Dinosaurs Had a Bloodsucking Enemy

♩♩Intro♩♩ This week on SciShow News, we’re talking about bugs and brains. Except… not really true bugs, just some arachnids. But “arachnids and brains” didn't sound as catchy. Anyway, in a paper published this week in Nature Communications, scientists found two separate clues that teach us a little more about dinosaurs and their parasites. For one, these researchers discovered an extinct tick entangled in a piece of a dinosaur feather. This sample was trapped in a 99-million-year-old chunk of amber from Myanmar, and dates back to the Cretaceous period. The big news here isn’t the feather itself, though. It’s the tick! Because finding ticks preserved with direct evidence of what they fed on is really rare. In fact, this is the oldest known example. The bit of feather is about two centimeters long and includes more than 50 barbs along a section of the central shaft. It’s pretty similar to modern-day bird feathers, but a whole range of dinosaurs from the Cretaceous period had feathers like this, including ground-running dinos and more bird-like species. So we don’t know exactly what kind of dinosaur the tick was feeding on, but since this was before modern birds existed, we can definitely rule them out. And that one species wasn’t alone in its taste for dinosaur blood. This paper also looked at a separate piece of amber from the same period, with /indirect/ evidence that a different extinct tick was also a dinosaur parasite. These ticks weren’t all tangled up in feathers, which is why it’s indirect evidence. One was full of blood, and another pair of two ticks were preserved close together. The pair had some other junk on them, too — these hair-like structures called setae that came from larval dermestid beetles. This family of beetles is still around today and some species like to hang out in bird nests, eating stray bits of feathers and skin... all that delicious stuff. We know some dinosaurs built nests too, so both the ticks and beetles were probably living in one, hoping to score a meal. The researchers also say that a drip of plant resin would be more likely to trap two unfed ticks at once if they were hanging out in a nest together. But, Jurassic Park aside, we won’t be able to clone a feathered dinosaur from blood in any of these old ticks. No one’s ever actually extracted DNA from insects preserved in amber — there are just too many things that can go wrong or break down. So for now, that’s still the stuff of sci-fi. But our second topic is something that happens to humans all the time. Picture this: you’re walking down the sidewalk when you realize that, right where your foot is about to land, is a pile of dog poop. You see it there, and you desperately try to adjust, but you know... plop. You're weight is going down any way and... it's happened But a group of researchers from Johns Hopkins University may have figured out why it’s so hard to stop doing something while your body is in motion. Previously, scientists thought that only one region of the brain — part of the prefrontal cortex — was involved in sending that last-minute “stop!” signal after the brain directs our muscles to move. But now we know that getting this signal out actually requires super-fast coordination between two different parts of the prefrontal cortex, plus part of the premotor cortex. To figure this out, scientists gave 21 human subjects and one macaque monkey mostly similar tasks while taking a peek at what their brains were doing. The humans had their brain activity monitored with fMRI, which measures general blood flow patterns. And the monkey had electrodes implanted in its brain to monitor some individual neurons. We didn't do that to the people... because we didn't want to cut their brains open. In the main test, the subjects saw one of two shapes on a computer screen, which told them whether blue was going to mean go and yellow was going to mean stop, or vice versa. Then, a black circle would pop up, and the study participants would quickly move their eyes to look at it. But if a blue or yellow dot appeared, they would have to either stop or keep going with their eye movement, depending on that initial shape and its meaning. A previous version of this experiment used a simpler task. But doing it this way let the researchers estimate signals related to different parts of it, like watching for the shape on the screen versus sending the message to stop motion. The data suggest that one part of the prefrontal cortex identifies and interprets information signals, and another part registers the intent to stop the motion. Both regions seem to coordinate with another brain region in the premotor cortex, which controls the eye movement. And whether they successfully stopped or not or not depended on the timing. The researchers calculated that if a subject’s decision took more than about a quarter of a second, then the original “move!” signal was already on its way to the muscles and couldn’t be changed or stopped. They even suggest that this could help explain why people might stumble more as they get older — aging brains communicate more slowly, so they might not be able to put on the brakes as easily when they need to. But, as always, there’s a lot more research left to do. Thanks for watching this episode of SciShow News, and thanks especially to all of our patrons on Patreon who make this show possible. If you want to help us keep making videos like this for the whole world for free, you can go to patreon.com/scishow­. And don’t forget to go to youtube.com/scishow and subscribe! ♩♩Outro♩♩

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