able to respond—whether that means giving her some space or welcoming a wet, slobbery kiss. 

1. What you’ll see: Your dog is standing with his legs and body relaxed and tail low. His ears are up, but not pointed forward. His mouth is slightly open, he’s panting lightly, and his tongue is loose. His eyes? Soft or maybe slightly squinty from getting his smile on.

What it means: “Hey there, friend!” Your pup is in a calm, relaxed state. He’s open to mingling, which means you can feel comfortable letting friends say hi.

2. What you’ll see: Your dog is standing with her body leaning forward. Her ears are erect and angled forward—or have at least perked up if they’re floppy—and her mouth is closed. Her tail might be sticking out horizontally or sticking straight up and wagging slightly.

What it means: “Hark! Who goes there?!” Something caught your pup’s attention and now she’s on high alert, trying to discern whether or not the person, animal, or situation is a threat. She’ll likely stay on guard until she feels safe or becomes distracted.

3. What you’ll see: Your dog is standing, leaning slightly forward. His body and legs are tense, and his hackles—those hairs along his back and neck—are raised. His tail is stiff and twitching, not swooping playfully. His mouth is open, teeth are exposed, and he may be snarling, snapping, or barking excessively.

What it means: “Don’t mess with me!” This dog is asserting his social dominance and letting others know that he might attack if they don’t defer accordingly. A dog in this stance could be either offensively aggressive or defensively aggressive. If you encounter a dog in this state, play it safe and back away slowly without making eye contact.

4. What you’ll see: As another dog approaches, your dog lies down on his back with his tail tucked in between his legs. His paws are tucked in too, his ears are flat, and he isn’t making direct eye contact with the other dog standing over him.

What it means: “I come in peace!” Your pooch is displaying signs of submission to a more dominant dog, conveying total surrender to avoid physical confrontation. Other, less obvious, signs of submission include ears that are flattened back against the head, an avoidance of eye contact, a tongue flick, and bared teeth. Yup—a dog might bare his teeth while still being submissive, but they’ll likely be clenched together, the lips opened horizontally rather than curled up to show the front canines. A submissive dog will also slink backward or inward rather than forward, which would indicate more aggressive behavior.

5. What you’ll see: Your dog is crouching with her back hunched, tail tucked, and the corner of her mouth pulled back with lips slightly curled. Her shoulders, or hackles, are raised and her ears are flattened. She’s avoiding eye contact.

What it means: “I’m scared, but will fight you if I have to.” This dog’s fight or flight instincts have been activated. It’s best to keep your distance from a dog in this emotional state because she could attack if she feels cornered.

6. What you’ll see: You’re staring at your dog, holding eye contact. Your dog looks away from you, tentatively looks back, then looks away again. After some time, he licks his chops and yawns.

What it means: “I don’t know what’s going on and it’s weirding me out.” Your dog doesn’t know what to make of the situation, but rather than nipping or barking, he’ll stick to behaviors he knows are OK, like yawning, licking his chops, or shaking as if he’s wet. You’ll want to intervene by removing whatever it is causing him discomfort—such as an overly grabby child—and giving him some space to relax.

7. What you’ll see: Your dog has her front paws bent and lowered onto the ground with her rear in the air. Her body is relaxed, loose, and wiggly, and her tail is up and wagging from side to side. She might also let out a high-pitched or impatient bark.

What it means: “What’s the hold up? Let’s play!” This classic stance, known to dog trainers and behaviorists as “the play bow,” is a sign she’s ready to let the good times roll. Get ready for a round of fetch or tug of war, or for a good long outing at the dog park.

8. What you’ll see: You’ve just gotten home from work and your dog rushes over. He can’t stop wiggling his backside, and he may even lower himself into a giant stretch, like he’s doing yoga.

What it means: “OhmygoshImsohappytoseeyou I love you so much you’re my best friend foreverandeverandever!!!!” This one’s easy: Your pup is overjoyed his BFF is back. That big stretch is something dogs don’t pull out for just anyone; they save that for the people they truly love. Show him you feel the same way with a good belly rub and a handful of his favorite treats.

The best way to say “I love you” in dog? A monthly subscription to BarkBox. Your favorite pup will get a package filled with treats, toys, and other good stuff (and in return, you’ll probably get lots of sloppy kisses). Visit BarkBox to learn more.

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